DIYstompboxes.com

It seems to be semi-irresistible for folks to take an amplifier schematic, delete the triodes and replace them with JFETs, diddle the biasing and then call it an XXXX emulator.

We know that JFETs and triodes do not distort alike, but the process of emulating an amp by rote seems to be satisfying to people.

I have this suspicion that the frequency determining elements filtering the distortion is what is so attractive, not the distortion. That being the case, I suspect that you could sub in for instance opamp distortion stages for the triodes/JFETs and have just as interesting SOUNDING "emulation", albeit not with as big an emotional hook.

Anyone ever tried this, other than Stephen Moeller?

Yes RG, the chap who put together the LXH2 JCM800 sim :D
Use's ( from memory ) 9 opamps for the preamp section and another 11 ! for the
speaker sim.
Sounds wonderful BTW !

http://www.diystompboxes.com/smfforum/index.php?topic=40339.0

Marty.

I had a happy accident with an op amp recently that sounds "marshally" in a scary good way. I didn't sit down and work out transfer functions or anything. Just simple bode and transient plots of another design of mine I was trying to improve and simplify. A few tweaks and it turned into this. Emulation? No. But I've campaigned against the use of the word "emulation" from day one, <sigh>...

The Moeller thing is interesting but way too complex for what it "emulates". For me it would be much simpler to just build an AC30 tube amp (or derivative with top boost pre and push/pull output stage) than to fool with a complex SS circuit that may or may not get you there. "Emulations"... <sigh...>

Quote from: Doug_H on November 16, 2006, 11:50:07 AM
The Moeller thing is interesting but way too complex for what it "emulates". For me it would be much simpler to just build an AC30 tube amp (or derivative with top boost pre and push/pull output stage) than to fool with a complex SS circuit that may or may not get you there. "Emulations"... <sigh...>

most of us are afraid of high voltage tube amps :(

I built the Marshall (LXH2) sim two 9 opamps, great, amazing undescribable, wonderful, gorgeous...............
And right now Im gogin out of my house to buy the parts to build the stephen mioeller one ;D ;D ;D ;D ;D
Cheeers
Rafa

Quote from: Doug_H on November 16, 2006, 11:50:07 AM
But I've campaigned against the use of the word "emulation" from day one, <sigh>...
"Emulations"... <sigh...>

I'm with you on the valve amp track, having just built a small 5 watter that sounds "Superb" :D
However, the Bassman '59 and PV Classic 30 "sims" ! that I did , got very, very close to the tone
as compared to originals of both !  ( Bassman owner was gobsmacked ! )

Probably the "analog" sims are better than the "Digital" ones ...... POD anyone !!   :icon_wink:

MM

I guess I'm "one of those folks" that happen to like "emulators" :icon_mrgreen:

Really, I know what a tube amp is. I know these circuits (for the lack of a better term to describe them :icon_mrgreen:) will never make you sound like a tube amp. I see them as nice sounding distortion pedals, which up to a certain extent have a similar kind of tone to some amps. The Dr. Boogey has a rectifier-ish quality to it that's for sure. I see them just as an extension of the other "normal" dirt boxes like a Rat or a DS1. I would never make a preamp out of a Thunderchief or a cauldron of Gain....

If I look back, 1 year ago I was holding a soldering iron in my hands for the first time, drilled a hammond box also for the first time. These "JFET circuits" are very helpful for some noobs like me because their archirtecture is modular, and it's easy to understand how they work, hence the interest. I'd love being able to design more complex circuits including hex inverters and opamps, however i'm not at that level yet.

We discover new ideas every day in this forum. You guys need to understand our excitement. I think this is the most informative forum I've ever seen. I've learned more about electronics in this forum in one year, than in all my life until now.

Thanks for all the help, in my book you guys rule.

I've sort of noticed that circuits I build are more 'predictable' based on the filtering than one what actually 'powers' them, especially if you use diodes for clipping.  In fact, the more I learn about stuff, the more predictable things get, and the more that the magic and mystery goes away. :(

As far as "emulation", I'm useless.  I'm always trying to invent something new, to a fault. In vain.



Oh yeah.  I'm not ready to work on tube stuff either.  I'm not even sure if my DVOM can handle the voltages or if it will just go up in $300 smoke.

What would be a better word to use???

I'm curious about the characteristics the stages with the negative feed-back and more complicated biasing add, that is sort of unique to these type circuits, but missing from other multi-stage distortions like the Obsidian or Shakka Express.   :icon_cool:

The thing to remember about "emulators" is that:

• a great many desirable amps are essentially textbook, appnotes-based applications of a couple of fairly standard and similar tube circuits; differences between their front end are often (though certainly not always) simply a matter the various permutations and combinations of gain-stage, tonestack, volume control.
• a huge part of the "magic" of any tube amp lies in the power supply, and how tubes respond to variations in that; highly doubtful that 9v would reliably mimic any and every amp's response just by swapping FETs for triodes.
• another huge part of tube sound is the output transformer and any negative feedback applied from the speaker side of the transformer; I have yet to see any amp emulators using transformers in creative ways
• a third huge part of any amp is the speakers; many amps from the "golden era" were electronically identical to other big name amps based on the same tube manual circuits, except they were stuck with crappy speakers in crappy cabs, often with crappy output transformers
• everyone here tends to use them as either a pedal going into a front end, or if fed directly to a power amp, that "power amp" is generally an LM386 rather than a long-tailed phase-splitter and a pair of 6550's or EL84's; it is rare that anyone uses them "as if" it were the front end of an entire gigging amp

My intent is not to diss emulators or op-amp vs FET emulators, merely to note that there is a whole lot missing from the equation.  Next time you want a romantic evening, throw a pair of high heels, a bottle of perfume, some naughty undergarments, and two small silicon-filled pouches in a bag and try to persuade yourself you're with the woman of your dreams.  Doesn't quite feel complete, eh?

I have no doubts that op-amp circuits could accomplish all one wishes to accomplish with FET-for-triode substitutions.  Certainly hasn't stopped Sans Amp, has it?  On the other hand, those simple FET-for-triode (let's just call 'em "F4T") circuits make it easy to start thinking about how the sequencing of the basic building blocks can result in different sounds.  In other words, they are great to think with, and the F4T approach has lent clarity to that thinking.  In some ways, they are also pleasingly uncomplicated, or at least we haven't been tempted to introduce complications in the same way we might with op-amps.  I'm actually quite glad that slew-rate, voltage-swing, input impedance, and all the other op-amp properties have NOT entered into the fray.  To the extent that this group tends to think about FETs in a rather monolithic way (i.e., a J201 is a J201 is a J201, the way a 12AX7 is a 12AX7 is a 12AX7), that has been very helpful at this stage in the game.

Happily, as Marty and Xavier have pointed out, you get outcomes that are either remarkably similar in many sonic properties, or else if not same-sounding then good-sounding. 

Jfet emu's have a major "flaw" which is being almost zero percent repeatable with even exact
components , due to the differences in the fets.
OK for a "DIY" one off, but if you were to go commercial !!  :icon_eek:
But then you can have someone check all the fets and match them ... by the thousand !
I love the OD/Dist from Jfet's , they dont seem to "Fart" like so many diode clipping circuits do, on the
decay stage of chords etc ....

MM.

Quote from: WGTP on November 16, 2006, 12:59:10 PMWhat would be a better word to use???

Distortion circuit?  8)

I think the major flaw is that you don't have anything in there replicating the pentode power amp section or the output transformer.

Plus, when put in front of a tube amp, these circuits essentially become pre-pre-amps and are still contoured by the used amps' tone stack as well.

And I REALLY do not like the trim-on-the-drain biasing approach.

But that is just me. Caveat Emptor.

Quote from: Xavier on November 16, 2006, 12:31:14 PM
I see them as nice sounding distortion pedals, which up to a certain extent have a similar kind of tone to some amps.

I agree 100%.

My problem with the word "emulation" is that it always invites comparison to "the real thing". As good as some of these pedals sound, they will always fail an A/B comparison to "the real thing" IMO. I know we know what we mean by "emulation" in here. Although I don't want to wordsmith this to death, it would be nice to have a more accurate word to describe the original intent- that is to use some ideas found in amps in pedals.

Personally I've gotten away from the jfet stuff because I think they are more complex than need be to build a "good sounding" pedal. Some of my old favorites are still the one or two stage boosters & fuzzes. Some of the simple stuff I've built I like as well or better than the stuff that requires stringing 4 or 5 jfet stgs together. The jfet circuits are a fun learning experience though, I'll grant you that.

Quote from: R.G. on November 16, 2006, 11:01:23 AM
It seems to be semi-irresistible for folks to take an amplifier schematic, delete the triodes and replace them with JFETs, diddle the biasing and then call it an XXXX emulator.

We know that JFETs and triodes do not distort alike, but the process of emulating an amp by rote seems to be satisfying to people.

I have this suspicion that the frequency determining elements filtering the distortion is what is so attractive, not the distortion. That being the case, I suspect that you could sub in for instance opamp distortion stages for the triodes/JFETs and have just as interesting SOUNDING "emulation", albeit not with as big an emotional hook.

Anyone ever tried this, other than Stephen Moeller?

The word 'emulator' or 'sim' should not be applied to these circuits... I like the term 'adaptation...'

So R.G. - have you built one?

They are great pedals - compared to the everyday stuff like TS, DS1..... diode clippers... Sure, in a 'purest' sense - these calling these emulators is like calling my kids' finger painting an emulation of the impressionists, but the better ones, of these pedals, put a crappy amp well into the ball park of a given sound in a lot of cases.

Quote from: mojotron on November 16, 2006, 01:43:11 PM
... I like the term 'adaptation...'

I was thinking along the same lines, a solid state adaptation of tube circuitry.

  All Tube amps are experiments. Many designs, some of them good, were abandon for one reason or another. Others have stood the test of time and may have benefitted from field application feedback guiding alterations seen to be improvements to an original experiment.
 Control field tests are implicitly inconclusive because one to the next off the line [for the most part] the amps will exhibit differences, to one extent or the other, strict control environments for these tests are rare compared to the wildly diverse [most often not subcontexed because of the impossible complexity/non-congruity of subtexting wildly varying control elements] control elements in real world, like speaker response, pickup height, string thickness...TONS of etcetera that has been rehashed odd infinitum...
 I'd get the Fet's on the board and basically biasing, with 'larger' value source resistors/'smaller value caps' [or the inverse...you can decide whether to multiply or divide to tune values]...on all stages.
 Stick Q's in sockets and bias, adjust Q choice or source R or Drain R to get a bias on it.
 Then start at the front and put higher gain Q or lower R source [mess with bypass cap if any], rebias drain...see if you like the gain structure to be high from Q's 1-? [how many?].
 Reset that to 'normal', then try increasing the gain of later stages.
 At this point you probably have voicing wants, a good time to try some filtering alterations on the SP...TC yet?
 Just start with something close to something that works, then diddle with that experiment 'till you don't like these suggestions anymore or you see my point!
 I had a MkII Master Lead, I thought that's what it was and how it should work...because ____ ...until...
 I took that spike in the head treble content and tamed it while making ChI volume usable...
 I had a Plexi didn't work at all like Bills Plexi.
 Jfet's are different than tubes, I'd be moslty worried about finding 'it' in a Jfet circuit than...
 My 2c+...messin' about with those source R/C values and voicing/gain structuring might be more fun/easier to bias/get to breaking over to distortion more to 'your' liking that sticking to the part of the schematic between tubes and ground...Drain bias V and R sure seems to want to and get to go all over the place...lol...
 
 

They are great pedals - compared to the everyday stuff like TS, DS1..... diode clippers.
  They can be !! They do well to be all figured or fiddled with IME.
  What's THiS Jfet Going to do? What does that do to the other JfetS? What's response is my amp capable of with all this going on?

QuoteJfet emu's have a major "flaw" which is being almost zero percent repeatable with even exact
components , due to the differences in the fets.

Has anyone done a test on these? From my limited building, I have found the J201 batches to bias pretty darn close lately.

Quote from: Mark Hammer on November 16, 2006, 01:10:22 PM
...
Next time you want a romantic evening, throw a pair of high heels, a bottle of perfume, some naughty undergarments, and two small silicon-filled pouches in a bag and try to persuade yourself you're with the woman of your dreams.  Doesn't quite feel complete, eh?
...

Well Mark, I'll just have to try that out this weekend :icon_lol:

Quote from: aron on November 16, 2006, 03:18:01 PM

QuoteJfet emu's have a major "flaw" which is being almost zero percent repeatable with even exact
components , due to the differences in the fets.

Has anyone done a test on these? From my limited building, I have found the J201 batches to bias pretty darn close lately.

Yep, not that I build a lot these days, but I have found that the Fairchild J201 parts do have some level of consistency with the last few batches I got from them.

Don't worry folks, I'm sure next year we'll be building BSIABIIs with 12AU7s and cd4007s in place of JFETs.  :icon_wink:

Seriously though, at some point a few of us will have a good idea of what to do with stuff like this, do some actual design with that idea and come up with something really great. I'm pretty jazzed about that.

QuoteWe discover new ideas every day in this forum. You guys need to understand our excitement.

Yes, this is a great place! However, if possible, I do believe in giving credit whenever possible and it should not be forgotten that Jack Orman:

1: advocated FETs for the DIY more than anyone else in the early days.
2: started this whole "emulation/adaptation" scenario with a complete, thought-out circuit.
3: continues to pave the way with FET usage.

History can try to be rewritten, but I will do my best to keep the archives complete for people to see where things came from.

My guitars are largely emulations of more (ridiculously) expensive makes, my playing is largely an emulation of other (professional)musicians, so why shouldn't I emulate valve amps with JFETs? As long as the resulting sound is (a) pleasant to the majority of the audience and (b) okay to my tin ears, the "real thing" is largely meaningless and the "emulation" is good enough for me, if not better than the real thing. The rest is just semantics.

Quote from: aron on November 16, 2006, 03:21:52 PM

QuoteWe discover new ideas every day in this forum. You guys need to understand our excitement.

Yes, this is a great place! However, if possible, I do believe in giving credit whenever possible and it should not be forgotten that Jack Orman:

1: advocated FETs for the DIY more than anyone else in the early days.
2: started this whole "emulation/adaptation" scenario with a complete, thought-out circuit.
3: continues to pave the way with FET usage.

History can try to be rewritten, but I will do my best to keep the archives complete for people to see where things came from.

Yes - thanks Aron....

Jack Orman, RG, Mark, Doug, Zach, yourself Aron, ROG, JD/GGG... (there's a long list of very bright/patient people) <insert many, many names here> (by the way, anyone checked out AC's - aka Dragonfly - stuff lately - Brother, where do you get all the ideas!!)... I think in all areas we have to recognize that most of us a dancing on the shoulders of giants with this stuff. To me it's as obvious that we owe a lot of credit to many, but to be honest I generally just credit 'the forum', as it is a very long list, I hope that does not offend anyone - Thanks to all!!

The cool thing is that as time goes by we seem to make big steps, tweak that a bit, make another big step and repeat the process. I think a 'real-deal' commercial builder would have to be pretty darn good to come up with an original idea that would persuade me to buy their gear based on originality, sound quality - etc - these days. That said, now I've been there - done that - bought the T-shirt - and now I'm a little burned out on FETs these days - I'm going go fiddle with pics and LDRs to build a bobbin winder.... I'll post what I come up with :)

Quote from: mojotron on November 16, 2006, 04:03:51 PM
I think a 'real-deal' commercial builder would have to be pretty darn good to come up with an original idea that would persuade me to buy their gear based on originality, sound quality - etc - these days.

The one that has me "tempted" is the Blackstone Appliances Mosfet OD, sounds incredible, but is a little
expensive .... nice package though :D
Actually, thinking about it, it's probably worth the asking price and seems to be one of the more original
commercial things out there .

MM.

I must admmit all emulators sound not even close to the original amps, but they still sound amazing, so why factories like Fender put horrible distortions in their SS amps?
I have a Princeton 112 whcih I love the clean tones but the distorion is bad.
Are Fender engineers muscinas?  If other people like Stephen moeller could make a good adaptation of the tube amp, why they cant?
Trying to sell tube amps maybe,
Cheers
Rafa

hey doug,
any chance that you tell us more about your marshall accident?

cheers
ghandi

Quote from: Rafa on November 16, 2006, 05:18:39 PM
I must admmit all emulators sound not even close to the original amps, ...

Got to disagree with that dogmatic statement. Have you listened to ROG's comparison of their "Supreaux" with a Supro?

Your other comments I support 100%.

I also agree that we shouldn’t name these circuits as emulators (although I’ve mistakenly done so in the past).
They are just distortion units which may or may not sound like the amp but sometimes they sound really good. The reason I like them is because the sound is amplified/clipped usually from 3 to 5 gain stages rather than one or two like in most commercial effects. To my ears this sounds way more physical and close to the philosophy of amplifier circuits.
Marty I disagree that these circuits are for a DIY one off and not for commercial use . I can think of at least 3 world class famous boutique builders that sell some overdrive/distortion pedals for 200-300$ and they are nothing but Jack Orman,Doug Hammond or ROG’s F4T circuits built with “expensive-mojo” components…

Haven’t tried to build a moeller’s ac30 sim yet but I have tried many emulations-adaptations or whatever, using opamps having much better results than fets.
The last two years for example I was trying to get a decent fender clean tone and a smooth dumble-like overdriven tone with fets but I didn’t gave the excellent results I had with a couple of ICs.  I think that especially from clean to overdrive the opamps are clearly better. For higher gain issues so far I would probably stick with fets.

Chris

 Oh jeeze, if these aren't emulators, then what is? I admit having limited experience with these, having only built the Thunderchief so far, but, really, has anyone compared them with a POD or ZOOM? Well, I have. And I can honestly say that to my ears, even though the Thunderchief is a one trick pony, it sure beats any digital Marshall emulation I've heard so far.  Sure, it's not a tube amp, that's what makes it an emulation! But the digital imitations I've heard just don't really even remind me of what they're claiming to sound like. They don't even really SOUND very good.

This is nothing but semantics as has been said earlier by Ge_Whiz. If someone puts in the effort to design or adapt a circuit with the intention of emulating the tone of that amp thru solid state adaptation of a tube circuit, I feel they have earned the right to name and classify it. I think referring to these kind of effects as FET emulations is both accurate and appropriate. Everyone knows what is meant by that, and I can't possibly understand how anyone could be offended by that.

Are we to refer to the dead as "existance challenged" now?

Quote from: Meanderthal on November 16, 2006, 08:26:33 PM
Are we to refer to the dead as "existance challenged" now?

That made ME smile !  :icon_wink:

I guess to me the word "emulation" just infers that the pedal is supposed to sound somewhat like whatever it emulates.  These pedals do sound somewhat like the amps they are based on.  The use of fets has been discussed in the past because of the problems involved, and I think many of us would be interested in a, uh, emulator that doesn't use fets.  The other thing about the fets is that they sound good and keep the circuit very simple.

They may not be very accurate emulators, but they are simple and sound good in a way that is reminiscent of the amp they are based on.

well, as far as disambiguation goes, emulation means (at least in the realm of hardware/sofware) to completely fool the software into thinking the host is what it wants it to be.  in a musical analogy, the hardware is the pedal or tube amp, and the software would be our ears.  The ears want that tube sound, and the tube amp delivers, 100%.  The pedal, is probably somewhere like 75%.  So not an emulation, per se.  A damn good imitation though. ^_^

Fender: Don't emulate, innovate.  ;)

QuoteThe ears want that tube sound, and the tube amp delivers, 100%.  The pedal, is probably somewhere like 75%.  So not an emulation, per se.  A damn good imitation though. ^_^

OK, I'll play the semantics game here. So only a clone qualifies an emulation then? I'd call that a clone. And then there's the circuit itself- Whether it sounds like the amp or not the circuit itself is a solid state emulation of the tube circuit. Suppose you have a pedal that sounds 75% like a Fender Twin... wouldn't that be an emulation with 75% efficiency(as if you could measure something like that, heh)? What happens if it sounds 98% like something? Hell, suppose a pedal somehow sounds 100% like an amp(now THERE'S a nonsense concept)? Can you find any 2 tube amps that are absolute 100% sound-alikes? That would require the identical arrangement of molecules in perfectly matched quantities and patterns, not the 75% or so that happens in reality.(a ballpark imaginary figure, until someone fires up the electron microscope and maps every single atom in a tube amp for million year project). So, then, even 2 supposedly identical amps are really not close enough by that definition to be emulations of themselves.
I could go on and on, but then I would probably be emulating a clone of myself that actually cared....

I'm just stating that to me, it's not purely "emulation," in this sense.  This comes from years of computer/video game/terminal emultion software.  It's fooling the programs I need (written for a C64, WinXP machine, Super Nintendo, etc.) into thinking they are on the intended device. 

Quote from: R.G. on November 16, 2006, 11:01:23 AM
I have this suspicion that the frequency determining elements filtering the distortion is what is so attractive, not the distortion. That being the case, I suspect that you could sub in for instance opamp distortion stages for the triodes/JFETs and have just as interesting SOUNDING "emulation", albeit not with as big an emotional hook.

You could probably use BJTs or opamps to replace the triodes and get a similar sounding circuit. But then, you'd have to change the biasing networks, add feedback loops and generally change the circuit so much it would be quite far off from the original amp.

The "magic" of FETs is the very fact that you CAN replace triodes with them and get a working circuit with (almost) the same topology.

For my part, the ROG designs were a great learning experience. Especially when I started comparing them with the original schematics to see where the differences where. That's what eventually got me to actually build a real tube amp...

QuoteThe "magic" of FETs is the very fact that you CAN replace triodes with them and get a working circuit with (almost) the same topology.

True!
I`ve successfully simulated emulations of some of my pure tube pedals (non-distortion) in a "spice" version,
replacing the (original`s) 12AX7 by  2N3819 models.
(needed some slight increasing of the cathode-resistors by ~50%)

The traces on the screen looked very close to the oscilloscoped tube curves.

Haven`t tried it out in real live though,
coz the simulation flawlessly works with a B+ of 300V,
but I`m not sure about those "real world" 2N3819`s  :icon_eek:

Emulator shmemulator... Tubes shmoobs...



Sorry, I just wanted to say "shmoobs" this morning... :icon_biggrin:


Seriously though, tone is where it's at- doesn't matter how you get there. And yes, the "emulator" thing is a semantic discussion. But it's a fun one. :icon_biggrin:

The question one has to ask is what exactly is being emulated.  Digital emulations (well, the cheap ones at any rate) often seem to emulate only the most saturated tones of a given amp, as if the amp-to-amp difference was only in the differences in harmonic distribution at max volume.  When he was in town the other week, hairyandy was waxing poetic to me while we were driving around about a Trainwreck amp he had played recently and its breathtaking responsiveness.  Clearly "emulation" of the experience of playing a Trainwreck would involve more than simply mimicking its distortion quality.  Rather, it is the particular dynamic transition from clean to dirty that seems to constitute the essence of that amp.

I think that's a bit of what is missing in the emulation game.  At least the low-end emulation game as practiced here in the F4T format, and as practised in the how-many-algorithms-can-we-pack-in-for-a-buck approach of some of the digitally-focussed companies.  That's part of why I raised the issue of power supplies.  JC Maillet (the viva analog guy) was kind enough to send me a copy of his excellent "Inside Fender and Marshall Tube Amplifiers" book earlier this year, and he draws attention to the power-supply differences between various amps with distinctive tones.  The power supply is part of what makes for the difference in clean-to-dirty transitions in amps.

I'm not going to pooh-pooh the F4T emulations.  I'll simply say that in the evolution of discrete SS emulations, we're still collectively very young and at the shallow end of the learning curve.  Doesn't mean there is nothing to like about what we have so far.  Rather, what it emulates is only part of the story.

Quote from: puretube on November 17, 2006, 03:50:12 AM

QuoteThe "magic" of FETs is the very fact that you CAN replace triodes with them and get a working circuit with (almost) the same topology.

Haven`t tried it out in real live though,
coz the simulation flawlessly works with a B+ of 300V,
but I`m not sure about those "real world" 2N3819`s  :icon_eek:

R u serious? Software allows +300VDC on discrete fets? Woo-Hoo!!! There be smoke!

I love J-fet adaptations! They are very dynamic and way less compressed than whatever opamp/diode clippers I've heard. But I think I will lean towards the fact that they are not amplifier simulators. If anything, they are preamps + one mock poweramp/negative feedback stage.

Poor emulators shmemulators!
Shame on you guys :-)   Small stompboxes with the 8-Volt headroom vs 300 Volts and 50 pounds of copper, tungsten, steel and glass?
However, some of these tiny gadgets succesfully struggle against tube dictatorship.
At the same time, if we'll take at least 24 V power supply for FET/BJT/OpAmp simulation... did anybody try?

Wow, this sure brought a lot of folks out.  Again demonstrating the overall coolness of this place.   :icon_cool:

I really have to give this "movement" credit for helping me understand tube amps way better than I did, giving me the confidence to really look past the high voltage stuff and see what was going on.

To me this reinforces what R.G. and others have said for some time about the EQ being as important, if not more so, than the clipping mechanism.  Since many of the real amps are associated with different speaker systems, and the power output stages aren't being addressed, the EQ would seem to account for the largest part of the differences.

I remember 30 years ago being told that plugging a Fender head into a Marshall 1/2 stack made the 2 amps sound much more similar.

I guess we need to stick a Srypp/Mu/Blackfire/etc. stage at the end to cover the output stages.

As pointed out, there are many more similarities between the different versions than there are differneces.  I have wondered if a GENERIC 3-5 stage version couldn't be built with a few switches to account for the differences.

It is cool that you can plug Jfets into these circuits, designed for tubes and get a similar EQ effect.

Maybe we need to make up a word to describe these.  Anyone know any Latin?  Aron, you do the honors.

  It isn't a 'coup' by Jfets to 'take over' anything...Emu...Simulator...whatever, if you see a 9v supply you can rest assured it's not a tube amp or tube preamp...[LV Tubes being the possible exception].
  So we know what we're looking at or can read it, and all about it, no hidden surprized.
  "Emu', IMO doesn't infringe on any existing names...nor can Jfets be confused with any four legged/hooved animals...it's just short for 'emulate'...ok Jfets don't emulate PS Sag and aren't exactly tubes..but do 'emulate' certain characteristics of a tube amp when 'carbon copied' into a Tube Preamp schematic '9v overlay'.
  "Emu' Seems to have stuck, as has countless other somewhat more innapropriate names...I like it cause it's short and is descriptive about what it 'does'.
  Read all about it or build 'em...and find out more for sure what's what W/ the Emu's..
  Not that there isn't a better nomenclature for these type devices....suggestions?

ya know, I haven't built many of the EMU circuits but I have to say that the English Channel is a great sounding circuit for what it is. If I close my eyes it still sounds like a drive type pedal going through my Twin Reverb but, it sounds good none-the-less. I've learned a bunch from these circuits too.
This has been an interesting discussion to read.
Thanks fellas!!

I guess it's time for me to say why I started this mess.

I'm very protective of beginners in the sense that if they ever get a wrong idea down as the truth, they then have to go UN-learn it before they can advance.

I think that a beginner seeing the term "JFET amp emulator" can easily get the idea that these are simple, straightforward recreations of the amps. We've seen examples of this view popping up in the forum frequently.

I don't think JFET triode replacement is a bad thing. Many of this kind of circuit sounds good on its own. But it will be reminiscent of the amp, not a re-creation of the amp. I think that the tone shaping over multiple stages is what is really giving the amp flavor, and that what does the distortion is less relevant.

I see the arguments about JFETs being simpler than an opamp distorter, but with the exception of the power pins, an opamp has the same number of pins as a JFET - three. Even taking into account the power pins, an opamp has either 4 pins per opamp (a dual) or 3.5 pins per opamp (quad). The circuits tend to take about the same number of resistors and caps. You'll need a diode or two extra to make the opamps distort, but it's much more predictable, especially than a JFET.

What the JFET replacements are is seemingly similar. There is an appeal to "well, just take out the triode and whip in a JFET in the same place, and it's the same". My interest in this is that the distortion/filtering/tone shaping get explored and understood, not just left at replacing triodes with JFETs

  I like "Amp Sim"...
  Definition and pronunciation of 'Emulation'
  Effort or ambition to equal or surpass another.
Imitation of another.
  Jfet amp sims don't 'surpass' nor do they imitate particularly.
  And Simulation
  The act or process of simulating.
An imitation; a sham.
Assumption of a false appearance.
  *Imitation or representation, as of a potential situation or in experimental testing.
Representation of the operation or features of one process or system through the use of another:
  "Sham" is a bit Harsh, 'False appearance'..[if you haven't looked at the tube schematic...] *Imitation...
  I think by definition 'Sim' is closest to being appropriate...
  Kind of alludes to 'sim-ple'...Jfet Amp Sim's are certainly much simpler to do than a Tube Jfet Simulator.
  "Emu' is just fine by me, funny sounding word IMO...guides my thought train past the mammal every time...lol.
 

Maybe "golem" applies  :)

a little out of topic
I dont mind sb use 7 JFETto make a dirt box,
but use 9 opamps in serires  -- like Marshall (LXH2) sim two 9 opamps

I dont build one,but I believe it can sound good,but I do think it will completely kill the
dynamic - picking sensitivity, makebe good for recording - one way,but I dont think it is good for
practice - need dynamic,interactive.

anybody can tell me that I am completely wrong.

QuoteI dont build one,but I believe it can sound good,but I do think it will completely kill the
dynamic - picking sensitivity, makebe good for recording - one way,but I dont think it is good for
practice - need dynamic,interactive.

anybody can tell me that I am completely wrong.

I think you are completely wrong.

Dynamic picking sensitivity can be had either way, and can be killed either way.

Of course, anyone can tell me I'm completely wrong.   :)

For a while my cousin used my ROG English Channel (Vox sim) as a preamp that he would run directly into the power amp of a Peavey 1x12 combo amp, and it sounded very good.  Whether or not it sounded much like a Vox is certainly questionable (I believe it is what we are discussing in this thread, right?), but it had a certain Voxiness, and certainly sounded much, much more tube like than the Peavey preamp it replaced.  So from my experience I have to say that it does not kill the sensitivity, and is in fact much more sensitive than most solid state amps.  My feeling about these pedals is that when properly tuned they manage to be better than most SS preamps, but not as good a real tube preamp.  I feel like many younger diyers who don't have nice amps could get A LOT of mileage from building a couple of these guys and using them as preamps.  Do they sound exactly like the amps upon which they are based? No, but they still sound very good.  My only real complaint is that to my ears (others here have disagreed with me before) they sound weird when driven with a dist/fuzz/booster.  But if you don't push the circuit too hard with a signal booster, they sound great.

I understand the problems with fet consistency, but if it were possible, a cheapo Marshall/Vox/Fender SS 1x12 using one of these would blow away the cheap crap they produce now. 

QuoteAt the same time, if we'll take at least 24 V power supply for FET/BJT/OpAmp simulation... did anybody try?

Of course. See the Shaka HV.

We've tried higher voltage, lower voltage, regulated voltage and lots of other things. Check the archives.

Op amp circuits can be very dynamic - and in a completely stable fashion.

So while we are talking "feel", I will venture to say that for the most part - that's my problem with most "digital" modelers. Except for hi-gain distortion, the feel is not right at all when played through hi-quality monitors etc...

It may "sound" alike, but not feel the same at all.

wha,R.G. said I am completely wrong.I am think about change my ID and shutup  :)

I am kind of picky guy about picking dynamic,I use finger only,and play really light to a little heavy.
I do have a thought about how many onamps will kill picking dynamic.

lets say 7, put 7 onamp buffers in serires.....
of course,that is not fair, but just my thought.

I do respect, R.G. and a lot guys here. seriously.

Let me add some things

Lets think about this

look at the gain of the tube triode preamp stages then look at the operating points cathode voltage, plate voltage and plate current and B+

then look at the rp dynamic plate R

then check did you scale the output drive of the fet to the vol control EQ network

Then cal or measure the gain of the fet stage and then think about the 9V.  Your gain to output swing ratio could be different between a fet and tube circuit.  And you need to check the Vgd spec if you want to raise the voltage

then you need to think about input headroom

Here are some things to try

with opamp stages you can control each sections gain.  You can even offset the ref it does not have to be at 1/2. 
You might not want the output stage to be at 1/2 the 9V

If you look at the schematics on the web of trainwreck amps alot of the design seemed to be getting the Low pass and High pass and the stages gain just right.

Now if you read this far THINK BJTs

Simple BJT stages  can sound very good and you can control the gain, operation points Ic etc,( LPB, NPN and others)  You could design it so almost any Si small signal could drop in

Then download the duncan tone stack program and play.  First run some plots of tube amps you like so you know what you might want.

Check the solid state preamps in some marshalls like the 3005

Like R.G. posted it might be more the EQ.


If you look at the J201 specs they seem to be "tighter" than  some other fets IDSS .2ma to 1ma IIRC

FWIW I bought a bag of 1000 fairchild proccess 50 FETS and out of the hundreds I tested so far I have IDSS reading of 2ma to 15ma
I posted IDSS because it is a simple easy to do sort.

Quote from: aron on November 17, 2006, 06:00:39 PM

QuoteAt the same time, if we'll take at least 24 V power supply for FET/BJT/OpAmp simulation... did anybody try?

Of course. See the Shaka HV.

We've tried higher voltage, lower voltage, regulated voltage and lots of other things. Check the archives.

Jack's Mini-tubes ran at 36v-40v IIRC. I think that's where we first got the idea to try higher voltages. :icon_wink:

Quote
Op amp circuits can be very dynamic - and in a completely stable fashion.

Yes, the op amp circuit I mentioned earlier is much more touch-sensitive, finger-responsive, etc etc than any JFET circuits I've played with. It has nothing to do with the device type though.

The thing I could never get around with 9v pedal circuits is the fact that tube pre's are usually running around 200-250v for their supply voltage. Then there is a tradeoff between gain and clipping headroom that you can't duplicate at 9v- unless you attenuate the guitar signal down to scale it for the circuit. So a 100mv guitar signal @ 250v scales down to a 3.6mv signal @ 9v, if you have the same gain characterstic with the JFET that you would with a tube.

I could never figure out a way of doing that without overcomplicating it to a ridiculous point. In the end it's easier just to build a damn tube amp or - quit worrying about it, learn a few things from how amps are voiced and just concentrate on building some cool sounding pedals.

Well... It all comes down to what comes out of the speaker and into your ears. If you like what you hear then that's a "good" sound.

There is no point in comparing JFet bassed amp emulators to real tube amps but then there are a lot of amps that sound different even within the same model. Just because we all start with with the same schematic does not mean that we will end up the the same sound due to the amp, guitar speaker.... Then you go into amp choice, guitar, string, tube choice, speakers, guitar cables, picks, barometric pressure, phase of the moon,  etc etc etc.

There are a lot of variables. Everyone thinks differently and processes sound differently as well.

Even though a mesa Dual recitfier may sound different from the JFET Dr boogie, the DR boogie sounds really good (to my ears) and will get you at least 3/4 of the way there. Just the same as if you had a real DR and played it through a HIFI speaker. It's still a Boogie, it sounds a little different, but it's close enough...

John

Oh for crying out loud, SansAMP uses op-amps exclusively and one curent buffe BJT on the output! Does it has less dynamics that a FET based circuit? No no and no! But look up the schem and see how much frequency filtering/EQ goes on there! :icon_eek:

actually,I fround myself into some situation that I dont wanna into,
but on another hand,this is also a personal taste thing.

I like GDI21(GT2 clone) for a while,then after into some clean sound,I feel bad for it.
I really remember the day when someone ask how about base on 4049 chips pedal--dynamic or not.
I dont doubt why he ask,maybe I am wrong.

I can give one example is BOSS SD-2, one side 1 onamp,the other 5 in serires,
you know which one I hate and which one I like.

in a sentence,said JFET better than onamp---that is bull shit
actually I found my self dont like --say more than 5 onamp in serires.
of coures this is depend on shematics.

but in my poor knowledge,I assume there is at least 2 or more than 2 JFET in 1 onamp,and sometimes I can heard people say: the dual onamp chip has buffer inside
so buffer - bufer - buffer/onamp -onamp -onamp  .......

I think I made my point.
and I just assume that 5 JFET and 5 onamp(xx JFET inside) is a little different
------------------------------------------
and after I learn a few parallel design, maybe in - KLON/SPARKLE DRIVE/TONE PRESS
I found that a lot onamp in serires is not that popular,and suit my taste.

bite my taste if you can  :icon_neutral:

some early web-mentioning (http://www.till.com/articles/GuitarPreamp/index.html) of FET/12AX7 similarity...

Quote from: puretube on November 19, 2006, 06:10:24 AM
some early web-mentioning (http://www.till.com/articles/GuitarPreamp/index.html) of FET/12AX7 similarity...

Jeez .... Tillman had the "Fenderish" Jfet preamp in '92  !!

Hmmmm.......

Yeah all props to Jack with his mini-tubes, but the minibooster was really a different kind of gain block than just a CS JFET stage. But there's nothing really new about the idea of using JFETs to mimic tubes. My 1982 SS yamaha amp uses FETs for that exact thing. That was touted as a "big deal" back then.

Personally, I think that "emulation" of amps is merely a commercial term to gain attention that became so popular we've got used to it and use it ourselves for JFET distortion.  I'm not a good DIYer, I got only 2 builds working out of around 10 of 'em (BSIAB II and Jawari).  But I have owned ALOT of gear in the past 15 years I've been playing guitar... Some of them include BOSS processors with CMOS emulations... Being digital, some of them WERE good, some of them WERE bad.  MOST of the bad ones were high gain emulations (like Mesa Boogie, Marshall, etc.).  BUT, if you EQed them well, they COULD sound good.  As for FET emulation, I have used the BSIAB II on many amps and to be honest, this circuit sounds best on SS amps.  As for IC distortions, for me, they seem to sound BETTER on a tube amp than on a SS amp (but it's just my personal taste).  I play with a Peavey Classic 50 and the BSIAB II sounds horrible on it... I think EQing is the answer to have a good "emulation" of the "real" thing, but will never be the real thing... especially with tube amps, no matter how inconsistent they may be from one to another.

Am I being stupid here?  :icon_lol:

Quote from: solarplexus on November 19, 2006, 10:10:06 AM
Personally, I think that "emulation" of amps is merely a commercial term to gain attention that became so popular we've got used to it and use it ourselves for JFET distortion.  I'm not a good DIYer, I got only 2 builds working out of around 10 of 'em (BSIAB II and Jawari).  But I have owned ALOT of gear in the past 15 years I've been playing guitar... Some of them include BOSS processors with CMOS emulations... Being digital, some of them WERE good, some of them WERE bad.  MOST of the bad ones were high gain emulations (like Mesa Boogie, Marshall, etc.).  BUT, if you EQed them well, they COULD sound good.  As for FET emulation, I have used the BSIAB II on many amps and to be honest, this circuit sounds best on SS amps.  As for IC distortions, for me, they seem to sound BETTER on a tube amp than on a SS amp (but it's just my personal taste).  I play with a Peavey Classic 50 and the BSIAB II sounds horrible on it... I think EQing is the answer to have a good "emulation" of the "real" thing, but will never be the real thing... especially with tube amps, no matter how inconsistent they may be from one to another.

Am I being stupid here?  :icon_lol:

Not stupid at all...in my opinion...and that's the rub here, I think.
Does it matter if a 9v stomp built for about $20 doesn't sound like a $2000 tube amp? Yes and no. For some commercial builders here, there is an interest in these devices NOT sounding like tube amps, because of a perceived cut into their profit margin. For others, if they can get close to their idea of a holy grail sound, well, close is good enough. There will always be naysayers-you can be playing through a real Superlead or a real Dumble, and SOMEBODY, usually a guitar player will say, "sounds good, but not as good as..."
Semantics aside, the bottom line always has to be the sound. If you feel you're getting a good sound, you'll play well, and the audience won't know (or give a damn) whether it's tubes opampa, jfets, or digital...especially by the 3rd set when they're all shitfaced...

The emulators sounded appealing to me because I'm not much of a stomper, but really do want a good tone: boosters, preamps. They don't have to sound like this or that, I just want them to sound good in combination with my amp.

If you really don't need jfet in them, let's try and make some opamp versions!

Quote from: Xavier on November 16, 2006, 12:31:14 PM
We discover new ideas every day in this forum. You guys need to understand our excitement. I think this is the most informative forum I've ever seen. I've learned more about electronics in this forum in one year, than in all my life until now.

This is indeed one of the greatest guitar electronics boards on the web. I love it, but still I regret that so much work that was done goes to waste. This might be inherent to the forum form but still.

When I started out, started buying germanium transistors like crazy, until some months later somebody explained me how you don't really need them (piggybacking). Browsing through searches isn't everything. Same thing with the JFETs, after building solid si fuzz with them and seeing the minibooster familiy and the emulators, just thought I only needed jfets. Then advanced builders tell me they don't even start buidling circuits with fets. At the same time other people encourage me to try and get the bias of my Flipster right with resistors soldered to the trimpots.

All the info is there, but there's so much to wade through.

I found a lot of info in this forum, but also heaps in personal webpages. Built reports should really receive a special status, because they are so helpful for other people.

zj

zjokka, remember that every component has its use.  Ge transistors can be great in fuzzes, and have their own sound that Si can't quite do.  Jfets also have very cool applications, and these simulators are one of them.  The problem with jfets are the inconsistencies between them (very much like Ge transistors).  These inconsistencies make them less useful for pedal manufacturers, but still very useful for DIY use.  Ideally, you should read what everybody has to say here, but build any pedal that looks interesting and decide for yourself if it sounds good or not.

I built some ROG designs and they are good sounding pedals but as was said before in this thread they sound good in front of tube amps. Also I don't think the sound of the Eighteen for example is a close "emulation"  of the original when it is plugged in front of a Laney, Mesa or Jazz Chorus. My Laneys will introduce their own voicing. It up to your taste if the final result is pleasing and/or close to the original. More, how close can any "simulator" be using 9V and without the power stage and those high voltage caps? Maybe Mark and RG can bring some light here.

IMO we need to define what an "emulator" is.
1. Is a black box, digital or analog, between the guitar and the PA, recording console or pc sound card that faithfully reproduce the sound of a given amp? Guitar<--->emu box<--->PA or console or pc sound card
2. Is a SS amp that sound close to some vintage tube amps?
3. Is a preamp box that will guarantee the sound of certain vintage amps independently of the voicing of the amp, SS or tube, where it is connected?
4. Your suggestions here.

I'm not an elect eng but the only similarity between a jfet and a tube is the biasing schem. The physics inside them are totally different, with tubes being a little more Newtonian than fets if you allow me the expression. After decades of SS  amps and other SS devices that never reproduced the sonic characteristics of a tube amp, the question is, can it be done? Mathematicians always take the inverse path after failing to probe something. A part of me will like to hear a yes to this answer but the other part will miss these little bottles. As long as we have manufacturers making tubes, and given the simplicity of design and those new cheap small tube amps on the market, do we need emulators?

mac

I read somewhere that it has alreday (mathematically i think) been probed that with opamps and diodes you can perfectly simulate a tube.
Cheers
Rafa

Take a look:
http://milbert.com/articles/CoolSoundOfTubes/#t2

It seems that we have to use IRF822 high voltage mosfet,

Can anyone explain me this

Quote* 2N5457 low-voltage junction FET:
Unlike the high-voltage MOSFET, the JFET has excellent noise performance (-140 dB) but poor distortion (second harmonic is only 30 dB down). Because of the lower I_dss of available junction FETs, the drain resistor was raised to 10 k(omega); the bias was adjusted to give about 1/2 V_DD at the output.

I thought that more 2nd harmonics was more tubey?

Cheers

Rafa

Thanks for the link Rafa.

mac

If we want a better understanding for the word emulation, why no search google for:
define: emulation    ;D ;D ;D

Personally I'll stick w/ the idea of having somewhat simlar sound to what it tries to emulate. I mean, even a tube amp could actually emulate a Roland Cube-40 SS combo   ;)  Some emulators are rather crappy and others are very good, that's why soundclips are so important. Playing style (ie. picking, phrasing, pressure and much more) will certainly effect the sound very much and in some way even a crappy amp can sound rather good in the right hands...

I'll post a small 5 minutes eval of the original pod at my site some day, may (or may not  :icon_lol:) be interesting...

/Krister
http://hem.passagen.se/amps

What i personally would like to ask is.

Is it possible to get the exact sound from any tube amp (lets say JCM800)
using some sort of device like FET ot BJT, op amps for example????

That is the question here.

Simulation, emulation, copy, It does not matter the right word.

Here in Brazil, is not that EASY to get tubes and parts for the amp.

I know that nobody is worried about that, but to me, is one important matter of fact.

And besides that high voltage is a problem worth to be considered.

In Stephan moeller work the resistors values are not available,
but if we take a close look at the project, it is too much simple.
Not so complex like some guys always say.

And we DO NOT have there the work on the speaker and transformer of vox ac30.

Until now, NOBODY had done some "scientific" study about that matter.

Just to mention, some russians guys have done special work with SENSATION CIRCUIT.
And other guys have done some others special ideas too. Its important to take a look
at these ideas.

I still hope that some day i will have my JCM800 INABOX at my home.

Regards
Rodrigo

QuoteIs it possible to get the exact sound from any tube amp (lets say JCM800) using some sort of device like FET ot BJT, op amps for example?

And gentlemen, this is a perfect illustration of the reason I have bad feelings about the use of the word "emulations".  It leads people who are not familiar with the technology to believe that this may in fact be possible.

No, rodrick1, it is not possible to get the exact sound of a tube amp with a solid state emulation. If it was, there would be no tube amps from the major vendors on the market. Tubes are a bad deal from the practical standpoint. They are big, fragile, and wear out quickly. They are expensive and use dangerously high voltages. If there was a way to get exactly their sound from something that is small, cheap, safer, tough, and long lasting like semiconductors, there would be almost no tubes in use. However, there is nothing that provides exactly the sounds that can be had with tubes, and that is why tubes are still here. When we can get exactly the same sound from something cheaper, smaller, and more rugged, tubes will vanish.

As I've said many times, we keep getting closer to the sound, but we are not there yet. And we've been trying for several decades already.

QuoteSimulation, emulation, copy, It does not matter the right word.

Words matter because they lead to expectations. The use of the word "emulation" let YOU to believe that something that is currently impossible might in fact be possible. And that is the sum of my objection to the word use in a nutshell.

QuoteIn Stephan moeller work the resistors values are not available, but if we take a close look at the project, it is too much simple. Not so complex like some guys always say.

Stephan Moeller's AC30 simulator does a remarkably good job of emulation - that is, coming close to the sound - of one and only one amplifier, the AC30. I understand that it took Stephan a long time to get it to sound that way. And although it is quite a good sound, it is not a full replacement for an AC30.

QuoteAnd we DO NOT have there the work on the speaker and transformer of vox ac30.

... as you note here.

QuoteUntil now, NOBODY had done some "scientific" study about that matter.

Actually, that is incorrect. The major amplifier makers, and many inventors have tried for almost fifty years to make things that sound "just like tubes". There are literally dozens if not hundreds of patents for solid state circuits that sound "just like tubes". All of them capture some facet of tube sound, but not all of it.

QuoteJust to mention, some russians guys have done special work with SENSATION CIRCUIT. And other guys have done some others special ideas too. Its important to take a look at these ideas.  I still hope that some day i will have my JCM800 INABOX at my home.

I understand your hope that one day tube sound will be easy, cheap, rugged, quiet, long lasting, and so on - a solid state device that sounds just like a tube. Maybe some day we'll get there. For now, we are not there, and simple approaches like just using JFETs instead of triodes were tried as long as 35 years ago.

These approaches may make good sounds in their own right, but they do not sound "just like tubes". So use them for the good sounds they do make. Nothing says that tubes are the only thing that can sound good. But keep your eyes open and don't be blinded by what you think you should want. Use your ears!

Let us not forget that what many people here want from an "emulator" is a distortion sound, not necessarily a clean sound.  Of course, given the fact that these circuits all produce an increase in output level, feeding them into the preamp stages of a guitar amp will almost necessarily produce an increase in distortion, which will not really be the natural sound of the host amp or the amp being emulated.  Indeed, if I took the output of an actual AC30 preamp, and fed it to the input of an actual Twin Reverb, I doubt very much that the resulting sound would strongly resemble either a Twin or an AC30.

A big chunk of what keeps tubes in the game is not just how they distort, but in how they sound when clean (as the Workhorse amps were more or less intended to demonstrate).  Few of the so-called emulators are really directed at that particular goal.  That's not a bad thing, but it is not the same thing.

Another quesyion whats technically the difference between a SS amp and a tube amp when both are clean, as far as I know when distorted they change a lot, but some time ago I played with a big tube amp and the sound was almost the same as my SS fender amp which was next to it, there were some burned tubes but abyway there was no big difference, ( the tube amp was schafnner with 4x6l6 and 4xecc83 I think)

Quote from: Rafa on November 22, 2006, 09:00:38 AM
Another quesyion whats technically the difference between a SS amp and a tube amp when both are clean, as far as I know when distorted they change a lot, but some time ago I played with a big tube amp and the sound was almost the same as my SS fender amp which was next to it, there were some burned tubes but abyway there was no big difference, ( the tube amp was schafnner with 4x6l6 and 4xecc83 I think)

I think "clean" in tubespeak is still slightly compressed.

Hi thanks again for atention.

THAT QUESTION IS FUNNY AND GIVE ME PLESURE SOMETIMES.
SOUNDS LIKE ENDLESS...

When i say that NOBODY has done one scientific work about that matter, I would try to
fix things saying that nobody has done:

ONE ENTIRE (not all of it), EVIDENT, REALLY OPENED SCIENTIFIC WORK ABOUT COMPLETE SIMULATION OF A COMERCIAL TUBE AMP.

To me it would not matter if it is about VOX AC30 or MARSHALL. I am curious about
what is REAAAAALLLLY behind the SOUND OF TUBE AMPS.

A long time ago we know that cheap transistor amps have TIM (TRANSIENT INTER MODULATION???) distortion.
One very bad type of distortion.

It is the low realimentation, the low harmonics, the cabinet, the output transformer, the speaker, the power energy source or the dinamics??????

My god, do you know one good article for that??? I am just one curious guy...
Of course i know it is one entire set of things that make tube amps particular sound.
(i am seriously conscious of the many patents available, and the work
of stephan moeller, the john murphy from carvin and many others)
 
I feel the lack for that explanation.
I could say that its a lot cheaper just say, tube amps are GOOD.

For "scientific", i consider a work that gives us "real evidences". What is expected from scientific work.
All works and patents are always full of secrets...

I would say that some work of that level would consume too much time and MONEY.
Maybe it is not really interesting to take this work at the end (comercially speaking).
Why should i buy some expensive marshall "copy" just for the advantage of not having
the tubes.
Besides that tubes have the charm, that vintage mojo...

About the expectations:
We can not avoid that somebody would say (like i myself did before) that has done one simulation/emulation/copy/replication of certain tube amp without facts to prove that.
I personally could say somethings here, that would generate EXPECTATIONS.

The questions is, can i ensure that i am able to prove my words?????
Words can determine true and precise concepts that maybe do not exist at our age (time).
That is another question.

Anyone can get here and say: Hey, i got that sound in my circuit. Just listen to it.
Like many did before.
But the COMERCIAL+MARKET+SECRET+PROTECTION is always lying underneath.

I would not like the discussion of the taste of the cake.
But somebody can tell me the recipe of the cake????

Actually, i could NEVER expect that one simple "fet" device would be able to acomplish the task to
BEHAVE  like "lets say,(FOR MORE COMPLICATION) chinese 12ax7".
FETS are not made for the task to be like triodes.

We could endlessly discuss that there are many kinds of 12ax7 sound too.

Ok, but we all can agree that TUBE AMPS HAVE ITS PARTICULAR BEHAVIOR that we are trying
to "replicate" (another word) here.

Another thing is: Its is umbelievable how many SPICE MODELS WE HAVE FOR 12AX7.
And we know that the most of it are not precise. That is another problem...
The linx site has one precise model for 12ax7 but it is too much heavy on calculations for the spice.

ANYWAY I specially like the LXH2 SITE work.

Of course i like this forum too much either.

Thanks again
Rodrigo

Well lets supsose the answer is no, so with fets or opamps its impossible to simulate tube amps.
Now we get another question: how close can we get to the sound of amp ``X´´, are any audible difference or not??
My point of view is that the thing its to complicated at this point, simulating an amp will require lots of studiyng and experimentation, that will end up in good but complicated circuit like stephans moeller one or even more coplicated, and to do study the amp you should probalby need to own it. I think that the best chocie is start saving some money, build a small tube amp, which may not be so expensive.
At LXH2 theres an amp using an el84 which works with 15V which is not loud but if you are afraid with high voltages its a good starting point.

http://home3.netcarrier.com/~lxh2/lowpsch.html
Here tube amps runing with 12V or 30V
http://www.sopht.ca/mambo/index.php?option=com_content&task=section&id=5&Itemid=36

Rodrigo: at mercadolibre.com.ar there are some people who sell tubes considerably cheap comparing to the prices I get here in Uruguay, the 12ax7 is around US$14 and the EL84 is around US$ 17 maybe the ship to Brazil.
Cheers
Rafa

Especially I love the following part in above mentioned http://www.sopht.ca/mambo/index.php - link:

QuoteOut of these requirements came this design. Please note that I got a lot of help from a lot of nice people from Aron's Stompbox forum. Without Tone God, puretube and the guys over at runoffgroove (check out their killer jfet amp emulators!), none of this would have happened!

(from: the hybrid Ruby Tuby)
:icon_biggrin:

Once again, think about what it is you are trying to mimic.

The Mesa Dual Rectifier amps illustrate quite clearly that the very "same" amp with different power supply properties has a different sound and feel.  The many many recommendations for swapping this power tube for that one, or this preamp tube for that one (e.g., 12AY7 or 12AT7 for 12AX7, etc.) also illustrate that the "same" amp with a different gain structure also sounds different.

Then you get hybrid amps like the Music Man or earliest Peavey Classics where the power section is tube and the preamp is entirely solid state yet people find them highly desirable as "tube" amps.

So what the heck is it that people find so pleasing about these amps, and is the aspect that pleases so much actually capable of being imitated plausibly within the restrictions of a small-signal FET-based, 9v powered preamp stage?  Maybe, maybe not.  Depends what it is one is trying to mimic.  First you have to know just what aspects of the original are responsible for what you like.  It may very well be the tonestack corner frequencies, or it may be the amount of gain, or the way the gain straucture is cascaded, or any of a number of things that are found primarily in the front end.  But...it may also be in the power tubes, the transformer, the presence feedback loop from speaker side of the transformer to the phase splitter, or any of a number of things that sit well beyond the send side of the volume pot.  Poke around the net and you'll see reams of material on the differences between a master volume in the preamp stage vs the power-stage master volume between phase splitter and power tubes.

I don't have a quarrel with the use of the term "emulation" itself.  What I might quibble about is when the term is misapplied such that it is intended to suggest mimickry of many aspects of an amp that provide its unique character, but is actually tacked onto a solid-state facsimile of the first 3 preamp tubes.

Now, I don't think that ANY of the good folks who have studied schematics of great amps and wondered what would happen if they whipped up a F4T (Fet-for-triode) mimic of the front end believe, or intend to suggest, that they have somehow captured the soul, the essence, the döppelganger of those amps.  But as noted by others that doesn't stop young eager minds from thinking that one can capture such things in a 2" x 2" PCB.

Just keep everything in theproper perspective and remember what it is that you ARE and AREN'T "emulating".

Quote from: Doug_H on November 22, 2006, 09:48:19 AM

Quote from: Rafa on November 22, 2006, 09:00:38 AM
Another quesyion whats technically the difference between a SS amp and a tube amp when both are clean, as far as I know when distorted they change a lot, but some time ago I played with a big tube amp and the sound was almost the same as my SS fender amp which was next to it, there were some burned tubes but abyway there was no big difference, ( the tube amp was schafnner with 4x6l6 and 4xecc83 I think)

I think "clean" in tubespeak is still slightly compressed.

Yes. A good "clean" guitar sound is not clean (as in hifi) at all. You want some subtle compression from the pre- and poweramp, and possibly some light clipping on the peaks. Things that you can feel more than hear. A completely clean guitar sound is sterile and lifeless, regardless if it comes from a solid state or tube amp, IMHO.

What does IMHO menas??
Cheers
Rafa

QuoteWhat does IMHO menas??

In My Humble Opinion.

Quote
What I might quibble about is when the term is misapplied such that it is intended to suggest mimickry of many aspects of an amp that provide its unique character, but is actually tacked onto a solid-state facsimile of the first 3 preamp tubes.

No "might" about it. I'm quibbling.  :)

Here's another thing to consider:
There is a young woman standing next to me. I think she is beautiful. Do you think she is beautiful?

I think she is more beautiful than that young lady over there. Who do you think is more beautiful?

I have a group of beautiful young ladies in this room. Are they all equally beautiful?

I have here a beautiful young lady and a wax life sized model of her, made out of wax, that in every respect looks just like the young lady, but is solid wax. Is the wax model just as beautiful? Is the wax model an emulation? How accurate is the emulation?

Quote from: R.G. on November 22, 2006, 02:36:18 PMI have here a beautiful young lady and a wax life sized model of her, made out of wax, that in every respect looks just like the young lady, but is solid wax. Is the wax model just as beautiful? Is the wax model an emulation? How accurate is the emulation?

Alright, maybe just an inflatable girlfriend--but if that is all you can get...   :-\



Ben

I knew someone would pop in with that.  ::)

OK, sure, we can do that. My opinion of inflatable girlfriends is that they are remarkably worse in every respect than the real thing. They are not a particularly good emulation in any way that I can think of. Especially if we're comparing in terms of beauty.

I'd put inflatable girlfriends at about the same place on the scale of beautiful women as I'd put playing guitar through a cheap home stereo on amp emulations. It's what you do if you're desperate and will put up with something that is an "emulation" primarily in your own mind.

Frankly, I was thinking more of the differences in "beauty" between real, live women and a poor similacrum; and to prove the point that we might all perceive beauty as being somewhat different.

Im thinking about building my first tube amp or preamp, I saw the first fenders look easy I would like a tweed deluxe but it has 5 tubes so I thoghut about the small champ which has 3 tubes, is the sound similar between this two amps, can I build it with bright input instead of the common??
Whats the difference between 12ax7 and 7025? whcih one sounds best?
Can I use a SS rectifier to avoid using a third tube, will the sound change much?
Thanksss
Rafa

The problem with this stuff is the wrong end of the amp is being modeled what ever you want to call it.  companies put tubes in the pre because it is cheaper is my guess: however with bass a nice tube pre with a high power solid state amp can sound very good.

Look at the Music man amps and some others all solid state till the output tubes and transformer.  Have you heard a music man amp? the opamp type does seem to make a difference lf353s, 4558s or even TL072s I have been told..

Pentodes and beam tubes interacting with the transfomer speaker load mess being driven hard is what most of the sound is from IMO. You got screen grid current sometimes and how the heck do you model that mess of overdriven pentode beam to a M what ever alloy stack of iron and copper that might be wound different ways?

Don't believe me do a test take a solid state pre into the effect loop for solid state pre to tube power amp..

I have a PRS head ICs and solid state outputs interesting amp.  I think only 190 made.  I bought mine at a guitar show it is in not so good shape but it does sound good. 

edit

R.G.'s comparison genuinely provoked me and reminded me of the question of, let me say, the inner beauty. you call it what you like since this got metaphysical already.

i give you an anecdote, sincerely not intending to hurt anyones feelings, it was my wrong in the least. here it is: one time, at the sauna me and some of my male friends offered our female colleague to join us.  :o  promptly, one of my friends who did not join us in that proposition told her: 'don't be bothered. i'm the only one married, you have to understand them, they haven't seen how it looks like yet.'

now, back to the sound(ness). i got first non MV Marshall when i was 16. i strongly thought that everything that preceeded it was an exagerration. i thought of it not only as a burden in sheer weight but also as of a huge disappointment. then one day i happen to come to a proper rehearsal room. the drummer was so loud or so i thought and it never occured to me that he should be after all the gigs i have had seen up to that moment. so, i turned my volume to 6. ok, maybe 7.

...

nowdays, sort of retired, with most of my buddies not anymore interested in playing, and myself being in financial narrows, im confined to my room. neighbours and the rest of the 'real life' surroundings. i just accept the 'jfet emulation' as a white lie and it warms my heart.

Quote
I have here a beautiful young lady and a wax life sized model of her, made out of wax, that in every respect looks just like the young lady, but is solid wax. Is the wax model just as beautiful? Is the wax model an emulation? How accurate is the emulation?

Good & funny example RG!

Both J900 and AVT2000 look very cool externally, but my ... emmhh... "distorted" :icon_twisted: mind like to "gig" with the real thing... no wax, inflatable or silicon surgery emulation... but I admit I like to experiment sometimes... :icon_redface:

But there are so many people under the sun, and some of them do really like inflatable girls, some do need a silent Playboy mag, some simply can not afford a beautiful girl, some like both worlds!  :icon_mrgreen:

---

I remember one day in Buenos Aires six month ago. I was in a crowdy music store looking for a 15 to 40 Watt tube amp. The salesman told me to try a chinese AC30 2x12 @ U$S1.350 which is out of the budget for many people here. There were a couple of kids near me testing Digitech GNX,  Boss GT and Marshall AVT. They looked very pleased with that toys, but when I crancked the Vox and played a few chords, most kids were surprised by the real thing. They all came closer to listen and ask. Finally the Vox seemed too overpricey for me and went for a Laney VC30. The salesmen not only failed to sell me the Vox but the digital processors and AVTs to those kids, who are probably saving peso over peso to buy their first tube amp.


mac

  Like Jfets' do...
  Sound alot like a tube amp, @ low volume, More like a cranked tube amp than a big tube amp turned way down.
  What do tubes and Jfets have in common?
  They can boost
  They can distort
  They can be compressed
  They can be voiced and can drive tone controls etc.
  They can both provide a wide variety of sounds.
  They both do stuff the other doesn't
  Where do they differ?...
  Gus mentioned a good one...Jfet Emu's stay near the front of the chain.
  Tubes Drive speakers
  Speakers load tube outputs
  Small Signal Jfets Don't drive speakers
  There is Alot that can get to going on when a tube amp is 'leaned on' that doesn't happen in a 9v [low voltage] Jfet circuit which follows a cropped tube amp schematic.
  Power supply Sag.
  Output section and speaker doing their dance...
  Even with a stiff supply and no speaker...Jfets'll sound differnt than tubes...better and worse...depending on...all the schtuff it depends on...

Peter:
So if we take for example the professor tweed and we modify it to make an amp it involves we change the fet that should be in the power amp for another and we supply it with higher voltage (and the speaker of course), should it be closer to the real amp?

Who stated Fets are like tubes??
Fairchild, scientifics, some anonymous guy??
Which is the susbtitute for the 12ax7? the mpf 102, if so why j201 sounds better

This f4t thing is not really clear for me,
This might be a question for ROG guys why do you use mostly always the j201 to substitute 12zx7.ecc83,6l6,6v6,el34

Cheers
Rafa

I do not know if there is a fet that can work at 100-200V and deliver 5-15 watt in single-ended class A. I think of a 2 or 3 fets at 100-200V in the preamp and a single-ended output fet + output transformer driving a speaker. Or mosfet, assuming they sound the same.
But I guess that someone has already built it if it is possible.
How will it sound? No idea.

mac

yes, there are such devices...

Are they good?

I've stayed out of this thread till now, but I figure I should get my $.02 in ! :)

Really, what the hell does it matter ? To quote R.G. "beauty is in the eye of the beholder"....well, some may love the sound of a jfet amp emu, some may not. I know people who LOVE Fuzz Faces, and people that think theyre the plague of the Earth. Are either of them right? Are either of them wrong ?

People build kit cars of Lamborghini's because they can't afford a real one. All the people who own "real" Lamborghini's turn their noses up at them. But the people who own and drive the "kit versions" are plenty happy driving around in their cars. Are the kit car and the real Lambo the same ? Of course not. But I would venture a guess that many of the kit car owners get as much, and sometimes more, enjoyment from their vehicles than the Lambo owners. Less maintenance, less hassle, less worry, similar styling.

So, to sum it up....if YOU like it, then who the hell cares ? To quote Joe Meek "If it sounds good, then it is good".  And to paraphrase R.G, "Beauty is in the ear of the beholder".

AC

And BTW...IMO, they should be called "emulations". Just because you "emulate" your older brother, does it mean you're "the same"?  Of course not.

Quotepeople that think theyre the plague of the Earth

Im one of that guys, I havent played god fuzzes but I didnt liked the ones which Ive played,
Cheers
Rafa
As I see (as dragonfly said), if its sounds good its a good stompbox, but the problem I think is which sounds best are tube amps, so people does not feel happy with the emulators available, they want to get as close as possible and f4t is not an accurate method maybe.
IMHO<---(Now that I know what it means  ;D)
Cheers
Rafa

Quote from: Rafa on November 23, 2006, 12:03:02 PM

Quotepeople that think theyre the plague of the Earth

Im one of that guys, I havent played god fuzzes but I didnt liked the ones which Ive played,
Cheers
Rafa
As I see (as dragonfly said), if its sounds good its a good stompbox, but the problem I think is which sounds best are tube amps, so people does not feel happy with the emulators available, they want to get as close as possible and f4t is not an accurate method maybe.
IMHO<---(Now that I know what it means  ;D)
Cheers
Rafa

If you haven't, you need to build some of these ROG simulators.  They sound more tube-like than almost any solid state circuit I've heard, certainly more tube-like than any solid state amp I've ever heard.

Quote from: Rafa on November 22, 2006, 06:27:26 PM
Im thinking about building my first tube amp or preamp, I saw the first fenders look easy I would like a tweed deluxe but it has 5 tubes so I thoghut about the small champ which has 3 tubes, is the sound similar between this two amps, can I build it with bright input instead of the common??
Whats the difference between 12ax7 and 7025? whcih one sounds best?
Can I use a SS rectifier to avoid using a third tube, will the sound change much?

Go for a full amp, not just a pre. The poweramp is where the biggest difference in sound between tube and solid state is.

Take a look at www.ax84.com. That's like a "DIYstompboxes" for tube amps. The AX84 P1 amp could be a perfect project for you. It is a simple single-ended amp, like a Champ but with a full tonestack. This leaves lots of room for tweaking and modding. You can expect lots of support from the AX84 community, as well as thousands of ideas and tips for mods and tweaks.

In a single-ended amp, the choice of rectifier type does not matter for the sound. This is because the amp will be Class A and therefore have no powersupply sag. The only difference will be the voltage (tube rectifiers drop 30V or so compared to solid state rectifiers).

I think the 7025 is a "military" grade version of a 12AX7. From what I understand it's a bit more "hifi" sounding, so I guess it works well for clean preamps. They are very similar, so you can just swap them to see which one you like best.

so it looks like what is searched for is:

Triode-clipping, and Pentode-saturation ( "TCPS" )

without power-supply sag ( "PSS" ),

plus output-transformer hysteresis ( "OTH" ),

no negative feedback ( "NNF" )

out-of-their linear range speakers ( "ORS" ),

and cabinet resonances ( "CR" ).

All of that miked well ( "MW" ).
:icon_smile:


BTW: I do wonder, whether all that distortion coming from
the phase-inverter working in its non-linear region is in fact
the audible distortion that is mainly the cause of some amplifiers`
sound,
(like it has been mentioned at various places on the web),
or if the non-linear behaviour of that tube is of the kind
that is being outbalanced
in the output-transformer`s two "antiparallel" windings...
:icon_wink:

Thankss a lot guys
Its true the only fet stompbox Ive built is the Blue Magic, So Ill have to try a ROG one
Which one is the most touch sensitive for you guys?
For the tube amp Im saving some money becuase right now Im bankrupt
Cheers
Rafa

Quote from: Rafa on November 23, 2006, 02:05:36 PM
Thankss a lot guys
Its true the only fet stompbox Ive built is the Blue Magic, So Ill have to try a ROG one
Which one is the most touch sensitive for you guys?
For the tube amp Im saving some money becuase right now Im bankrupt
Cheers
Rafa

Eighteen = really crunchy Marshall over drive
Thunderchief = Plexi styled distortion
Uno = hot Fender distortion
English Channel = Vox OD that is almost a distortion
Prof Tweed = Fender OD

I'd say any but the T-Chief is gonna be fairly touch sensitive, so pick what sounds good to you.

What about the ROG matchless (matchbox) is it as touch sensitive as the other ones.
Cheers
Rafa

some good posts in this thread

I am not again the JFET circuits they can be cool and IMO are their own sound.

IIRC there was a dumble schematic or two on the web in the past (Ampage years ago?) the overdrive channel had it's own tone control section.

To add about tube amps I heard a old metal face mark 4 50 watt  that was worked on by Ken Fisher(what I was told I am in NJ so this could be true) On a 1960 with green backs.

WOW what a sound when it was turned up.

Tube amps could be the PI and outputs and transfomer just hitting this certain power level, clipping and the distortions just making that SOUND.

Quote from: Rafa on November 23, 2006, 02:28:12 PM
What about the ROG matchless (matchbox) is it as touch sensitive as the other ones.
Cheers
Rafa

I haven't built the Matchbox, but I suspect it's like a higher gain version of the Vox, which is essentially what a Matchless amp is.  So, probly less touch sensitive with the gain maxed; however, if you back off the gain it's probly good.  For me, the biggest thing is whether you want the Vox style EQ or the Matchless style tone switch.

The English Channel is a real nice one indeed.
Gotta be one of the best ROG circuits IMO.

Quote from: Gus on November 23, 2006, 10:38:22 PM
some good posts in this thread

I am not again the JFET circuits they can be cool and IMO are their own sound.

IIRC there was a dumble schematic or two on the web in the past (Ampage years ago?) the overdrive channel had it's own tone control section.

To add about tube amps I heard a old metal face mark 4 50 watt  that was worked on by Ken Fisher(what I was told I am in NJ so this could be true) On a 1960 with green backs.

WOW what a sound when it was turned up.

Tube amps could be the PI and outputs and transfomer just hitting this certain power level, clipping and the distortions just making that SOUND.

I bet it was !!
Would it make ANY sense Gus, to throw an amp sim up against a small "audio transformer" at the back end ?
Or something to induce that OT type compression/slight breakup ( I know we have stm's speaker sat simulator too )
It would have to be set up to only come on at "higher" gain/vol settings ,,,,, ?

I'm probably talkin' crap - just thinking out loud :D
Happy Thanksgiving to all the US members :D

MM.

QuoteThey sound more tube-like than

...

This is the second time in a week I've seen a comment like this. No one responded the first time so I'll try again. What do you mean by "tube-like"? I would like to see explanations of terms like "tube-like", "tubeyness", etc, etc.

I've played around with a lot of my own ideas using JFET circuits to mimic popular tube amps. I suspect it is like R.G. said at the beginning- it's the EQ that is the real attraction here, not the distortion, or what device-type it supposedly sounds like, etc. In fact I believe most people wouldn't be able to discern device-types in 2 different circuits in a blind test. There are just too many variables involved in what sounds "good" to people.

The JFET pedal circuits sound good. They do mimic certain aspects of the amps they are inspired from (esp due to the EQ-ing I believe) but I would not call them "emulators". And yes, I think words are important. Text-based internet communication tends to either minimize the significant or maximize the trivial. So I think its important to be clear about what we really mean.

QuoteIn fact I believe most people wouldn't be able to discern device-types in 2 different circuits in a blind test. There are just too many variables involved in what sounds "good" to people.

Don't ask me where I saw it, but I recall several times where a recording engineer had asked professional recording musicians to see if they could tell which track was a recording from the mic'ed Marshall tube amp and which was the output of a Marshall amp simulator, and they COULDN'T tell which was which.

But I have seen other "studies" where musicians COULD tell which was the output of an actual tube amp, and which was an EQUAL LOUDNESS HI-FI AMPLIFIED emulation, while blindfolded - WHEN they were playing a guitar through the amp live.

Of course, it's hard to say whether that was due to the presence of artifacts of the amp switching circuitry, tweeter reproduced hiss vs 12 inch speakers, or whatever other largely unimportant tonal factors - or really due to sonic differences in the actual amp "sound" or "feel", or just a lame emulation. The "studies" try to be semi-scientific, but that just isn't very easy to do.

FWIW, I know that when I've played a good tube emulation through a good sound system turned up loud like a Marshall, it sounds and feels a helluva lot like playing through a Marshall stack to me.

I do share some of the concerns expressed here about just dropping a JFET into a tube preamp circuit and expecting it to be a convincing emulation of the sound of that particular tube amp model. The EQ isn't even comparable to the tube circuit if the amp uses lower value caps for cathode bypass to boost the highs - because it isn't the R-C product that sets the EQ ,it's the transconductance of the tube and the capacitor value that determine the frequency response.

In some instances, what people mean by "tube-like" can refer to how they conceptualize the distortion properties of a solid-state pedal vs those of an overdriven tube amp.  IN other words, they are saying "I like the way a tube amp breaks up, and I wish I could get that in a pedal but they are usually too buzzy or intense".  So, it is kind of a mélange of both distortion amount/intensity and EQ/contour.

Quote from: Doug_H on November 24, 2006, 08:34:54 AM

QuoteThey sound more tube-like than

...

This is the second time in a week I've seen a comment like this. No one responded the first time so I'll try again. What do you mean by "tube-like"? I would like to see explanations of terms like "tube-like", "tubeyness", etc, etc.

I've played around with a lot of my own ideas using JFET circuits to mimic popular tube amps. I suspect it is like R.G. said at the beginning- it's the EQ that is the real attraction here, not the distortion, or what device-type it supposedly sounds like, etc. In fact I believe most people wouldn't be able to discern device-types in 2 different circuits in a blind test. There are just too many variables involved in what sounds "good" to people.

The JFET pedal circuits sound good. They do mimic certain aspects of the amps they are inspired from (esp due to the EQ-ing I believe) but I would not call them "emulators". And yes, I think words are important. Text-based internet communication tends to either minimize the significant or maximize the trivial. So I think its important to be clear about what we really mean.

Without looking, I'm pretty sure I said earlier in the thread that I agreed that much of the character of an amp sim is the EQing of the circuit.  If I didn't say it earlier, let me say now that I agree with you guys in this.  However, the tubiness manifests itself in a tiny bit of compression that I hear in the circuit as well as their extremely touch sensitive nature.  Most SS preamps aren't touch sensitive at all, so for that reason alone I would describe these pedals as tubey.  Even you if set these to be on the edge between clean and dirty you can still hear the tiniest bit of compression that the circuit introduces.  That touch sensitivity combined with EQing that is very similar to the amp the pedal is based on makes a great sounding pedal that is very reminiscent of a classic tube amp.  Yes, they absolutely are not a substitute for the real deal, but for a DIYer without the money to buy a nice amp they are a great solution.

I have never built a sim not using jfets, so I am not saying that they are a better choice than an opamp or any other component.  But these jfet based pedals sound great and strike me as sounding tubelike, at least, more so than most distortions.

Another Hint

Look close at  musicman amp schematics

Often one of the opamp gain stages has an interesting transistor resistor section of the feedback network

Musicman amps had some cool well thought out circuits.


http://www.drtube.com/guitamp.htm#MusicMan

And years ago R.G. had a cool mystery circuit fragment from a VOX solid state amp(s0

Yeah- I tried the MusicMan thing a couple of times, I didn't hear much difference. I think it also has to be done on a bigger suppky voltage than 9v

QuoteYes, they absolutely are not a substitute for the real deal, but for a DIYer without the money to buy a nice amp they are a great solution.

I totally agree

QuoteI have never built a Sim not using jfets, so I am not saying that they are a better choice than an opamp or any other component.

I think you should try the LXH2 Marshall simulator, If it seems too complicated you can omit the cabinet simulator, (I haven't the cabinet simulator)
The sound clips are my page are not really good (I was in a hurry whren I recorded them), but when I finish my exam period Ill probably record new soundclips.

Cheers
Rafa

QUOTE:
"This is the second time in a week I've seen a comment like this. No one responded the first time so I'll try again. What do you mean by "tube-like"? I would like to see explanations of terms like "tube-like", "tubeyness", etc, etc."


A typical argument in the tubes vs. SS/chip amp debate:

"nothing sounds like a tube amp. You just can't match the 'warmth' that tubes give the tone...."
"yeah? Well, what's this 'warmth'? exactly?"
"what's 'warmth'? Dude, that's the tone you get from a tube amp!"


Another interesting series involves sneering at anything that's not a 1960s Marshall, and then claiming that no SS amp can hope to come close to that sound. The tube-advocate usually omits the fact that very few TUBE amps can come close to that sound.

In the interest of full disclosure, I own tube and non-tube amps, and like both kinds. Nothing high-dollar, mostly because my playing is low-dollar and music isn't my day job. My ears aren't oscilliscopes, but they tell me that with the right effects chain, speakers, etc., it is very difficult to tell the difference between a tube amp and a modelled/emulated SS amp. I won't say impossible, and I've only heard the world through my 2 ears (such as they are), but very difficult. Again, I don't deny that tube amps are cool; they are. But I've yet to hear (maybe the key word) a convincing case that what makes them cool is a tone that nothing else can approximate.

From an economic standpoint, it seems to me that it's also relevant to look at the debate in terms of the scale of any differences, if there are any. In other words, there may well be some audio "distance" between a reasonably priced SS amp and a tube amp. But this has to be set against the distance that separates a new set of strings from an old set, mods to the speaker cab, the various tone-boosters available on this site, etc. At least some of the people sitting around lusting after tube amps could enjoy a similar step-up in tone quality if they would just swap out the speaker or buy new strings, but there's not a lot of cachet in talking about that.

Have a good weekend everyone  ;D

idlechatterbox

Posted a good point.

Speakers.  You want to have some fun take a small practice soild state anp and connect it to a good set of speakers.  A two x12 or a marshall cab or.........................................

Quote from: Gus on November 24, 2006, 06:51:22 PM
idlechatterbox

Posted a good point.

Speakers.  You want to have some fun take a small practice soild state anp and connect it to a good set of speakers.  A two x12 or a marshall cab or.........................................

Gus is absolutely right about that!

When I put one of my works crappy Marshall Valvestate through my own 4x12" Marshall cab with old "greenbacks" they sound amazingly cool.
On the other hand, when I connect my old Marshall's to the speakers in the Valvestate it sounds VERY mediocre! Something to keep in mind, the speaker cab have a HUGE impact on the sound, sometimes I think much more than anything else, mics, distboxes, preampss etc. Not that they don't change the sound....

Tobias

IMO the general reason (or the Holy Grail) is hidden in the interaction of the output (tubes + transformer) stage with the GUITAR speaker.

QuoteIMO the general reason (or the Holy Grail) is hidden in the interaction of the output (tubes + transformer) stage with the GUITAR speaker.

Quote

Exactly right DDD, my criteria are: is the emulation capable of producing something that sounds like the perfect crunch sound.
This has to do with harmonics happening and a speaker compressing ( and distortion slowly setting in).
The OT contributing with certain a certain colouring of the signal.
It's all very complex.
The sound  I like for example is the guitarsound of Tom Petty and his frontman Mike Campbell; mainly Voxes and small fender amps I read.
An amp emulation will need to helped by either a speaker simulator or like some people suggested by an OT and  an Alnico speaker.


Alf

This is a very enlightening topic indeed.
Hot for sure but, enlightenting never-the-less.
Check my current avatar.....that's all one Really needs to sound Awesome ;D

Quote from: markm on November 25, 2006, 10:46:33 AM
This is a very enlightening topic indeed.
Hot for sure but, enlightenting never-the-less.
Check my current avatar.....that's all one Really needs to sound Awesome ;D

I bet it would sound even better with a Fetzer Valve in between!

 :icon_lol:

.....well, and a comp!!

JFet amp emulator into a  Bobtavia (minus diodes), worth a quick experiment when I get time.

"Touch-sensitive"  There is another one that has multiple meanings.  For some folks, touch-sensitive means that they can still hear volume differences, depending on how hard they pick.  Touch-sensitive =  less compressed.  Sort of like the difference between a 2-diode clipper like a TS-9 and a 3-diode clipper like an SD-1.

For other folks, "touch-sensitive" means the difference in how the harmonics are introduced.  In this frame of reference, more "sensitive" means that any clipping introduced comes on gradually (as opposed to on or off) and that the character or quality of the clipping changes with picking intensity (as opposed to simply the amount).  From first hand accounts, this is the magic in things like the Ken Fischer amps - the amp only has three knobs because the remainder of the knobs are in your fingers.

I think most people reffer to the second one,

QuoteFor other folks, "touch-sensitive" means the difference in how the harmonics are introduced.  In this frame of reference, more "sensitive" means that any clipping introduced comes on gradually (as opposed to on or off) and that the character or quality of the clipping changes with picking intensity (as opposed to simply the amount).

Sorry to ask again:
Are ROG emulators touch sensitive according to this definition?
Maybe the previous answer was missleading as it was not clear what touch sensitive is.
Thank
Cheers
Rafa

  The ice is broken
 To sound, a speaker must be used.
 How well you do here influences all sounds.
 ...building a rig.
 Choose the speaker[s/cab arrangement that fits your needs...and that tends toward the 'bang for bukk' business...you can circumvent some of that with careful shopping [having the capitol to spring on a deal that pops up etc.]...and of the thousands of choices, I tend to prefer ones that are fashioned after or are 'older celestion or jensen type'...YMMV...wholly an OT subject...
 'Many speaker choices may disallow the type of response your'e looking for'.
 Speaker connections should always be excellent.
 Then you get to the amp...another 'thousands of choices' affair/bang for bukk...many amp choices may disallow the type of response you're looking for.
 Cable>Guitar...pretty much same as above...
 At this point you can make electric guitar sound, hopefully it can sound good already.
 NOW you can try 9v circuits...whether any of them are 'tube like'...again...thousands if not millions of choices for a response to 'is it tube-like'?...most if not all of those responses having missing subcontexts...and that's the way it will be.
 It's like we're comparing a tire type, ...whether it works like a racing tire on a motorcycle or a truck...I venture to say we're all driving different type vehicles...that difference probably equates directly to the differences in our chains...Including ALL the links...speaker/amp/guitar etc.
 You tell me what 'tube like' IS and I'll take that with a grain of salt.
 

Quote from: Gus on November 24, 2006, 01:28:22 PM
Often one of the opamp gain stages has an interesting transistor resistor section of the feedback network

I find this very interesting, I always wondered whether the clipping thresholds of diodes could be dynamically varied like this. (I know this may not be technically precise...)
I'm a freak regarding "touch-sensitive" clipping.
Do you know of any pedals that use such a network?

Grant

Theory-noob

All this 'comparison' stuff is a red herring, too - when an audience hears you playing through an SS amp, with or without an, for the want of a better word, emulator, they are not mentally comparing your sound to a valve amp. They are only listening to your sound in the context of all the other sounds going on at the same time. If some musicians have trouble distinguishing 'real' from 'emulation', you can bet most audiences don't even notice. Of course, some musicians are more concerned with 'tone' than music.

Those FET-emulations work quite well on 32V DC and with this supply voltage the dynamic is quite good. FETs have a different reaction and generate a harsher distortion structure compared to preamps tubes.

Some older Randall preamps use a Marshall JCM 800-FET-emulation for the preamp but most of the sound on those amps is generated by the power tubes and the speakers. Randall has droppes this concept, Ampeg too and both use tube preamps on their new designs. MESA tried a FETRON on the Boggie Mk2 and dropped it after a short time and Dumble cancelled the FET-Booster on the newer amps.

Emulations powered on 9V are only OD/distortion boxes with some filtering and they are no substitutes for good tube-preamps, nothing more.

JHS

QuoteOften one of the opamp gain stages has an interesting transistor resistor section of the feedback network


I find this very interesting, I always wondered whether the clipping thresholds of diodes could be dynamically varied like this. (I know this may not be technically precise...)
I'm a freak regarding "touch-sensitive" clipping.
Do you know of any pedals that use such a network?

That would be great
Cheers
Rafa

The MM GP3 circuit uses this trannie circuit. Both trannies are ZTX109 but in my schem one is drawn as NPN and the other as PNP. The diode generates the collector voltage for the trannie, this is is more precise than generating it it with a resistor. Never seen this in a pedal.

JHS

Quote from: Ge_Whiz on November 27, 2006, 05:20:15 PM
All this 'comparison' stuff is a red herring, too - when an audience hears you playing through an SS amp, with or without an, for the want of a better word, emulator, they are not mentally comparing your sound to a valve amp. They are only listening to your sound in the context of all the other sounds going on at the same time. If some musicians have trouble distinguishing 'real' from 'emulation', you can bet most audiences don't even notice. Of course, some musicians are more concerned with 'tone' than music.

It's not about what the audience hears, AFAIC. It's about sounding/feeling a way to inspire me when I'm playing.

QuoteIt's about sounding/feeling a way to inspire me when I'm playing.

Good point! If your tone sounds bad to you it will affect your performance, but a happy camper plays better. Which of course affects the audience perception of your performance.

I meant to add (but missed the edit window)- If all I cared about was the what the audience heard, I wouldn't lug around my amp, build stuff, and would have no use for this forum. I'd just get a POD, plug it into the p.a. and call it a day...

Doug, that is a very good point.

Whats the

QuoteMM GP3

?
Cheers
Rafa

What do you think is closer to the real thing, or will win the race, fets or computer physical models?

mac

Gotta qualify that.  One always has to work in real time, and is encumbered by size, cost, and physical reliability.  The other has no physical limitations, and does not always HAVE to function in real time.

Maybe I should have asked,
How close do you think fets and computer based pedals will get to tubes?  :icon_lol:

mac

DSP will win, if it hasn't already.

There are physical limitations to the properties of FETs and physical circuits.  The only limitations to DSP-based emulation is our capacity to measure and describe what is "different" about tubes and turn that into algorithms of varying complexity.  There MAY be limits to whether that can work in real time or not, but those all eventually fall in the face of newer processors anyways.

I thought that digital modeling could never have that feel which real amps have.
So why GT-6 and POD are so far away of  good simulations of real amps?
Is it difficult to measure an amp ``characteristics´´.
Cheers
Rafa

The sound quality is not "built in" to the technology.  Rather it depends on how the technology is used.

If I use a 320 x 200 screen, EVERYTHING will look jagged no matter how good an artist I am.  If my screen was 3200 x 2000 pixels, the image would be *potentially* less jagged and more realistic, but I would still have to be a good artist to make it *look* that way.

Current generation DSP is capable of doing a high quality job but several things have to be in place:
1) You can't ask the technology to take on too many tasks at once (e.g., reverb, compression AND distortion) and still expect quality in real time.  The things that DSP handles well with ease are the simple tasks like delay-based effects, EQ, compression, etc. because their relationship to inpu amplitude is relatively simple and straightforward.  Distortion properties are several orders of magnitude more complex.
2) You have to have an articulate detailed model and understanding of the phenomenon you are trying to emulate.  There are many things we understand pretty thoroughly/flawlessly about different types of effects, but a complete description of what happens in a tube context in response to variations in input signal still awaits us. 

And as always in science if you can't describe it, you can't predict it or control or replicate it.

  Power Supply
 Tube output section
 Iron
 Whatever else is 'mojo' in there...
 These items are co-dependantly interactive in a tube amp, capturing even the elemental ones necessary to make a fair replication necessitates complex algorythms, it is my belief that any processor will introduce some latency, the more complex the greater the number of calculations = the greater amount of time to perform them.
 For recording purposes the timing can be compensated for and synchronized.
 If time is of any consequence, simply processing to achieve 'x' tone cuts time big time...getting a tube amp/guitar/effects to sound cool/be low noise is expensive and time consuming, as is the Mic/Pre/and any effects you want added...alot of figuring out...by the time all that got done you could have accomplished Alot of recording as opposed to gathering up batches of hardware items and working with them.
 As far as stage sound goes, [I'll stick with my opinionated self, based on experience...I've seen and used ALOT of tube and tube-like amps]...and say it depends exactly on how your hardware and or software solutions are working for you, the way you're applying them.

Distortion properties are several orders of magnitude more complex.
  I would like to add that the rate at which these complex algorythms occur is 'quite fast'.
 

Quote from: petemoore on November 28, 2006, 12:21:55 PM
Distortion properties are several orders of magnitude more complex.
  I would like to add that the rate at which these complex algorythms occur is 'quite fast'.

Correct.  Which is why if you are attempting to "simultaneously" do compression, distortion, EQ, phasing, delay, and noise gating all in the same DSP-based floor or rack unit, there is a good chance that the algorithms for the distortion will be wanting.  Dedicated DSPs are more likely to be successful in doing what needs to be done for real-time authenticity - in all its complexity - than DSPs asked to multi-task.  Same reason why console game-machines were always so much faster and smoother in their graphics than multi-tasking desktop PCs running at even faster speeds.

But we've had this discussion before....many times. :icon_rolleyes:

I have a digitech unit that uses 2 12AX7s in preamp distortion section that gives loads of flexibility as far as distortion along with the digital distortion.  The main issue is that things that are time based like reverb, echo, flanger take up a ton of memory.  I used to use the unit a lot, but found it a bit artificial sounding a couple of years ago and quit using it.  I am now looking at using the effects loop for echo and reverb.  The amp emulation is pretty decent but I find these units like a swiss army knife, they do a lot of things decently but nothing really outstanding.

Stan

The output tube(s) to the transformer is going to be hard to model

I build and mod condensers microphones for fun In my learning I have relammed and bought a number of different >20 transformers to use in tube and solid state microphones.  Amorphous core, 49% Ni Mu, 80%Ni  Mu, Mixed Mu Co Fe lams, China alloy lams don't know what it is.    Besides the inductance change and winding method and size the alloy type(s) make a difference.  They all sound different.  I friend of mine that has a studio and DIYed alot of it  can often tell the transformer brand by ear.   Look at the distortion curves of the transfomer vs level; and other parameters(look around cinemags site at some PDFs)

Take M6 M29 etc used in guitar transformers.  The same stuff does not work well at microphone output levels but if it gets a big enought signal  it works well.  Then you have the BH curves and inductance that change with level.  Who know whats going on in the pentode(s) when the amp is clipping. 

The overdriven output stage seems to matter a lot.

Quote from: Meanderthal on November 27, 2006, 08:52:36 PM

QuoteIt's about sounding/feeling a way to inspire me when I'm playing.

Good point! If your tone sounds bad to you it will affect your performance, but a happy camper plays better. Which of course affects the audience perception of your performance.

Point made. You see, not only do our perceptions of the sound differ, we're not even playing to the same purpose. Fun, but ultimately pointless, discussion. Personally, I make a point never to play with 'bad tone', and what inspires me is the music I'm playing, not my perception of my own 'rock-godness'. No offense meant.

I want "TZD" : towards zero distortion.
now - not after processing
no latency...  :icon_smile:

Quote from: puretube on November 28, 2006, 07:58:18 PM
I want "TZD" : towards zero distortion.

So, no use having a valve amp, then?  :icon_wink:

that`s a "zero" in the time-domain: instantly - not after having waited for the "processor" to have completed its calculations...

(zero latency)

Acoustic guitar?

Quote from: Ge_Whiz on November 28, 2006, 07:30:10 PM
Personally, I make a point never to play with 'bad tone', and what inspires me is the music I'm playing, not my perception of my own 'rock-godness'. No offense meant.

For me, a lot of different things inspire me: The music I'm playing as well as my sound/performance, the sound/interaction/performance of the band as a whole, etc, etc. My main motive when playing is to touch the people we're playing for. If any of those things are "off" or if I'm uninspired or bored with what I'm doing it can distract from that.  Yes I do care about the audience, so I need what I'm hearing to feed back into my playing so they will get a good performance.

Is that more clear?

 

QuoteFor me, a lot of different things inspire me: The music I'm playing as well as my sound/performance, the sound/interaction/performance of the band as a whole, etc, etc. My main motive when playing is to touch the people we're playing for. If any of those things are "off" or if I'm uninspired or bored with what I'm doing it can distract from that.  Yes I do care about the audience, so I need what I'm hearing to feed back into my playing so they will get a good performance.

Ditto.

And if a jfet emulator/whatever gets me there, fine by me. Not at the moment(no tubes at all or emulators in my current live rig), but I'm eyeing up the Flipster...

Quote from: Meanderthal on November 29, 2006, 06:00:11 PM
And if a jfet emulator/whatever gets me there, fine by me.

I agree 100%. So why call it an "emulator" when we are not trying to imitate something "better"- it's a very good sound in its own right.

IMHO we can call them amp ``X´´ adapted as a stompbox, or amp ``X´´ stompbox adaptation
In an shorter way, ie: Vox Ac30 SA
I dont think its neccessary to clarify that the tubes have been changed for transistors as most stompboxes dont have tubes.
Cheers
Rafa

more "professional"
Tube Amp FAT Emus (http://www.pat2pdf.org/patents/pat5761317.pdf)
and Tube Leds (http://www.pat2pdf.org/patents/pat6507240.pdf)  :icon_eek:

Rafa,don't sweat it ...........listen,I have built at least 20 tube amps,anything from a trainwreck to a firefly with everything in between..............I havent heard a single amp that can do everything from clean to full out distortion the way I would like it......how can we expect a little box full of chips to do that convincingly?(at least at the point the technology is right now,remember that also the box has to cost less than the famous  50 thousand dollar hammer for NASA).

Like you I have a Princeton SS (Princeton Chorus 212) that I like for cleans,I like the distortion on my SLO,crunch is cool too...maybe too agressive......see what I mean?..............endless tweaking,but in order to be "happy" I have to cary a truckload of sh*t to the gig.

I recently upgraded my digital stompbox to the latest model..........the presets (70) sound like "crap" if you ask me and I almost returned the box for a credit bit I started fiddling with the individual effects and I was floored!!,nevermind that the tuner alone pays for the box but the wah simulations are some of the best wahs I've heard,reverbs are lush,chorus is great.......the problem is that people put a string of 20 efects on the chain and expect the thing to sound like what?.it would sound like crap with 20 analog effects too.
Then they plug into a crappy SS amp with an 8" speaker and want 412 "emulation"?.

Distortion is another problem,like MArk says.............but I even that,I've run a  distrotion emulation through an HO amp on "clean" setting and the the resulting distrotion was the best ZZtop emulation of BGs guitar I've yet to hear but then it won't do cleans well if you know what I mean.

I have a friend that's a professional guitarrist for more than 30 years.
He either owns or has owned every amp ever,he's got tweeds,bassmans I've played through them,some sound like crap to me some are really nice....one thing for sure,he can almost make them all sound most excellent..........you know what I'm getting at...........

If you ever go to a tube amp forum you will see people argue about what tubes sound better,what brands and if that is not enough ............what year or batch number..................

I say get some decent gear that you like and can afford and play your heart out..............in the end once you get your perfect sound in the bedroom you still have to filter all that through the noise in the bar,beer goggles and that chick in the corner that is making faces at you and makes you forget what song you are playing.
This is rock and roll after all...........come to think of it the players I admire the most played through whatever loaner they could find and a tele with no effects.....but thats me.
I'm sure technology will get there sometime in the near future...............did I mention I don't like samplers?

Aharon

What a long and great response Aharon
Clearly youre much more expirenced than me, lately Ive been very busy with university, (I havent been around much), so I havent had much time to finish my projects. But one of my projects I want to finish soon Is a small champ, Which I already have all the tubes except from the rectifier which Im going to use diodes. I must admitt that what motivated me to build the amp was this long and endless discussion between SS and tubes. As I said before SS distortions never called my attention but on the other hand I havent palyed thorugh many tube amps in my life, so building my own seemed the best idea. I agree with you maybe I worry too much about equipment,
Cheers
Rafa

Good luck with the Champ.. :)

Did you ever go to the Ax84 forum?..............there's a couple of amps that could be made with the same parts as the champ (give or take a few) that may be better suited to what you are looking for.
Have you looked into the HotBox,if what you want is tube preamp distortion maybe it's a good alternative....true,it does not include power tubes or output transformer but it's "simpler" to build and less expensive and you can plug it into your SS amp.
PM me if you need anything.
Aharon