Amp Emulations

[aron]

We 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.

[Ge_Whiz]

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.

[mojotron]

We 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

[MartyMart]

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
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.

[Rafa]

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

[Ghandi]

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

cheers
ghandi

[Ge_Whiz]

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%.

[electrictabs]

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

[Meanderthal]

 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?

[MartyMart]

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

That made ME smile ! 

[tcobretti]

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.

[Somicide]

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. ^_^

[wui223]

Fender: Don't emulate, innovate. 

[Meanderthal]

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. ^_^

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....

[Somicide]

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. 

[d95err]

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...

[puretube]

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.

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 

[Doug_H]

Emulator shmemulator... Tubes shmoobs...



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


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.

[Mark Hammer]

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.

[jrc4558]

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.

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 

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