Amp Emulations

[Doug_H]

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.

[solarplexus]

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? 

[ildar]

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? 

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...

[zjokka]

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!

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

[tcobretti]

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.

[mac]

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

[Rafa]

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

[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

* 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

[mac]

Thanks for the link Rafa.

mac

[krille2]

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

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  ) be interesting...

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

[rodriki1]

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

[R.G.]

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?

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.

Simulation, 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.

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.

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.

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

... as you note here.

Until 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.

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.

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!

[Mark Hammer]

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.

[Rafa]

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)

[Doug_H]

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.

[rodriki1]

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

[Rafa]

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

[puretube]

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

Out 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)

[Mark Hammer]

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".

[d95err]

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.