How far from close valve emulation with SS; a statusquo?

Steben · March 12, 2007, 06:33:04 AM

As I look at CMOS inverters, jfet mu-amps and the most recent fetzer evolution, I sense a big smile on my face. I always let myself into the quest for great tone with cheap semiconductor techniques.
If you did let go of low 9V supplies and did choose between different symmetric soft clipping circuits, you were able in the past to produce nice high gain sounds. But the clean to smooth drive glimmering was hard.

But the last puzzle pieces emerge. If one can bias a jFET into non-feedback triode response these days, what a progression indeed. If you add some power sag techniques there is no single item I can see unanswered. The question may rise: if you can make an easy-money SS amp sound like a vintage valve amp, why pay for the latter, since you can make the well-known easy additions on your SS alternative. Indeed, your FET's can be switched to more non-linearity and back, your clipping can be moved from soft to hard, the sag can be tailored in detail and character. But the opposite is true as well: a small amp with some well-biased jFET's and a single power IC can sound perfect for only a couple of $. In other words: thought-through analog SS (the enemy of today's purists) may as well be the real economic stand-up against digital in the future. In 20 years from now, analog SS can possibly be the new mojo in a ferocious digital world, laughing already with prehistoric unefficient valve amps.

Hence my question: How far or close are we with analog solid state? Are we far "from" close or far "to" close? Admit it, the sound of the latest SS "blue amp on video" was astonishing and no digital discussion there.

PS.:Puretube, don't take this personal ;-).

Meanderthal · March 12, 2007, 07:27:53 AM

Depends on who ya ask, it's very subjective. Tube elitists would say not even close, guys like me would say wow, that's pretty close.

puretube · March 12, 2007, 08:52:23 AM

WGTP · March 12, 2007, 09:37:00 AM

I think it may also depend on which Tube distortion your talking about. The pre-amp distortion generated by hi-gain multistage pre-amps, or the output stage distortion.

petemoore · March 12, 2007, 09:50:07 AM

Jfet/Tube comparisons...yuupp.
For the preamps, quite comparable yet with differences.
Output tubes however do some 'hoop tricks' that are going to be difficult to make SS device subs jump through.
Part of this is that it's not just the tube influencing the sound, the speaker loads the amp in a high speed, dynamic way, load increases and decreases have very complex algorythms, the way an output tube distorts also changes freq response in a certain way.
I think Part of the reason transistor amps aren't so-mo-jo-ey like tube amps is because tube amps had a head start.
And the approach of SS amps seem very often to have 'tube related goals' in mind. Tubes...you just hook 'em up, load 'em down and they do 'that', SS amps want to be linear or non-linear in a less-musical way unless 'directed' to act in a more musical sounding non-linear fashion, most of this work is done to the preamp, and in my field tests seems to be 'goal specific', ie 'does distort' or 'distorts with sag', and can be very successful..alot like tube amp, some sorting, working with, and tweeking can produce outstanding results, 'like tube amp' is one thing, like 'great amp' is another.
It's pretty easy once a tube amp is running, to just 'lean on it', drive the input, load the output, it'll get 'squozed' in the middle, and produce non-linear response, tending toward a smaller frequency band, having a 'springy, spongy ceiling', SS amps tend toward linear response that turns to 'spikes' for distorting, more attention to what the signal swings are 'hitting against' and 'where' [preamp usually]..unless I've missed some recent discoveries, an SS output to speakers 'unsaid rule' is 'keep the output amp linear', once it goes beyond a certain point of non-linear-ness, it'll begin to throw nasty 'spikes' in the speaker.
But, that doesn't rule them out by any means for various applications, nor does it preclude SS applications to being 'lesser'. AFAIK not much work has been done in the 'touch response' as far as introducing sag and reduced frequency response under high input voltage conditions.
Did I just start typing about 'SS Vs. Glass' again?
The phrase "Works Like Tube" isn't really accurate, and probably limits the research done on SS amps, with an often used response to that phrase "Why not just use tubes" used..
I know for certain, most of the SS amps I've seen used are of 'pre-chosen' voicings, ie an internal distortion pre-amp matched to an SS output amp, produced, consumed, and applied as-is, some work good with distorter boxes, very many have 'prevoiced' clean and distortion channels which dont' lend themselves to being 'revoiced, then prevoiced again', so the choices of tone are mostly what parameters are chosen for the production line design.
I have seen some SS power amps used to great end results...a ''fancy' preamp driving a linear amp into guitar speakers..and there have been really cool production amps that do great tones, clean and distortion...'great sounding' is the term I'd choose, but 'tube like' is often [mis] used [IMO]...sounds like tube [tube under a specific set of conditions, [or two, or three or more, probably in the preamp], but doesn't 'work like tube'...you can't just increase the voltage swings of the source input and expect 'tube like distortion'.

Steben · March 12, 2007, 01:10:03 PM

It's painfully pleasant to realize that designing what a powerful DC detector (following the guitar's signal) can do. It can be used to produce a sag-regulating voltage, yet it can also regulate a frequency response. If you make clipping (see amz) frequency-related, it's a step ahead.

My view: It's not impossible yet no one actually put an effort in it. It's hard to analyse those tube-things but I am convinced it's worth it. In fact, the digital world is much harder yet they do make emulations of every power amp distortion possible. AND they dared starting a couple of years ago with something flabby.
Tube amps are indeed "easy": let the tubes do it. But I am afraid I see it as laziness, which means it can be ok as a choice, but not totalitarian.

It's typical anglo-american to me: no precedent? probably not possible I tell you...

puretube · March 12, 2007, 01:23:36 PM

a few linx are missing in my last post... ("peavey" / "sondermayer" - content a.s.o.)

WGTP · March 12, 2007, 01:34:42 PM

Is it possible to move beyound the quest for tube sound to somthing we like even better? Either SS or Digital. Some folks already like there DS-1 or TS clones better than tubes. I use both.

Phorhas · March 12, 2007, 01:58:02 PM

Steben,

What is your goal, a SS amp that will sound great in both clean and distortion modes, or pedal that will give good tone with the "quality" of tube distortion?

puretube · March 12, 2007, 02:05:18 PM

that latest BJT-thing of today (mentioned above) is sooo cool - I`m gonna turn that one into a pure tube design !

Steben · March 13, 2007, 07:36:18 AM

Quote from: Phorhas on March 12, 2007, 01:58:02 PM
Steben,

What is your goal, a SS amp that will sound great in both clean and distortion modes, or pedal that will give good tone with the "quality" of tube distortion?

Both are nice though...

Phorhas · March 13, 2007, 08:19:44 AM

Well, for amps at least, I don't think we should even bother and here's why:

Why replace a winning horse? Tube amps are not that expensive (at least, most mass produced combos), and you can get sound sound for a low price with entry level tube amps. So, why bother building an emulator when the stuff you really want is readily available.

But, for pedals, now there's something different. Even tube pedals don't give the real "feel" of playing in front of a well-driven tube amp, rattling as a whole. So, I think we should not bother to emulate the tubes themselves, but rather try to build a profile of good tone and then maybe see how this could be produced with low voltage SS design.

But, when I just want good tone I drive the hell out of an amp and don't even bother with pedals other than boosters.

Ronsonic · March 13, 2007, 08:50:51 AM

The analog emulation of a tube amp has not, to my ears, been improved since the solid state Vox amps of the mid to late 60s. They worked very hard at making those amps sound right and were very successful. If I ever felt the need to try an emulated tube amp project I'd probably start with a Vox Viscount.

Ron

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How far from close valve emulation with SS; a statusquo?