Re: Guitar Amp Modelers
There has been a great deal or work done on tube mimics. Peavey was an active participant in that fox hunt and IIRC got a patent or two on their technology, while there are plenty others.
As you well know the sound character of a tube guitar amp involve multiple moving parts. Beyond the static transfer function characteristics (like distortion) there are dynamic mechanisms going on inside the tube. That I am probably not describing accurately but when you significantly overdrive a tube the internal charges can shift around inside the bottle and alter the tube behavior, until that rogue bias state decays and returns to normal.
While not exactly the same thing as this thread is talking about I have heard Peavey solid state amps that were designed to mimic tube amps that sounded very good to my "not a guitar player" ears. In fact and I have shared this before, Peavey did a single blind A/B demo at a NAMM show (probably 15-20 years ago now) where the majority of players could not tell the solid state amp from a real tube amp. A nice thing about the solid state tube mimics is you can play games with adjusting the special tricks. The saturation effect could be dialed down to give the screaming overdriven sound at modest, less than ear splitting levels... Some real tube guys use a tiny amp to get that effect or variac down a bigger amp. Another tube mimic is to artificially alter the amp output impedance to increase interaction with the speaker/cabinet. Doing this in solid state allows you to not only make this variable, but tweak HF and LF amp output impedance separately. Of course this becomes too many knobs to turn for the typical guitar guy, I could imagine fun in the recording studio.
By definition a solid state amp will never be a tube amp, but we have the technology to get pretty damn close, and for feeding a PA close enough.
On a related note I tried to get one of the junior guitar amp engineers at peavey interested in making a solid state tube mimic that was actually better than a tube amp. My premise was that using extremely low noise JFETs and transistors in a tube mimic circuit could make a tube-like amp with lower noise floor and wider dynamic range. AFAIK he never took the bait and pursued that. :-(
IMO for many the attraction to tube amps is more a fashion statement than about absolute sound quality (not all tube amps sounded good), kind of like like the old school audio-phools and their vinyl.
JR
