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
Like you John I have also followed the transition of transistorized amplifiers to todays modeling amps wondering if some day the technology would come to a point where the replication of a complex tube circuit could be produced using a DSP. I'll agree that the latest technology available can almost faithfully replicate most of the more well known and desirable amplifiers. A VOX AC30, Fender Deluxe Reverb, Marshall JTM45, etc. have been around long enough to be recognized instantly. That being said, replicating the sound is one thing, but replicating the feel which translates back to the player is another matter entirely. That feel which translates back to the guitar can be a subtle as a harmonic or the amount of perceived pressure used to bend a string. This is what's lacking in modeling amps IMO, the same thing that was lacking in the first transistorized amps of the mid/late 60's.
Now, with all that being said the use of a modeling amp is becomes more acceptable depending on the style of music played. Mimicking stomp boxes has never been much of a problem because they are an added effect and with few exceptions based on the reaction of some 3 legged dummies, a few diodes, or a single chip. But even those emulation can be inaccurate. As an example the SM57 of the stomp box world, the venerable tube screamer suffered from the use of newer technology when the tone and response characteristics changed as the latest chips were manufactured to tighter tolerances, enough so that sales dipped and Ibanez felt compelled to release a re-issue using specially manufactured loose tolerance chips. To someone who is not a player, or a player with no experience with these older units, the difference may go unnoticed, but to most players the sterile sound of the new chips meant everything.
I have had a chance to try the Kempler and the Fractal modelers, and I'll have to say they are amazing. The emulations are for the most part spot on and just fine for that person who needs something to cover a dozen styles of music, or for someone who wants to replace their stomp boxes. I found some differences, or failings if you please, in that emulating a small open back cabinet with a D120 in it compared to replacing a D120 with a clone speaker. Close but no cigar. I also found it difficult to emulate a number of compressors, specifically a Ross compressor. Delays and reverbs were fine, but the reverbs didn't come close to anything I've ever heard coming from any Fender with the word reverb attached to the name. I did like the Leslie emulation I was able to dial up and just about everything else sounded just fine. I didn't feel either unit was very touch sensitive. The best experience was when I pushed the modeler through my board, through a small QSC amp, and then to the cabinet of a Super Reverb loaded with Warehouse 10" speakers (4ea.). Thanks to my friend Tim who took the time bring the unit over for the listening test and who put up with my constant requests for changes to his settings.
John, Your not so good ear was spot on. Many of the Peavey transistorized amps fall into a small line of acceptable solid state amps. It's no secret that a good number of amplifier manufactures shot themselves in the foot after turning to the 3 legged dummy as the replacement for the tube. However, Peavey was not one of those companies. Put them in a category with a couple of the old Gibson amps, LAB 5, Roland JC120, or SG Systems (hybrid). Many is the country stage I've seen where Peavey amps rule supreme when set beside a Twin Reverb or equal, a statement that holds true to this day. Ask yourself why BB still uses a LAB 5? There are exceptions to every rule.
For me, and with the style I play, there is no modeler made that can replace my beloved Fenders, and very few boutique amps for that matter. And after I blueprint an amp, well nice try. But that's not to say modelers don't have their place, and what's one old fart got to do with their acceptance. Not much I would think. So, maybe before the dirt nap when I can't pick up the old iron, maybe then will be the time for me.
~:-D~:grin:
