Hello,I look forward to being a active participant on this site.Guess I missed this one............there are a lot of great amplifiers around...................some of them ARE Solid State..............and I think I own one of the best. IMHO : ) Glad to be on board! Gary
Wow what are the odds. My first time here as well, poking around, looking for advice.
G2r, G2x, now recently a Mesa LoneStarSpecial Compact.
Cheers :tu:
Hey thats Cool! Welcome! These guys know their stuff, this should be interesting and fun! G.
Please post whatever you can (pictures, MP3, schematics, manuals, whatever), these are the Rolls Royce of SS amps.
I don't know anything about Pearce amps at all, so I second the thought - please post anything you have :-)
Those were designed by Daniel Pearce, a member of the Moog design team that devised those Lab Series amplifiers in the mid 1970's.
In his Pearce Amplification venture Daniel basically revised the design to somewhat more modern standards: dual channels, footswitchable, more gain for serious overdrive + gain controls, boost feature, etc. Basic design is still pretty similar to its precessor featuring:
- active tone controls, mid-range control being parametric
- distortion based on overdriving an OTA* to either symmetric or asymmetric distortion (for added distortion the Pearce amps also feature plain diode clipping).
- Compressor/limiter
- linear power amp with lot's of headroom
* overdriving an open loop operational transconductance amplifier stage without "diode compensation" in use results to very soft clipping. The iabc terminal can be used to adjust the clipping into asymmetric one by feeding the terminal with the input signal. Refer to Lab Series L5/L7/L9/L11 schematic or to Moog's patent covering the design.
Schematics to Pearce G1 and BC1 models should be found from some website dedicated to Pearce amps (can't remember the site's name but Google should find it easily). For all info about Pearce that site is pretty much the must-see featuring scans of schematics, manuals, mods, advertisements, and even an article about the company's history from its beginnings to its downfall, written by Daniel Pearce himself. I haven't found G2r schematic yet (unfortunately the site doesn't feature one yet) but I doubt that it differes much from the earlier models.
After these things, around the mid 1990's, Daniel started to work for A.R.T. and helped to design some solid-state amps for them, Attack, DST-and SGX series, etc. These were basically similar to all Pearce's designs (see above similarities) but now came with digitally controlled switching for analog circuits, which allowed storing "tone" patches like in modern modelling units. In addition to the traditional OTA distortion they also featured an overdriven triode stage with low plate voltage. The circuit was used for extreme amounts of distortion. Basically, I think these product should be raised to the same pedestal as Pearce amps (they were Great solid-state products), but they never just got the same commercial success nor the same amount of famous endorsees. (Which is nice, because if you're lucky you can find a nice DST-series amp with quarter the price of a much more famous Pearce amp and it hangs with it just fine, actually goes even further to the downright extreme metal territory).
Hey friends, trying to find a manual for a Pearce A1 mono power amp.
Thanks @teemuk, haven't used a lot of OTA's myself, and then in instruments not amps, so I wasn't aware of this soft clipping characteristic.