Rivera era Fender Concert amps - any experience?

Stuckfast

Thanks. Sounds like a good plan -- I don't mind the existing sound on that channel but it doesn't go very far into distortion even fully cranked. Probably one for a tech to attempt rather than me, though.

ICBM

Stuckfast said:

Thanks. Sounds like a good plan -- I don't mind the existing sound on that channel but it doesn't go very far into distortion even fully cranked. Probably one for a tech to attempt rather than me, though.

It does increase the amount of gain available hugely - the insertion loss of the tone stack is huge and really restricts it when it’s at the beginning of the signal path, and is then rather uselessly boosted by the following stages without adding much more distortion. That’s why in the original circuit there is a fixed attenuation of about 7dB via the 82K and 22K resistors, in order that the overdrive channel isn’t massively louder than the clean. If you put the tone stack at the end instead, the problem cures itself - normally you would just use a 100K resistor there, but 104K is so close there’s no point in replacing the resistors.

It’s actually slightly puzzling why Paul Rivera didn’t realise that, but it may be because contrary to popular belief he wasn’t entirely responsible for the design, he was just a consultant - the actual designer was Fender’s long-serving R&D chief Ed Jahns, who was very much an old-school ‘proper’ electronics engineer and regarded clean power as the goal and distortion as a fad. Getting Jahns to add a distortion circuit to the Twin hadn’t been successful because apparently he couldn’t tell the difference between ‘good sounding’ and ‘bad sounding’ distortion, it all just sounded bad to him.