Ampeg Treble Boost

[unclej]

when i was working on the gemini II i noticed that both channels had treble control pots with on/off switching for treble boost. i don't know exactly why this popped into my head at 11:30 last night but it did. since the on/off mechanism engages at the end of the clockwise rotation and that activates the boost i'm assuming that it's disengaging something rather than engaging. am i correct and if so what's it taking out of the circuit? a cap or two? i looked up the schematic but since i'm still somewhat schematically challenged i couldn't figure it out on my own.

[lovekraft]

The "Ultra-High" rocker switches over each channel simply switched in a bleeder cap in parallel with the volume pot, like a Fender "bright" switch. Are you saying that the one you worked on had switchpots instead of the rocker switches?

[unclej]

yes..each channel had a switchpot and i couldn't really tell what went where because the volume, bass and treble controls for each channel were soldered to a small circuit board and a lot of the amp's wiring ran between the boards and the chassis and under the pots so it was hard for me to trace anything.

now that you mention it i do remember there being a large, rectangular ceramic cap and a ceramic disc cap soldered to the board. so one or both of those could be what's being switched in and out of the circuit?

[lovekraft]

Sounds like the Phantom Modder has been at work!