Adding Feedback & A Presence Control To A Gibson GA-8T (Cathodyne Phase Inverter model)

[One10]

Removed, wrong catagory. Thanks Loudthud for the info.

[loudthud]

This might be a case of trying to do too much with too little. First step is to measure the gain (power amp input to speaker) with all feedback and bypass caps on the 2.2K disconnected. Next, measure the gain again with the 2.2K fully bypassed with something like 22uF. This will tell you how much boost you might expect with caps across the 2.2K. Lastly, connect feedback to the 100 Ohm resistor with the Presence control disconnected. The gain difference between the first measurement and this one will tell you how much boost the Presence control can give. Select the feedback resistor for numbers like 10X gain difference or 20dB are high, but not uncommon. That much gain reduction might be too much and cause the amp to oscillate.