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I parted out a hammond M-103 organ and found a cool sounding AO-35 reverb amp. I plugged my guitar into the Chassis mounted RCA jack that said input hooked up a speaker and got a ton of articulate gain, overdrive, compression, sweet harmonics and controllable feedback! I need to re-work the first gain stage of the input to match the impedance of a guitar pickup as it was designed for a reverb coil. I am going to add a grounded power cord, ground switch, on off switch, standby switch, 1/4" input jack, 1/4" speaker jack , pilot light (110 volt led), fuse holder, volume control and possible a single tone control. I read on the net that Dr. Z copied the Hammond AO-35 to a T and called it the Carmen Ghia. Does anyone know where I could obtain a Dr. Z Carmen Ghia schematic? I would like to see how he wired the volume control, single tone control and impedance front end rework modifications. I found a schematic for the AO-35. I don't need any directions to do the simple mods like the power cord, input and speaker jacks, pilot light , standby, power, ground switches or fuse holder, all that I have done many times before. I just don't want to damage this real cool amp fiddling with the actual circuitry design as I noticed some weird DC stabilizing circuitry going to the driver and am afraid to mess too much with the circuit until I can find out more about it or obtain the mods in the form of a schematic. Any help you could give me or direction you could point me in would be greatly appreciated. I read on the net that Dr. Z copied the Hammond AO-35 to a T and called it the Carmen Ghia. Does anyone know where I could obtain a Dr. ZCarmen Ghia schematic? Thanks! Best Regards Amp Techs!
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Remove the negative feedback. This will give you more gain, and allow for decent sounding overdrive (remove the wire from the speaker out that goes back to the 3.3Meg resistor on the board). You may find that it has enough gain for you at this point.
Change the resistor and cap across the input of course, as possibly remove the .0022 cap from the grid to the cathode of the input tube.
Reduce the coupling cap between sections to keep the bottom from overdriving too much - try .001. Alternatively, reduce the coupling caps ahead of the output tubes instead. (Try both and see which you prefer.)
There may be more gain available in the second stage - I'm not up on my resistor values Vs. gain. Check the post EQ stage of a Fender or Marshall and try those values.
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