I just got a converted Hammond organ amp. It was converted into an Ampeg M15 circuit. It has two 6L6 (KT66) power tubes, three 6SL7 preamp tubes and a 5U4 rectifier. The amp has tremolo. Here is the only schematic I could find (it doesn't have voltages.) http://www.freeinfosociety.com/media/pdf/3366.pdf This amp sounds really amazing. There is only one issue. It isn't very loud. I am talking Champ or Princeton loud. My 64 Fender Deluxe is waaayyyy louder. I will also say the amp is quiet at idle. I have had amps in the past with bad filter caps that robbed volume, but they also didn't sound that good. What do you guys think might be wrong with it and what should I do? Since it sounds so good, maybe I will just accept the lower volume. I just checked the voltages. The B+ voltage is 480 volts. The screen voltage is 380 volts. The voltage at V1 is 95 volts. The resistor going to V1 is 270K which is what is shown on the schematic. I see some other Ampeg schematics with 6sl7 preamp tubes with a 120K resistor in the same spot. (maybe the schematic is wrong??) The schematic I have referenced above doesn't have any voltages on it so I am not sure what they are supposed to be. BTW, I have KT66's in it instead of 6L6's so the 480 volts should be ok right? I think 6SL7's should run at about 130 volts in these amps is that correct? Thanks for any help.