Low volume but still great tone???

[straightblues]

I just got a converted Hammond organ amp. It was converted into an Ampeg M15 circuit. It has two 6L6 power tubes, three 6SL7 preamp tubes and a 5U4 rectifier. The amp has tremolo.

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.

[52 Bill]

Because of the fact that this is a conversion circuit, there is no easy way to judge how loud the amp should be. Whenever I see a push pull power amp with 6L6's, I assume that there will usually be at least 30 watts.

What I'd suggest to you, is to start by taking voltage readings in the power amp and then figure out what sort of wattage you should expect from the amp. Then run a few tests and see what wattage the amp is actually putting out. If the actual is far below the theoretical wattage, then start looking for mis-wired or off value components, etc.

How does the actual circuit compare to the Ampeg M15 circuit?

[straightblues]

I don't have much experience working on amps. But what I have been told and looking at the schematic, it looks like a faithfull recreation of the M15 circuit.

[straightblues]

Here is a link to the schematic. http://www.freeinfosociety.com/media/pdf/3366.pdf

[big_teee]

I would want to know what the B+ measures.
If the B+ is low, The volume will be low also.
The B+ Rail Voltage would be a good place to start measuring.
Be careful!
B_T

[straightblues]

Ok, finally got a chance to check 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 right?

Thanks for any help.