Different tubes affect tone
Hi Skip, so I have this Bogen ph10 amp that had been rebuilt in to a Gibson ga6 circuit 12ay7 6sl7 2 6v6 5y3. all the tubes are vintage but all test very good. So I play it and the tone is kinda thin no break up ,no bottom , just real flat and dull sounding. So I though maybe no good for harp sell it to a guitar player right. Well the other night I decided to do some tube rolling, put in a old groove tube 12ax7 and a tung so RI 6sn7 in and dam! The tone fattened up great break up no feedback great volume just a completely different amp, not for sale now. I actually have a 1957 ga6 with the 2 12ax7s and that to I had to put a 5751 and a 12au7 in and it sounds killer with that tube set up also, they are both stock circuits. it seems that the low gain tubes in the phase inverter position seem to fatten and smoothe the tone out, on my amps anyway. Is that normal? I know the lower gain tubes run higher currents , I have 1w resistors in so they should last longer than the 1/2 w ones? I guess what I learned from this is if it don't sound right try different gain tubes cause the right combo can really make or break amp tone. I'm just amazed how good the amp sounds now!
Great job Bluevan! And to think that you were going to sell it! Actually, what you really learned was that even the simplest thing can offer endless variation. Beer is made from just a few ingredients,but just think about how many kinds of beer there are (and how tricky it is to make yourself!).
One-watt plate resistors should last indefinitely in a well-designed circuit.