The Amp Garage

Actually, I was referring to the heater wires at the sockets. Don't lay the grid wires on top of them. Also the placement of the pan is a big deal. Be sure the output end of the pan is as far away from the power transformer as possible.

Do you use AC filaments throughout the amp? I suggest watching you don't place audio signal wires in top of the filament wires. Looks like you may have done that in the reverb area? You mentioned the reverb hums?

There are a few Bogner and Friedman spices mixed in too. The correct combination of parts is the one that sounds and feels best to you.

If your idea is to parallel the two different tube pairs (quads), you would more likely tap the primary at the desired impedances rather than two individual windings. Look at the Boogie Simulclass circuit. Though not exactly what you are doing, it is a similar concept.

See this attachment.

Different input circuits require different transformer specs.

Next Sunday (June 1). Frank and I will be there with tons of amp and guitar parts. Come early.

I understand. Are you guys saying that all amps (including Dumble) will sound "better" (subjective) as they age? Clearly aging filter capacitors are not a good thing I assume, so at what point does one determine that some components are properly/adequately broken in and others are not. Is there a sc...

Well I'm not as much of a scientist as you guys but, every Dumble amp I've worked on had stock Fender transformers (or SVT as in the SRV/SSS). Are you saying the Dumble amps were not "magical" until the transformers reached a certain age?

I see you guys discuss the 150 watt Steel String Singer a lot. I once worked on Stevie Ray's live gear and he had a 300 watt SSS with six 6550 power tubes. Can't say it was sort of like and SVT because it was an SVT power amp. The head contained an Ampeg SVT power amp chassis with the Dumble Fender ...

Are we still talking about guitar amps here?

I use a THD hotplate set to off (silent) on occasion just for that.

Do you have someone who can look at it on an oscilloscope? Possibly a high frequency oscillation? Do you have the original tubes that worked? Can you put those back in?

A transformer doesn't "really" have a specific impedance of it's own. The primary impedance is determined by the load. It is a ratio, not an absolute value. In this case, if you connect the 8 ohm pan, instead of 4 ohm, the impedance that the tube sees will probably be in the "mid 20K" range.

More likely a bad input tube.