The Amp Garage

This might help.

And what in terms of your playing needs would as you say “ sound fabulous “?

If you start reducing the power supply voltage enough then what you like about the amps preamp section will be lost and at that point your truly better off to keep the amp as it is and open up your wallet to get a attenuator box on the output of the amp.

The only time I used 6V6 outputs at that high a voltage was in a Highwatt 50, and they where JJ brand since they are stated to be good up to 500 volts, and after having them in the high watt I do not question that.

All that has to be done is to remove a knob from the amp in question and compare.

This is front pot board and a chassis mounted pot for comparison.

Silvertone 1484 with KT66 outputs.

Just to be 100% clear, my reasoning for what I posted is grounded in many decades of replacing power transformers in amps that have only a mains Fuse. In terms of a vintage amp that’s seen 40 plus years of use ( effects of heat accumulation) and the situation of repetitive blowing of the mains fuse ...

A HT fuss will cover the whole DC side of the amp, but you mainly have filters that can go bad and output tubes. Filters will give you notice before they go south enough to pop the main fuse, but output tubes do not when they short . In light of this I would be more inclined to place in line with th...

The chassis I would say is not a one of since the nuts that will tie it up into the cabinet are tack welled in, so the amp started life as something else.

If your looking for any mid boost with aFender type tonestack the only way to get any of that or even get a flat response out of it is to turn the volume way up, crank full up the middle and set the bass and treble very low.

Well it’s got very hard to find knobs from a Heathkit from what I can tell. It’s got a T03 cased transistor mounted near the fuses so I would have to assume it’s DC powered heaters. It looks like it’s got a old paper cased filter in there and 2 other filters that could be old and out of a Highwatt o...

I have used the jtm45 PT in a 65 Fender Bassman and one would be hard pressed to hear the difference with the slightly lesser B+ voltage.

If you can surmount the mechanical difference I say go for it, and you would likely save the owner 100 bucks in the end also.

You did not mention if you tried different known good preamp tubes.

I have had a condition like that a few times that was due to a preamp tube.

Have you tried a different speaker?

Yes they are not at the bottom of the ladder any more.

Note that 6BQ5 PP output stage needs 10 volts less of grid to grid drive signal then a 6V6 output stage does.