Bugs in a scratch built JTM45

[g1]

To run EL34's you will probably need to go to the 15K. With the resistor you have now your range is from about 8watts to 20 watts. You shouldn't need to go that cold (8W) so see what kind of range you get with the 15K.
Also note the B+ (pin3) is coming down as the bias is increased. The high voltage issue was partly due to the amp being biased so cold.

Edit: Or you could leave the 23K in there as MWJB suggested, and then see what kind of range you get with EL34's.

[guitician]

The loud hum was cured by swapping the OT secondary wires around.

That's what I thought when I first looked at this thread because the same thing happened to me when I fired up mine. Set the phasing on the transformer per the color coded wires and BRRRRRRRRR! lol Somebody wasn't testing their stuff...

[g1]

Set the phasing on the transformer per the color coded wires and BRRRRRRRRR! lol Somebody wasn't testing their stuff...

There is a note about this on the Weber schematic. Sometimes the OT leads need to be reversed. It is a common issue that can come up whenever installing OT's in tube amps, so good to take note!

[mort]

There is a note about this on the Weber schematic. Sometimes the OT leads need to be reversed. It is a common issue that can come up whenever installing OT's in tube amps, so good to take note!
[ATTACH=CONFIG]22446[/ATTACH]

I certainly got it now!

I was noticing on that schematic [and on the weber layout], they don't show a cap on the diode in the bias supply. My bias was all wonky without it. Is that an error on the drawings?

[g1]

Yes, it appears to be an error in the drawings. Seems to be a fair amount of online discussion about bias problems with this particular kit. Yet no mention of the missing cap anywhere. You were lucky MWJB caught it.

[guitician]

There is a note about this on the Weber schematic. Sometimes the OT leads need to be reversed. It is a common issue that can come up whenever installing OT's in tube amps, so good to take note!
[ATTACH=CONFIG]22446[/ATTACH]

The issue is that color coding the Blue/Brown wires is worthless if they don't test for phasing primary-to-secondary when making the transformer.