Tube Amp Archive

xtian wrote:Is there a cap can under the middle of the board, mounted on the outside of the chassis?

No, i checked. Could this explain the extra noise I'm getting in the preamp circuit?

Am I missing a preamp filter capacitor right in the middle of the board?
It would be the largest one like on this guys board:
http://vintageamps.com/plexiboard/viewt ... 4&p=822955

I build for a company in seattle, but I don't know whether or not I should advertise. I haven't been told not too, but i've been known to shoot my mouth off from time to time so I wouldn't want that to come back to my employers. Anyway, I like to ground to the chassis at the input jack. Usually I g...

Do the heaters have a good ground reference, ie check resistance between each side of the heaters and chassis/ground? The green/yellow wire may be it, but it's as well to confirm that. The B+caps all seem to share the same ground reference; that's a big no-no. There will be significant ripple curre...

I spent some time shortening wires. I used shielded coax from the input jacks to the board. The hum is still there. How does this look?

Will I need to relocate the signal leads to the opposite side of the turret board or can I get away with just shortening them as long as they are positioned away from heater wires? I do have copper shielding in the cab.

Too bad they don't sell wire hair gel

You guys rock. Thanks for the good input. I guess I'll start around the input and preamp section... Laying those signal wires back against the chassis and shortening them to mimic the example pictures of that cleanly wired amp. If anyone has the inclination to draw notes over my pics pointing out th...

I just picked up a brand new JTM45 clone in a trade. Small parts are from Mojotone. The previous owner had a friend build it for him. It really hasn't even been broken in. The guy who built it apparently moved away and never resolved the hum/noise issue that was present upon first power up. The amp ...