[guf]

I took a class in San Francisco a few years ago and built a KT88 amp. I never really used it but hooked it up today and loved how it sounded except for the terrible hum. How do I go about trouble shooting it to see if I can reduce the hum. My speaker are fairly efficient at 95db. I bought decent tubes at the time except for a pair of cheap Chinese 5U4GB. Do you need to see the bottom of the amp? I didn't learn that much except that I'm not that skilled on building but I can follow instructions.

[poseidonsvoice]

Start with posting the schematic (clearly) and photos of the underside, again, clearly. DIYAUDIO is also an excellent forum to post this, specifically the tube forum.

Best,
Anand.

[Thirsty]

Sounds like it may be a grounding issue. First thing to look at would be the ground wire on the power cable, make
sure it is tightly attached to the chassis, next thing to look at would be all the wires connected to ground, it's probably star grounded, anyway
make sure all the ground wires are snug.
Oh yeah, don't forget to unplug it and bleed the voltage off the caps, otherwise it could be a shocking experience, it hurts.

[Speedskater]

a] Is this a new problem or in the past with different speakers might it have always hummed?
b] Make shorting plugs for both RCA inputs. How? take cheap interconnects and cut to make two 6 inch'ish stubs. Strip the insulation and tightly twist the center conductor together.
c] If this is a new problem, then it's the electrolytic capacitors or a connection or joint that went bad.
d] If it always was this way, it comes down to internal shielding, twisted pair wires and grounding.
e] With shorted RCA inputs AC power grounding is not part of the problem.

[guf]

Here is a picture.

I have a variety of speakers and amps and preamps and I am positive this is a problem with the above amp and not a separate issue. IT always had a hum so I never really used it. It's 4 years later and I'm trying to see if I can get this addressed to use the amps. Also it is both amps so I guess it's a design thing.

I searched my email for an over all Schematic and wasn't able to find one. I will continue to search.