Ampeg Svt Question (hum)

[Nighttrain1127]

 I have a 75 SVT and the hum is getting out of hand and the hum balance does nothing to help. So am I looking at a recap job or does anyone have any other Ideas?   Does this need to go into the shop?

[clankenstein]

is the input jack in any way loose?

[Nighttrain1127]

 The Jacks are tight .  It started as a low level hum and just continues to get worse. It was humming a little a year ago but I thought some was normal(or should it be quiet?).

[rahock]

If it's strictly a hum and no crackle, it is less likely to be a cold solder joint but it's still a possibility. They can cause a lot of strange troubles and can be difficult to find. Do a visual inspection and look for a discolored solder joint. Something that looks darker than the other joints is what you want to look for. I had this issue with a solid state Seymour Duncan amp a while back and it drove me crazy. I knew what to look for and I even looked right at the bad solder joint a dozen times and discounted it as not being dark enough to cause the problem .
Rick

[Nighttrain1127]

I tried a few things one being a cheater plug that does not use the ground pin. That did nothing but with the amp plugged into a speaker cab and a bass plugged in if I turn up the vol pot the hum decreases until you turn up the vol on the bass. There is no crackeling nothing but hum.  So I guess it is due for a trip to the tech get it gone thgrough if it has not been recapped I might get that done even if it is not the problem just to know it is done.    Thanks for the help guys I can't think of anything else to do at this point that can be dome here at home.

[Psycho Bass Guy]

The hum may be filter caps, but if the amp has seen regular use, it's unlikely unless they've just dried up suddenly. Bias problems can also cause hum, but your output tubes would be redplating (which they may be- you didn't say). At any rate, it's tech time.  And BTW, a healthy SVT should be dead quiet with nothing plugged into it. There is no "normal" level for hum.

[mc2NY]

Roll off the treble and have the guitarist and drummer play louder

[Nighttrain1127]

The tubes are not redplating .