Microphonic bottle in V1?
ok, i have a problem. i just picked up a DB with the 15" speaker about a month ago. about two weeks ago, it started to have this nasty hum with the guitar volumes up. the amp sits quiet with the volume rolled off, but when i turn it up it hums at around 30% as loud as the actual guitar volume. (it hums on both clean and overdrive)
i've tried it with a friends gretsch country gentleman as well as my les paul and tele. its there with all of them on multiple cables, so i think that i can rule out it just being the guitar.
I replaced the stock tubes with JJs in hope that they would rectify the problem, but no luck. I'm figuring i could probably fix the whole thing with an electroharmonix Hum Debugger, but i was hoping for a cheaper fix. any ideas what the problem could be? help is appreciated. thanks
Loss of solid ground connection to input jack? V1 with heater short? Broken jumper wire between board sections?
You mention "with guitar volumes up." Does that mean the hum goes away if the guitar volume knob is at zero?
Is the reverb working ? Is the reverb turned up ? If so turn it off and try because the reverb is a big contributor to hu8m in this amp. Could be the reverb op-amp. If one tube has lost it's bias as in a bad or cold solder joint or any ground connection as Enzo pointed out could do it. Of course thinking the worst a power tube short could have taken something out causing a failure you may not detect without taking the boards out and further examining and testing.
thanks for the quick responses.
what i mean with the quitar volume up is that it goes away when i roll the onboard volume off on the guitar, the hum leaves. bring the guitar volume up again and it returns. it happens on humbuckers and single coils. was happening before i switched tubes as well. (one of the reasons i swapped them out) hums with or without reverb engaged.
im going to call the shop tomorrow and see about getting it looked at. it has a two year warranty, so that should be helpful.
could it still be tubes after having switched them? i dont really want to have to take it in, but i feel im too inept to crack open the amp and tinker. (that and my warranty goes away if i choose that path)
If the volume control ON THE GUITAR turns the hum off, then the hum is coming from your pickups, not the amp.
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