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Discussion in 'Shock Brother's DIY Amps' started by h4ck.b0x7, Mar 11, 2018.
The preamp filter caps are grounded to the preamp buss wire.
Now I'm confused. I could have sworn there was a clear photo of that. I must be mixing this up with another thread, or photo from somewhere. My apologies.
I'd still use shielded wires to the reverb pot.
If you remove the reverb tank from the bag, and move the tank physically further away from the chassis (with the reverb cables connected), does the reverb noise problem get any better?
If yes, next try putting the reverb unit back into the amp, facing the opposite direction that it originally was. Does it help if you do that?
Asking the above because another homebrew guy was able to resolve his noisy reverb problem simply by reversing the reverb tank.
(Here's the thread, scroll through it before you change anything on your amp. Note what his reverb prob was and how he solved it: http://www.tdpri.com/threads/prince...h-deluxe-pt-and-ot.758188/page-2#post-7911886)
I swapped the tank and the cables. No real change that I can tell.
One thing I should mention though is that my house has CRAZY EMI. Single coils hum like a banshee.
When I changed the tank today I tested it with the tank on the floor 2-3 feet away from the amp with no difference.
Now I feel like an idiot.
I took apart the amp and set the chassis up on the bench in the basement and used a different reverb tank.
When I had it apart it didn’t hum. I did notice if I moved the return plug of the reverb tank close to the power transformer it would hum, ok that’s normal.
As I put the amp back together I tested it at various points. I was getting some hum but not a lot when a lightbulb went off in my head. The amp was sitting in a different place than when I had it pulled apart.
I finished putting the amp back together, moved my chassis stand, and set the amp on the bench where the amp stand had been when the chassis was on it. Hit the switch, cranked the reverb knob, and no hum whatsoever.
I took the amp up to the living room and plugged it in to test again. No hum. I took it back into the room it was in originally and put it back in the spot I had it. I hit the switch, cranked the reverb knob, and it hummed like a banshee.
I guess I’m not surprised seeing as my guitars hum so bad even my Les Paul hums.
Wait, what? No understood reason, you just have a 'hum spot' in your music room, that happens to be right where your amp was? The fix is just don't set it over there? Bizarre.
There’s a transformer on a pole and power lines roughly 40 feet from that exact corner of the house. Tomorrow im going to grab the 100ft. extension cord from the garage and plug the amp into the outlet in the living room while it is sitting upstairs. I don’t believe it will make a difference but I just want to eliminate power as a culprit.
My wife mentioned wanting to trade me rooms, she has an art studio and I have a music room. The other room is in the opposite corner of the house and is considerably larger so I’m ok with that.
Well, it’s not dirty power causing the issue. No matter how I orient the amp in that corner of the house it hums.
However, if I move the amp 3 feet out from the corner and orient it so it is parallel to the power lines in the backyard it is 100% hum free. The hum increases as the amp is turned until it reaches maximum hum when perpendicular to the power lines.
Jeez, you need to make yourself a room-size Faraday cage...
I seriously contemplated that but a faraday cage wouldn’t stop the magnetic flux generated by the transformer which is the issue. MuMetal would solve it but I’d be better off buying a new house at that point.
Switching rooms with the wife sounds like the best idea.
I had a similar hum problem I couldn't solve with a tweed deluxe kit that I built. Since it was my first build and I had little experience I finally gave up and didn't touch the amp for months. Then I had a couple buddies come over and ask what became of the amp I was building. I told them about the hum but they wanted to play through it. Plug it in, no hum. I couldn't believe it. The issue turned out to be the fluorescent lights over my work bench. Put it up on the bench and the hum returned. I guess sometimes it's the crazy things that get ya.