tube ringing?

kill_surf_city · 1366

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Offline kill_surf_city

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on: January 18, 2021, 05:13:52 PM
This only occurs once I've had the Crack on for an extended period of time, like an hour. I believe the problem lies within the larger tube, in this case it's my Tung Sol 6520 with the domino flat plates. When I start to notice the ringing, which is quite faint, it's only in my right channel and it stops for a while if tap the tube or chassis near the tube. I decided to swap out the tube to see if it was the tube or if the problem is somewhere else. I plugged in my old RCA 6AS7G and it all seemed fine until I got about an hour and then I noticed the ringing again, but with this tube in I heard it in both channels and the sound was much more pronounced - something I believe to be because of the tube. The Tung Sol just has lower noise and is a nicer tube. So I'm not sure if it's the tubes that are giving off this ringing sound or if the problem is somewhere else in the amp. Where should I start with this problem? Re-flow some joints? I feel like I've done this over a dozen times now, but who knows.

Anyone else ever face this problem?

also, just to be thorough, my other tube in the small socket is an RCA 12BH7A. And as I'm typing this I have yet to swap that tube out to see if that resolves the problem. I'll try that later and update.



Offline Paul Birkeland

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Reply #1 on: January 19, 2021, 04:54:34 AM
Yes, I would try swapping out the 9 pin tube.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline kill_surf_city

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Reply #2 on: January 19, 2021, 06:44:28 AM
Yes, I would try swapping out the 9 pin tube.

I was so sure it was the 6520 tube that I didn't think to swap out the 9 pin tube til i was writing this last night. pretty sure that was it. which is a bummer cos I really liked the way that 12BH7A sounded.



Offline kill_surf_city

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Reply #3 on: January 21, 2021, 11:50:20 AM
Yes, I would try swapping out the 9 pin tube.

Hey I'm all of a sudden having a new problem. I switched out that 9 pin tube and stuff cleared up...initially. I replaced it with a 12AU7 and it was running smoothly until just a moment ago. I was just sitting watching a video and all of a sudden I start to hear this very low hum. I tap the tube and it goes away for a second then comes back. When I shut the amp off, I hear this loud CRACK! Scared the shit outta me. I swapped out all the tubes, tried all kinds of combinations and even put back in the stock tubes and I'm still getting this low hum in the background. All the LEDs are on. Idk what it could possibly be. I've been using the amp for nearly a year with no problems. Only new thing is I upgraded to the Speedball a few months back, but that's been smooth as well. Anything I should check for?

Edit: also now when I tap the chassis I hear a staticky noise that wasn't there before.
« Last Edit: January 21, 2021, 11:53:16 AM by kill_surf_city »



Offline Paul Birkeland

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Reply #4 on: January 21, 2021, 11:51:51 AM
Solder joints.

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline kill_surf_city

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Reply #5 on: January 21, 2021, 12:05:28 PM
Solder joints.

Found it. When I lifted off the chassis last time I must've dropped it down on that capacitor that's on the side of the transformer and knocked it loose. Thanks!