DSL 401 Buzzing Noise - Please Help Diagnose?

[riffin-rich]

Hi folks. Just wondering if anyone can help me diagnose my amp problem please. Could it be transformer(s) needing to be potted? Or not? Thank you so much!



Sincerely,
Rich

 

[Georgiatec]

@JohnH knows these amps pretty well. Hopefully he will know the issue.
To me it sounds like an earthing issue somewhere. Could even be a trapped or badly routed wire.
Try testing the amp with it out of the cabinet. You are going to have to do this to fix it, so look for something simple first.

 

[SkyMonkey]

Can we ask if you have checked all the tubes against known good ones and Deoxited the s#it out of the pots and jacks?
This is usually the first advice you get on any tube amp fault diagnosis.

Also, @FracStrat has a wealth of DSL401 experience, so attracting him to this thread would be a good thing.

 

[JohnH]

I don't know what that might be. Is it a sound that is coming from somewhere another than the speaker? I e a tranny? vibrating?

How about (carefully) using a plastic chopstick to probe and see if touching certain parts can damp the effect

 

[FracStrat]

Can we ask if you have checked all the tubes against known good ones and Deoxited the s#it out of the pots and jacks?
This is usually the first advice you get on any tube amp fault diagnosis.

Also, @FracStrat has a wealth of DSL401 experience, so attracting him to this thread would be a good thing.

@JohnH is top dog under the hood with the 401s …… Thanks Sky !!

 

[Max Gahne]

Are you on US or UK voltage? Sounds higher than 50 - 60 cycles to me, more like 100 - 120. Which could be a filter cap. If you think it's 50 - 60 cycles check the tubes. Never hurts to check the tubes first.