Electra Dyne buzzing/humming problem

Chris Thompson · May 30, 2011

I have a small problem with a used electradyne I purchased a few weeks ago. If I set the trim switch on the back of the amp to any setting other than the "clean" trim setting I get a pretty good amount of buzz/hum type noise on the clean channel only. The vintage Hi Low setting sound fine. Now, if I set the trim switch to "clean" trim, the clean channel sounds fine even with the preamp volume pot turned to any posistion from 0 thru full gain. If the switch is set to bypass or to the Hi Low trim setting the volume control will buzz/hum starting at 11:00 and get worse till I hit 3:00 or so and then completely go away around 4:00 thru 5:00 and sound normal. The amount of gain thru out all of this adjustment sounds as it should. The only problem is the buzzing and hum. I have swapped preamp tubes, used new ones, and tried everything logical I can think of. Also when I am in the clean trim mode the full rotation of the preamp volume control sounds smooth and completely normal with out the buzzing and hum. I was wondering if any other ED users have ever had this happen with thier amps or have known anyone with the same type of issue that owns an EDyne. Also EQ adjustments make no diffence with the buzzing and hum. If I turn the master volume to 0 there is no hum so it isn't the amp its self at idle with no volume. It also makes no difference where the "clean" volume pot on the back of the amp is set. Wide open, halfway ect. Of couse if I turn it completely off there is no noise just like the Master volume on the front of the amp when it is turned completely off. I know that those 2 volume controls work together. I would appreciate any opinions or experiences any one might have with this type of problem and greatly appreciate any advise that you can give. Thanks so much for taking the time to read this post. I appreciate it very much.

Assumer · May 31, 2011

I have not had any buzzing or hum. Have you tried it somewhere other then your home?

primal · May 31, 2011

Unfortunately I have not read of anybody having a similar problem. The Electra Dyne's have been pretty issue free. I have a slight popping noise when going into standby, but it isn't really loud and is nothing like channel switching on a Roadking/Roadster

If you have swapped all the preamp tubes, then I say take it to a tech (certified Mesa Tech). Should still be under warranty.

My Grasp of the obvious is impecable as clearly what ever is being shorted out of the circuit when the gain trim is set to clean is the faulty component.

I wonder. The gain trim did not come on the first run Electra Dynes and was a mod that was added by the techs. Can you tell if yours was added after the fact? If so the tech who did the job may not have done it completely correct.

Either way, take it to a tech. Something is not right.

Chris Thompson · Jun 1, 2011

Thanks to you both for your thoughts and experiences. We had some or our electric in the house redone 7 years or so ago and it is pretty good now. I used to have a terrible time with the power around here before the work was done but all is well now. My other amps all sound really good with no interference so I was able to rule out electric issues. Thanks for that idea about the power in the house. That is one that could easily be overlooked. About my Electra Dyne's trim switch, I am 99% sure the mod was done after the amp was already built. The trim switch and clean volume knob has a sticker with it's info on it instead of being printed on the back panel. I do not know if the mod was done at Mesa or by someone somewhere else. primal, I believe you have hit the nail on the head. With what both of you all are telling me about your Edyne experiences, maybe there is a faulty component to blame or, perhaps something got wired wrong. Thank you Assumer and primal for your help. I will be giving Mesa a call.

primal · Jun 4, 2011

Chris Thompson said:
Thanks to you both for your thoughts and experiences. We had some or our electric in the house redone 7 years or so ago and it is pretty good now. I used to have a terrible time with the power around here before the work was done but all is well now. My other amps all sound really good with no interference so I was able to rule out electric issues. Thanks for that idea about the power in the house. That is one that could easily be overlooked. About my Electra Dyne's trim switch, I am 99% sure the mod was done after the amp was already built. The trim switch and clean volume knob has a sticker with it's info on it instead of being printed on the back panel. I do not know if the mod was done at Mesa or by someone somewhere else. primal, I believe you have hit the nail on the head. With what both of you all are telling me about your Edyne experiences, maybe there is a faulty component to blame or, perhaps something got wired wrong. Thank you Assumer and primal for your help. I will be giving Mesa a call.

Please fill us in on what you find in the end. It is good info in case one of us run into the same issue.

Chris Thompson · Jun 5, 2011

I was able to spend a whole lot more time with my Edyne the other day. I took the chassis out and looked around in there to see if there was any thing that looked faulty or messed up. I made sure my filter caps were drained before doing anything and did some cleaning in there to remove any small particles of dust or anything else that might cause some trouble noise wise. I also replaced a little bit of the foil sheilding in the cabinet. It was kinda worn where the chassis bolt that helps with vibration and sheilding makes contact with the cabinet. After doing all of this things sounded fine. So I was able to take care of this myself. So maybe this info might be helpful to someone else. To any one who has never been inside of an amp before, Make sure your filter caps are drained because they can store a whole lot of charge. If the caps do not have ressisters soldered to them to "self drain" the caps there could be enough charge in those to kill you. You will have to drain them your self before poking around in there so don't do this if you are not sure of what to do. Thanks again to you all who chimed in with your thoughts and experiences with your Edyne amps. I greatly appreciate it.