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PostPosted: Thu Aug 25, 2016 3:22 pm 
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Mark I

Joined: Tue Aug 25, 2015 1:08 pm
Posts: 34
Hi guys,

I have an Express 525 that I recently retubed with Doug's Tubes, plus added a Tone Tubby 40/40. I occasionally/regularly get a lot of electric buzz (not hiss/hum) even when there is no cable plugged in. Today's symptoms are: light buzz in Clean, moderate buzz in Crunch, and flat out full volume armageddon buzz on the red channel (blues), like "turn it off before it explodes" buzz.

I just reseated the tubes and checked the connections, plus disconnected the footswitch plug from the circuit board.

Any ideas before I bring it in for service?

Thanks

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Electrics: Collings City Limits Deluxe / PRS Custom 22 / PRS CE 24
Acoustics: Martin HD28V / Ovation 1778T Elite
Amps: Mesa TA-15 / Mesa ElectraDyne 1x12 Wide / Roland GA-112 / Genz Benz Diablo 60


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PostPosted: Thu Aug 25, 2016 3:37 pm 
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Mark II

Joined: Sat May 31, 2014 11:00 pm
Posts: 80
Did the buzz start before or after the new tubes? Maybe roll in one of the old tubes and see if the noise goes away.


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PostPosted: Thu Aug 25, 2016 6:40 pm 
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Mark I

Joined: Tue Aug 25, 2015 1:08 pm
Posts: 34
royslead wrote:
Did the buzz start before or after the new tubes? Maybe roll in one of the old tubes and see if the noise goes away.


I think it was the same before & after but can't confirm so ya I could try that

thx

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Electrics: Collings City Limits Deluxe / PRS Custom 22 / PRS CE 24
Acoustics: Martin HD28V / Ovation 1778T Elite
Amps: Mesa TA-15 / Mesa ElectraDyne 1x12 Wide / Roland GA-112 / Genz Benz Diablo 60


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PostPosted: Thu Aug 25, 2016 9:16 pm 
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Mark I

Joined: Tue Aug 25, 2015 1:08 pm
Posts: 34
Did a full re-seat of all tubes and ribbon cables etc, now the cleans are almost perfect, esp on low gain, and even the "red" channels are significantly better (again at low gain under 10:00), but as soon as I go above 10:00 on hi gain , the buzz becomes horrible. This is a monotone electric buzz surrounded by background hiss. The fact that the tube reseat had a significant effect tells me I may have one or more bum new tubes, but not clear on where to start the diagnostic process to track it/them down.

Suggestions? Is "buzz" noise more likely to be preamp, or power?

Any wisdom appreciated :)

Cheers

_________________
Electrics: Collings City Limits Deluxe / PRS Custom 22 / PRS CE 24
Acoustics: Martin HD28V / Ovation 1778T Elite
Amps: Mesa TA-15 / Mesa ElectraDyne 1x12 Wide / Roland GA-112 / Genz Benz Diablo 60


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PostPosted: Sun Aug 28, 2016 10:28 am 
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Mark I

Joined: Tue Aug 25, 2015 1:08 pm
Posts: 34
Messed around again yesterday and there seems to be less buzz, almost none in fact unless I switch to Burn and turn the gain past 12 (again, I'm talking about electrical "buzz" not hi-gain hiss). Some weirdness going on, I guess I'll check it into the repair shop and get it checked.

_________________
Electrics: Collings City Limits Deluxe / PRS Custom 22 / PRS CE 24
Acoustics: Martin HD28V / Ovation 1778T Elite
Amps: Mesa TA-15 / Mesa ElectraDyne 1x12 Wide / Roland GA-112 / Genz Benz Diablo 60


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PostPosted: Sun Sep 04, 2016 9:44 pm 
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Mark II

Joined: Sat May 31, 2014 11:00 pm
Posts: 80
As I mentioned before (if you have not done so already), take one of your old preamp tubes and substitute it into each location, retesting for the buzz as you go. If it doesn't change anything, try it once more with another preamp tube. If still no success, contact a tech. I have limited knowledge, and it seems anybody would be very lucky to get any useable help on this forum. There used to be a few helpful members, perhaps they moved on; and now we are left with those that have a lack of knowledge, unwillingness to help, or if it's just a lame/dying site.


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PostPosted: Fri Sep 09, 2016 7:22 pm 
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Bottle Rocket

Joined: Sun Jan 27, 2013 11:06 pm
Posts: 9
Hi alphasports,

This sort of problem can be difficult to debug sometimes.

Before taking it to a tech who is experienced with Mesa's, check for things like:
- remove anything in the effects loop and/or try inserting & removing a plug in the return a few times.
- check if the buzz is changing with the eq settings.
- it's already been suggested that you change the tubes one at a time ... but ensure that you've checked both pre-amp and power tubes
- check the connections to reverb tank (or if the buzz varies with the reverb setting)
- try with and without the footswitch (it shouldn't make any difference, but you never know)
- try different power outlets, other rooms (using any extension cords? or powerbars?)
- keep notes on your experiments (it might help a tech)
- try calling Mesa support.

I realize that you may have tried some of these and some of these ideas are pretty generic. However, the troubleshooting process is more or less the same for all tube amps, Mesa or not.

Good luck and please tell us how the problem gets resolved.


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PostPosted: Sun Sep 11, 2016 10:00 am 
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Mark I

Joined: Tue Aug 25, 2015 1:08 pm
Posts: 34
Thanks Squier for the useful tips :)

Turns out the problem is apparently not one but two bad preamp tubes. I had already tried the one-at-a-time approach with no joy, but according to the Mesa service provider they swapped out a couple of Doug's brand new tubes with stock Mesas and the buzz disappeared. I'm a bit skeptical since I already swapped out the complete batch of Doug's tubes with the original Mesa set to no avail, but maybe one or more of them was bad as well.

Anyway the amp is still in the shop, installing a new DIN connector on the footswitch at the same time (I don't think this was part of the problem but who knows, with the switch completely disconnected the buzz was still as strong as ever). We'll see how it goes when it comes home.

Cheers

_________________
Electrics: Collings City Limits Deluxe / PRS Custom 22 / PRS CE 24
Acoustics: Martin HD28V / Ovation 1778T Elite
Amps: Mesa TA-15 / Mesa ElectraDyne 1x12 Wide / Roland GA-112 / Genz Benz Diablo 60


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