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Posted by: mhskeide May 31 2011, 04:38 PM

The last months my amp has been acting pretty weird. If playing heavy, or just loud enough on clean for about 40-60 minutes, it start making crackling noises and has sudden volume drops. At first I thought a tube had gone, but a amp technician has changed the tubes twice, and when I came back the third time, he gave up! He didn`t manage to get the bad noises him self, therefore not being able to repair anything.

So I now present to you, the terrible sounds it makes. And I exaggerated a bit, for example by using the octave pedal on the low B, just to provoke the amp to make the noise clearly. Sorry for clipping by the way, to high mic volume

 PeaveyCrackle.mp3 ( 1.11MB ) : 3691


Does anyone have a idea what it could be?

Posted by: Mudbone May 31 2011, 04:56 PM

Have you tried going on the Peavey forums?

Posted by: mhskeide May 31 2011, 05:12 PM

Haha! No, actually not. With some thought, that should be my first choise!

Thanks

Posted by: Ivan Milenkovic May 31 2011, 05:20 PM

If your amp tech cannot repair it, I suggest you find some other tech that can! Try asking around for people who fix these amps, it could be that some electronics went bad. I hope it's nothing serious man.

Posted by: Sollesnes May 31 2011, 05:36 PM

If he was not able to replicate the noises, could it be your house's electricity that is uneven?

Posted by: mhskeide May 31 2011, 05:43 PM

Nopes, it made the same exact sound at my school which is 600 km from here

A bit tricky question as a follow up: Instead of a repair, do you think it`s possible to sell the amp in this condition to anyone?
I mean, the noise is just showing up when playing really heavy, or pretty loud, so maybe somebody could use it as practise amp/clean amp, eventually I could sell it very cheap and they could fix it, and maybe get a good amp for almost nothing?

But I`m not sure what to advertise it for though...any suggestions? If you find the idea good that is.... I`m just so sick of trying to fix the amp, since I will sell it anyways.

Posted by: MickeM May 31 2011, 07:03 PM

I'd still say it's the power amp tubes. I had the exact same amp and the exact same noise (just a little less) when one of my tubes went bad.
Especially with EL84 tubes with bendable pins/legs it's important to add electric spray. Then jack the tube in and out a few times so the jacket becomes perfectly clean.
Try that as a last resort, since you got the tubes switched they should be alright. Surely there can be other less common reasons but that's what you have amp techicians for...

Posted by: Ivan Milenkovic May 31 2011, 10:26 PM

I wouldn't want to judge your amp tech, but are you sure he did a good job with replacing and biasing the power tubes?

Posted by: jstcrsn Jun 1 2011, 02:03 AM

i agree with th others either tubes , biasing or pins

Posted by: Azzaboi Jun 1 2011, 07:07 AM

Ever wonder why tube amps, have combos and head only options?

If it's a tube amp, they all do that when the tube is about to go (crackling or volume change). The harder you drive it, the quicker. If you don't replace it soon as it starts, it might explode damaging other components, I kidd you not! If the other components are damaged, it's sometimes cheaper to throw it away and buy a new one. That's the only reason I've been holding off getting one and avoid second hand.

Posted by: mhskeide Jun 1 2011, 12:28 PM

He is supposed to be one of the best within Trondheim (one of Norway`s larger cities), so I am actually a bit surprised he didn`t fix it properly. That said, the recordings I brought to him to demonstrate the noise, was of poor quality, with a drummer in the background also. Hopefully, someone in my hometown (I have moved home for the summer) can fix it without ruining me... :/

Posted by: Ivan Milenkovic Jun 1 2011, 08:59 PM

I understand the problem mate, there are few amp techs in general, and you never know who to trust. It could be that the guy did a proper work after all, just want to include that option too you know..

I'm not an amp tech myself, so not sure, it could be anything. But those particular symptoms usually mean that power tubes are running out/bad biased.

Posted by: Sinisa Cekic Jun 2 2011, 10:31 PM

Sometimes even the most complicated failure may be simple - the dust in the potentiometer, for example ..

Posted by: Mudbone Jun 2 2011, 10:52 PM

Try taking out all the tubes and spray some contact cleaner in each socket. Then take the tubes, insert them, and rock them around gently. Spray some more contact cleaner and do this a couple of times. Be very careful, you don't want to weaken the mountings on the tubes. Once you completed this wipe down each pin on the tubes with contact cleaner.

The purpose of this whole procedure is to remove any oxidation or dirt on the sockets. Oxidation can form on the sockets after only a couple of years.

One more thing, do this when the amp is off and unplugged. Also, wait for the capacitors to drain their charge, this could take a few hours or a day. Capacitors can store lethal voltages, thats why theres warnings on amps. Its no joke, it can really kill you. Some amp techs recommend keeping one hand in your pocket while you're tinkering around inside an amp. This minimizes the chance of lethal voltages passing through your body.

I wouldn't worry about it too much, seeing how you're not messing around inside the chassis. But I thought I'd give you a heads up

Posted by: Ivan Milenkovic Jun 4 2011, 10:26 PM

Hey I just remembered I had very similar crackling problem with my Marshall. It turns out there was dust on the master volume pot. I had it replaced very cheaply with an original Marshall metal pot, and it worked great!