Musicians Roadhouse

Hi everyone, I’ve literally had my JVM 205c about 3 weeks tops and already I seem to have a problem with it. With the master volume, either 1 or 2, at 4 or above I’m getting a horrible crackling sound. It is most prominent if I palm mute a G chord, and it’ll do it I almost any mode. The strange thing is it goes away. It did make this noise the first day I got it then it went away and didn’t do it again. But to be fair this is only the second time I’ve had the MV up around 5 or more. I’ve had it almost flat out and there seems to be plenty of volume just this annoying intermittent crackling. Has Anyone come across this before? I’ll try and attach video examples
Cheers

Remove each preamp tube, wipe the pins down with 000 steel wool, blow off the pins then wipe with DeOxit and reinsert.
Clean all jacks with deoxit. Use a Q-Tip to wipe off the contact points in the jack and let dry. Test amp.

Hi Anitoli, thanks for your advice. I take it Deoxit, is just a contact cleaner? I’ll take a look tomorrow I think, we’ve got a reversal Wednesday night so that’ll be the first chance lll get to turn it up unless the neighbours go out tomorrow. Is it worth putting contact cleaner on the tube pins and put them in and out the socket a couple of time to try and clean the socket?
Cheers.

Sounds like a bad preamp tube to me.

That would be handy if that’s is the case gainaddict, they’re less hassle to change at least. Quite happy to re bias an amp when fitting new output valves but on a new amp I really rather not have to! That said if I have it to bits to change preamps valves I perhaps should check the bias in it. Seeing as everyone says they come biased cold from the factory.

Is the amp brand new or just new to you?

It’s brand new. I checked the purchase date literally had it 2 weeks. Marshall HQ is only about an hour away, but I know warranty stuff usually has to go through the retailer and the amp came from a store in Portsmouth which would be a couple of hours each way at least. They were the only place that have any stock at the moment.

It's under warranty. Talk to Marshall. They will make it right.

Yeah an email has been sent with an audio clip so see what they come back with. Having not gone into a local shop to buy it there’s no shop- customer relationship so I’d rather just take it over to Marshall myself. And I can have another look around the museum too :D

Gixxalee wrote:Is it worth putting contact cleaner on the tube pins and put them in and out the socket a couple of time to try and clean the socket?
Cheers.

Yes. I do that whenever I change a tube. Cleaner on the old tube and in and out the socket a couple of times.

I took it into Marshall, all they found was a loose connection and replaced two preamp tubes which he said were going microphonic . Havent noticed the issue since but I’ve only had it turned up properly a couple of times. So time will tell. Thanks for the input guys