Peavey 5150II Tube Question

[djobson101]

Hey guys,

I'm currently running a Peavey 5150II half stack, which I have owned for a few years now. I've replaced the 4 power tubes only once since I've had it. Recently the amp sounds very muddy and breaks up even at the lowest of volumes on all channels. Do I have to replace the power tubes again or could this be a different problem? Thanks if anyone has any info.

[tim]

Unless you can look at the output waveform on a scope with a pure sine wave plugged into the input, then about the only way to know is to plug in a new set. It's possible that one (or more) or the power tubes aren't working or you could have an open screen resistor on one or more of the power tubes. If you plug in a new set and it still sounds like it is now than it's a safe bet that either something is amiss in the power tube circuit or something in the preamp is bad. Being able to look at the preamp out separately from the power amp circuit would be beneficial.

[rockon1]

Buy a set of backups if your keeping the amp.Whether one craps out completely or or just is questionable you will have them on hand. In other words you will need them sooner or later. Right now they would come in handy.

Also carry spare fuses. If a tube goes (shorts) hopefully it takes out a fuse. Peavey uses lots of internal fuse protection. Theres probably five fuses inside. They arent your problem at the moment -Im just pointing that out.

You might try putting a guitar cable in the loop (from the FX send to return) If the sound comes back you will know the contacts are dirty in the loop jacks. If not onto the tubes-pre amp tubes too. Bob

[djobson101]

Thanks for the pointers, I'm hopefully going to get a full new set of tubes soon.

Also, some things to mention that it does.. when you turn the amp on or off on either channel, there is a bit of 'white noise' for about 5 seconds. I'm not sure if this is helpful at all, but it usually does this every time. It sounds similair to the noise a speaker makes when you have the amp turned up very loud and aren't playing anything, it's odd though because even at low volumes it still does this.