software

This has been happening since I got my 5150 head used, and I'm finally getting pretty sick of it. On both channels, it has this high pitched whine. It's not very loud, and playing covers it up for the most part, but I can't imagine this will fare very well when recording. I know it's in the preamp, as it doesn't have the sound when I'm plugged into the FX loop return. It isn't my guitar or pedals; it does it with nothing plugged in. It also isn't just the head; it stops if I unplug the speaker cable.

Part of me is thinking that my preamp tubes need replacing, but I haven't heard of this kind of problem, so I figured I'd ask.

Got yourself a feedbacking pre-amp tube by the sound of it.

2nd that

3rd that. Maybe a power tube but they usually rattle.

While the amp is on amp; turned up take a screwdriver (or other metal object) and gently tap on each tube a couple of times. All the tubes are gonna make a little noise, but the bad tube will make a lot of noise.

Yeah, sounds like a flakey pre amp tube. Try tapping them with a key or something, if one rings longer or louder than the rest i think you've found your fault.

Moose beat me to it.


Originally Posted by J Moose3rd that. Maybe a power tube but they usually rattle.

While the amp is on amp; turned up take a screwdriver (or other metal object) and gently tap on each tube a couple of times. All the tubes are gonna make a little noise, but the bad tube will make a lot of noise.

GAH! No! Never stick any metal object in a tube amp, even if it's only outside the chassis. The approved tool for tapping on tubes is a wooden chopstick, available at any Chinese restaraunt.

That said, I agree with averyone else. You have a problem with feedabck inside the amp. In DIY amps, this is a common problem in high-gain amps, and is often an issue of lead dress - the routing of the signal wires inside the chassis. In a commercially-produced amp such as yours, it is almost certainly a microphonic tube. Tap until you find it, or just buy a spare 12AX7 and swap for each tube until the noise goes away.

Well, I needed a reason to replace all of the unlabeled tubes in it anyways, so I'll be making a call to Revolution Guitar this week. Thanks!

microphonic tube as every stated, #1 is the culprit i suspect, since the whine is in both channels. good luck!!

I LOVE THIS PLACE...learn something new everyday!

Get some GT12AX7C's from Todd @ www.revolutionguitar.com


Originally Posted by HossI LOVE THIS PLACE...learn something new everyday!

I hear ya....a great resource for guitar info...if only there was a forum like this for homework. chris


Originally Posted by Rich_SGAH! No! Never stick any metal object in a tube amp, even if it's only outside the chassis. The approved tool for tapping on tubes is a wooden chopstick, available at any Chinese restaraunt.

That said, I agree with averyone else. You have a problem with feedabck inside the amp. In DIY amps, this is a common problem in high-gain amps, and is often an issue of lead dress - the routing of the signal wires inside the chassis. In a commercially-produced amp such as yours, it is almost certainly a microphonic tube. Tap until you find it, or just buy a spare 12AX7 and swap for each tube until the noise goes away.

1 on that, I always have chopsticks around.

when i saw the thread title I thought this was gonna be a rant about pop-punk singers


Originally Posted by shredaholicwhen i saw the thread title I thought this was gonna be a rant about pop-punk singers

well i thought it was a rant abt his girlfriend !