Guitar Gear Forum

At practice last night, I noticed this odd sound out of my Rebel 30 head. The sound of the amp was normal, but there was this weird accompanying high-pitched whistle sound when I hit notes. More noticeable on the clean channel of course.

Anyone know what it might be? Guys in the band thought a bad tube, but I haven't checked yet.

Sounds like a bad pre amp tube.

yep microphonic preamp tube. Grab a wooden pencil and lightly tap each preamp tube, you will find the culprit real quick.

While the amp is on and set to a healthy (read: nice and loud) volume, tap the tubes gently with a pencil. You should hear a *ping" come through the speakers. The further back in the signal chain you go, the louder the ping will be. If you have a microphonic tube, the ping will be a lot louder than the other tubes and if you raise the volume more it'll ring for a while as well with a high pitched sound.

Just be careful not to touch the tubes with your hands as they get hot. And dont hit them too hard either for obvious reasons haha!

Bad tube. My speedtwin has a microphonic tube in it at the moment and it makes all sorts of odd pinging sounds

That's what I was hoping for! Thanks guys. I'll check tonight.

My Peavey Triumph Ultra Gain 1x12 60 completely DEVOURED pre-amp tubes. When those were going a high pitched whistle/whine would happen. Thankfully it was an easy diagnosis as there were only 2 pre-amp tubes in it.

She took a dump a bit ago, no sound at all but fires up. I should trouble shoot her as she was a quality sounding amp. Loud as FUCK.

Derek

Also could be a battery dying in a pedal in your chain. My Dano EQ makes that sound when the battery dies.