#1
First, lemme start out by saying yes, I used the search bar and found threads pertaining to my issue, but none of them seemed to be exactly what I'm experiencing or seemed to have some up with a concrete solution....

I have a valveking 112 and its my first tube amp. When I turn it up past 4 with the gain boost on I get a horrible squeal. Its not caused by the guitar because it happens with other instruments and without anything plugged in. I've read in some threads that "valvekings just do that..." which I have a hard time accepting because then why would anyone buy an amp that can't even go past half volume?

Also, I've read that it could be a bad tube. I don't have any spares to check and won't for another week, but I just replaced the tubes a little over a month ago with groove tubes all around (not the best choice but I'm a tube noob and got talked into it guitar center...oh well) I do understand its possible to get a bad tube though.

Also, I've read that if your tubes glow blue, they can be bad, but my power tubes have had a medium blue glow since I put them in. Does this sound like a tube issue? or maybe some component that interacts with the tubes directly? I haven't had the chance to study the schematic for anything that would look like it would produce internal feedback...

I really don't want to take it to a tech. I have an electronics degree so I shouldn't have to. I'm just not too familiar with tubes and sound equipment electronics.

I'm sure people get tired of this crap being asked...Sorry for being a tube noob
i play drums and guitar :
#2
Take a pencil and with the eraser tap on the preamp tubes with the amp on. If it makes a weird noise, the tube is microphonic. Then just get new preamp tubes.
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#3
I've heard of that. I'll definitely give it a try later. thanks for the reply.
i play drums and guitar :
#4
Valveking owner for 8-years.

I've read the blue glowing of the tubes is normal, so don't worry about that.

Try turning the reverb off & see if it happens. The amp basically has a reverb tank (spring in a box) in the chassis of the amp. It's a small rectangular box in the bottom of the amp. When your amp gets to high volumes it can cause this reverb pot to unintentionally vibrate & make a horrible feedback noise.

The other possible cause is a a preamp tubes has gone microphonic. Turn the amp on loud & tap all three of the preamp tubes. Remember to remove the cover.

Are you getting any horrible pingy noises?
#5
Quote by AndyGray
Valveking owner for 8-years.

I've read the blue glowing of the tubes is normal, so don't worry about that.

Try turning the reverb off & see if it happens. The amp basically has a reverb tank (spring in a box) in the chassis of the amp. It's a small rectangular box in the bottom of the amp. When your amp gets to high volumes it can cause this reverb pot to unintentionally vibrate & make a horrible feedback noise.

The other possible cause is a a preamp tubes has gone microphonic. Turn the amp on loud & tap all three of the preamp tubes. Remember to remove the cover.

Are you getting any horrible pingy noises?



The reverb tank was the first thing I checked. I'm at work right now, I'm definitely going to try to see if it s a microphonic tube. Thanks
i play drums and guitar :
#6
well one of my preamp tubes wasn't lighting up at all, so I'm going to assume thats the culprit. I guess I'll pick up a replacement on monday.

Now, I know that they say you should replace all tubes at once but they are only a little over a month old...so would it be ok to just replace the one since they aren't old tubes?
i play drums and guitar :
#7
Quote by bluehawk15620
well one of my preamp tubes wasn't lighting up at all, so I'm going to assume thats the culprit. I guess I'll pick up a replacement on monday.

Now, I know that they say you should replace all tubes at once but they are only a little over a month old...so would it be ok to just replace the one since they aren't old tubes?


Preamp tubes are a different animal.
IMO, replacing a single preamp tube is ok.
Its the power tubes that should all be replaced when needed.