Hi,

I am not sure if this is the right place for this question, but I figured out that many of you probably know about tube amp problems better than others (and me).

I own a Fender Deville 2x12 tube amp, and since I got it several months ago, I keep hearing a bell-like clicking sound from the tubes area. When I turned the amp around played my guitar (it happens when the sound is bass-ish), I saw that it comes from one of the small tubes (I think those are the 12AX7). Now when I tap with my finger on that specific tube, I hear what sounds like that bell-like clicking sound.

The amp works fine other then that - but when recording guitar playing, I can sometimes hear the bell-clicking sounds in my recording....

Any idea what might it be?

Thanks.

I suggest you pin point exactly which tube it is. What it sounds like is that lower frequencies are causing a reverberation in your amp. Inside of a tube, there could be a smaller part which could be loose but not disconnected rattling against either the wall of the tube or another part of the tube.
Similarly to when a light bulb breaks, there's a small metal wire inside which "shakes" around in the bulb.

I also think that it sounds like a dead light bulb (when you shake the bulb) - I know which tube it is - should I replace it?

This is a microphonic tube, it needs to be replaced. Modern tubes, specially chinesse ones, are more prone to microphonics than older ones.
So avoid China made tubes when you replace it with a fresh one. Better with NOS, but Sovtek, Tesla or Electro-Harmonix replacements will do a nice job.

first of all, if you've been touching your tubes without wearing gloves, thats one sure-fire way to screw them up. Sometimes those tubes that come from the factury are just duds. Try replacing the tube, or swaping them around. You're preamp will go out first 90% of the time.

One time my marshall was making this unearthly feedback noises, anytime i turned it on. I replaced the tubes and it kept making the noise, it turned out to be a tiny fuse.

I'm not sure about Fenders, but the replacement fuse was fairly cheap, and if its still under warrenty, I would go ahead and take it into a repairshop. After you try messing witht he tubes, of course.

theWB wrote:Any idea what might it be?

Thanks.

Snapcase is right, it's definitely a microphonic tube. I have a fender pro jr which had the same problem shortly after purchase. Same symptoms exactly.

To figure out which tube it is, take a piece of wood such as a non-sharpened pencil and tap on each tube while the amp is on. If you hear yourself doing this, as if the tube is a microphone, you have found the tube.

Danm wrote:first of all, if you've been touching your tubes without wearing gloves, thats one sure-fire way to screw them up.

I don't think that this is true.

Danm wrote:One time my marshall was making this unearthly feedback noises, anytime i turned it on. I replaced the tubes and it kept making the noise, it turned out to be a tiny fuse.

Hmm.. the purpose of a fuse is to break the circuit if abnormal levels of current are being passed through it, so its unlikely that your amp would be operating at all if there were a fuse blown. It's possible that someone replaced the fuse with an incorrect value to keep the amp running even though another component had burned out, causing the feedback. Or you are just being ripped off by your amp repair person.

That series of Fenders is notorious for tube rattle. Do the output tubes have retainers? Sometimes spring-type retainers will feel obliged to sing along with whatever you're playing. But it's probably just some rattle-y tubes.

When you produce thousands of amps and use tens of thousands of tubes. You can't check them all for real world issues. If they pass electrical testing it's tested enough, in their eyes. They can just plead the "shipping 5th".

Danm wrote:first of all, if you've been touching your tubes without wearing gloves, thats one sure-fire way to screw them up.

sixteenrev wrote:I don't think that this is true.

Yes indeed its true, the oil from your greasy fingers screws up the temper of the glass envelope and leads to much shorter tube life.

Same goes for lamps in lighting instruments. Ask any Squint.

Thanks for all the answers - I also think it's a defective tube - I'll go buy a new one somewhere.