Feedback Help!!!!!!!!!!!!!

[Gr8Scott]

Re: Feedback Help!!!!!!!!!!!!!

I agree with the consensus. Sounds like a microphonic tube. Replace the tube and then look at the pedal if it doesn't stop.

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

If there was a microphonic tube, wouldn't it be doing it all the time, even with the pedal off and the gain all the way up? I'm not doubting you guys at all, I just don't know how to diagnose those types of problems. How do I find out which tube it is? My amp has 1 preamp tube and 2 power tubes FYI. On another note, i"m going to email the previous owner and ask him if the pedal gave him the same problem and what he did about it.

 

[FAC]

Re: Feedback Help!!!!!!!!!!!!!

If there was a microphonic tube, wouldn't it be doing it all the time, even with the pedal off and the gain all the way up? I'm not doubting you guys at all, I just don't know how to diagnose those types of problems. How do I find out which tube it is? My amp has 1 preamp tube and 2 power tubes FYI. On another note, i"m going to email the previous owner and ask him if the pedal gave him the same problem and what he did about it.

Some advise against this, but one way to suss out microphonic preamp tubes is to gently (GENTLY!) tap them with a pencil or something while the amp is on. Microphonic ones should become self evident.

I've not had this problem so I have not tried it myself. Perhaps others would have some advice if this method works or should be avoided?

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

Thanks, I"ll wait for a couple more chimes, then I may give this a try. If the tube is mircophonic, that means I will hear the clicking from the pencil through the speakers? Dumb question?

 

[muttonchopsrule]

Re: Feedback Help!!!!!!!!!!!!!

if you tap on each preamp tube, you'll hear kind of a ping/ringing sound if it's bad.

 

[Rich_T]

Re: Feedback Help!!!!!!!!!!!!!

the metal muff is a noisy beast anyway. I had one for a while, sounded good, but it was very noisy. There is a such a huge amount of gain in it.

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

Update #2, I took out the chassis and blah blah and when I tap on the EL84 tube it does make a noise through the speakers. Must be it. Tomorrow I"ll change it out, when the guitar shop opens. Does that mean that the tube was not working at all or just kind of working. They were all glowing. The replacement will prolly make the amp sound even better if that tube was only working halfass.

 

[LesStrat]

Re: Feedback Help!!!!!!!!!!!!!

New power tubes can do wonders. How many EL 84s does it have? It's probably best to change the set.

Clarification for those like me: the tapping is done with the wooden pencil or a dowel, not the eraser.

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

1 12AX7, 1 EL84, 1 6V6GT. That is the tubes my amp has. I put a new JJ EL84 in today, and it helped the noise. The earlier comment about the metal muff being a noisey beast must come into play. Also, my bridge pickup is pretty microphonic; ie when I tap my pick anywhere on my guitar I can hear the tap through my speakers. I'm gonna repot the PU since theres been a few mag changes with it. That I'm sure will help, then I'll pull the trigger on a noise gate.

 

[FAC]

Re: Feedback Help!!!!!!!!!!!!!

1 12AX7, 1 EL84, 1 6V6GT. That is the tubes my amp has.

Is this a Valve Jr? I thought they had one 12AX7 and one EL84? What's up with the 6V6?

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

Mods Mods my friend

 

[danielz]

Re: Feedback Help!!!!!!!!!!!!!

if you tap on each preamp tube, you'll hear kind of a ping/ringing sound if it's bad.

you mean just like a light bulb??

can you explain more the term "microphonic tube" please??

 

[donahue]

Re: Feedback Help!!!!!!!!!!!!!

picks up sound, the tap he's referring to will come out of the speaker: its not supposed to.