Whats wrong with my amp?

Hi I have an f 30 combo and one of the power tubes keeps glowing really red! and it sounds horrible! no bass. I've only had this problem since i put new tubes in. why is it doing that? the problem seems to go away after i take them out and plug them in a few times. but it keeps coming back after a while.

is it the tubes? or something to do with the tube socket? they are new tubes about a month old. Groove Tube EL84's with a rating of 6. This is a real problem because my amp never sounds consistent. it either sounds fine but lacks gain,or it sounds thick and awesome for a little bit ,and then sounds !

Its called red-plating and its not good. Try swapping in a different set of tubes. If it continues you shouldnt use the amp. Seek professional help.

ohhh thanks for the reply. so does that mean the tubes are bad?

yes as far as i know

recto preo said:

Hi I have an f 30 combo and one of the power tubes keeps glowing really red! and it sounds horrible! no bass. I've only had this problem since i put new tubes in. why is it doing that? the problem seems to go away after i take them out and plug them in a few times. but it keeps coming back after a while.

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The red tube sounds suspect to me .

If removing / re-installing the tubes makes the problem go away for a while then it may just be a poor connection in the sockets. Sometimes the socket contacts can be spread open from repeated tube swaps. If the tube is red-plating, then its possible that the bias grid connection (pin 5) may be poor, allowing the tube to "run away" due to a lose of bias voltage.

Swap the tubes around and see if the problem follows the tube, or does the problem always happen in the same position? If it stays consistent in one socket then it may just be a poor connection.

Just watch the tubes and shut her down as soon as you see "red-plate". That is not a good situation for the amp to keep running in.

Also, you may want to see what the idle current (bias) is. Are these Mesa tubes? If not, they may just be too hot a tube.

This is where a bias probe is worth it's weight in gold.

Dom

****! well i live in hawaii and theres no mesa repairman here **** it.

but when i and my old mesa tubes in there they never redplated. so hopefully its just a bad tube.

well i think it is my tube socket actually. i swapped tubes aorund and stuff. teh tubes that red plate work fine in the other socket.

would a normal repairman be able to fix it or does it have to be a mesa guy?

I live in Hawaii and theres only one authorized repairman and its on another island

If the amp is under warrenty then you need a Mesa approved tech. for any repairs I believe.

Put your Mesa tubes back in and play the amp over several 20-30 min. periods to make sure that the amp is OK. This may just be a loose socket connection that any tech. could tighten up. If the amp red plates with your Mesa tubes, get it to a Mesa tech.

Dom