Feedback

[tubesornothing]

I am getting feedback from my amp when the reverb is cranked high, and after I unplug the instrument.  The tank is in a bag, with cardboard bottom and foam on top.

Suggestions?

[phsyconoodler]

What amp is it and what cathode bypass cap/resistor combination are you using?
  Did you try and swap reverb tubes?You may just have a micro-phonic tube.
To determine if it's a micro-phonic tube,simply grab the send or return tube when it starts to feedback.If it stops or changes significantly it's the tube.

[tubesornothing]

Yeah it was the recovery tube. F**K I hate tung sol.  Nothing but troubles with those tubes.  To bad they sound good.

[jojokeo]

grab the send or return tube

Ouch!  I hate it when I get burned even more so than when I get shocked.

Yeah it was the recovery tube. F**K I hate tung sol.  Nothing but troubles with those tubes.  To bad they sound good.

I think they sound good too. Was it the new ones? I haven't noticed trouble w/ these yet.

[phsyconoodler]

Quote: "Ouch!  cry I hate it when I get burned even more so than when I get shocked."

You must have thin skin.I can hold a reverb tube all day and not get even uncomfortable.YMMV.

I've had a few bad Tung sol tubes.I am not,however,a big fan of the tone.Generic at best to my ears.A little brighter than some.
  Better than most Sovteks except the LPS IMHO.
I've tried every tube from RCA to Phillips in my Custom Vibrolux and I keep coming back to Sovteks.Maybe my ears are dead?

[tubesornothing]

grab the send or return tube

Ouch!   I hate it when I get burned even more so than when I get shocked.

Preamp tubes?  Gotta thicken up that skin a bit.   



Yeah I have gone through a couple dozen Tung Sols so far out of about 100.  They are either very microphonic or noisy.  Within a month or so they would get really noisy.  PIA.

[bluesbear]

I've only bought 5 or 6 of the new ones (12AX7) but all have been good. I once got a deal on 20 NOS glass Tung Sol 6SC7's. I've used 16 so far and they were all great. Ditto on an old pair of 6V6GC's.
The only bad tubes I've ever bought were Groove Tubes and NOS stuff. I won't buy either anymore. 99% of the good NOS left are being hoarded. Even back then, a percentage of them were junk.
Dave