#1
I've had a 65 Fender Super Reverb Reissue for several weeks. Today I was playing with it, and turned the reverb setting up high just for giggles. It started making a high pitched tone that varied in loudness as I turned the reverb knob up (louder tone) or down (quieter tone).

I turned the amp off, let it sit a few minutes, then powered it back up. I tried the reverb knob, and everything was fine. A little while later I plugged in the foot switch (which needs a new plug), and started getting the high pitched tone again.

Would a tube going bad do something like this? I haven't had any problems with the amp otherwise.
#2
Yes.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#3
I had an early '80s Music Man 50W combo that did the same thing. Sounded like a phone dial tone on steroids. Rather than take it to a shop, I just turned the reverb down a bit, & never had a problem. Sold it that way on ebay (with full disclosure), & the guy never contacted me with any issue either. Not sure what causes it, but it worked fine for years.
Edit: Never even tried a new tube. Should've consulted Cathbard. Would've sold it anyway....
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Last edited by riffhog at Jun 11, 2013,
#4
If your going to get a new reverb tube, try a Jan Phillips 12AT7WC they are a nice tube for the reverb driver.
#6
A badly seated tube or a dirty tube socket can do a similar thing too. What you hear is a short arc that can sound like a high pitched ping. I've had a socket trick me into thinking that a tube had gone microphonic before, even responded to the tap test in a similar way. That could account for its intermittent nature.
Try pulling out the tubes, spray some contact cleaner liberally on the tube pins (deoxit is a good one but any proper electrical contact cleaner will do) and work it in and out of the socket a few times. Just pulling them out and reseating them can often do the trick too but spraying on some cleaner is preferable.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
Last edited by Cathbard at Jun 11, 2013,