static coming from my deluxe reverb amp

[chief ten beers]

I've got a fender deluxe reverb and you can hear a low noise static coming from it within a few minuets of turning on the amp.it's not very loud and it can't be heard once i start playing but when i stop playing it's there.any idea what's causing it?it not a buzzing sound,it definitely sounds more like static.thanks

[s2amps]

Sounds like a preamp tube misbehaving.

[Blue Strat]

Preamp tube, plate load resistors, treble cap, any cap in the signal path.

Does either volume control affect the noise level?

[chief ten beers]

Preamp tube, plate load resistors, treble cap, any cap in the signal path.

Does either volume control affect the noise level?no, nothing i do has any effect on it,the noise level remains the same turned all the way up or all down or anywhere in between.

[teleamp]

I've had a faulty rectifier tube do the same thing.

MikeY

[Blue Strat]

Could still be a preamp tube or other things. Try removing both V1 and V2 and see if the noise stops. If it does, install them one at a time and see what happens.

[s2amps]

If the volume knobs don't affect it, it is probably your PI tube.

[Mike T]

Check for carbon comp resisters in the signal path and start at the power tubes.

[67super]

The 100K plate load resistors do exactly that on most all old Fenders. You hear it all the time and it doesn't change no matter what you do. If tube swapping doesn't fix it replace these resistors. I replace these on all old BF fenders regardless, especially if you gig the amp.

[aboutdrill]

WOW!

I just have to say thanks guys!

I bought a 68' Super Reverb with the AB763 circuit and just love the amp but... it had static at idle all the time. I brought it to a reputable shop and they changed the big caps but they said they couldn't fix the static without replacing most of the stuff on the circuit board. I said no because I was afraid of losing the tone I loved. So I lived with the static until I read this post. I decided to replace the 100k plate load resistors myself and guess what! It worked!! No more static.

I love this place!

[Blue Strat]

If the volume knobs don't affect it, it is probably your PI tube.

Or the halves of V1 or V2 that are after the volume controls, or V4 or many resistors and capacitors.

[JJman]

I had a similar problem on my ’71 SFDR. I eliminated all the tubes as the possible problem and was able to isolate it to something in one particular gain stage area. I changed the cathode and plate resistors and still had the noise in that area. Then I noticed that pressing the board in that same area triggered the static. I had to lift the components out of a particular eyelet and mount them on a standoff to eliminate the problem.

I wasn’t using a dehumidifier in the (finished) basement and I believe moisture got into the board and perhaps mildew. I have a dehumidifier running in the summer now.

This is probably one of the least common causes of such a noise but the chopstick test is easy and free. Much more likely to be a tube problem. Pushing on the board itself would have saved me much time.

[s2amps]

Or the halves of V1 or V2 that are after the volume controls, or V4 or many resistors and capacitors.

One thing at a time, my friend. I've found the PI tube to be the culprit something like 75% of the time, so it is worth investigating 1st.

[Blue Strat]

One thing at a time, my friend. I've found the PI tube to be the culprit something like 75% of the time, so it is worth investigating 1st.

The order isn't important. I've rarely found the PI tube to be the cause....I'd place it more in the 10% area but YMMV.

Another important detail. Sometimes poor connections between tube pins and sockets can cause noise (or many other symptoms). Good general maintenance includes cleaning all tube pins and sockets. Check the FAQ on my website under Resources for details. It's amazing how many people ignore this advice and how often it actually works;)

[Norse]

Also worthy of consideration:

- ground contact at input jacks.
- "dirty" pot(s).

HTH,
Greg