Ampeg Reverberocket questions

[Laroosco!]

My Reverberocket is a '61 with the octal preamp tubes and 6V6's.

I was playing it today and noticed that there was an ugly undertone when playing notes on the wound strings. It seemed to get a little worse so I investigated a bit.

I tapped on the preamp tubes and got a really ugly sound. Kind of a scratchy hum that would go on for 10 seconds or until I tapped on the preamp tube again.

Also, the problem went away when I turned the reverb all the way down. Unfortunately, I do not want to play this amp without the reverb. The preamp tubes are all microphonic to different degrees. I can't imagine that they could all be bad, and contributing to this problem, but I'm no expert.

I went back a couple hours later and I can't get the problem to occur again to save my life. I tapped on the the tubes again to see if I could get it to happen again, but nothing. I did notice that the 6SN7's whistled quite a bit.

I'm glad that the problem is gone for now, but I need to get to the bottom of it. I will taking it to a tech soon.

Also, on another note If I am to assume that the outside 6SL7 in the input tube, then what are the others for? The two 6SN7's are in the middle and the other 6SL7 is next to the 6V6's.
Does that mean that the 6SN7's are reverb and trem drivers? and the 6SL7 next to the 6V6's is the PI?
I'm asking because I'm going to start replacing the preamp tubes and want to know which I should replace first.

Thanks
Lawrence

 

[Prattacaster]

Ugly undertones and hum are a symptom of worn filter caps. Not saying it couldnt be tube related but it sure sounds like a filter cap job is needed.

 

[slider313]

The New Sensor, Tung Sol, 6SL7's that I've tried are very quiet and the price is right. I would expect their 6SN7 is the same.

Most every NOS 6SL7 I've tried were microphonic or produced noise.

 

[Laroosco!]

I can't get the noise to come back no matter how hard I try. I Just played 3 sets with it tonight. I had it cranked and it gave me no trouble at all. I'm taking it back out tomorrow to see what happens.

I bought it from a good friend of mine and he had it completely gone through about 3 years ago. I'm gonna take it back in soon whether it gives me trouble or not.

All the 6SL7's and 6SN7's are the new Tung Sol's. They sound great so far.

 

[FFTT]

Sometimes firing up and burning in an old amp sounds like you're cooking all the dust mites.

When the pots haven't been used in a while there may be a deposit where
it sat, so Deoxit for the pots.

You may be getting mechanical feedback from the reverb if the pan
is not well cushioned against the enclosure vibration.

Small rubber pads between the pan and the wood usually solves that problem.

 

[zenas]

Your amps toast ! Pull the power transformer and ship it to me (I need one for my 62)
Looks like the amps had alot of new parts so I'm betting all the filter caps are new as well. Try new tubes first. But a new cap going bad is not unheard of.