'65 DRRI Reverb and Tremolo Issue

[funkyeah!]

Hey guys! Hoping to get some insight on my amp.

It's a '65 Deluxe Reverb Reissue but for a while now the vibrato hasn't worked. With the footswitch plugged in and with a different footswitch it still doesn't turn the vibrato on. I tried swapping V1 and V5 to see if it was a bad tube and I still got no vibrato coming through the vibrato channel.

Another issue that I've encountered (not as old as the vibrato issue) is the Reverb is damn hummy. Lots of ground noise. I tried tapping V4 to see if it's microphonic and it definitely is now. I can't get the ringing to totally go away now.

So I know V4 is half-devoted to vibrato gain and V5 is the makeup gain for it. Do you think swapping V4 will fix both of these issues?

[Squirrel]

Swapping V4 may well cure the reverb hum, if it's microphonic it needs to go anyway. My next port of call would probably be to replace all of the electrolytics in the reverb and vibrato sections, if they're the brand I think they are. Roughly how old is your amp?

[funkyeah!]

I’m not sure exactly. I bought it used from Atomic Music near Baltimore about a year and a half ago.

It has the Fritz mod already and somebody had an Eminence Sidewinder in it so it’s not stock at all.

If a cap has gone, would that likely cause the vibrato issue?

[ifallalot]

Could have someone removed the vibrato in order to make a gainer Vibrato channel?

I thought that was a mod some folks do

[funkyeah!]

No the amp's vibrato worked for a long time after buying it. It only recently started crapping out.

After some swapping I found V3 is the culprit of the reverb hum. Something interesting happened when I swapped V5 and V6: The 60 cycle hum is affected by the tremolo circuit but the guitar's signal is not. So I gotta figure that out, read up on that.

The previous owner had really put some work into this amp though. The majority of the 12AX7s are NOS RCAs but V1 has longer plates than the rest (and more bass), V3 is the stock Fender tube that's faulty, and they modded the amp for 6L6 tubes instead. I forgot to notice what brand they were but no wonder I can't turn this thing much past 2 1/2 before I'm too loud at band practice.

[funkyeah!]

Seems that it might be a faulty LDR?

https://www.tubesandmore.com/products/s ... ender-amps

I saw on a different forum somebody had the same problem of hiss being affected by vibrato knobs but not their signal. They replaced this thing and it fixed the issue so maybe I'll try that.