Rectoverb Crackle and volume drop out.

[Jimbo4085]

My series 2 Rectoverb will randomly start to crackle and the volume drops out intermittently, I've checked the back and the tubes (both Pre and Power) look normal, none respond when I tap them with a pencil. Since this problem is very intermittent (it drops out after 15-30 mins of playing) I'm having a hard time diagnosing the problem. FYI when this problem does occur it is on all modes and channels and is NOT responsive to gain adjustment.

Has anyone else had this problem or does anyone have any ideas on how to fix it?

 

[b0nkersx1]

Search for "cathode follower" on this forum and you might find the answers you are looking for. I don't remember exactly what the specifics are, but I think it goes like this:

If you have Chinese preamp tubes in certain positions, they will cause intermittent volume dropouts, and replacing them with Russian tubes (current Mesa tubes) fixes the problem.

A few years ago I had a problem with volume drop-out, and all of my tubes were JJs (known to be good). It ended up being a few bad caps. Mesa replaced them (under warranty) and everything has been fine since.

 

[Addictedtokaos]

To add to what B0nkersx1 says. It may be your cathode follower tubes. In a rectoverb its v3 and v4 tubes. Its Chinese tubes that are SAFE in those spots and not Russian.

see here
http://forum.grailtone.com/viewtopic.php?f=24&t=58704&p=413003&hilit=cathode+follower#p413003

 

[Jimbo4085]

Thanks for the suggestions guys, I tried swapping V1 with V5 and the problem went away, but as its an intermittent thing my bets are that it will return.

Can either of you tell me whats the difference between russian and chinese tubes?

 

[Addictedtokaos]

Funny thing is mine just started doing this today. Volume and lowend drops in waves and fizz and crackling. I guess I will be doing some tube rolling

Its not Chinese vs Russian per say but the filaments. I posted my findings in the "Did you get the memo" thread.


"The Electro-Harmonix 12AX7EH has a spiral filament and should not be used in cathode follower circuits. The Tung-Sol 12AX7, Mullard 12AX7, and Sovtek 12AX7LPS also have spiral filaments."

"The most rugged 12AX7 types for cathode follower service are the Sovtek 12AX7WA and WB."