Redhead Distortion Issue

[GonzoBfiddy]

Hey guys, can anyone describe what it sounds like when a 12AX7 tube dies in a SWR redhead? Halfway thru my gig Sat eve my tone went from marvelous to marshmallow for about 10 minutes. Then suddenly the distortion was gone. Had no other issues the rest of the gig but I know it wasn't just ear fatigue or anything like that because the drummer and guitarist heard it as well. Got it home last nite, plugged in and checked it out but it sounds great now. I bought it used about 2.5 yrs ago and it has been great up to this point. Was just wondering if anyone else had a similar experience.
Thanks!
Gonzo

 

[B-string]

When a tube goes soft, it doesn't "come back" when power is still applied. It may work okay from a cold startup until it has been used for a while again, but again once they die off they don't return until they cool off (unpowered). You may have an effects return jack or power amp In jack that needs cleaning. They have internal contacts between the preamp and power amps and especially unused they get a micro corrosion buildup (common to any amp with these series jacks). What you described is one of the more common "failure modes" of these contacts. A pedal loop cable from effects send to effects return and/or Preamp Out and Power amp In will bypass those contacts until you can get someone with experience to properly (with the proper chemicals) clean those internal contacts.

 

[BogeyBass]

there has been 2 or 3 threads about red head issues this month
and wanna say at least one was distortion.

no matter what it's a intermittent problem. which are the worst but likely points away from tube issues.