EVH keeps burning tubes

[Coma]

A few weeks ago I started getting screech noises from my EVH 100w. Around the same time, one of the power tubes started glowing like mad, leaving a burn mark on the inside of the glass.

Took the amp home, chopstick tested it. Sure enough, one of the preamp tubes had gone microphonic. Replaced that one and also replaced the burnt power tube as well as its pairing tube.

Played it maybe three times since then, everything seemed fine. Then after maybe 15 minutes of playing today, I start getting weird noises. Peek into the amp and sure enough, same power tube as before is glowing like a house on fire. Quickly shut off the amp. JJ logo printed on the tube looks burnt out, cant tell yet if anything on the inside got scorched as well.

Have two gigs abroad in five days, so I need to fix this ASAP.

Any clues where I should start looking? Will try to find a tech that can get it done pronto but figured it can't hurt to know what to look for from the get-go.

 

[JMP/HBE]

Re: EVH keeps burning tubes

Screen grid resistor maybe ?
Are you blowing fuses ?
Get rid of the JJ tubes.

 

[Coma]

Re: EVH keeps burning tubes

Screen grid resistor maybe ?
Are you blowing fuses ?
Get rid of the JJ tubes.

Get rid of the JJs as in "you need new tubes" or as in "that particular brand is not to my liking"?

Haven't opened up the amp yet, so no idea if any fuse is blown.

 

[LLL]

Re: EVH keeps burning tubes

For a moment I had a flashback about reading how Edward would supposedly crank his variac to 150V and melt tubes...

 

[devastone]

Re: EVH keeps burning tubes

Edward never did that, he lowered the voltage to ~80, he said that in the interviews though because A) it sounded cooler and B) he never gave away secrets in those days.

Back to the OP, I would have it on a tech's bench ASAP if you have big gigs coming up, definitely sounds like something in the bias circuit is toast. JJ tubes aren't always the best sounding tubes, but I've never heard of them not being pretty sturdy.

 

[FuseG4]

Re: EVH keeps burning tubes

Had the same kinda issues with a deluxe reverb once
Took it to a tech and got new screen grid resistors!
Sounds like what you need

Sent from my SM-G930U using Tapatalk

 

[JMP/HBE]

Re: EVH keeps burning tubes

Get rid of the JJs as in "you need new tubes" or as in "that particular brand is not to my liking"?

Haven't opened up the amp yet, so no idea if any fuse is blown.

Both. Put it on the bench with a qualified tech.

 

[Coma]

Re: EVH keeps burning tubes

Tech sorted it out. Turns out there was one right across the street from where we rehears. One tube was short-circuited across all pins. Another one was overheating so hard it had burnt a bunch of components around it. Screen grid resistor was shot. One big resistor rated for 5W had flat out exploded. Should've just handed it in when it first started acting up - the new pair of tubes I put in two weeks ago went straight in the bin.

Still, seems to be working now. Techie replaced all busted components and put in a new quad of power tubes (yes, JJs. They sound fine in that amp).

Asked me how I liked it biased. I had no idea how it was set before, so I just told him to set it to what he thought was best. But it seems to have lost a lot of headroom now, might ask him to adjust it for me when I'm back in the country.