Tube question

[cdntac]

Two weekends ago, while joining my buddy's band for some songs, my amp (Peavey Classic 50) was on for about 5 hours --- with it being used for a good chunk of that time (a bunch of guys were using it as they joined the band for a song or two).

 

I never used the amp again until this past weekend.

 

I noticed though that it had a distinct rattle to it.

 

Microphonic tube(s)? That was my first thought. The tubes would only rattle during certain sustaining notes (I assume the frequency had something to do with it).

 

So I took off the back cover and touched each power tube. A little pressure on each tube would make the rattle stop.

 

I put the tube cover back on, making sure it was tight up against the tubes, and cranked it up. The rattle was still there.

 

So last night I switched all four power tubes and realized that tubes that I replaced fit much more snug into the slots. Thinking I was crazy, I checked with one of the rattling tubes --- nope, the rattling tubes definitely weren't fitting as snug into the tube holder base.

 

Is this a sign of a worn out tube? I have no clue. Could the five hours of use have worn out the tubes (I put them in about 6 months ago).

 

If the tubes are worn out or have gone microphonic I'm certainly not going to buy Groove Tubes again. I would have thought the GT tubes would have last longer than six months. They only get a few hours use each week.

 

The tubes that are now in there thankfully don't rattle and fit tight into the slots.

 

Anyone have any thoughts?

[AXE®]

Never really heard of that. I'm curious as well.

 

Mick? Murph?

[bubba_leon]

A lot of the Peavey "Classic" series amps mainly the older models have tube rattle issues. It can be solved with an after market spring loaded tube cradle.

The newer amps have them already. With time and vibration tube can become slightly looser.

[Riffster]

Yea, I had a classic 30 and it would rattle tubes out until it ruin them. The main problem with the Classic 30 was the el84s though those tubes are frgile no matter what brand.

[L5Larry]

Part of general tube amp maintenance is cleaning and tightening the tube socket contacts. Loose or dirty connections can cause a lot more damage that just rattles.

 

There is a good chapter on tube amp maintenance in Aspen Pitman's (the founder of Groove Tubes) "The Tube Amp Book". A book every guitar player (that uses tube amps) should have.

[cdntac]

I'd assume it was the contacts if the other brands (Sovtek) didn't fit quite snug into the socket.

 

I've heard of Classic 30s rattling but not the Classic 50 (it has a guard housing the tubes already so the aftermarket holder would not work).

[Murph]

The Classic 50 with 4; EL84's and 3; 12AX7's has a metal cover with a dense sponge material that holds the EL84's secure. It's actually a pretty good design.

 

The older Peavey "Classic" had 2; 6L6's and a SS preamp and was the baby brother to the Deuce with 4 6L6's, and the monster Mace that had 6; 6L6's (Gary Rosingtons amp for decades).....

 

The EL84 Classic 50 is a pretty rugged amp with a fairly long history now for modern tube amps. Any tube can go bad at ANY TIME. I wouldn't sweat it. If new tubes fixed it you might be good for years.

 

Best of luck.