valve trouble - need reply ASAP please

[Michael6120]

Hey guys
Long story short,

I THINK im having troubles with my power amp valves
1) is it safe to take my 4 EL34's out and put in another 4, just for a second to see if my power amp valves are the problem ?

2) If it is the power amp valves, would I be able to get away with 1 gig with my old set of EL34's ??
Thanks

[sleepingtiger]

1.) It should be fine for a test without a bias set.
2.) Crap shoot, IMHO.

Tony

[hamfist]

1.) It should be fine for a test without a bias set.
2.) Crap shoot, IMHO.

Tony

Agreed.

I wouldn't risk a gig on a known dodgy set of tubes.

[SatelliteAmps]

If the amp is not working because of the power tubes, then no, you probably won't make it through a gig.

[rockon1]

What exactly is the trouble your having with what amp? Bob

[Michael6120]

Hey there guys.

Got through the gig.. My problem was when there was vibration the amp would CRACKLE really loud. If I beat the amp lightly with my fist it would CRACKLE very loud (it was volume dependant and also happened when the master was on 0, across both channels). If I jumped the amp would go CRACK again.. Not cool if you plan on being next to a drummer hehe

Anyway I took the valves out, put them back in and the problem seemed to be gone. I played the whole gig and the crackling came back luckily just on the last song of the night!!

The next day I could get the crackling to come back with some light fist hits on the amp. But then it went away and I havent heard it since... However one thing I noticed today is that the amp sounds very microphonic. If you tap the metal control panel with your finger you can clearly hear the 'tap' and 'valve echo' through the speakers (valve echo... imagine tapping a power amp tube with a pencil - that kinda sound coming through loud through my speakers). Once again this is dependant on volume but also comes through with all controls on 0. - I didnt notice the amp sounding microphonic yesterday but thats not to say I didnt miss it yesterday.. It could of been there. Im hoping the odd Crackling with vibrations and the microphonic sounds are the same problem. You woudnt expect 2 different faults within 24 hours from a Wizard modern classic would you!?

What the hell is wrong ?? lol

[hamfist]

There's every chance that it's just a dead set of power tubes. Stick a new quad in and see if all the problems resolve.
90% of problems with tube amps usually end up to be tube-related.

If the new set of power tubes doesn't sort it out, then I guess it's time to see a tech.

[Michael6120]

That would suck... only just put those winged C's in 2 months ago.

Hopefully its just a dodgy socket or something hehe

[Structo]

Sounds like dirty tube sockets.

Get some Caig's contact cleaner and spray some on the tubes pins.

Plug the tube in and out of the socket a few times. Wipe off the pins and let the cleaner evaporate before re-inserting the tube.

Do this to all the sockets in the amp.

You may also need to re-tension the pins of the sockets.
But be warned, the filter caps should be discharged before doing this.
If you are not knowledgable enough to do this take it to a tech.

And since it sounds like you are going to need a bias set, take it to a tech and have it serviced.