Redplating

[richard]

One of the two EL34s in my Cornford is redplating. Could this simply be a tube gone bad ?

[Dmoney]

If it was me I'd swap the EL34's in the sockets and see if the problem follows the valve.
That said, it's a cathode biased amp I think (Roadhouse?) so in theory MAYBE there are less things to go sketchy than in a fixed bias amp but you should get some valves asap and really stop using it if it's redplating. If it pops it could cause some collateral damage to the amp at varying degrees of expense. If you're unsure then get it looked over, if nothing is wrong then it shouldn't cost much for someone to take a look and check and you'll have peace of mind.

[richard]

Thanks, I've ordered some new valves from Hotrox and I'll wait for those to arrive before I start experimenting because the Roadhouse is a bugger to re-valve.

[Dmoney]

Thanks, I've ordered some new valves from Hotrox and I'll wait for those to arrive before I start experimenting because the Roadhouse is a bugger to re-valve.

Oh really? How come? Do you mean in terms of tone or physically?

[richard]

The valve sit horizontally and are behind the chassis which is mounted at the rear of the amp. Have to take the chassis out.

[jpfamps]

The Road House 30 is indeed cathode biased.

If one of the valves in a cathode biased amp starts redplating, then it's usually due to the other having expired.

I would try changing the valve first.

[Keven]

The Road House 30 is indeed cathode biased.

If one of the valves in a cathode biased amp starts redplating, then it's usually due to the other having expired.

I would try changing the valve first.

Great advice man! i've had a few experiences of redplating and usually tossed the tube that was plating aside, so i guess now the "bad tube" is in my backup stash, gonna have to check that out...