Very OT and dumb tube amp question

[ildar]

Ok, here's the deal: I bought a used amp based on the sound and price. Checked the basic functions and everything was copasetic. I got it home and took a good look at the rear of the amp. The amp calls for 6L6 power tubes, but actually has EL34s installed 
The question is: how quickly would it experience a meltdown if it was not biased for the EL34s? I'm hoping it was rebiased for these tubes somewhere down the line...

[jc]

The usual problem with switching from 6L6 to EL34 is that the EL34 draws more current for the filaments (heaters).  .9 amps (6L6) vs. 1.5 amps (EL34) for each tube. This doesn't have anything to do with the bias. What type of amplifier is it?

[The Tone God]

The filimant is a biggie. EL34s do need a slight bias change to run optimumly but if the EL34s are running at a 6L6 bias level it would probably not be off enough to cause damage. The other change that would have to be done is addressing pin 1 of the EL34. Most amps ground this pin.

Andrew

[ildar]

Right, I was under the assumption that if pin 1 was grounded, EL34s would not work.

[The Tone God]

The EL34 has an extra screen which is connect to pin 1 so it needs pin 1 to be ground. 6L6s do not have a pin 1 or they are not connected internally.

Andrew

[ildar]

So, am I safe in making the assumption that the amp has been adjusted for the EL34s, since it does in fact function?
I know I'll need to take it to a tech, but I'd like to get a few rehearsals out of it before I do.

[The Tone God]

So, am I safe in making the assumption that the amp has been adjusted for the EL34s, since it does in fact function?
I know I'll need to take it to a tech, but I'd like to get a few rehearsals out of it before I do.

If it is running I would say it has been modified EL34s. If it has been done properly (i.e. correct bias, filimant, plate resistors, etc.) will have to be determined by your tech. My feeling, go ahead and take it out for a few runs at the rehearsals being careful not to push it too hard then get it to your tech.

Andrew

[jrc4558]

If your PT is not overheating, you should be alright. Bias better be left to a technician.

[ildar]

Bias better be left to a technician.

Definitely.
I might get some yellow jackets, so I don't have to worry about rebiasing, and I like EL84s anyway.