Mark III Simulclass tubes - All 6L6?

[rippingrudy]

Hi Everyone -

Recently purchased a Mark III Simulclass combo. It is currently loaded with two 6L6s and two EL34s. According to the Mesa users manual you should not use 4 x 6L6s due to too many tube failures.

I noticed on the eurotubes site that they sell retube kits for this amp with all 6L6s (4) and with 2 x EL34 and 2 x 6L6.

Is what the mesa manual says accurate or does everyone run their Mark III simulclass with all 6L6s?

Thanks,
Chris

 

[Boogiebabies]

That manual was written at the height of crappy Chinese 6L6's. In the mid to late 80's, all we could get was NOS or Chinese and Russian tubes. The Chinese tubes, like Mesa STR-420's were great sounding tubes but were not known for their reliability or longevity.
You can run all 6L6's, but it's best to run a cooler set in the outer sockets because they are biased hotter than the inner set. The factory bias is -56v on the inner tubes and -45v on the outer. On some of the better made current production tubes like SED and JJ, you could run a matched quad will no problem. There 30 watt tubes in a 460 or lower plate voltage and can handle a bias of -48ma and last for a while. Don't let someone sell you tubes that are too cold. A JJ 6L6 from Eurotubes in a #26 will only draw a cool 17ma in these amps.

 

[rippingrudy]

Do you figure that the guy form Eurotubes will know all this stuff if I mention it to him?

First you said to run a cooler set in the outer sockets - Later you mentioned a matched quad. Could you please confirm which way I should go?

Thank you for the information.

 

[Boogiebabies]

Bob at Eurotubes will know what to do.