Someone said KT 77 tubes...

[kingster911]

Could I just replace the EL's in my RKII with 6L6's and just have the ultimate Triple Rec. sound on modern in Ch.'s 3 & 4? Just curious.

 

[Boogiebabies]

The RK II output transformer is very similar to the simul class version.
It has two different taps on the primary and blends the signal through the secondary. Now, the EL34 sockets are biased at -39V and the 6L6 at -51.
Here is the kicker. The EL34 sockets have an adjustable bias trim pot so you could in all actuality bias them to run 6L6's and have all the tubes biased at what natural current draw you are getting from the 4 6L6's.
The only thing I dont know is how it would sound. The 4 6L6's are running in a push pull configuration as are the EL34's, but since they have separate primaries I dont think it will give you the full Triple Rec vibe, bit it may be close !!!

 

[NoGlassNoClass]

You would have to mod the amp to run 6L6's in the EL34 sockets, as the bias will be way off (change the resistors or add an adjustable bias pot). You *might* be able to find some 6L6's that are cold enough to run in EL34 mode with questionable reliability.

IMO your best bet would be to run a pair of KT-77's in place of the EL34's. They are interchangeable with EL34-type tubes, and although not really 6L6-sounding, they have much deeper lows and more headroom than EL34s. Get them from a reputable dealer ( www.dougstubes.com www.eurotubes.com ) so they will be in spec with Mesa's fixed bias.

Note...running non-Mesa tubes voids your warranty.

 

[NoGlassNoClass]

...The EL34 sockets have an adjustable bias trim pot...

I stand corrected.

 

[MesaENGR412]

This post doesn't really have any suggestions, I just wanted to say that you guys are friggin' awesome. So knowledgable, it's great. This website is the single greatest Mesa Resource ever (besides Randall Smith himself). Thanks so much for being here haha. Awesome stuff.

-AJH

 

[Guitarzan]

Note...running non-Mesa tubes voids your warranty.

Not True. Mesa will tolerate the use of Groove Tubes #4 through #7. This will NOT void your warranty. Feel free to call Rich Longacre @ Mesa to verify.

 

[NoGlassNoClass]

Does Groove Tubes have the KT-77 yet?

 

[Guitarzan]

Not yet... They have the JJ 6L6's, 6V6's and the EL-34L's. Just look for the "S" on the suffix of the tube.

 

[Boogiebabies]

All Mesa does on the RK is have -39V at pin 5 of the EL34 sockets.
You can adjust this with you multi meter. They dont even put nail polish on it that breaks to prove you moved it !!!