Marshall Amp Forum - View Single Post - Power tubes?? Who, What, When Where how??

MartyStrat54 · 10-07-2009, 03:07 PM

This is a copy of a post that I left on the Preamp Tube Thread. It is about using an EL34 with a 6CA7 in a TSL602.

Well, I did it and it worked just fine. It gave the top end a little more sparkle. The power chords were very fat, as both tubes do have good bottom end. Oh, BTW, this is a 6CA7 Sylvania Fat Boy and a "Mullard" EL34 in one of my 602's. Both tubes tested the same and they biased right up with just the one bias trim pot. (You lucky DSL50 guys have two trim pots.) I guess I'll leave them in there for a while and see if I'm still liking it this weekend.

I would have to say it is sort of like pairing V1 and V2. In this arrangement, the Mullard gets the first part of the signal and then the Sylvania. So the Mullard's tonal characteristics are there "first" and then it goes into the cleaner sound of the Fat Boy. I guess just like V1 and V2, you could swap them around and see if that sounds different or better.

Time Warp-I swapped the tubes around and it does make a difference, especially on the Clean channel. With the Fat Boy in there first and the Mullard on the negative swing of the power cycle, it is a cleaner, tighter sound. The Sylvania has now become like V1 and it's flavor is dominant.

Now you might ask, "Try two Fat Boys." Well I can't. This pair I bought I got a bad deal. They were sold untested and one reads 79 and the other 88. You could probably bias them up in a DSL50. I don't know how wide a swing the amp will tolerate, but I don't like to go more than 8 points between tubes.

So this is sort of fascinating. That the tube on the positive side of the power cycle is like V1 and the characteristics of the negative side of the power cycle is like V2. The negative side adds to the power, but the flavor is stronger coming from the tube first in line with the power cycle.

I had PM'd JOE about Steelhorse's amp that runs the KT66's and the KT88's. He is getting flavor from two completely different sounding tubes. With the EL34 and the 6CA7, they are both electronically the same...pin for pin. However, even though this is true, they do not sound the same. A 6CA7 is more like a 6L6GC in sound. I told JOE that putting 6CA7's in your amp was a quick way to get the KT88 sound. No worries about the biasing as it will bias right up.

How's that for some tube info?