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If I were to run a DR-103 with two of the power valves pulled and half the output impedance, wouldn't this pretty much sound (volume wise), and preform exactly like a DR-504 ? After looking at the schematics on MHuss's site, it looks to me like they would be approximately the same. Thanks for the input.

lffish133 wrote:...exactly like a DR-504 ?

Pretty close. Never tried the two side-by-side, though.

Keep in mind that the output transformers are different between a DR103 and the DR504. So, you'd have an "oversized" transformer working at half capacity instead of a "perfectly sized" transformer working at 100%.

Dave

It should sound close. I haven't A/B'd them before either, but maybe we can at the convention for scientific research purposes?

-Clayton

Yeah I was thinking about the output transformer thing too, I'm sure they wouldn't be exact, but I'll bet they would be dang close, that would be interesting to A/B them side by side and listen for the differences.

I've put 4xEL34, 2xEL34, 4x6V6 and 2x6V6 in my '103 clone, and it always sounds good! The 4x6CA7 option is the one that puts hair on your toenails, however!

--mark

I guess this is directed at Mark or anyone who has used 2x6CA7, 4x6V6 or 2x6V6 in a 103. Were there mods required other than bias? Any harm running 4x6V6 for months / years?

Sorry if I am asking dumb questions but I haven't gotten a handle on output tubes and OTs.

Thanks,

Kenny

Only use the JJ 6V6s, as normal ones can't handle the high voltages.

Otherwise, yeah, just a bias tweak and you're good to go.

--mark