6k6 load line and 6v6 swing

naciketas · Post by **naciketas** » Sat Jul 12, 2014 12:17 pm

Hi, after completing a Liverpool inspired build, I'm considering replacing el84s with 6v6s to increase the cleans range.

I plotted the 6k6 load line for a plate voltage around 400v (as I understand, this value for a quad as in the Liverpool, should be doubled, 13k2 for a pair) and it looks that plates could swing as high as 550v, being 500v the maximum value of JJs!

I wonder if this limiting value is related to a static dc voltage which would means tubes operating in a safe area, or is it an absolute static/dynamic value that once exceeded would led to flashover and/or arcing?

Thanks

rooster · Post by **rooster** » Sat Jul 12, 2014 3:11 pm

I think a more practical view will answer your questions. The Fender Tweed Deluxe typically sees 385VDC on it's plates - using a 5Y3 and running in Class A. Swapping to a GZ34 boosts the plates to 405-410. Vintage Philips tubes can survive this and the JJ tubes just laugh at this situation. In either case it's just a cathode bias adjustment to assure the deed - even if your tube choice is weaker

Be like Leo, think less and do more.

naciketas · Post by **naciketas** » Sat Jul 12, 2014 3:28 pm

"And thus the native hue of resolution
Is sicklied o'er with the pale cast of thought"

If Hamlet had played through a BFDR, there would have been one tragedy less

So I'll let 'em swing!

Thanks

martin manning · Post by **martin manning** » Sat Jul 12, 2014 3:34 pm

A pair of 6V6 at 400V wants to see a load around 8k, a quad around 4k. 6k6 would work ok for a pair, but I think it'd be a bit too high for a quad.

naciketas · Post by **naciketas** » Sat Jul 12, 2014 3:57 pm

Maybe a 5k2 350/360v could do.

martin manning · Post by **martin manning** » Sat Jul 12, 2014 4:24 pm

5k2 would work, even at 400V, but I still like 4K better.

naciketas · Post by **naciketas** » Sat Jul 12, 2014 5:28 pm

With 6k6 or 5k2 (better) Rpp it looks closer to the typical wreck lines and most of all I want to use a Pacific transformer.
I redrawn the lines for 5k2 350v 0.028 mA (70%) and it all seems within the safe (500v) limit.
Thanks again

martin manning · Post by **martin manning** » Sat Jul 12, 2014 5:38 pm

naciketas wrote:With 6k6 or 5k2 (better) Rpp it looks closer to the typical wreck lines...

Note in the Express 6V6's are said to be usable with no adjustment in place of the EL34's, and that would be 6k6 for a pair.

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6k6 load line and 6v6 swing

6k6 load line and 6v6 swing

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