Will a pair of 6L6's take 3200 ohm load push pull?

[priesty]

Just doing some maths based on load impedances for a pair of 6L6’s running in push-pull at 450 Volts plate and c. 400V screens. Would they survive being run on a 3200ohm load? I’m looking for loud and clean guitar tone, so I’d be Biasing cold and have larger than normal screen resistors (2K perhaps). Hoping that I’d be able to squeeze 60 Watts out of a pair of tubes.

I fear I may be on a non-starter, your thoughts would be appreciated!

[Wilder Amplification]

Assuming the pair of 6L6s you're referring to have a plate dissipation rating of 30 watts, yes a 3200 ohm plate-plate load would be fine to run on that B+ voltage. Not sure why you'd wanna run such a high value screen resistor though.

[J M Fahey]

Personal opinion, I see it as a little low impedance, considering average, run of the mill 6Ls.
Yes, according to datasheets it can be done, they are noble beasts and accept a wide range of output impedances; problem is how much the ones you actually get follow them.
Maybe if you buy good quality ones and select the best among them ... you may get closer to your goal
60 "real/undistorted" watts seem to be a little optimistic with conventional drive and supply voltages; and cold biasing doesn't sound very good.
Rather than squeeze the last watt out of them, I'd gain a lot more headroom by using more efficient speakers.
Just my 2 ¢

[MWJB]

3.2K is typically no problem, some British amps ran as low as 2.5K, brown 3x10" Bandmaster ran a little over 2.5K, some Fender OTs can measure 3.6K. It will be fine, but I would avoid using a parallel speaker extension jack.

[priesty]

Thanks for your comments guys, This forum is the best!

[Diablo]

For 60 watts out of a push-pull pair of tubes, take a look at an old Ampeg V2 schematic. They used higher plate voltage, around 560 volts and also a very robust tube to handle the power - a 7027A. The 7027A was a high power version of the 6L6, rated for 35 watts. You can find NOS tubes on ebay if you hunt. They're not cheap, but available for around $60 a pair. One caution, the internal wiring of the 7027A is slightly different from a 6L6. Ampeg wired the socket so you could use either a 7027A or 6L6. You can't stick a 7027A into most Fender amps because some of the socket pins are used as anchor points for resistors.

[pdf64]

My experience with trying higher than 470 ohm screen grid resistors is that going to 2k will likely reduce your output power. As your screens are only 400V, they would be having an easier life than most amps give them anyway. If you were running them at 500V then 2k may be a good idea.
See p9 of GE datasheet for guidance on implications of varying the load (SE amp).
How were you planning on providing 450V to the plates, 400V to the screens - dual rail?
http://www.mif.pg.gda.pl/homepages/f...93/6/6L6GC.pdf
Fender 75 can manage 60 watts with modern tubes, but that's with 500V B+. I'll have to check the OT ratio on mine sometime.