Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Baguette on December 02, 2011, 08:33:31 am

Title: 3.4K or 6.8K for 6L6 in push pull?
Post by: Baguette on December 02, 2011, 08:33:31 am

Which load would you use for a Fender amp with 2 6L6GC at 470V on the plates?

Thanks!

Title: Re: 3.4K or 6.8K for 6L6 in push pull?
Post by: birt on December 02, 2011, 10:31:44 am

i would suggest looking at the specs of those OT's or replacements that are used in PP 6L6 fender amps.

Title: Re: 3.4K or 6.8K for 6L6 in push pull?
Post by: Baguette on December 02, 2011, 11:16:03 am

Most are in the 4K - 4.2K range.
However, IIRC, the early Tweeds with 2 6L6 had 6.6K load (Pro Amp, Super Amp etc.). But those had lower plate voltage.
So this makes me wonder...
Basically, I wanna get as much clean watts from the tubes. I'd bet 3.4K would get me there, but I'd like to have some other opinions, and I'm not against a bit of math too.

Thanks!

Title: Re: 3.4K or 6.8K for 6L6 in push pull?
Post by: phsyconoodler on December 02, 2011, 03:34:10 pm

3.4k is close to marshall specs,Fender used 4k and 4.2k.  6.6k is often used when the amps are cathode biased but have less headroom and sometimes a nicer overdriven tone.
  I love the tone of a pair of 6L6's through a 6.6k load.

 

Title: Re: 3.4K or 6.8K for 6L6 in push pull?
Post by: PRR on December 02, 2011, 08:58:55 pm

> early Tweeds with 2 6L6 had 6.6K load (Pro Amp, Super Amp etc.). But those had lower plate voltage.

Mostly: they are cathode-bias, right? And perhaps with some drop from plate to screen?

In fix-bias, with screen near plate voltage above 400V, 6L6CG will pull a 4K load, and that's what Fender did.