azazello wrote:
1.6E5P in triod mode has u=50 , in SRPP u will be 30% more, and I doubt that is enough
for driving GM70 with bias 80-100 v, maybe more.
2.850 v is small +B for good sound. My friend Manakov- tube russian guru advice me use
+B= 1100-1200 v, with bias 100-120 v. And SRPP 6E5P in triode doesn't enoudgh drive GM70
/I'll prefer SE GM70, my IMO is that SE is better PP for HiEnd sounding....in russian forum I sow heating 20 v from lap-top PSU - 4A, this is a good idea!/.
6E5P is exelente tube for driving power triodes and I'll advice You use it in penthod mode.
Sound is very detail and superior! /I used it in my 2 projects SE 6S33S like driver - only in penthode mode to drive 6S33S with bias 75-80 v. I tried use it like triode and u really!! didn't enough with input signal 1 v.from CD /.
3. I think that power triodes can use only in SE, IMO....
azazello,
I have considered your advice and decided to take some of it. I take back the statement about the transformer being the limiting factor. Actually it appears the transformer can handle everything the tubes can throw at it.
There are a couple of errors in my previous post about the voltages and power.I need to increase B+ over 1000 volts. I miscalculated!!!
Here's the load line for one tube across half of a 20K primary with B+ at 1200 and the bias at 100 mA. Ignore the marks on the line.

The 6E5P will not drive the GM70 at this bias and voltage to full power. I need to do some more number crunching.
Thanks for pointing these things out.
EDIT: Crunched some more numbers. I don't think I can get more than 50 watts per channel using a B+ of 1200 volts no matter what I do. I also need a driver that can swing an output of 240 volts! The only way I can see getting any more power is to go with parallel tubes. I don't think I want to go there. This stuff already won't fit in the case I got.
My latest load line puts the grid bias at -120 volts and it can swing as low as -240 and as high as 0. B+ is 1200, and the bias is 100mA per tube.
For all I know I made a mistake. If anybody sees how I can get more than 50 watts per push pull pair please enlighten me.
To get 100 watts at the transformer's design impedance of 10K would require 2830 volts peak to peak across the primary, or about 1400 volts across each side of the primary. However, 10K is too low for the plates of the GM70, so the transformer will be run as a 20K transformer. Assuming I can get that large of a voltage swing, across a 20K primary the same 2830 volts will give me about 50 watts with much improved linearity over a 10K load.
This is my current understanding. That could and is always subject to change.
Thanks.