Even two sides of a 6SN7 in parallel won't be happy driving 2.4K at higher levels. I'd use a 4:1 output, then try to make up the extra 6dB of loss somewhere else... perhaps use 1/2 6SL7 for the input stage, one side for each channel. And there's your three-bottle, two-channel preamp.
mmm. If I would use a 10k primary, I would probably try a single triode driving it. Do you think a half 6SN7 / 6CG7 would do it?
If yes, I would arrive into a very nice design, just one bottle for channel, easy to get tubes, enought gain for most uses, low heater power needed, low parts count, very simple to build, level control with regular log pots, from 0 to max with 600 Z output for driving anything from tape machines to semi-pro level inputs.. If you need more gain, I´ll include a switch at the output for driving unbalanced high Z loads directly, with 12dB more gain.
If the one bottle concept will drive the 10k output iron nicely, I may get crazy and try to put eight channels of those into a 1U rack enclosure, with an out of the box PSU, obviously...
I have many beyer 1:15 comming, so maybe I could use those for getting more gain at the first stage, instead of 1:7 transformers, and still use the 6SN7 / 6CG7 tubes...
The level pot doesn't need to be 1M, and such a large value will cause high frequency rolloff, looking into the grid of the following stage
Yeah, I´ll try a 220k pot. PRR told me about it in his post above, but I forgot to include this mod in my first redraw. Thanks for the heads up.
Don't put a lot of faith in those tube models in Circuitmaker. They tend to predict better performance (especially with large signals) than what you'll get in real life. Diddling around with a simulator is fun, but it's no substitute for real design work.
Yes, I know about CM tube models, and all. I´m actually trying to do like the dead man did, looking into tube curves and using formulas, but it´s the first time, so it´s stil very easy for me to get confused with all the parameters, formulas and curves. I´m not taking the simulation so serious this time.
It's not going to be too tolerant of abuse as it stands, particularly in regards to the peak fault currents in the transistors (can you say PAFFFF goes the silicon?).
Argh! I´m really not a fan of these high voltage discreet regulators. They do it all the time and I rate when they do it, like paffff...
I´m just trying to get low ripple without a choke and all those big caps.
Any easy way to make it more PAFFFF PROOOOF ?
Be mindful of zener dissipation too.
Yes, the idea is to use three or four in parallel for summing dissipation and get high voltage reference without having to import zeners from Germany or England. I´m thinking local stores...