It seems some people don't like the battery in series with the grid, but nobody tell me the reason to avoid.
That's what I thought. The only reason not to like a battery in series is the shelf life of the battery. However, I've pulled a D battery out of a VTVM and after 50 years it was still 1.52V. Eveready for the win, right?
Ni-Cd won't work well on the grid, they go dead in like 30 days, but using it for cathode bias will work. It will charge while the amp is on.
R6 serves no purpose as it's in parallel with R36, which is 100k. That's fine, and with the 1uF cap makes a -3db point of 1.59Hz. Using this as a preamp is overkill though, unless you're driving a hundred feet of interconnect (if you are, make the 1uF cap larger). It will work fine, but there are much more efficient ways of doing this...
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If you factor for a 1k load (old JLH design) then you need a 100uF cap for a -3db of 1.59Hz. My preamp is 50k (2 100k pots in parallel) so 4uF gives 0.7Hz.
As I understood R36 is the load so not a resistor. 100K is the input impedance of my power amps & 300 ohms is the impedance of my headphones.
For interstage or for output cap?
R6 serves to discharge C1?
Exactly I use 0.47uF dor interstage capacitor.
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@merlin el mago - please stop repeating the same question!