Andre Jute wrote:
I have the second circuit you sent, Patrick, the one you have had
running for a few months.
The schemo I sent is only provisional, and has never run.
Its been on my mind for the 18mths since I began the project.
Its the basic thing that will need to be de-bugged following
initial trials, and that will mean slight changes to voltages and
part values.
Since virtually all my provisional designs have worked as proposed
then i reckon this one will too.
That one seems ready for primetime, if very
complicated. (I recently did a series of amps with a split rail, and
just automatically made it symmetrical.) Why not publish your 845 amp
and lead us through it step by step, making separately named
subthreads for the introduction and for each stage so that the whole
thread doesn't bog down in one person's incomprehension or
stubbornness, as happens too often with interesting threads.
If anyone is able read schematics then they will easily figure
how it all works, just two very simple CR coupled cascaded gain stages,
one optional CF buffer for A2 op, and then 845/211 output tube or pair
of parallel tubes using about +850V and -350V rails.
The split rails allow the OPT to idle with only +850V present,
and the P-S insulation isn't seriously challenged as it would be with
say 1,600V if I did a Mills derived circuit with everything
"standing on" 0V as the basic rail.
I have one more re-engineering job on an ARC VT100 to finish,
and then I can spend a month on the 845 project.
I sold a pair of speakers today, so between now and Xmas I can
return to completion of 3 big projects, the 845 50 watters,
the ESL speakers I began and failed to complete last autumn,
and to complete another pair of 300 watters, now about 3/4 finished.
Maybe in 2027, I will find time to take a break....
Patrick Turner.
Andre Jute
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