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In the Forum: Melquiades Amplifier
In the Thread: To drive the 6C33C...

Post Subject: Irrelevancy of my question and 6336Posted by N-set on: 11/3/2010

Thank you Romy, that was very informative and instructive!
I don't completely agree that OP is absolutely irrelevant for linearity.
It can happen that some regions, under given design constraints, will
not give "a proposer harmonic structure of your sound", irrespectively
of the load, simple because the characteristics bend oddly there.
Using your procedure one can (hope to) navigate away from them
but I have the HV constraint: without enough voltage swing and fast slew rate
electrostats sound anemic.
So my question was rather: do there potentially exist conditions
in the HV/low current region for getting a good harmonic structure,
under some optimal load?
However I've just realized that my question is irrelevant for other reason:
what works well for a SET, OPT coupled to a speaker is probably irrelevant
for a PP directly coupled to a GIVEN capacitive load...I have no possiblity to
manouver here with the load seen by the tube, e.g. by turns ratio.
The only parameter somehow tuning the coupling
is the plate load choke. For example a very quick (and perhaps very
flawed) Spice model showed that I would need around 30H choke per plate for a 6C33C
to have a +/- acceptable harmonic spectrum at 20Hz (OP is 320V/-150V/60mA, full tube, 100pF load).
Probably this is what one needs to make the load ellipse, posed by 100pF@20Hz
not to cut the tube at LF.

On a related tube: the mentioned 6336 looks very interesting, esp. that I could
use both halves for the PP. Any input on this tube highly appreciated (incl.
a good spice model for one section). Or better yet 6528..

Cheers,
N-set

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