G7 - any benefits from higher B+ voltage than 160V? Lowering also polarisation V

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ln76d

Well-known member
Joined
Aug 11, 2012
Messages
2,486
Location
Gallifrey
Hi Guys,

i rebuild my G7 after a long time and now is the time for tweaks :)

Am using teflon CK12 and E80F tube.
Right now my polarisation voltages are 160V/80V.  Capsule works ok, maybe a little bit too bright.

Is there any benefit of higher B+ voltage than 160V or maybe lower it simultaneously lowering polarisation voltage?

I want to make polarisation voltage drop to 150V/75V or 140V/70V or even 130V/65V (i will test each combination).
Since i want to make  separately the lower polarisation voltage i can leave B+ 160V, but it can be also higher - let say 185V.

Any ideas?
 
A lower voltage will improve the frequency response of the capsule. 160/80 volts is too high for a CK12. 120/60 or even lower  would be better.
 
Hello Tim,

thank you for the reply.
I agree, that's why i want to lower polarisation voltage.
These capsules works ok with higher voltage but i want to make it darker.
Main question is what about B+ voltage?  :)
Higher plate voltage, more headroom.
I'll be testing it anyway but i wonder what's the others experience and subjective feelings.
 
After subjective tests...
I don't know what's the better  ;D
Right now lowering B+ voltage,  audible difference in HF response is when polarisation voltage is around 55V.
It isn't huge difference in HF but overall it sounds worse - weak LF response and of course much lower output level,
On a days i will do some tests with high plate voltage and lower polarisation voltage.
Maybe hf smoothing capacitor will do the better job?
 
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