E80CF and a new phase-splitter

Moonraker

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fredeb said:
I quite like your idea of driving Electrostats directly , I never knew it was possible . I guess it could be dangerous if something went wrong . How does it work ? Does one disconnect the electrostat transformer ?

Off topic:

I don't see why not.  The electrostatics require a push-pull drive, I believe. 
Driving them basically off the anodes of the PP output stage should be possible.
With some fine tuning to make things safe and stable of course.

Imagine the original Quad2 driving electrostats, as intended. 
The amplifier OT steps down the impedance down to the level of typical electrodynamic LS. 
And the loudspeaker's transformer reverses the impedance ratio again. 
Kind of a waste... and distortion!
 

V4lve Lover

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fredeb said:
Thanks for the warning [member=144]Ampdog[/member] . What is the way to detect such leakage ? My modded ST70 has a board that uses ECF82/6U8 instead of 7199 , I bought it like that . I suppose the change was made because of how expensive 7199 had become , if you can find them at all . What would the symptoms of above mentioned cathode to filament leakage be ?

Cheers
- Ari

You can run PCF82 with a dropper resistor in place of ECF82, if you need any let me know, i have over 100, same for most of the other series tubes. You can have them for postage.

 

fredeb

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V4lve Lover said:
You can run PCF82 with a dropper resistor in place of ECF82, if you need any let me know, i have over 100, same for most of the other series tubes. You can have them for postage.

Good to see you active here [member=24540]V4lve Lover[/member] !  ;) Thanks for the offer , I may take you up on that later .

 

Ampdog

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fredeb said:
I wonder if it was the power and output transformers that limited the Radford to 25W , compared to the rated 35W the ST70 is said to put out ?

I did not do arithmetic, but much of the reason would lie in Radford having cathode-biased output stages compared to the fixed bias in the ST70. (The cathode drop voltage must therefore be subtracted from the h.t. for the actual EL34 cathode-anode voltage in the Radford.) That is assuming the same power supply voltage - I cannot recall right now.. . .
 
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