6F5P/ECL85/6GV8 SET Amplifier

the thermionic watercooler

Postby mashaffer » Mon Apr 25, 2011 4:52 pm

What happens if you eliminate the gNFB and use only the plate to plate?

mike
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Postby Geek » Mon Apr 25, 2011 8:27 pm

Anode follower type dealie?

That's always worth a try ;)

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby Yves » Tue Apr 26, 2011 2:55 am

Plate to Plate NFB increases the second harmonic produced by the driver because its plate load is reduced (more vertical load line).
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Postby Geek » Tue Apr 26, 2011 4:25 am

Merci for that Yves.... I thought it was because of harmonic addition/subtraction.

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby mashaffer » Tue Apr 26, 2011 5:57 pm

Say, Since you are set up to do some measurements what do you say you try it with about 20k of resistance from the driver plate to C1 and bring the FB resistor to that junction instead of directly to the plate and see what it does?

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Postby Brik » Fri Nov 18, 2011 5:31 pm

mashaffer wrote:Say, Since you are set up to do some measurements what do you say you try it with about 20k of resistance from the driver plate to C1 and bring the FB resistor to that junction instead of directly to the plate and see what it does?

mike

Hi Mike,
It would be equivalent to increasing the numerical value of the P2PFB resistor by 20K ohms and inserting a voltage dividing network to reduce the signal voltage swing at C1 somewhat.

I would love to try what you suggest, but, ever since I installed Windows 7 to the computer that I use as an audio workstation, the FFT software/audio card stopped working probably due to the driver mismatch. It may take me a while to get it back to working order. =:o(sick) :'(
/b
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