Switch mode between Hawksford error correction and NFB by Unity Gain - diyAudio
 Switch mode between Hawksford error correction and NFB by Unity Gain
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diyAudio Member

Join Date: Jul 2005
Location: D-55629 Schwarzerden
Switch mode between Hawksford error correction and NFB by Unity Gain

Here an theoretical possible for select between two kinds for reduce of distortion. Anybody tested?
Attached Files
 C_...Hawksford+NFB.pdf (6.6 KB, 189 views)

diyAudio Member

Join Date: May 2002
Location: The great city of Turnhout, BE
Blog Entries: 8
Quote:
 Originally Posted by tiefbassuebertr Here an theoretical possible for select between two kinds for reduce of distortion. Anybody tested?
Hi,

I've build some hawksford ec amps, but not tested this specific topology, and I have trouble understanding the Hawksford ec case. Can you post the schematic for 'Hawksford ec' like you did for 'nfb' please?

Edit: I now see, it's the upper case. Forget my post ....

jd
__________________
Music is dither to the brain; lets me think below the usual chaos - me
Linear Audio Vol 13 is out! Check out my Autoranger and SilentSwitcher

Last edited by jan.didden; 5th October 2009 at 06:14 PM.

 5th October 2009, 06:20 PM #3 diyAudio Member     Join Date: May 2002 Location: The great city of Turnhout, BE Blog Entries: 8 I don't think that ec case works. Assume the opamp has gain A, the buffer is ideal and the load voltage is Vo. We see that the opamp Vout=Vo. The inverting input is also Vo. The non-inverting input is also Vo. Vout opamp = A(-Vo+Vo)=Vo so Vo = 0. Independent of Vi. jd __________________ Music is dither to the brain; lets me think below the usual chaos - me Linear Audio Vol 13 is out! Check out my Autoranger and SilentSwitcher
 5th October 2009, 06:31 PM #4 diyAudio Member     Join Date: Jul 2005 Location: D-55629 Schwarzerden The OP-Amp must be a diamond transistor, not a normal type (see datasheet for AD844 e. g.) http://www.analog.com/static/importe...eets/AD844.pdf The buffer symbol in my simplefield schematics represented the internal buffer of the op amp so as an external power push pull buffer.
diyAudio Member

Join Date: May 2002
Location: The great city of Turnhout, BE
Blog Entries: 8
Quote:
 Originally Posted by tiefbassuebertr The OP-Amp must be a diamond transistor, not a normal type (see datasheet for AD844 e. g.) http://www.analog.com/static/importe...eets/AD844.pdf The buffer symbol in my simplefield schematics represented the internal buffer of the op amp so as an external power push pull buffer.
Ahh yes, I used that too. You must have read my article on the Hawksford ec amp in Elektor or AudioXpress...

So the opamp non-inverting input is a high-impedance voltage input, the inverting input is a low-impedance current input, and this current comes out of the opamp output in reverse polarity? Is that what you mean?

Yes that'll work.

jd
__________________
Music is dither to the brain; lets me think below the usual chaos - me
Linear Audio Vol 13 is out! Check out my Autoranger and SilentSwitcher

Last edited by jan.didden; 5th October 2009 at 06:48 PM.

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