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-   -   NFB-free discrete IU (http://www.diyaudio.com/forums/digital-line-level/210211-nfb-free-discrete-iu.html)

anli 5th April 2012 08:46 PM

NFB-free discrete IU
 
2 Attachment(s)
...for +/- 2 mA input: schematics and "harmonics' SPL". I have designed it to be used (and it is in use) with PCM63.

jcx 5th April 2012 09:07 PM

sorry but EF are 100% negative feedback circuits - check EE textbooks instead of Audiophile rags ad copy

anli 5th April 2012 09:16 PM

Quote:

Originally Posted by jcx (Post 2974245)
sorry but EF are 100% negative feedback circuits - check EE textbooks instead of Audiophile rags ad copy

Thanks for your so deep schematics analysis! :D

Please, stop terminology war here, OK? And, please, stop speculations about forum members' reading - you don't know me, my education, my reading and so on. Just stop. And be kind. Aha? :)

jcx 5th April 2012 09:27 PM

"no negative feedback" is a Audiophile marketing construct - doesn't help diy memebers learn how to design, evaluate circuits

few useful electronic circuits can be designed without negative feedback - in your circuit's case there are multiple local negative feedback subcircuits

don't title threads with such loaded terms and you won't have "terminology war" "problems" I wouldn't bother if you accurately used "no Global negative feedback" in the title

anli 5th April 2012 09:52 PM

Unsubscribing..

Trevor White 7th April 2012 12:39 AM

Quote:

Originally Posted by anli (Post 2974233)
...for +/- 2 mA input: schematics and "harmonics' SPL". I have designed it to be used (and it is in use) with PCM63.

what is the input impedance of this circuit ?

For an IV converter it needs to be very low but I don't think it is much better than one grounded base circuit.

tinitus 7th April 2012 08:43 AM

whats up guys ?

why do you behave like this, just because of a 'simple' schematic ?

if you have no interest, just walk away

personal posts removed

:cop:
moderation

anli 7th April 2012 09:45 AM

Quote:

Originally Posted by Trevor White (Post 2975641)
what is the input impedance of this circuit ?

Few Ohms - depending on used Q4.

Quote:

Originally Posted by Trevor White (Post 2975641)
For an IV converter it needs to be very low

Any schematics is a result of compromises in designer's model of the world (and, in audio, it depends on experience of multi-years music listening and correlation between used schematics topology and subjective opinion) :) To my taste input impedance is sufficient for the case (DAC output impedance about 670 Ohms - it is simulated with Rdac).

Quote:

Originally Posted by Trevor White (Post 2975641)
I don't think it is much better than one grounded base circuit.

It is common base - Q2 just fixes input voltage about zero in thermo-independent way.

Torchwood421 8th April 2012 09:41 PM

Hi anli, How does it sound? I'd be interested in using it with a TDA1541A. Have you tried an AD844 based I/V? Thanks for any comments... :) Dave

anli 8th April 2012 10:03 PM

1 Attachment(s)
Before current one I have used an IU as attached (the schematics isn't my, as a result - fragment only). To my taste, current IU is distinctly better (the difference isn't subtle): "Cu is Cu rather Al" - you see? ;) While technologically it is easy to replace an IU (it is separated from main DAC board), during almost two yeas I haven't any intentions to design something better (but, say new amplifier has appeared :)). Mostly I listen to live records (mainstream 50-60 jazz and different classical music).

You see, it is just subjective opinion.


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