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-   -   Low distortion, pure resistive I/V stage for Sabre Reference DAC (http://www.diyaudio.com/forums/digital-source/218247-low-distortion-pure-resistive-i-v-stage-sabre-reference-dac.html)

roender 20th August 2012 12:45 PM

Low distortion, pure resistive I/V stage for Sabre Reference DAC
 
4 Attachment(s)
Is pleasing my ears now with very good micro-details, accurate mids and a phenomenal bass.
Enjoy!

Ken Newton 20th August 2012 01:17 PM

The 0.81 ohm indicated value of R6 and R9 must be an error, yes?

roender 20th August 2012 01:22 PM

Nope :-)
0.82ohm, 0.1% 5ppm/C ... I/V resistor ;-)

smms73 20th August 2012 04:28 PM

0.82 ohms are very low. Did you experiment with higher value?
I like the way you connect the bipolar and jfet. Did you experience stability problems ?

roender 20th August 2012 04:51 PM

Quote:

Originally Posted by smms73 (Post 3133672)
0.82 ohms are very low. Did you experiment with higher value?
I like the way you connect the bipolar and jfet. Did you experience stability problems ?

Yes I did, but I perceived better sound by putting lower and lower I/V resistors. I had to stay at 0.81ohm value because there is no much gain in the circuit.
I have not find any stability problems until now.

roender 23rd August 2012 01:06 PM

125dB SNR
But most important, It sounds really good for a such simple I/V stage.

roender 24th August 2012 05:05 PM

1 Attachment(s)
Improved SNR and much lower distortion, mostly 3th at -114dB.
Was tested with square waves and didn't show any instabilities. :)
Zin = 1.8ohm

smms73 31st August 2012 05:49 PM

Very nice, I have a idea that uses that kind of connection but without the jfets , with only transistors, have you try using bjt in the place of jfets ? I get less distortion using bjt.

Joachim Gerhard 31st August 2012 05:54 PM

Is the output really loaded with a 1kOhm resistor ?

smms73 31st August 2012 06:23 PM

I have see this type of connection in Cordell book page 530. He call it jfet-bipolar CFPs.
Jochim this can be a good idea for you to try in your new MC amplifier. It has very low distortion and low impedance. I prefer with only bjt.


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