Low distortion, pure resistive I/V stage for Sabre Reference DAC - diyAudio
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Old 20th August 2012, 01:45 PM   #1
roender is offline roender  Romania
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Default Low distortion, pure resistive I/V stage for Sabre Reference DAC

Is pleasing my ears now with very good micro-details, accurate mids and a phenomenal bass.
Enjoy!
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File Type: jpg fft20khz.jpg (30.6 KB, 904 views)
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Old 20th August 2012, 02:17 PM   #2
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The 0.81 ohm indicated value of R6 and R9 must be an error, yes?
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Last edited by Ken Newton; 20th August 2012 at 02:19 PM.
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Old 20th August 2012, 02:22 PM   #3
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Nope :-)
0.82ohm, 0.1% 5ppm/C ... I/V resistor ;-)
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Old 20th August 2012, 05:28 PM   #4
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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 ?
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Old 20th August 2012, 05:51 PM   #5
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Quote:
Originally Posted by smms73 View Post
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.
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Old 23rd August 2012, 02:06 PM   #6
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125dB SNR
But most important, It sounds really good for a such simple I/V stage.
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Old 24th August 2012, 06:05 PM   #7
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Improved SNR and much lower distortion, mostly 3th at -114dB.
Was tested with square waves and didn't show any instabilities.
Zin = 1.8ohm
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Old 31st August 2012, 06:49 PM   #8
smms73 is offline smms73  Portugal
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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.
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Old 31st August 2012, 06:54 PM   #9
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Is the output really loaded with a 1kOhm resistor ?
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Old 31st August 2012, 07:23 PM   #10
smms73 is offline smms73  Portugal
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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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