Low distortion, pure resistive I/V stage for Sabre Reference DAC - Page 3 - diyAudio
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Old 2nd September 2012, 04:58 PM   #21
roender is offline roender  Romania
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Quote:
Originally Posted by merlin el mago View Post
Wich Idss for 170s & for 117s? Sorry my ignorance inputs are V2 & V3, right? Is powered only with +15VDC?
Should be BL grade each of them.
V2 and V3 plus R12 and R13 are inside of Sabre DAC ;-)
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Old 3rd September 2012, 09:18 AM   #22
roender is offline roender  Romania
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Quote:
Originally Posted by Joachim Gerhard View Post
I also think that a simple but good circuit has the potential to sound very good. Is now post 18 the favorite ?
The post 18 contains the final solution for IV stage.
I'm done with the transport. I have found Nirvana :-) which is SDtrans384 plus Sabre Reference DAC in sync mode with the transport. SDtrans now generates the MCLK for the DAC but in the future it ewill be a dual clock board tided closely to the DAC and it will send back to the transport the required clock for the played source file, standard or high resolution PCM.
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Old 3rd September 2012, 09:58 AM   #23
ryanj is offline ryanj  Australia
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Hi roender,

May I ask where you purchased your SD transport?
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Old 3rd September 2012, 10:29 AM   #24
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Originally Posted by ryanj View Post
Hi roender,

May I ask where you purchased your SD transport?
Ask Bunpei member.

Cheers
Felipe
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Old 3rd September 2012, 11:37 AM   #25
ryanj is offline ryanj  Australia
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Thanks Felipe.
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Old 3rd September 2012, 11:42 AM   #26
qusp is offline qusp  Australia
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get ready for $$$$ =) Ryan. sdtrans is very nice, but the price is high due to small runs and high quality parts

btw interesting circuit, does AVCC/2 play a part for gate bias? I cannot tell if R14/R19 are connected across actual ground, or across AVCC. IV resistors are increased to 2r2? I ask because I have some very nice TX220 texas components sfoil in 0.5% 0r66 that I could combine to make for 0r99 easily enough.

sk369 could be interesting here too, I have some matched, high gM quads

Last edited by qusp; 3rd September 2012 at 11:48 AM.
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Old 3rd September 2012, 12:04 PM   #27
roender is offline roender  Romania
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Quote:
Originally Posted by qusp View Post
get ready for $$$$ =) Ryan. sdtrans is very nice, but the price is high due to small runs and high quality parts

btw interesting circuit, does AVCC/2 play a part for gate bias? I cannot tell if R14/R19 are connected across actual ground, or across AVCC. IV resistors are increased to 2r2? I ask because I have some very nice TX220 texas components sfoil in 0.5% 0r66 that I could combine to make for 0r99 easily enough.

sk369 could be interesting here too, I have some matched, high gM quads
The offset voltage generated by the DAC do not mater. R14/19 are connected from the output of the DAC to ground.
This I/V stage can be seen as a microphone amplifier. The input resistor was increased to 2r2 in order to improve SNR to more than 125dB over 10-20kHz bandwidth. The Sabre Reference DAC is working now in "voltage mode" ... but is a voltage DAC anyway no mater what ESS is telling
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Old 4th September 2012, 12:21 PM   #28
ryanj is offline ryanj  Australia
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Originally Posted by qusp View Post
get ready for $$$$ =) Ryan. sdtrans is very nice, but the price is high due to small runs and high quality parts
Yes, as i just recently discovered , i think ill stick with the cheap QA550 for now.
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Old 29th September 2012, 05:58 PM   #29
orelli is offline orelli  Italy
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Quote:
Originally Posted by roender View Post
No, it isn't. It was just for simulation. The only load seen by the I/V stage is the 22k volume attenuator located into the power amplifier.

Guys, as far as I listened, this is the best sounding I/V stage I have tested. And i had listened many.
It is very simple to construct, just be sure that jfets are sorted to the same Idss in every similar symmetrically position
Hi Roender, compliments ,have you listened the Sen I/V of Patrick EUVL also?
I don't understood how you connect the Buffalo to I/V converter.
I think you connect Iout+ of BIII to J1 gate, the Iout- to J2 gate and the 2.2 resistors between the gates and out ground of BIII. I'm right?
Why some resistors have strange values (235 ,360 and 80 Ohm)? Are these values mandatory? Please let me know. Thanks in advance.

Best, Orazio
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Old 30th September 2012, 09:25 AM   #30
roender is offline roender  Romania
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Originally Posted by orelli View Post
Hi Roender, compliments ,have you listened the Sen I/V of Patrick EUVL also?
I don't understood how you connect the Buffalo to I/V converter.
I think you connect Iout+ of BIII to J1 gate, the Iout- to J2 gate and the 2.2 resistors between the gates and out ground of BIII. I'm right?
Why some resistors have strange values (235 ,360 and 80 Ohm)? Are these values mandatory? Please let me know. Thanks in advance.

Best, Orazio

Hi Orazio,

I had listened to many I/V stages but I do not wanna give names and subjectively review them.
You are correct regarding how to connect analog outputs of the DAC to the I/V converter.
Now, regarding resistors, 80 ohms is just in simulation in order to get the same current value as the one in real life. Instead of resistors value I will post a schematic with currents for every stage.
Stay tuned.
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