Highly application specific Resistor question

ThorstenL · 13th June 2003, 10:19 AM

Koinichiwa,

I am just interested if anyone has done some studies which resistors sound best to their ears when used in the Feedback loop of an OPA627 used as I/V converter.

The I/V converter will be followed by a Cathode Follower operating as "Jennifer Lowpass", is anyone is interested.

Sayonara

HpW · 13th June 2003, 12:13 PM

Hi,

I used first with my PCM63 and OPA627 some smd's.

Then I changed to Alpha electronic's (Japan) with overall better
natural sound improvment. Also the feedback compensation
could also be lowered (overshut compensation).

May look at www.alpha-amer.com

The types I used http://www.alpha-amer.com/images/pdf/resistor-m/ema.pdf

Cheers

HpW

ThorstenL · 13th June 2003, 12:35 PM

Koinichiwa,

Quote:

Originally posted by HpW
I used first with my PCM63 and OPA627 some smd's.

Then I changed to Alpha electronic's (Japan) with overall better
natural sound improvment. Also the feedback compensation
could also be lowered (overshut compensation).

Arigato gozaimasu

Sayonara

MBK · 14th June 2003, 05:22 PM

Hmmm, I used an OPA2134 with a biased BSS170 follower, I/V is through garden variety metal film.

What I noticed worth mentioning:

- tried OPA627, couldn't get it stable (my poor veroboard layout I guess). OPA 2134 was less picky.

- even so I needed a small R (47R) between the transistor and the actual I(out) of the 1541 for stability

- on the AD797 data sheet they show some I/V applications. I used one of their tricks, an RF shunt cap between (+)in and (-)in, value 1000 pF. That configuration ended up working best, with more punch (dynamics) than straight I/V via feedback loop.

- gate resistor 100R

- FWIW I used a 3 pole Bessel 20 kHz post-I/V (it's NOS), 1st pole is a primary filter by a cap parallel with the I/V resistor

MBK

13th June 2003, 10:19 AM	#1
ThorstenL Previously: Kuei Yang Wang Join Date: Nov 2002 Location: Somewhere nice on planet earth	Highly application specific Resistor question Koinichiwa, I am just interested if anyone has done some studies which resistors sound best to their ears when used in the Feedback loop of an OPA627 used as I/V converter. The I/V converter will be followed by a Cathode Follower operating as "Jennifer Lowpass", is anyone is interested. Sayonara

13th June 2003, 12:13 PM	#2
HpW diyAudio Member Join Date: Mar 2002 Location: Switzerland (Bern)	Hi, I used first with my PCM63 and OPA627 some smd's. Then I changed to Alpha electronic's (Japan) with overall better natural sound improvment. Also the feedback compensation could also be lowered (overshut compensation). May look at www.alpha-amer.com The types I used http://www.alpha-amer.com/images/pdf/resistor-m/ema.pdf Cheers HpW __________________ www.hpw-works.com

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14th June 2003, 05:22 PM	#4
MBK diyAudio Member Join Date: Apr 2002 Location: Singapore	Hmmm, I used an OPA2134 with a biased BSS170 follower, I/V is through garden variety metal film. What I noticed worth mentioning: - tried OPA627, couldn't get it stable (my poor veroboard layout I guess). OPA 2134 was less picky. - even so I needed a small R (47R) between the transistor and the actual I(out) of the 1541 for stability - on the AD797 data sheet they show some I/V applications. I used one of their tricks, an RF shunt cap between (+)in and (-)in, value 1000 pF. That configuration ended up working best, with more punch (dynamics) than straight I/V via feedback loop. - gate resistor 100R - FWIW I used a 3 pole Bessel 20 kHz post-I/V (it's NOS), 1st pole is a primary filter by a cap parallel with the I/V resistor MBK

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