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Old 23rd April 2010, 06:33 PM   #21
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Yes, PSU rejection detorientates at higher frequencies in OPamps and shunts can have a very low impedance to higher frequencies. The LME series of Opamps on the other hand has very good PSU rejection up to high frequencies. Look at the new LME49990.
The problem with very low impedance shunts can be oscilation on the other hand.
I did not say that i did not hear a difference. I just have a problem when listeners claim gigantic and miraculous gains. At the end of the day its a bit like cooking. Everything counts and what we hear is a combination of first order and second order effects so FdWs solution may sound excellent despite some choices he made that whould be done in a differnt way by others.
When you look into integrated intrumentation OPs also consider the INA163.
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Old 23rd April 2010, 07:36 PM   #22
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Did you compare the shunts to 78**/79** or to a discrete series reg? I realise we all have different criteria but good regulators are IME more important than using the newest opamp.
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Old 23rd April 2010, 07:58 PM   #23
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I compared the Placid ( discrete Shunt) with the LC Audio Low Noise PSU ( discrete series) i anhanced with 27mH coils plus lokal decoupling. I have some experience with LM317 type of regulators that where not totally satisfying. I can not remember that I used fixed regulators since the LM317 came out and that is a long time ago.
I also have some good experience with he TL line splitter but with a lot of decoupling caps. I own a Horwege DAC and Horwege Phono that both use this and sound very dynamic. I think the webpage is Willkommen bei der HiFiWERKSTATT hoer-wege
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Old 23rd April 2010, 08:19 PM   #24
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In that case, Joachim, we are in agreement. I find the difference between a good series and a good shunt reg to be quite trivial with a mild preference for the shunt. A fixed 3-terminal is something very different and in my view inappropriate for high end equipment.
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Old 23rd April 2010, 11:10 PM   #25
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I will soon try a shunt that Salas designed for my MPP, so i will get some more experiences with shunts. I am happy that we agree.
Happy listening with whatever floats your boat.
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Old 24th April 2010, 09:15 AM   #26
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@Joachim

I compared Placid vs Salas V1.0 with remote sensing +5.5V 500mA in the DAC Buffalo II of Twisted Pear, please be so kind to let me know your opinion.

The Salas reg. was do it with 2.200uF/63V cap PSU filter, the rest of components: Elna Silmic II 100uF/25V, Xicon & Koa Speer both carbon film resistors & 1 trimmer Bourns, I detail the components used because as you said before all count.

For both reg. I used a R-Core Tx 9V 230V 30VA.

Click the image to open in full size.

Last edited by merlin el mago; 24th April 2010 at 09:30 AM.
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Old 24th April 2010, 09:45 AM   #27
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Sofar i did not have the luxury to try C core. How does your build sound ? I asume great.
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Old 24th April 2010, 09:46 AM   #28
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Quote:
Originally Posted by analog_sa View Post
In that case, Joachim, we are in agreement. I find the difference between a good series and a good shunt reg to be quite trivial with a mild preference for the shunt. A fixed 3-terminal is something very different and in my view inappropriate for high end equipment.
Quote:
Originally Posted by Joachim Gerhard View Post
I will soon try a shunt that Salas designed for my MPP, so i will get some more experiences with shunts. I am happy that we agree.
Happy listening with whatever floats your boat.
Now I have to try it I will replace the series regulators with shunt regulators. The current boards do not allow for a discrete build, and thus I am getting a few drop-in replacements. To fit them in their current spot TO220 models are needed (with fixing hole) and I found NewClassD (NewClassD UWB Regulator) with the types that I need (but only up to 15V). After exchanging some mail with the very helpful people there they offered to supply me with 24V versions (custom build). And that is what I am going to do keep the fingers crossed.

The quick simulation that I did last night convinced me the shunt regulators could be an improvement. I have the schema of that simulation attached. The schema is not optimized in any way, but it was the most simple implementation of a series and a shunt regulator, both with about the same type and amount of components.

Regards,
Frans de Wit.

Compare Shunt-Series PSU.jpg
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Old 24th April 2010, 09:58 AM   #29
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You are really dedicated to make somthing good. It will be very interesting to know if the application of a Shunt brings you any benefit. I have seen the design you will use and i am curios how it will work.
I aso did a little circuit that uses your MC input scheme but has lower noise. You could also try the LME49990 that has even less distortion and better PSU rejection.
In the case of the LME49990 i whould use 10 Ohm and 300 Ohm resistors because it can only drive 20mA in comparison to 40mA of the AD chip.
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File Type: pdf DSJG Simple Balanced Input.TSC - TINA.pdf (39.6 KB, 303 views)
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Old 24th April 2010, 10:28 AM   #30
FdW is offline FdW  Netherlands
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Quote:
Originally Posted by Joachim Gerhard View Post
You are really dedicated to make somthing good. It will be very interesting to know if the application of a Shunt brings you any benefit. I have seen the design you will use and i am curios how it will work.
I aso did a little circuit that uses your MC input scheme but has lower noise. You could also try the LME49990 that has even less distortion and better PSU rejection.
In the case of the LME49990 i whould use 10 Ohm and 300 Ohm resistors because it can only drive 20mA in comparison to 40mA of the AD chip.
I will install the LME49990 in the diff input stage.

I am not convinced about the lower values resistors. Using lower values will reduce noise, but, it will also make for a mismatched impedance to the cartridge. The MC preamp is used with a Koetsu Rosewood Signature it is specified as needing a 100ohms load impedance and will then deliver 600uV.

The question remaining, and that I would like to see answered, is this; is using lower value resistors a tradeoff between noise and impedance matching? and to what effect?

Regards,
Frans.
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