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Old 6th December 2011, 09:51 AM   #91
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nonlinear bandwith limiting ferrrrrrrrite beads on signal path? Do SC care about performance or EMI supression?

Could be there another reason behind their marketing?
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Old 6th December 2011, 10:06 AM   #92
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Ah I begin to see a reason for Jocko not caring about CM noise so much. Thanks for the link. Its an issue for me though because I use el cheapo 99rmb DVD players as transports, they have el cheapo SMPSUs inside with minimal filtering.

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Do SC care about performance or EMI supression?
In my experience its not either/or its both/and - a performing system is a suppressed one.
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Old 6th December 2011, 11:37 AM   #93
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Hi,

Quote:
Originally Posted by abraxalito View Post
Its an issue for me though because I use el cheapo 99rmb DVD players as transports, they have el cheapo SMPSUs inside with minimal filtering.
Ah I begin to see a reason for you being so concerned about CM noise.

I personally tend to fit a decent output stage WITH an optimised output transformer (and a Tube as buffer as it so happens) which already much reduces the common mode noise floating around on the SPDIF link...

I then like to combine this output with a signal conditioning circuit which incorporates a transformer (and that uses a Tube as Amplification device plus other secret sauce).

I also like to terminate the link very close to the BNC sockets.

There is after the fact a mild bandwidth limit introduced by the tubes, around 60MHz or so and the signal that goes through is "picture perfect", even using the next best thing to wet string as cable and violating impedances etc. grossly.

Ciao T

PS, the reason that I use Tubes for SPDIF is the same given by Dirk Pitt as reason why some angel wing clams glow in the dark under water in the movie Sahara (there are several scientific/factual errors in that scene but it gets the point across beautifully):

Dirk Pitt: "Tell you my theory is that they do because they can."
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Old 8th December 2011, 01:08 PM   #94
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Quote:
Originally Posted by abraxalito View Post
Ah I begin to see a reason for Jocko not caring about CM noise so much. Thanks for the link. Its an issue for me though because I use el cheapo 99rmb DVD players as transports, they have el cheapo SMPSUs inside with minimal filtering.



In my experience its not either/or its both/and - a performing system is a suppressed one.


I have the legato looked inside briefly he does care about CM noise but deals with it before the transformer.
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Old 8th December 2011, 01:16 PM   #95
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What's the expert's solution then? Are you at liberty to reveal it?
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Old 8th December 2011, 02:05 PM   #96
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Originally Posted by abraxalito View Post
What's the expert's solution then? Are you at liberty to reveal it?
Well here is a hint. And I believed this prior to buying the Legato. Asynch-USB works best spitting out SPDIF. I know that sounds like blasephemy as we all hate SPDIF but when you share a computers ground you are going to have to add jitter even skipping spdif and using I2s direct. So take advantage of the sdif strengths, Jocko I think was public about the engineering marvel that the DIT4192 is, but you have to use it not just make a spot for it on the PCB.

There is a lot of stuff inside this Legato that are engenious and remind me of good old fashioed high-end CDP's, but I am staring to sound like a shill. I want so much to tear it apart and make a masterclocked NOS TDA1541 but am holding off untill the computer to i2s tchnoogy has matured with open source UAC2.0 for windows, lightpeak, hdmi, high ram fifo, whatever.

As far as the WM8805 boards I bought one too and I would like to set it up but I just don't understand the concept of how it could actually be running a synchronous pll/reclocking with "any freuqncy from 10mhz to 27mhz." Just haven't had the time to research it but one would think without software control there could be a lot of pitfalls iterfacing with an NOS 1541 setup? I think a quality transport and a cs8412 a safer bet for the old DAC's unless you really have a lot of time.

Last edited by regal; 8th December 2011 at 02:21 PM.
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Old 8th December 2011, 02:15 PM   #97
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Quote:
Originally Posted by regal View Post
Well here is a hint. And I believed this prior to buying the Legato. Asynch-USB works best spitting out SPDIF. I know that sounds like blasephemy as we all hate SPDIF but when you share a computers ground you are going to have to add jitter even skipping spdif and using I2s direct.
You've successfully put your finger on the very reason I'm not an SPDIF hater like the rest of you That reason being minimal noise when done right owing to relative ease of isolation from nasty fast logic and CM hash.

Quote:
As far as the WM8805 boards I bought one too and I would like to set it up but I just don't understand the concept of how it could actually be running a synchronous pll/reclocking with "any freuqncy from 10mhz to 27mhz." Just haven't had the time to research it but one would think without software control there could be a lot of pitfalls iterfacing with an NOS 1541 setup? I think a quality transport and a cs8412 a safer bet for the old DAC's unless you really have a lot of time.
This board does use a CPU - I have mine now so I can say for sure. I also have a board from the same guy with 4 * TDA1543 (NOS) which I have the impression sounds better than a similar implementation done with CS8414. So I reckon the WM8805 is definitely worth persevering with.
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Old 8th December 2011, 02:23 PM   #98
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Originally Posted by abraxalito View Post

This board does use a CPU - I have mine now so I can say for sure. I also have a board from the same guy with 4 * TDA1543 (NOS) which I have the impression sounds better than a similar implementation done with CS8414. So I reckon the WM8805 is definitely worth persevering with.
I've been contemplating getting that same TDA1541 board if its the same one I'm thinking of, just has I-out and you get to add your own I/V stage without hacking up the PCB?
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Old 8th December 2011, 02:34 PM   #99
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I feel this is one of those rare moments when one can directly compare apples to apples, philosophy to philosophy.
In this thread, praising those SC transformers, there is an AES document linked in, written by Jon D. Paul, vice president of S.C.

At the end of the document, there is a graph showing the reflection loss performance of that design discussed here, with those ferrrite beads.

The mesurement was done by an HP3577 vector network analyzer, the same one that happens to be used by Jocko Homo, too.
And yes, he had used it to measure the output return loss of his Legato device.
The first is the return loss graph, of the S.C. setup, the second is the output return loss
as measured by Jocko. Because they use different vertical resolution, the result is that the S.C. graph, once projected onto the one of the Ar-T, would touch the -30dB black reference line only in one small zone...
The simple, ferrite beaded 110ohm version, I would call an "open end" for all practical purposes above 1MHz.
Attached Images
File Type: jpg SC_out_S11_r.jpg (224.9 KB, 172 views)
File Type: gif Legato_output_return_loss.gif (12.0 KB, 169 views)

Last edited by Joseph K; 8th December 2011 at 02:36 PM.
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Old 8th December 2011, 03:07 PM   #100
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Quote:
Originally Posted by regal View Post
I've been contemplating getting that same TDA1541 board if its the same one I'm thinking of, just has I-out and you get to add your own I/V stage without hacking up the PCB?
Mine's not 1541, I don't play with that chip as its kinda unavailable in the longer term. Do you mean this one:
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