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Russ White  
#21 Posted : Sunday, September 18, 2011 12:51:08 PM(UTC)
Russ White

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Also is the balanced output correct? No offset?
88bruce  
#22 Posted : Sunday, September 18, 2011 1:02:53 PM(UTC)
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I had the Legato running with the old board and it sounded good. I made the mistake of thinking
I needed to get the I2S working, that's why I went through the process of getting a replacement
board. There may be nothing wrong with the replacement board.

Edited by user Friday, October 7, 2011 3:25:07 AM(UTC)  | Reason: Not specified

Russ White  
#23 Posted : Sunday, September 18, 2011 1:09:19 PM(UTC)
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Well It would be good to establish what might be going first. Lets concentrate on the current issue. Could you please answer my questions?
88bruce  
#24 Posted : Sunday, September 18, 2011 1:40:20 PM(UTC)
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I don't have a camera to show the detail you are requesting. The balanced offset is adjusted
to zero. Jumpers to omit the buffers are installed correctly.




Edited by user Friday, October 7, 2011 3:22:00 AM(UTC)  | Reason: Not specified

Russ White  
#25 Posted : Sunday, September 18, 2011 1:44:01 PM(UTC)
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But earlier you were saying something about SE offset. So that leads me to believe there is something wrong with the legato. If there is SE offset with no balanced offset then there is an issue outside of the DAC. So i would hope you would want to clear that up first. :)
88bruce  
#26 Posted : Sunday, September 18, 2011 1:52:26 PM(UTC)
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The SE offset moves in tandem with the balanced offset, so I may have erroneously measured
that SE offset.
Russ White  
#27 Posted : Sunday, September 18, 2011 1:54:44 PM(UTC)
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So which is it? Is there offset at the balanced outputs? If so is it only on one side(left or right)? Is it only the Left as you stated earlier?

Edited by user Sunday, September 18, 2011 2:03:25 PM(UTC)  | Reason: Not specified

Russ White  
#28 Posted : Sunday, September 18, 2011 2:00:37 PM(UTC)
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Double and triple check the jumpers on the bottom of the Buffalo III at the outputs.
88bruce  
#29 Posted : Sunday, September 18, 2011 2:48:10 PM(UTC)
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The voltage on the left SE output was a misread, although the current drop on the positive
rail of the Legato power supply was not. Brian installed the JPCM1-3 and J1-12 jumpers on
this board, and the continuity checked out on them.

Edited by user Sunday, September 18, 2011 2:58:57 PM(UTC)  | Reason: Not specified

Russ White  
#30 Posted : Sunday, September 18, 2011 3:13:05 PM(UTC)
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Are you using PCM input? Or SPDIF?

Edited by user Sunday, September 18, 2011 3:31:27 PM(UTC)  | Reason: Not specified

88bruce  
#31 Posted : Sunday, September 18, 2011 4:36:21 PM(UTC)
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SPDIF.
Come to think of it, the old board sounded its best after removing the PCM jumpers.
I thought this was due to the increased input impedance from removing the paralleled
shorted data inputs.
Russ White  
#32 Posted : Sunday, September 18, 2011 5:41:38 PM(UTC)
Russ White

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Yes if your using SPDIF then remove the PCM jumpers.
88bruce  
#33 Posted : Monday, September 19, 2011 12:13:38 PM(UTC)
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Removing the PCM jumpers has cleared up the issues. The system sounds good today.
I guess the current fluctuation on one power supply rail is not out of the ordinary.

Russ, I think you need to sell me my old board so I can have a spare.

Edited by user Tuesday, September 20, 2011 7:27:19 AM(UTC)  | Reason: Not specified

88bruce  
#34 Posted : Monday, September 26, 2011 4:42:10 PM(UTC)
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I figured it out, it wasn't just the removal of the PCM jumpers on the old board, it was the short
on D1 and D2 that caused the increased clarity in the sound. The reduced input impedance from
two data inputs paralleled (23.5K) was allowing an uncorrupted SPDIF signal?

This was replicated on the new board by running a line from D2, and tying D1 and D2 together
at the data out on the USB board.


Edited by user Tuesday, September 27, 2011 8:03:27 AM(UTC)  | Reason: Not specified

Russ White  
#35 Posted : Monday, September 26, 2011 6:10:07 PM(UTC)
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The SPDIF signal would not be "corrupt" in either case. :) I am glad you are happy. It would be simpler just to add a resistor from D1 to GND if you feel strongly this pleases you. :)
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