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I suspect Right channel sounds high level or more clear than Left channel, I measured using REW (PC audio signal generator) 1kHz Sine Wave -3dB FS and the measurements : Left channel gnd to + 399-401mVAC gnd to - 391-393mVAC Right channel gnd to + 395-397mVAC gnd to - 386-388mVAC Measurements done with 0VDC between + and - on the balanced oututs. N.B. My unit is Board Revision 3.1.0 Edited by user Tuesday, November 20, 2012 3:23:39 PM(UTC)
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?? You are measuring within 1-2%. Edited by user Tuesday, November 20, 2012 6:46:31 PM(UTC)
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Yes I know but are OK my measurements? I expected 1.5VRMS instead 0.4VRMS? Edited by user Tuesday, November 20, 2012 7:37:08 PM(UTC)
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BIII is outputing 6mVAC in each channel & in each +-
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Hey guys,
Please help, posted asking help 3 days ago.
Thanks
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Changed R1-4 to 200R to achieve 2VAC RMS, sine wave signal 1kHz -3dB FS
SE output
Left max 1.052VAC
Right max 1.038VAC
Balanced output
Left max 1.050VAC
Right max 1.038VAC
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You don't measure balanced signals to 0V. Measure from output to output. How are things loaded? Edited by user Saturday, November 24, 2012 4:40:26 PM(UTC)
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What is it you are expecting? Stock Legato does not output 2VRMS exactly. But it will be pretty close (about 1.6 if I recall correctly) Remember that your test signal is -3db. Edited by user Saturday, November 24, 2012 4:51:15 PM(UTC)
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Originally Posted by: Russ White  You don't measure balanced signals to 0V. Measure from output to output.
How are things loaded? Balanced output measured between hot (+) & cold (-) signals Left max 1.050VAC Right max 1.038VAC Measured unloaded, please let me know the dummy load value to check correctly the Legato?
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Originally Posted by: Russ White What is it you are expecting? Stock Legato does not output 2VRMS exactly. But it will be pretty close (about 1.6 if I recall correctly) Remember that your test signal is -3db. I'm expecting with original R1-4 resistors have an output of 1.5VRMS & changing R1-4 resistors to 200R have an output of 2VRMS both as per your specs. Yes I know my test signal is -3dB but 0.5VRMS of difference for the -3dBs & unloaded seems to big the difference, when you tell me the load value can have a more accurate measurement, thanks.
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Originally Posted by: felipe Originally Posted by: Russ White What is it you are expecting? Stock Legato does not output 2VRMS exactly. But it will be pretty close (about 1.6 if I recall correctly) Remember that your test signal is -3db. I'm expecting with original R1-4 resistors have an output of 1.5VRMS & changing R1-4 resistors to 200R have an output of 2VRMS both as per your specs. Yes I know my test signal is -3dB but 0.5VRMS of difference for the -3dBs & unloaded seems to big the difference, when you tell me the load value can have a more accurate measurement, thanks. Try to give your test setup 0db - and then watch. I'm pretty sure you'll find things in perfect working order.
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Also make sure that the SPDIF signal is actually the level you expect. Some windows drivers reduce the level at SPDIF to prevent clipping. Nasty trick that. :) Edited by user Sunday, November 25, 2012 4:58:14 AM(UTC)
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Originally Posted by: avr300 Originally Posted by: felipe Originally Posted by: Russ White What is it you are expecting? Stock Legato does not output 2VRMS exactly. But it will be pretty close (about 1.6 if I recall correctly) Remember that your test signal is -3db. I'm expecting with original R1-4 resistors have an output of 1.5VRMS & changing R1-4 resistors to 200R have an output of 2VRMS both as per your specs. Yes I know my test signal is -3dB but 0.5VRMS of difference for the -3dBs & unloaded seems to big the difference, when you tell me the load value can have a more accurate measurement, thanks. Try to give your test setup 0db - and then watch. I'm pretty sure you'll find things in perfect working order. I used REW so can't go 0dB max.can go is -3dB, do you know other way to generate 0dB?
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Originally Posted by: Russ White Also make sure that the SPDIF signal is actually the level you expect. Some windows drivers reduce the level at SPDIF to prevent clipping. Nasty trick that. :) I'm using USB-I2S converter, no SPDIF signal used. Please let me know the value of dummy load to check the Legato?
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No load.
I didn't mean SPDIF specifically, but digital in general. USB included.
In any case if you want more output than you are seeing - the manual describes how to get it. :)
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Thanks Russ, yes I know & I have changed R1-4 resitors to 200R but help me & let me know wich value of dummy load I need to do the right measurements?
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Whatever your anticipated running load is. :) Any load > 10K will not effect the measurements much. Also remember that the BAL/SE stage asymmetrically loads the balanced output - so one end of the BAL/SE will always be very slightly lower output than the other. This is perfectly normal and does not harm anything at all. It will however become more pronounced as the output impedance of the BAL output increases - as happens when you increase gain. For that reason I would not go over 357R unless you really need to. :) Edited by user Sunday, November 25, 2012 3:29:48 PM(UTC)
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One other note, it is always best to run the BAL/SE stage with as little gain as you can get away with. The reason is that it allows the DAC to operate at it's region of highest dynamic range (nearest full volume) without the need to attenuate elsewhere.
Cheers!
Russ
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