Clipping distortion on digital inputs the NAD C658

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    Sam R.

    I don't have the equipment to test but I've escalated your case. One of our members will be in touch.

    Regards,
    Sam R.

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    Eli Barbie

    Here is a recording of the distortion:

     

    https://www.dropbox.com/s/w4cqm060qsj6j9q/dist%20.mp3?dl=0


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    Eli Barbie

    Hi

     

    I've done some tests and now I have new info to better describe the issue:

     

    It's not female voice distortion it's clipping distortion on ALL digital inputs: HDMI input on module, Roon playback as an endpoint, library playback, coax input, Tidal, Deezer, Radio paradise.

    It started after I did a full factory reset of the C685 to clear the Dirac sluts. I even did another reset and updated the FW to latest 3.14.2 still did not resolve the problem. Here the results of four tests I did:


    1) Connected my external Squeezebox touch player via analog out to Line 1 on the C658 and tested the same tracks. The result - NO distortion!

    2) Connected my external Squeezebox touch player via digital out to coax 1 on the C658 and tested the same tracks. The result - Distortion is present!

    3) Connected my external Squeezebox touch player via digital out to coax 1 on the C658, but changes its audion settings from "fixed" volume to 90% variable volume of digital out and tested the same tracks. The result -NO distortion!

    4) Tested Roon playback with C658 as endpoint with same tracks. The result - Distortion is present!

    5) Tested Roon playback with C658 as endpoint with same tracks, but attenuated the SPL using Roon DSP (added 6dB headroom filter). The result - NO distortion!

     

    Conclusion: My C658 is experiencing clipping distortion on ALL digital sources, whenever the signal exceeds -10dB level according to another test using by PC HDMI out and Foobar2000. Activating replaygain on Foorbar2000 resolves the clipping for most tracks.

    This problem has started after a factory reset of the C658. I'll try to rerun Dirac and see if this fixes the issue since this is the only remaining change since the reset.


    My C658's warranty will expire in 3 months so I need to know if it's faulty or is it just a FW bug that wasn't detected until now (DAC reference voltage or gain is too high when Dirac filters are not loaded?)

    Please advice

     

    Thanks

     

     

     

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