Clipping distortion on digital inputs the NAD C658
Answered
Hi
I've noticed that on some tracks I can hear a distortion on some female vocals when playing music from any service or library on my NAD C658.
Can someone please do the following test:
Use any music service or library playback and play Lana Del Ray album 'Chemtrails over the country club's last track called "for free"
At around 0:50 to 1:10 when she sings "waiting for the walking green" let me know if you can hear distortion in her voice (background noise). See links at and of the post.
This isn't the only track with such a problem that only affects female vocals.
This only happens with the C658! With either headphones or an external amp (Hypex NC400). I've tested my Yamaha A2070 and the voice is clear as a bell with no issues.
I think the DAC on the C658 is badly implemented (what can cause such phenomena? I know it's not my Focal Aria 906 speakers because I can hear the distortion on the headphones even more clearly).
Please let me know if it's only my unit.
Link to track on Deezer:
https://deezer.page.link/FQ2yAr2UbPrpi9Yy7
Link to track on Tidal (MQA):
https://tidal.com/browse/track/177375681
Link to track on Tidal (non MQA):
https://tidal.com/browse/track/177375665
Thanks
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Official comment
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. -
Here is a recording of the distortion:
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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 adviceThanks
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Hi Eli,
Were you able to resolve this?
I’ve had a similar discussion with NAD about their receivers.
Having done similar amounts of testing to you, I concluded that digital signals are clipping.
They advised me that it must be an issue with the source, yet I’ve tried many different ones.
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