Any NAD C658 owners here? - need help to confirm hardware bug

[EB1000]

Hi


I've had my C658 preamp for 3 months, besides the frustrating issue of very low subwoofer output and no subwoofer volume levels, every now and then I hear a thud/pop/click sound randomly coming from the subwoofers when Line 1 is selected. Recently after disconnecting the RCA cables from Line 1, I've noticed that there is a constant scratching noise coming from the subwoofer outputs. I've contacted NAD and they told me that it sounds like a hardware malfunction and suggested I send it back. The store gave me a new unit but it has the exact same issues. Also, the subwoofer output level is very low compared to the preout levels. Can someone please confirm this issue?

These are the instructions to recreate the issue:

Scratching noises from subwoofer outputs:

1. Enable subwoofer output from setup.
2. Set the crossover to any desired value
3. Select Line 1, but DO NOT connect an RCA cable to Line 1
4. Connect a subwoofer to the subwoofer outputs on the C658. or connect any other amplifier with speakers to the subwoofer outputs, such as headphones amp
5. Listen while the master volume is above -20db. Make sure the subwoofer gain is high enough
6. Can you hear the constant scratching noises?
7. Connect an RCA cable to Line 1. It should drastically attenuate the noise.


Can you hear the noise? If you connect RCA cables to the Line 1 input, the noise fades away and will be replaced by random thuds...


This was NAD support response:

Thank you for contacting NAD Support.

I'm sorry to hear you are experiencing issues with your C658's subwoofer output. From what you have described it may be the case that this issue is due to a hardware fault on the C658. However, before assuming this is the case can you please provide let me know the version of firmware you are currently running on your C658? You can find this information by going to System Info on the front panel of the C658 and please let me know the current BluOS, MCU and LCD version on your player.

Please let me know and I will gladly look into this further for you.

Regards,
Wesley P.
Senior Support Crew Analyst



Another user has reported the same issue on AVS forum:

https://www.avsforum.com/forum/90-receivers-amps-processors/3038854-official-nad-c658-thread-44.html

see post #1318

He also had a replacement and ended up with the exact same problem with the new unit...


The second NAD reply did not help much:

• Thank you for contacting the NAD Electronics Support Crew!
  
  We are aware of these AVS forum posts regarding our C 658 and our Engineering team is looking into this behavior to see if we can provide a fix via firmware.
  
  Unfortunately us here in technical support are not provided a timeline on future development and releases so I can not say for certain when this update will become available. However rest assured that our engineering team will be doing everything they can to resolve this issue as soon as possible.
  
  Our engineering team may reach out to you directly if they require any further specifics about this issue you are experiencing.
  
  I'm sorry I do not have a more immediate solution for you but in the meantime if you have any further questions for me, please feel free to let me know.
  
  Regards,
  Jade L.
  NAD Support Crew Analyst

This request is closed for comments. You can create a follow-up.

 

[Tks]

We can barely get the thing to function in the first place..

 

[samysound]

@EB1000 I have recent NAD M10 and seems to have subwoofer low output issues as well. Has there been any resolution from NAD

 

[EB1000]

@EB1000 I have recent NAD M10 and seems to have subwoofer low output issues as well. Has there been any resolution from NAD

Slight. On the latest firmware the subwoofer output was raised by +3db. Still not high enough. I found a workaround - got a minidsp 2x4hd and hooked it up between sub outs and the subs. I use it to tweak before running Dirac Live calibration.

 

[Hephaestus]

Slight. On the latest firmware the subwoofer output was raised by +3db. Still not high enough. I found a workaround - got a minidsp 2x4hd and hooked it up between sub outs and the subs. I use it to tweak before running Dirac Live calibration.

Thanks for the report.

I did an observation as well. Plopping sounds are related to the DSP crossover that NAD "suppose" to apply.

When I ran my Beolab 19 its internal crossover disabled and NAD C658 crossover set to 80Hz that damn thing still passes everything thru. How do I know this? Beolab 19 is a very special subwoofer indeed - it can play up to 680Hz when internal crossover is disabled. That is exactly what I got!
Sick! Nad C658 is a shameful piece of crappy engineering.

Now, solution to get rid of the plopping: surprise...surprise.... activate Beolab 19 LP filter and set it to 80Hz. Basically we can say that the crossover implementation is completely broken in NAD.