Naim Nova speaker noise

Dear forum members,

I have already searched a great deal on this forum to try to find an explanation for the following issue, but have not yet found a clear explanation. Maybe you can help me out:

I experience a humming sound (also white noise, but that is almost not audible and seems normal to me) from one speaker only. It only appears after playing a song (or after being turned on for a while and on every input) and stays constant after that (independent of volume level). I can hear it from around 3m away.

Sometimes I also hear a 'thud' through the speakers after having turned the Nova off. This is less a problem for me, but just to check that it is in fact normal.

I have tried switching the speaker cables on the Nova and the noise problem moved to the other speaker. This tells me that the issue is not with the speakers or the speaker cables.

Sometimes when turning the unit on I immediately hear the noise and also more clearly, but then I just switch the unit off and on and the issue is gone.

Some information about my setup:

- Marantz receiver connected to Nova via RCA (for surround sound)

- Stereo speakers (B&W CM9) connected to Nova via Audioquest biwire 6m long cables.

- Whole setup connected to APC together with all entertainment equipment (TV, router, ...)

I've already taken the unit back to the dealer, and there it plays without any issues.

I hope you can help me to get rid of this annoying sound, it always draws my attention away from whatever I'm playing. I'm happy to respond should you need additional info.

Original Post

For a bit more info, I would try the following and note the result:

Load some music tracks to a USB thumbdrive and plug directly to the Nova USB. Remove the rca interconnect between the receiver and the Nova, then play the tracks from the usb drive while no other source is connected. 

If this plays without hum, try plugging back in the RCA cables one at a time and retest. See if the hum reappears when one or both of the RCA's are connected. If hum comes back with only one cable, try swapping the RCA left and right cables at the nova end and see if the hum changes to the other speaker?

Also, what country are you in? Are you using the supplied Nova power cable and what kind of plug does this have for your unit?

I’d expect the hum to be due to the Marantz; if you disconnect does the hum go away? If so it’s an earth loop. If it’s only on one channel it may be a dodgy cable connecting the Marantz. 

You shouldn’t need to turn the Nova off - just put it in standby. I’d also advise against biwire cables as Naim amps seem to work best single wired. And if the APC is a UPS, you’d be better connecting the Nova direct to the mains, ideally with its own clean supply. 

Thanks for the quick response!

I have tried unplugging the RCA and until now it's complete silence (apart from the source playing)! I feel stupid not having tried this before myself...

Could it be the Marantz unit itself (RCA connected to pre-out) or is only a faulty RCA cable responsible? I'll have to find other cables to test this...

Thanks for this surprisingly quick solution!

Did you try switching the signal ground switch over to 'floating' as suggested by Mercky ???    

The noise as you described it is possibly caused by more than one signal ground point (a ground/earth loop)   The switch is purpose designed to disconnect the Nova's own internal signal ground connection & to use the external source components ground/earth.  

gilliaef posted:

Thanks for the quick response!

I have tried unplugging the RCA and until now it's complete silence (apart from the source playing)! I feel stupid not having tried this before myself...

Could it be the Marantz unit itself (RCA connected to pre-out) or is only a faulty RCA cable responsible? I'll have to find other cables to test this...

Thanks for this surprisingly quick solution!

You are bound to have the same problem. One of the issues is caused by the fact that like most Japanese consumer electronics, your Marantz probably only uses 2 pins for a mains connection.

The best and simplest cure for earth loops, is an isolation transformer. Typically they retail for around EUR 15.

 

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OK great, I'll just try this since it's an easy and cheap solution.

The Marantz has indeed only a 2 pin mains connection. I'm not the expert, but I'm surprised this has an influence on the Nova. I'm not at home right now, but doesn't the Nova have a 3 pin mains connection and thus should have a decent earth connection? Even when connected via RCA to other equipment...

What is the influence on sound quality of an isolation transformer? Are there brands you recommend (or not)?

gilliaef posted:

The Marantz has indeed only a 2 pin mains connection. I'm not the expert, but I'm surprised this has an influence on the Nova.

Is the Marantz connected to a TV - which is connected to - and so on until possibility of a problem?

AV hum problems are not just restricted the unit closest to the amplifier. Like STDs, one has to investigate the network of connections.

http://forums.naimaudio.com/to...129#1566878604398129 

A little update on the situation: I tried all sorts of things but the issue never went away. I also tried plugging the unit in another outlet in another room and deconnecting all other cables (RCA and ethernet), but alas.

The strangest thing for me is still that the noise is coming from only 1 speaker...

gilliaef posted:

A little update on the situation: I tried all sorts of things but the issue never went away. I also tried plugging the unit in another outlet in another room and deconnecting all other cables (RCA and ethernet), but alas.

The strangest thing for me is still that the noise is coming from only 1 speaker...

Last time I had this problem 1 RCA phono connector wasn't pushed fully home.  A faulty cable (RCA connector outer shell connection fault) can also cause this.

However if the noise is coming from only 1 speaker and the only things connected are the digital data (via WiFi or USB memory stick), the mains and the speakers, then, unfortunately has to be a hardware fault in the Nova.  Your dealer (and Naim) will sort you out.

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