Random audible noise from speakers even when pre amp has no active source

Source has no influence?

Is it even present with a non playing CD player selected?

You've eliminated the power supplies as the DR one shouldn't need a service yet even if the others do so that really only leaves the 202, or maybe the PSC, try it without the PSC, does it still do it?

Pissed off cats can be quite entertaining but you can probably grow tired of that, especially if they decide to attack the speakers.

Yes source input makes no difference 

sometimes I leave it on mute with a non connected source selected and sound still appears 

volume is always down to zero and still happens 

I've replaced the NAPSC with one of the flatcap supply and still the same (the flatcap did the job until I introduced the headline) 

But yes beginning to think this might be the 202 but trying to get it verified as the issue before I run out and spend money getting it looked at (nearly did this when I thought it was the speakers but a talk with ATC calmed me down somewhat)

Presumably you've tested the speakers and amp pack by leaving them powered up and connected to a powered down 202.

Next step is to talk to Naim customer services.

Hi Yeti 

yes amps\speakers run fine with with no issues (did a load of tests with ATC who couldn't find any issues) 

but yes looks like a call to Naim 

Do you have a mobile phone in your pocket or close to the system when it happens?

I sometimes used get a similar issue - a very faint rustling noise now and then - and removing the mobile phone from the room cured it.  Having said that, it used to be only when the pre-amp was set to the Superline, so maybe you have something different.

It could be some kind of RFI being introduced through the interconnects .  I assume they are rather long and not balanced?

Hi Richard 

the noise isn't faint it is audible (a few time VERY audible so much so I get a 3:00 am kick from the sleepy other half saying 'it's doing the noise thing again')

it could be the interconnects but talking to ATC they tell me they have no issues with Naim and ATC running pseudo balanced cables (mine are from flashback) but to eliminate this I have run the cables away from everything into the room then back to the speakers to make sure they are not crossing any mains cables etc..

It could be RFI but the thing is it's intermittent when it happens (it's can be fine for a few days then the noise appears or like last night I powered it all up and nothing then about 3 hours later the noise started )

But I do have issues with where the mains cables are and the signal cables as the area is rather tight so perhaps I may need to look at moving the power extension to a different location (but don't know where unless I knock a hole in the wall and out it in the dining room (and SWMBO would not be happy with this solution ) 

I would suggest that the mobile phone idea has much merit to it.  It would be (apparently) random, and the volume would vary depending on where the phone is compared with whatever piece of kit is causing the problem, and with how busy your local mast is, whether it has to up the power to get to it. And mobile phones often do affect audio kit.  I first started noticing this sort of thing with car audio systems, but have heard it on other domestic systems.  Not heard it on my Naim system, but there are so many factors that affect this.

But (fairly) easy to test - turn all mobile phones and mobile phone kit off for a while.  I know, you will feel cut off from civilisation, possibly suffer from extreme anxiety, maybe heart palpitations, but it may be worth it :-)

Cheers

Steve

Hi Steve I'm lucky the phone is rarely on and when it it is it's usually in the car on on my desk at work (I'm old enough to still consider them a sodding pain and an intrusion into life ) 

But yes will turn off all 'mobile' devices and see if this makes a difference 

I'm also, as I'm at the point of shipping the NAC to Naim, going to try one last test with the set up I'm going to disconnect everything except the 202 and speakers so no sources will be connected (or powered) and all devices not in use will be powered down and cables removed

so it will be NAC202 --> NAPSC --> HiCapDR (as this is the newer of the HiCaps) --> ATC100ASL's 

I will, if this does not have any issues, start connecting sources back up one at a time 

Sorry to make it clear the random noise is 'random' when it starts and once it has started it does not stop until I power everything down.

Is it a short, repeating, series of even shorter pulses?  Really hard to describe, but sort-of BRDDDDT BRDDDDT BRDDDT BRDDDT  (usually 4 to 6 of these at a time)?

There is a recording of an example at http://www.windytan.com/2013/01/the-gsm-buzz.html

also at http://blog.shure.com/whats-th...e-and-how-to-fix-it/ - look for the GSM Noise recording

Cheers

Steve

Have you tried turning the Naim kit off and leaving the ATCs connected i.e. powered up? (if this is advisable)

Is there perhaps an irregular contamination of your local mains e.g. somebody using contaminating kit on a primary supply you may share? 

It's (obviously) very odd this is happening when the NAC202 is muted. 

Hi 

Beachcomber posted:

Is it a short, repeating, series of even shorter pulses? 

 

No it's more of a fluttering sound with no repeating characteristics (which is why it alarms the cats so much) rather than a repeating set of sounds.  but the link you gave is not the sound I'm hearing

Tonight I'll power it up as is and wait for the issue to start then I'll record it so you can hear it for your self

Happy Listener posted:

Have you tried turning the Naim kit off and leaving the ATCs connected i.e. powered up? (if this is advisable)

Is there perhaps an irregular contamination of your local mains e.g. somebody using contaminating kit on a primary supply you may share? 

It's (obviously) very odd this is happening when the NAC202 is muted. 

Yes done this after the conversation with ATC. 

House is detached and the mains is a dedicated supply just for the audio (Russ Andrews fuse box and 2 * 2 way sockets) 

But yes muting the NAC makes no difference at all to this.

Hobonono posted:

Hi 

Beachcomber posted:

Is it a short, repeating, series of even shorter pulses? 

 

No it's more of a fluttering sound with no repeating characteristics (which is why it alarms the cats so much) rather than a repeating set of sounds.  but the link you gave is not the sound I'm hearing

Tonight I'll power it up as is and wait for the issue to start then I'll record it so you can hear it for your self

 

 

Ah - well, it sounds less like mobile phone interference.  

I'd be interested to hear it...

Cheers

Steve

Hobonono posted:

Sorry to make it clear the random noise is 'random' when it starts and once it has started it does not stop until I power everything down.

 

 

That does sound more like some fault within a component.  Is it the same on both channels?  

Cheers

Steve

Beachcomber posted:

Hobonono posted:

Sorry to make it clear the random noise is 'random' when it starts and once it has started it does not stop until I power everything down.

 

 

That does sound more like some fault within a component.  Is it the same on both channels?  

Cheers

Steve

Yes happens on both channels.  

Disconnect the audio inputs to the speakers.  If the sound continues, it the amps in the speakers.  If it stops, it sounds like the naim gear.  

I recognise the symptoms the OP has described - random mechanical noise, emitted from the speakers, even with gear muted.

[@mention:73230012052470286] - could you please describe your electrical circuit and the building you live in (not whether it's nice - I'm sure it is), but is it a detached house, a block of flats, etc.

Hi SKTN77a yes done this and speakers are silky quite with the audio disconnected,

Adam Zielinski posted:

I recognise the symptoms the OP has described - random mechanical noise, emitted from the speakers, even with gear muted.

[@mention:73230012052470286] - could you please describe your electrical circuit and the building you live in (not whether it's nice - I'm sure it is), but is it a detached house, a block of flats, etc.

Hi Adam

Detached house. 

Separate RIng main with a Russ Andrews consumer unit and 2 * 2 way RA Sockets behind the speakers.  One of these (the left) has a speaker and a 6way extension (in the whole mains supply this is the 'cheapest link') connected which then supplies the Naim kit.  All power cables bar one are Naim the other is Russ Andrews and this connects to a RA power supply that in turn supplies the MS200.

It could be instability from the preamp. Naim preamps aren’t designed to drive long interconnects, when asked to do so instability can be the result. How long are the cables? How capacitive? Are they loaded in any way?

Hobonono posted:

Adam Zielinski posted:

I recognise the symptoms the OP has described - random mechanical noise, emitted from the speakers, even with gear muted.

[@mention:73230012052470286] - could you please describe your electrical circuit and the building you live in (not whether it's nice - I'm sure it is), but is it a detached house, a block of flats, etc.

Hi Adam

Detached house. 

Separate RIng main with a Russ Andrews consumer unit and 2 * 2 way RA Sockets behind the speakers.  One of these (the left) has a speaker and a 6way extension (in the whole mains supply this is the 'cheapest link') connected which then supplies the Naim kit.  All power cables bar one are Naim the other is Russ Andrews and this connects to a RA power supply that in turn supplies the MS200.

 

 

Ok - so that pretty much rules out your mains (unless grounding / earthing) has gone 'loose' somewhere....

Hi, this does sound like radio breakthrough ... especially because of the times of the day you describe it most apparent.. this will be most apparent  late at night after sunset and possibly at its peak at sunrise and the fact it comes and goes.  To me this suggests you have an output  somewhere which is seeing a connected input impedance far far higher than it is expecting.. possibly coupled with some sort of floating ground. Culprits are poor or faulty interconnects or a genuine electronic fault (capacitor gone high impedance etc). Try changing interconnects between pre and actives... also check the connectivity from the HiCap.. any difference if you plug into a different DIN out. Check all earthing and grounding.

i suggest it’s unlikely to be mobile phone as, radio break through there will typically be a grinding/buzzing type sound... and really be apparent when the phone is being rung or used... again unless extrememely close, break through here suggests a sub optimal screen or major impedance mismatch or fault.

Richard Dane posted:

It could be instability from the preamp. Naim preamps aren’t designed to drive long interconnects, when asked to do so instability can be the result. How long are the cables? How capacitive? Are they loaded in any way?

The only non Naim cables are the 3.5mm to Dinn for the Sooloos and the 3.5M Dinn to XLR for the speakers both from flashback (I have spoken to Atc and they do not see any issues with these (they make a similar set for Naim-Atc)  but I've not spoken to Naim) 

But must admit even when its working the noise from the speakers when no signal is present (no connented input select and in mute) is audible in the room if you are listening for it (in a very quite room it is possible to hear them hiss from about 4m away) 

Disconnected the speakers make no noise at all (this is why ATC think it;s not an issue with the speakers) 

Simon-in-Suffolk posted:

Hi, this does sound like radio breakthrough ... especially because of the times of the day you describe it most apparent.. this will be most apparent  late at night after sunset and possibly at its peak at sunrise and the fact it comes and goes.  To me this suggests you have an output  somewhere which is seeing a connected input impedance far far higher than it is expecting.. possibly coupled with some sort of floating ground. Culprits are poor or faulty interconnects or a genuine electronic fault (capacitor gone high impedance etc). Try changing interconnects between pre and actives... also check the connectivity from the HiCap.. any difference if you plug into a different DIN out. Check all earthing and grounding.

i suggest it’s unlikely to be mobile phone as, radio break through there will typically be a grinding/buzzing type sound... and really be apparent when the phone is being rung or used... again unless extrememely close, break through here suggests a sub optimal screen or major impedance mismatch or fault.

Hi

When it comes it usually does not go until I have powered everything down and back up.

It also happens on inputs with nothing connected and with the pre in mute.

But I only have one set of cables for the link between HiCap and Speakers so these are the ones I can't change (may invest in a second set for testing purposes)