Minimising noise and interference in high end-use system

lersince1991

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I've just upgraded my equipment and thought that there would be zero noise in my system, but there still is some noise and when playing low volumes is annoying since I sit right in front of my speakers using my computer.

The system
ALAC 16/44.1hz music files

iTunes

Fisual 5m Optical cable

Arcam A22 with DAVE 5.1 DAC

Chord Carnival Silverscreen 2x 4m cable with decent z-plugs each side (A22 has BFA connections and wanted to make them the same both sides since z-plugs are fairly universal)

B&W 685 speakers

Other components
I also have a variety of other components in the system such as xbox 360, free view hd box, monitor, 2 bay external HDD. but they are all using optical.

I have 2x Tacima cs929 power conditioner / surge protector / extension lead both going to a double gang wall socket. I have separated the amp from the other major components such as xbox, macbook, monitor etc... (in the other tacima power lead). I have a decent quality power cable connected to the Amp (its actually an Apple mains cable that comes with their mac pros) and I have organised everything as best as I can to separate speaker leads and other cables from mains cables and everything to minimise interference. I even wrapped a huge amount of aluminium foil around the xbox power pack as its very noisy. (left vents open of course).

I'm going to solder the 8x z-plugs onto the chord carnival silver screen 2x 4m cable tomorrow to make the best connection possible using decent silver solder and then head shrink over it all.

But although there is hardly any noise, it still annoys me. I want to make it as best as I can.

The Noise
The noise isn't any ground loops or anything like electrical noise, its simply a very constant, neutral noise just from the tweeters.

Solutions?
What other tweaks can I do to minimise this noise?

Shorting input plugs
Some people believe that shorting the unused RCA INPUTS would lower the noise floor with shorting pins but as I have 38 unused rca sockets, even the cheapest of ebay would cost about £40!! Link to cheapest RCA shorting caps

Shortening the speaker cable length
I guess one of the only other things left is using much shorter speaker cable lengths but I can't do this, but I might get a very short length of some really good speaker cable and test it, the short extra HQ cable to one speaker and my current cable to the other, then I would know if thats the problem or not.

Damping pads
Reducing vibrations and rattling equipement (N/A to me), but also reduces interference from nearby equipment? I could put this under my amp as its at the top of my equipment shelf. Something like this from russ andrews maybe...

Ferrite rings
Fit loads of ferrite rings around my cables to absorb as much noise as possible, power cords and speaker cables? I heard these choke some interference out.

Anything else I can do to reduce this noise?

I look forward to your replies.
Thanks!
 
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Do you use a digital volume control via itunes or anything like that? I had a hiss issue which was driving me up the wall. My main source is a Squeezebox Touch and I was using this to control the volume, it has a setting to disable the volume and the background noise went altogether. I think any where that has a digital volume control in the chain can potentially cause this, either switch it off or set at 100% if you can an control the volume on your amp only.

May or may not work but worth a try.
 
I been playing with different ways of controlling the volume as when the macbook is using optical it disables the system volume, iTunes volume is always set at max and sound check and everything is off. As far as I've looked theres no reason for it to be in the macbook but I seem to remember playing music once and pausing it and there was no noise at all, but I may be miss-remembering it and it could have been there all along... So it could possibly be, good suggestion, I'll have another look into it.

Few more details;
The noise is EXACTLY the same whether the amp is set to the lowest but one volume (when its on its lowest I think it mutes as the noise goes all together) and the noise doesn't change at all even at the highest possible amp volume.

When I was playing around I connected the analogue lead (QED Jack to 2x RCA) and then the noise was very small but changed with the amps volume, i.e. when on full the noise was very noticeable but when on lowest but one it was completely gone. So at lower volumes connecting via analogue connection has less noise but higher volumes the constant digital connection noise was better.

Is it the DAC in the Arcam A22? is it the computers digital feed? or is it an accumulation of lots of little tweaks which can be solved by shortening speaker cables, using shorting caps, damping pads and ferrite rings.

I'll check the system on a different digital input and source such as xbox.

Thanks
 
Just checked it with the xbox and the noise is still there, suggesting that the noise is not the source, but the Arcam A22 or other.

Actually on the xbox when I put the volume on max there is like a windy sound when just idle on the dashboard, I guess this is the xbox outputting a very small feed to ensure the dac doesn't shut down (hogs it), or that its an effect for the dashboard to add an atmosphere at high volumes.

But I'd say this is all evidence proving that its not the source, but the amp or connections.

Thanks
 
Thanks again but since its directly using optical and no other components and its not just one source, I can't see a use of attenuators anywhere, and also since the noise is the same from all my sources using optical - macbook, xbox, freeview box and airport express, I can't see that this is an issue with the source. I believe its at the Arcam amp or between the speakers and arcam amp, i.e. the speaker cable. hence the possible solutions I have listed, i.e. shorter speaker cables, ferrite rings, shorting caps and dampening pads.

Thanks
 
I've just emailed superfi to see if they can lend me a really short speaker cable they use for demos or to provide me with a sample of a top of the range speaker cable such as chord odyssey or even epic cable, would only need 15cm to do my testing as I can move the amp
 

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