Mains question

Posted by: RICHYH on 09 July 2016

A quick question to the mains experts please. I have run a new separate spur to my power amps sockets and, because the the cable runs behind the rest of the system, I bought a high quality shielded copper 15a cable from one of the hi-fi mains cable suppliers. I now wonder if the shielded was the right thing to do, as it might have an adverse effect on sound quality. Does anyone have any experience or advise?It is 3m run to the socket and then I use power lines.

Thanks in advance

Posted on: 09 July 2016 by Simon-in-Suffolk

I can't see how that it will have an adverse affect. I run some of my wiring in earthed metal trunking, which acts as a shield and it works great.

Posted on: 09 July 2016 by Mike-B

I am not aware of any adverse effects on SQ using shielded/screened cable, the companies that supply screened cable in either ready made assemblies & bulk cable claim positive effects, I'm not 100% sold on that, but for sure nothing negative. All my cables, from wall the power block & to the individual Naim boxes are all screened. I use it to reduce possible negative affects on nearby signal & speaker cables.

Posted on: 09 July 2016 by RICHYH

Many thanks, I appreciate the reassurances.

Posted on: 09 July 2016 by Graham Clarke

When I had a separate mains spur installed I used 10mm2 shielded spur cable. Big jump in sound quality, probably the cheapest upgrade I've made. I didn't compare to unshielded cable but I don't see how it could have been detrimental given the improvement.

Posted on: 09 July 2016 by ChrisSU

20 years ago my (Linn) dealer suggested I instal a spur using fire alarm cable, because it's shielded. I was vinyl only at the time, and was just chatting about how I might give this streaming thing a try, and I didn't really have a clue what he was on about.

Posted on: 09 July 2016 by Chag...

I also read and thought that shielding wasn't an universal answer to EM interferences. I would tend to believe that just like many other things, issue is also with how it is realized. Questions may be then, what could be a bad shielding and its related risks or effects on SQ.

Chag -

Posted on: 10 July 2016 by Mike-B

There's a lot of myth & snake oil around cables & mains cable & to shield or not to shield is no different.

Most shielding with audio is more concerned with RFI rather than EMI/EMF. EMI concerns a magnetic field (EMF). Its a complex subject but just keeping it to home audio applications:- the level of 50/60Hz EMF is dependant on the current passing in the cable. In home audio its extremely low, usually less that 1amp & any EMF is negligible. The 3 core twist on a cable reduces it significantly & a shield will pretty well reduce it to nothing.

General rules with shielding/screening ......... EMI - braid shields are the most effective, low resistance of shield is important & for very lowest frequencies (50Hz) only conduit is effective. RFI - foil shields are the most effective, braid shields can be wavelength dependent.