Advice sought on unwanted noise.

[snaphappybob]

Hi folks.
I keep getting intermittent buzzes through my system which I'm guessing are entering through the speaker cables. They sound like the noise you used to get just before your mobile phone starts to ring. There is a sequence of four or five short buzzes through the speakers.
System from mains to speakers is Russ Andrews powerblock with mainly RA leads. (all checked and in good order) a mac mini with ifi Zen DAC used as a music server, an Arcam Alpha 5+ cd player, Oppo UDP-203, Naim NAC 82, Teddy Pardo Dual Teddycap (brand new purchased to replace Hicap) Naim NAP250 with Avondale 220 boards, 5 metre NACA5 speaker cable to mk2 Naim SBLs.
I can discount all of the sources as it happens when they're all turned off so I am assuming that the NACA5 is acting like an aerial. One cable is layed over itself rather than coiled but the buzzes come from both speakers anyway.
Any advice as to what the culprit may be?
FYI this has occurred with other speakers and with the Hicap so its not the Teddy or the SBLs.

 

[Mike P]

Are your interconnect cables all shielded/coaxial?

 

[R-J]

Are you, by any chance, using powerline adapters to link to your hub? I found these introduced noise into my system.

 

[trick cyclist]

What brand and model of cable are you using to the 250? The original naim one has a habit of picking up rf as it is made from unshielded mains cable.

 

[snaphappybob]

Not sure, one is Mogami 2965, one Kimber PBJ, the rest are flashback

 

[snaphappybob]

Are you, by any chance, using powerline adapters to link to your hub? I found these introduced noise into my system.

no, it is through wifi directly to the hub but the buzzing occurs even when its turned off.

 

[snaphappybob]

What brand and model of cable are you using to the 250? The original naim one has a habit of picking up rf as it is made from unshielded mains cable.

Using the premium flashback cable. Tried via P/S and straight to the 250 but same thing happens.

 

[trick cyclist]

I have used flashback DIN to XLR for my setup, and though I did not appear to get any rf issues, that could be down to luck. Mine is the premier cable, does not look shielded to me, so that could be the issue?

Edit to add, no clues to construction on the website.

 

[Mike P]

I suggest swapping out the RA PBJ (and any other non shielded cables) for coaxial cables.

 

[Jim Audiomisc]

Buy some suitably sized clip-on ferrite blocks. Experiment with clipping them to the outside of the leads entering the amp's box. Fit them with as short a length of cable from the amp box as is convenient.

When doing this with the speaker cables, use one block for the left speaker pair and another for the right speaker pair.

If that doesn't work, try them on other leads.

Can't be sure, but that should reduce RFI unless it is fairly low frequency..

 

[snaphappybob]

Looks like I've found the culprit.
1st prize goes to Mike P
I replaced the Russ Andrews PBJ cable with a pair of old Cambridge coax cables and thus far no buzzing.
Thanks for all the suggestions.

 

[Jim Audiomisc]

Ah.

1) Uncle Russ

2) Not actually co-ax.

IMHO => Avoid.

 

[hifinutt]

Bit of useless knowledge but I think pbj stands for peanut butter and jelly ! Glad you sorted it