Nait 5si picking up unwanted radio signal

Is there a plasma or large screen TV anywhere nearby and/or plugged in to the same supply circuit?

If so, suggest unplugging and see what this changes.

AFAIK, most of these RFI issues are down to wires/kit acting as radio aerials (hence the ferrite ring acts to subdue/remove). IME, large TVs can be peachy quasi-aerials!

I doubt very much if a ferrite on the power lead will help,  ferrite(s) on the signal input cable(s) might be useful.  What is connected to the amp (your profile page is empty - hint)   ".....even when volume level is zero and even when no other components/sources are connected....."  indicates it's being picked up by the speaker leads & because the Naim & Denon have different  output stage stabilization methods would explain the differences,  but that said it must a powerful transmitter thats doing this,  its far from common & a lot of happy Naim users don't get this:  were do you live?  & can you identify the radio station ?

Mike, thanks for starting to asking the questions.  I was just so frustrated by utter lack of any useful detail this post that I couldn't respond.

As Mike says it must be a very powerful transmitter - are you in the UK or elsewhere?  Have you spoken to your supplying dealer?  What speaker cabling are you using?  Is it properly terminated?  How's the system earthing?  What else do you have connected to the system? Have you tried with and without anything connected?

Huge posted:

Mike, thanks for starting to asking the questions       ..........................

I was over excited with the prospect of ferrite farming again ...........  who can resist those dear little bundles of furry fun.  

Seriously I am interested as its most likely a radio problem. 

Hi, yes this is usually referred to as Radio Breakthrough (RFI is typically something else) and as suggested is probably down to the type, length and orientation of your speakers and speaker cables. Try changing perhaps temporarily the speaker cable runs or orientation to see if the breakthrough goes. 

Simon

Richard Dane posted:

As Mike says it must be a very powerful transmitter - are you in the UK or elsewhere?  Have you spoken to your supplying dealer?  What speaker cabling are you using?  Is it properly terminated?  How's the system earthing?  What else do you have connected to the system? Have you tried with and without anything connected?

Sorry guys, here I am to provide more details about this situation.

There is an actual big transmitter about 200 metres from my room and the 5si is picking up the FM 89 Mhz channel, very loud and clear. I tried earthing and tried ferrite clamps - nothing changed.

My speaker cables are the ordinary copper ones with gold-plated plugs and conventional rubber wrapping. I am considering changing to higher-grade cables to see if this problem goes away, but the question is these very same cables did not pick up any radio signal when tested with the Denon amp, so can I safely say that the trouble lies somewhere else?

I am also contacting Naim for support and they seem intrigued that my 5si has this issue because it was tested before reaching the market, and that the Denon is immune although in the same system.

Wow - that's close. You'll find the slightly different output stage configuration of each amp will make one more susceptible to RF pickup via the speaker cables. 

What length are the cables and what type are they - you don't want to make the problem worse by having lengths that are resonant at the strong signal frequency.