Speaker FM Radio Interference

[Amether]

So I've recently moved flat and in my new place I've got UK station Smooth Radio (102.2MHz) quietly but audibly coming from the speaker by the window. I have a pair of KRK VXT8s. Once I am playing music it isn't so bad but it's at times like these when everything's quiet that it really irritates.

I have swapped my speakers over, and it is always the one by the window which has the music in. The other has it, but much much quieter - barely audible over the hiss of the speakers.

They have this regardless of whether my audio cable is attached or not but is definitely worse when there is an audio cable.

I've changed the power leads, changed sockets, wrapped tinfoil around the cable, tried moving the cable away from the window (not the speaker, logistics don't afford this option at the moment) and nothing seems to make a difference.

Please help. Smooth Radio really isn't to my taste. Just had Pete Waterman's Friday Night Fever.

EDIT: It might be worth mentioning I've just moved pretty much next door to this:



Which broadcasts the station. Maybe it's something I can take up with my MP.

[Nip]

Consider yourself lucky not having radio channel detection in your teeth - it does exist actually.

Just kidding...

I had different issues with tv aireals for cable and such in the house.

I imagine also broadband, unless wireless, might be involved.

So I would try and unplug anything of above items and see if change at all.

Such HF may go backward into main power.

Mains surge filter may worth a try.

Using other power outlets from another room may help as well. Wall outlets usually go on the same phase(and fuse) in the same room - not always but worth a try.

But if there is detection in electronic circuits in monitors - there is really nothing to do. I think you tried it all already.

Anyway, a few things to try...

[fixerdave]

hello, are your speakers active speakers? if they are, does the interference go when you disconnect the cables at the back of the speakers? if interference is being picked up on the speaker cables you could try a piece of coaxial cable (tv aerial cable) connected across the speaker terminals, inner to + terminal and screen to - terminal (at the speaker)..the length would be approx 74cm. leave the loose end open circuit. if this is anyway effective, put a slightly longer piece on and it will be less effective, NOW cut 5mm at a time off the loose end and the interference will drop each time. when you cut off a bit and it gets worse...put a new bit on, that length + the length of the bit you chopped off. this would be called a 1/4 wave stub. at the open end the impedance at 102.2mhz will be infinite but at the speaker end the impedance will short circuit.. hope this works.. dave
ps: it is strange to get audio from an FM station, usually it's from an AM station cause it can be detected by transistor junctions inside, FM usually needs an fm decoder.

[planetnine]

If you say that the "window" speaker is worse with the audio cable attached, have you tried different lengths? I'm presuming you are using balanced XLR cable, or at least balanced TRS jack to XLR.

If you are getting the pickup near the window, have you tried moving the monitor while "on" to see where the reception is worse (yes, I know how heavy they are, I have a pair of VXT-8s, sorry). Maybe the quieter one is being shielded by the wall.

I would try some XLR leads made from Canford "foil screen Twin" cable or other balanced or quad foil screened cable. It's not as flexible as braid-screened, but the screening is better, and I'm serious about trying different lengths as it can affect the resonance, the tuning and susceptability to pick up RF (although it sounds like it's the monitor and the input cable is acting as an aerial.

Beyond that, you could try ferric rings on the input cable and a sheet of metal (connected to mains earth) as a shield for the speakers. Do you know anyone else with active monitors to borrow to see if it's just the KRKs? (VXT-8s in a flat, seriously!). Do Smooth FM have phone-ins? Can you ring them up and ask them to be quiet during mixes?

Is that crystal palace?


>

[SafeandSound]

Not as uncommon as one might think, I suffered this in a VO studio with a Neumann mic. Seemed to be coupling with the mic cable somehow to produce a tuned circuit (FM station as well, pirate on the block down the road). It was extremely high passed filtered like 12-20kHz of the spectrum making it through. The temporary solution was pulling the cable out of the preamp and plugging it back in ! I was not responsible for maintenance at this facility as I was freelancing. Must have been some resistive build up on one of the contacts or some such.

If it does it with no cables it could be getting directly into insufficiently shielded electronics (although being fair next to a very large RF source thats a tad unfair to suggest it's "at fault" per se) There is a slight chance it is in your mains as well if all the above advice fails.

If you have RFI protected mains strips remove them and try a standard one with no RFI filtering and if you don't maybe try an RFI filtered one.

Star quad cable is also an option.

Good luck.

SafeandSound Mastering
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[Amether]

Thanks everyone for your replies.

So yes I thought the same thing about picking up FM - but it's definitely Smooth Radio and as far as I can see, there isn't a MW broadcast of it... ?!?

Can't remember tbh if I have a surge protector on the strip (not at home atm). Will have a look into that. My flat isn't big enough for more than one phase.

That's a great tip about the Coax cable - they are active speakers and I get the interference even when I have no signal cable attached. I would estimate the speaker and power cables are responsible for about the same amount of interference. Balanced TRS - XLR.

And yes. That's Crystal Palace but it's not THE Crystal Palace tower... we have quite a few of them up here.