Fm Radio quality

Dear all - I haven't posted for a while, however can someone please help me here - as I thought a fault exists in my system.

At the system core is a Naim Unilite & a "JS" modded Musical Fidelity A1 power amp. I use Martin Logan bookshelf speakers, rotel tuner & I've a record deck. The Naim was serviced recently.

The question is simple. Sometimes the FM quality is superb and other times it degrades severely - I can hear distortion. Usually after it's been on over 30 mins, but not always...

I tried without the power amp & tried another tuner & other interconnects. Also after 7pm I notice an improvement too for some reason on FM. I use a large roof antenna with good signal (4 out of 5 bars).

Is this atmospheric? Me? or the equipment

Thanks for any additional insights or thoughts

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I listen to a lot of FM but with a vastly inferior aerial to you, ATM R4 has a buzzing stereo interference which is seemingly like an insect whizzing around the room here.

Alan Shaw of Harbeth pointed out that FM is second WW technology and can produce up to 10% distortion. Multipath reception can at times be a problem, and I think industrial machinery can affect it, thus making it better at weekends.

It is generally thought to be better in the evenings, probably for that reason, but I find weather conditions affect it greatly, this also applying to DVB. Also to be considered is Optimod processing by the station, and the ineptness of the BBC in mic. usage.

The problem persisted with a different tuner?

Interesting - yes similar with another tuner. I changed the tuner & there was some improvement. The difference at after 7pm is remarkable.... I was beginning to doubt my ears & question my investments.
That said I never paid more than £50 for a tuner.. unlike the rest of my hifi!

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So it looks as though the tuners differed slightly in spec. or sensitivity, and that the problems are in the air.

I'm more inclined to think that the problem is in the equipment. If the distortion usually starts after 30 minutes after switch on that implies that a dodgy component is heating up enough to go bad in that time. I've had that happen. sometimes it is quicker than 30 minutes sometimes longer.

Needs a complete fault-finding session. I'd start with connecting a cd player or tape deck and running that for an hour or so to see if the same fault occurs. If it does then you know it is the amplification at fault. If not then look to the rest of the set up. I'd say the broadcast signal is the least likely to be the fault otherwise everyone would be complaining about it already.

Thanks - I'll try the record deck for an hour or more...

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If you changed tuners and still have a problem I would check your antenna. How is your location? FM signals like a clean path without buildings or other obstructions. To totally rule out a tuner problem do you have a friend that gets good FM reception? See if you can take your tuner to their home and see how it fares.

I had my unilite checked at Niam (free of charge as they replaced the CD transport a few months ago). they were very helpful & it seems ok now. However there was no report of what they did & because of lockdown communication wasnt brilliant.


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