Reply to post: Re: Wi-fi, a hostile environment for vinyl

Re: Wi-fi, a hostile environment for vinyl

Umm... Harman Mogul who complained about the problem reported that it goes away when WiFi's turned off.

The question is not whether or not WiFi can result in an audible problem - in this case, it's been shown to do so; the question is WHY does this problem occur? That'd take a careful analysis of the set-up in question - so many possibilities indeed.

Certainly, high frequency radio can induce current in quite short bits of wire, and there's generally a bit of unscreened conductor between the pickup coil and the start of the screened cable run to the amplifier, and never mind the effect of a WiFi signal on the actual pickup coil.

There's another long length of unscreened wire generally involved in a hi fi setup: the speaker cables. Many years ago when I was young, my dad had a Ferrograph F307 amplifier driving a pair of Lowther PM6A drivers in the small Acousta cabinets - I forget the exact name for them.

So what? Well, a radio ham moved in over the road and even when the amplifier was definitely switched off, we could hear his transmissions through the notably efficient speakers. The diagnosis was roughly this: long speaker cables picked up the radio signal, the bipolar junction output transistors in the amp along with whatever stray capacitance was around did the job of detecting the signal, and the limited bandwidth of the speakers if nothing else meant that the RF got ignored leaving only the speech frequencies. My dad had a word with him, he moved his aerial to the back garden, and the problem went away.

This sort of thing used to be quite common: car radio cassette players back in the old days were infamous for reproducing transmissions of any nearby police car - which was a bother, because it used to be illegal to listen to police transmissions. As I understand it, the problem goes away when you've got a MOSFET output stage (no rectification as with bipolar junction transistors).

These days, if you want to hear a modern equivalent problem, try using a landline phone next to a mobile phone that's sending or receiving an SMS message.

Anyway, my point is that commonly used radio signals might well be well above audio frequencies but that doesn't mean they can't interfere with your audio reproduction gear.