rob aylestone
Moderator
To put this into some kind of perspective - with today being a litigeous society, you will now find warnings applied to RF products, even the Chinese ones when they are needed. At radio sites, not just the mega power broadcasting ones, it is common to find the access to the ladders restricted. Some so restricted that with power to the transmitter racks applied, the key is interlocked so you can only climb isolated masts. With cellular radio the most common source, exposure to the antennas, by proximity has to be restricted as Bouldersound mentioned above - they are in essence microwave ovens. People have sort of slid this science to mean that any RF source is dangerous, or at least a risk. If you want to read more, google ionising and non-ionising radiation. It's well understood.
We must manage risk, but here, there seems no risk we can actually detect.
Going back to the IEM thing - one thing nobody has mentioned is stereo. IEMs are very rarely two totally separate channels. Being able to shift multiple sources left to right really helps - in the band I had me and my bass 75% right and everyone else 75% left - this helped me hear myself much better. It is also an area that never gets mentioned in reviews. Many of the cheaper Chinese IEM products are actually mono! The receivers do not have stereo at all. The proper stereo ones, Sennheiser, in my case use a very similar system to FM stereo, but it doesn't produce two separate streams, it's done by a sum and difference technique - a bit like how we do M/S. So the main signal is mono, and the extra channel pulls some of the stream left and the other right. It's done using a system called multiplex - two signals stacked one above the other. The downside is that if you send something 100% left, it leaks a bit into the right. Not much, so most don't even notice. The chinese ones have left/right and mono inputs, but all the ones I have had just seem to merge left and right and as far as I can tell, are just mono. Nobody has actually mentioned this that I've seen. The Chinese receivers (I have a few left over) do NOT decode a proper stereo IEM signal. You get a fine mono signal, but they are not stereo. Funny how nobody ever mentions this. I've had three systems from China, spread out over two years and all were mono.
While we're talking about IEMs we should also remember that wireless in general is unreliable. The best wireless system is nearky as good as a $10 cable. Signal strength is the thing we all talk about, but really the problem are the common, unpredictable RF black holes. You take a step forward and a perfect signal just vanishes. RF systems in the same band can suffer from desensitisation - a transmitter pack in your pocket makes the receiver in another pocket, deaf. I had this with my bass. A sennheiser pack taped to the strap. My IEM receiver in my pocket. It just made the black holes a bit worse, and if your IEM cuts out, you are stuffed. I swapped to a line 6 system for my bass, which was much more reliable and didn't upset the IEM. Actually a great system, but a rubbish battery compartment clip, which needed copious gaffer tape to keep closed.
We must manage risk, but here, there seems no risk we can actually detect.
Going back to the IEM thing - one thing nobody has mentioned is stereo. IEMs are very rarely two totally separate channels. Being able to shift multiple sources left to right really helps - in the band I had me and my bass 75% right and everyone else 75% left - this helped me hear myself much better. It is also an area that never gets mentioned in reviews. Many of the cheaper Chinese IEM products are actually mono! The receivers do not have stereo at all. The proper stereo ones, Sennheiser, in my case use a very similar system to FM stereo, but it doesn't produce two separate streams, it's done by a sum and difference technique - a bit like how we do M/S. So the main signal is mono, and the extra channel pulls some of the stream left and the other right. It's done using a system called multiplex - two signals stacked one above the other. The downside is that if you send something 100% left, it leaks a bit into the right. Not much, so most don't even notice. The chinese ones have left/right and mono inputs, but all the ones I have had just seem to merge left and right and as far as I can tell, are just mono. Nobody has actually mentioned this that I've seen. The Chinese receivers (I have a few left over) do NOT decode a proper stereo IEM signal. You get a fine mono signal, but they are not stereo. Funny how nobody ever mentions this. I've had three systems from China, spread out over two years and all were mono.
While we're talking about IEMs we should also remember that wireless in general is unreliable. The best wireless system is nearky as good as a $10 cable. Signal strength is the thing we all talk about, but really the problem are the common, unpredictable RF black holes. You take a step forward and a perfect signal just vanishes. RF systems in the same band can suffer from desensitisation - a transmitter pack in your pocket makes the receiver in another pocket, deaf. I had this with my bass. A sennheiser pack taped to the strap. My IEM receiver in my pocket. It just made the black holes a bit worse, and if your IEM cuts out, you are stuffed. I swapped to a line 6 system for my bass, which was much more reliable and didn't upset the IEM. Actually a great system, but a rubbish battery compartment clip, which needed copious gaffer tape to keep closed.
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