"Marnok.com" wrote:

"Ian Iveson" wrote in message
John Williamson wrote:

I just bought some (fairly cheap) IR stereo headphones. They work ok,
but with a very audible hiss even at very low volume when there is no
sound from the source (PC). This could quickly get annoying. I wondered
if anyone could tell me, is it that I just have a poor quality product
or is this sort of noise somehow inherent in the technology?
Thanks for any help.
You get what you pay for? I've got a pair of Philips cheapies that use
analogue modulation on IR, they're sitting in the cupboard waiting to get
thrown out, they sound that bad. Just about useable for low fidelity
speech, IMO.

In theory, digital transmission using IR can be made as clean as CD or
DVD. In practice, it's not cheap or easy to do it that way.

I wonder if gain is partly controlled by carrier amplitude, to compensate
for changes in IR signal strength as you move about? That could explain
why noise, from receiving circuit and background, gets so much worse in
the absence of a signal.

Assuming the listener's head is itself not a noisy IR source, then the the
high noise when the receptors are blocked must come from the combination
of a noisy receiving circuit and high gain.

Perhaps it might be worth trying to return them for a refund?


Yes, I think I might try the refund route and maybe look at a more expensive
set. If the shop thinks this model ought to be quieter, I'll be happy to try
another pair in store and have a listen. I don't mind a bit of noise, but
this level could get annoying. (I might get my head examined again, I don't
think the doctors checked for IR emissions, I can change the channel on my
TV by concentrating and blinking, is that a bad sign?)

LOL !


Thanks everyone for you help. I don't know much about headphones and audio
equipment, all I wanted was wireless so I wouldn't keep catching the wire on
something. I went for IR because I was worried that radio signals might
interfere with or suffer from interference more readily, also that the radio
waves might not be good for me in prolonged use. I'll shop around more.

Good luck. BTW you dropped in and asked a sensible question. You'd be amazed how
many people take ages to getting round to saying what they meant in the first
place. Welcome back any time.

Graham