Question about IR headphones
 

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.

Question about IR headphones
 

"Marnok.com" 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?

What's the brand/model ?

IR links may well be subject to some background hiss anyway. Think of all the IR
sources in the room.

Graham

Question about IR headphones
 

Marnok.com 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.

--
Tciao for Now!

John.

Question about IR headphones
 

"Eeyore" wrote in message
...


"Marnok.com" 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?

What's the brand/model ?

IR links may well be subject to some background hiss anyway. Think of all
the IR
sources in the room.

Graham


Hi,

These are Pro-Luxe IR-650ST.

They were pretty cheap, and they make me look a bit like a cyberman :)

I tried shutting the curtains, turning the lights out and switching my
monitor off in case any of that was an IR source, none of it seemed to make
any difference.

One thing is, these phones make an awful racket - about 10x louder - when
the transmitter is off or I cover the receptors. If I had been wearing them
at full volume when I popped the batteries in and switched on, I might have
suffered damage!

Question about IR headphones
 

Marnok.com wrote:

These are Pro-Luxe IR-650ST.

They were pretty cheap, and they make me look a bit like a cyberman :)

I tried shutting the curtains, turning the lights out and switching my
monitor off in case any of that was an IR source, none of it seemed to make
any difference.


You need to pipe cold liquid nitrogen into the IR receiver modules to
reduce the noise floor. Looking like a cyberman does help ;-)

Better headphones using digital encoding over radio seem to be the
answer. As it is a PC as source, why not try some Bluetooth ones?

--
Adrian C

Question about IR headphones
 

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?

Ian

Question about IR headphones
 

"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?

Ian


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?)

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.

Question about IR headphones
 

Ian Iveson wrote:

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.

The receiver in mine seems to be a normal FM demodulator connected to an
IR receiver instead of a tuner, so you get all the benefits of marginal
FM reception with no squelch control as well as the insensitivity of a
cheap IR transmitter/ receiver pair. The signal comes over the link as
an IR signal modulated with a standard FM stereo signal. Harder to
explain than design. The whole lot cost less than a reasonable set of
earbuds. The IR emitted by a head is pretty well shielded from the
receiver in this case, not to mention being in the wrong band and
unmodulated, but flouresecent lamps put out quite a lot of modulated IR,
& incandescent lamps or the sun in the room can put out enough to almost
swamp most IR transmitters the makers can build for a sensible price.

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?

You could *try* for a refund or exchange, but the chances are that the
headphones aren't defective, just badly designed & built. If they get a
signal you can hear, they're probably going to be regarded as fit for
purpose under the Sale of Goods Act, or whatever the local equivalent
is. Just possibly, they're a defective set, in which case another set
may work better.

--
Tciao for Now!

John.

Question about IR headphones
 

"Marnok.com" wrote:

Yes, I think I might try the refund route and maybe look at a more expensive
set.

Sennheiser do some. And Sennheiser are GOOD at everything they do.

Also consider wireless.

Here's a few to choose from.
http://www.noisefreeheadphones.com/w...headphones.htm

Graham

Question about IR headphones
 

"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