"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

"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

Marnok.com wrote

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?)

Can't everyone do that? Er...except Eeyore...

Ian

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.

Ian Iveson wrote:

Marnok.com wrote

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?)

Can't everyone do that? Er...except Eeyore...

Indeed. My eyes only operate in the X-ray band.

Graham

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.

"Marnok.com"

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?


** Seems you have bought these:

http://tiranossaurus.com/product.asp?id=055253

The specs reveal it uses twin carriers ( 2.3 and 2.8 MHz) and FM modulation
of the pulsed IR light.

The receiver ICs are generally the same as those in FM demodulators - so
will hiss loudly in the absence of signal.

The claimed 55dB s/n is probably optimistic or heavily weighted or both.

Similar IR phones from Sennheiser claim only 46 dB s/n.

Good enough for low dynamic range stuff like TV listening.



...... Phil

"Marnok.com" wrote in message
...
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.


UPDATE

thanks to everyone for helping out.

I took them back this morning for cheery refund (after the guy in the store
played around for half an hour trying to make them sound OK)

Found a new set - Philips SHC2000 - these are MUCH better and also have a
recharging cable and rechargable batteries, and I got them from Argos for
less than £20. No hiss, sound is fine, I don't look as much like an extra on
Dr Who but I can live with that.

"Marnok.com"

UPDATE

thanks to everyone for helping out.

I took them back this morning for cheery refund (after the guy in the
store played around for half an hour trying to make them sound OK)



** Just LOVE the sight of a hi-fi salesman SQUIRMING in the morning
.....





..... Phil

"Marnok.com" wrote in message
...
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.

**I've used cheap IR 'phones and reasonably priced ones (Senneheiser). The
cheap ones are noisy, whilst the reasonably priced ones (I won't call them
expensive, because they're not) are not.

You get what you pay for.


--
Trevor Wilson
www.rageaudio.com.au