It's like a constant air blowing noise. It comes from all my Sony Bravia 5.1 speakers. I can only hear it when I stand only a feet or two away, more than that and I can't hear it at all. It doesn't increase with an increase of the volume, and occurs even when all other components, including the TV, are off.
yup.. it's shot noise.. caused by electrons passing through the semiconductor junctions. You can sometimes track it down to a noisy resistor of transistor.. but really these days the only cure is to buy better hardware.
Well I went to Futureshop and found my speakers on two displays. I put an ear against them to test and heard the same hiss. I tried other speakers and couldn't hear it (I only tried a few though). Seems it's confined to this particular model. It's this model for anyone interested: http://www.futureshop.ca/catalog/proddetail.asp?logon=&langid=EN&sku_id=0770HDS0010124780&catid=19701 I would return them, but it doesn't really bother me. I don't sit 1-2 feet away from them so I can't hear it at all.
partition noise is inherent in ALL amplifying devices.. some speakers are more sensitive than others (it would probably be annoying on my 105dB/w jbl's) The problem these days is most so called quality hardware is thrown together out of the same sort of junk components the cheap stuff has in it. I well remember my pair of 1940's Vortexion class A tube amps.. the speaker output was as close to silent as you could get on no signal conditions... but the actual amp boxes buzzed like demons... nice big old skool mains hum. like a substation.. and they would keep your coffee warm all day from the 4 807 output bottles. so as before.. it isn't the input, the source of the hiss is a natural and normal happening in semiconductor devices.. it comes down to plain physics.. electric current is a flow of electrons.. discrete particles.. and in some devices that makes noise as they cross from one layer in the substrate to another.(or bounce off the plate and arrive again.. millions of em) As there ain't nothing you can do about it without rebuilding the whole device till you find which component is responsible for making an unusually large amount of "transition noise" I guess it just has to be put up with.. Go to a quality hifi shop and check out the amps costing $1K and above.. they will be as close to silent on full output no signal as you can get.. but even those will have a very small amount of hiss just shows.. a ripoff brand name on the front.. hahahaha $ony the overpriced scam artists and purveyors of crap.. doesn't signify quality. Now you have to excuse me while I go and enjoy this beauty Radford tube amp that has just been recapped and set up properly.