[mariusconst]

I recently started to experience a noise problem in my audio system and I would really appreciate your input as I tried everything that I could have think of.
 
My system is comprised of (starting from speakers):
1. B&W Nautilus 803
2. Transparent MusicWave Plus Biwire Speaker Cable
3. Bryston 9BSST (2 ch.)
4. Transparent MusicLink Plus Balanced Interconnect
5. Bryston SP 1.7
6. XLO Type 4a coaxial digital cable
7. Sony DVD Player
8. Belkin PureAV™ Home Theater Power Console PF40
 
As you know B&W Nautilus 803 are very sensitive speakers, especially the tweeters - and that is why I choose Bryston amp and sound processor, famous for their low noise floor and transparency. One year ago, I could barely hear any noise at all with my ears near the speakers tweeters!
 
I have not done any changes to my system in the last year, however, recently I started to hear a noise - a hiss, first in the left speaker, and then in both of them. The hiss was obvious at night when there is less noise and I turn down the volume.

This hiss does NOT increase in intensity with the volume and remains present even if I press the mute button and it does not depend if I use digital domain in SP1.7 or I move to 2 chn bypass.  I turned off and disconnected the DVD player form SP1.7 and the hiss was still there - this helped me rule out the DVD player as the source of this noise.

Two days ago, I was watching a movie and during some silent passages I heard again the hiss, this time with a light rhythmic tick sound also, coming from both speakers. As it was late in the night, I was able to hear it from the couch - that is around 4 feet distance.

I have disconnected the Transparent MusicLink Plus Balanced Interconnect feeding the right channel from the SP1.7 in the 9B SST and after the disconnect I could barely hear a noise. Once it get connected back, the noise was there.
 
The other problem that I am facing is to be able to reproduce this issue as it is not consistent. Sometimes is the hiss only, but sometimes there this also this light poc-poc-poc rhythmic tick sound.

I am not sure what kind of additional tests should I do to figure out where is the noise coming from, hence this post. 
 
Thanks in advance for your help,
Marius

[Phil A]

Sounds like it could be some sort of electrical issue.  Have you tried plugging stuff into a different circuit in the house?  What else is plugged into the same circuit as the equipment?

[Phil A]

PS - if it is AC noise, you may wish to do Google searches on products like Audioprism's Quiet Line Filter or PS Audio's Noise Harvester.

[Mag]

I'm in the 'somethings not grounded camp'? Look for grounding switches on back of units.

[jethro]

Marius,

I second PhilA's recommendation about trying other plugs without the belkin.

I had a bad hiss one time when using a halogen torchiere type
lamp. The lamp was one a separate circuit and at the far end of my house
and it still caused problems.  Any changes to your lighting ?

HTH

[Phil A]

Dimmers and fluorescent fixtures often can cause issues even on other circuits as well as refrigerators and other things that can consume some decent amts. of power.

[Mag]

There should be no noise at all. There is a difference between a hiss and a humm. If its a humm then I agree with the others that you have somekind of line noise from a fan or light. A hiss its something like a source interference, like you could have a radio signal mixing with the dvd source. On my Yamaha, which I use for a pre-amp I have to have the source switch, switched to an input that's not being used for anything or else I got a hiss.
Hope this helps.

[bobgenie]

I had a few problems and found that my (very expensive) interconnects were the root of it. My advice would be first to try a less sensitive interconnect and see what changes develop (if any). 

[Phil A]

Not necessarily.  There could be something in the pre/pro that makes it more susceptible to electrical issues than another component.  But you are on the right track for narrowing down the problem and eliminating potential causes.  Does it happen in any mode on any input on the SP 1.7 or are some worse?

[nuhi]

Don't know if it's related to this but when I heard this interference noise example from this link:
http://en.wikipedia.org/wiki/Electromagnetic_interference (The EMI sound sample)
I remembered this forum post.