Takaharu

Every now and then my speakers tend to give off a sound that I can only describe as sounding like wind gently blowing past a microphone. This is only evident when I don't have any sound coming from them (it actually disappears, rather than being drowned out) and when they have been idle for a short while.
I got a replacement surge protector a few months ago to combat the issue of my speakers occasionally giving off a horrible feedback sound. It resolved that issue but I'm stuck with a substantially more bearable one, albeit still a tad annoying.
I'm using Logitech Z-5500s bought back in (if memory serves) 2003, plugged into an ASUS Xonar D2X and my power is drawn from a Belkin SurgeMaster (model F9G726sa3m-GRY I think).
I'm positive it's something to do with the speakers themselves because I don't have any issue with headphones plugged into the soundcard.

Any ideas?

__________________

Tyrsonswood

Outside electrical interference.... In other words, something else running in the house on the same circuit (or the other leg of that circuit) can cause this. When it happens, see if something else in the house has just turned on, then see if the sound goes away if you turn it off.

__________________

Takaharu

Nope, literally when it's been idle for a while. This one's been proven.
Also, my bedroom's sockets are their own ring circuit; the ring has its own trip switch that isn't shared by any other sockets or lights. Obviously it doesn't have its own fuse box but I know for a fact that no other electrical components in my house change in any way at most points during the day.

__________________

Tipstaff

You said you don't have this issue when using your headphones, but are you connecting your headphones directly to the computer, or via the headphone port on the 5500s Control Center box? Do you have this issue with all 5 speakers, or is it specific to 1, such as the center? Do you hear it from the sub too? Also, how are you connecting to the Control Center? Via optical, coax, or individual stereo inputs?

What I'm thinking is that it's not a problem with the speakers themselves, but the sub-woofer. All your speakers are plugged into the sub, and that is directly connected to the power while all the connections from the computer go into the Control Center THEN to the sub via the serial cable.

My advice would be to disconnect the serial cable from the Control Center on the sub side, and blow out the connector itself, then try the speakers again. I would even go so far as maybe wiping down the pins and surrounding metal with rubbing alcohol and a Q-Tip just in case the problem is caused by oxidation. I would do the same for all the connectors leading to the speakers too. While you're at it I would also (while you hear the humming/whistling) try disconnecting each speaker, one at a time, to see if the humming goes away (just in case it's feedback from one specific speaker or not).

__________________

jiiteepee

If the sub unit has reflex tube which has too small diameter then, it's possible to hear winding sounds when speaker coating moves enough fast/much (this was quite common issue earlier with turntable playback because of high level resonance frequencies (vinyl and arm setup)).
You can check this by removing the front cover of sub bass unit.

Another matter is why the speaker coating moves even in idle state.

jiiteepee

__________________

asedsa

Once I had similar case, when PC was connected on TV, I tried everything to find what cause that stupid sound, and after few days I found out that antenna cable connected to TV causes that sound.

So, if you have something like that connected, check antenna cables.

Regards