Hearing Things: computer noises showing up in speakers and cans

Hi all,
I am hearing very low level (but none the less maddening) noises from inside my computer coming through both speakers and headphones. The noises seem to be related to the computer "thinking", drawing windows, accessing discs and, most noticeably and reproducibly, mouse movement which causes a zipper like sound.

I have found a few similar references in searching "computer noise", "mouse noise", etc., but none of the situations seems quite exactly like mine. In particular, I would say that this is NOT the sound associated with "computer whine" and not I don't think it seems necessarily related to the video card but I could be wrong.

I have replaced the power supply and the main fan. I thought for a long time that it may be related to my firewire interface with a non TI chipset on MOBO. I put in a dedicated TI card and still had problem. Eventually I upgraded my audio interface from m-audio 410 to a Roland Octacapture (USB) and the problem persists. I know that this is not a Sonar issue because it is present when Sonar is shut down and I just have the computer on without even having a stand alone VSTi running. If the computer is off and I play keyboard (Kurz PC3X) thru the Octacapture stand alone the sound disappears (duh!) so I know for sure it is coming "from" the computer.Interestingly, but probably not surprising, the sound will disappear if I use the digital outs on the Octacapture to feed my monitors (JBL 4328's).

The computer is a 2 year old Dell with i7, 3 hard drives (1 is eSATA - no diff if that is disconneccted), video card is a 1Gb nVidea running two 24" monitors in HD, Windows 7 (aero is on). Avast anti-virus (makes no diff if turned off).

Hoping to find any ideas or advice. I am loathe to swap vid card only to find that is not the culprit but I will if I have too. Is there any way in BIOS to bypass the vid card? I think the MOBO has intel video chipset but not entirely sure about that.

Brian

I've seen/heard of this problem before.  It has nothing to do with your recording equipment or Sonar.  Its a basic issue, and the first thing to do is turn off all Windows sounds.  Go to the Control Panel/Hardware and Sound and finally the Sound Panel.  In the Sound Panel, click on the Sounds Tab and then change the "Sound Scheme" to "No Sounds".   This is a first start.  

I used to do a lot of user support on the Dell forums.  Depending on what model Dell you have, there was a problem with an XPS model with noise being heard in the front panel headphone jack.  This was traced back to being caused by the routing of the front panel headphone/mic jack cable from the motherboard.  The cable was routed close to the hard drive and noise was being introduced into the headphone line from the hard drive.  Relocating the cable away from the drive fixed the problem.   

What proprietary USB cable do you have for the Octa-Capture?  I'm just using a standard USB cable, and its working properly.

I have now tried TRS-XLR cables and they have made zero diffrence. In the Sonar forum, Crig Anderton suggested grounding the octa to my computer. I hadn't even noticed that there was a grounding screw on the back before. I just did that and, after trying a few different spots on the computer chassis,  it definitely does make a significant improvement. I can still hear the noise but it is probably reduced by about 60-75%. Funny, I thought that when I finally hit upon the solution it would totally fix the problem. Either I need to find a better grounding site or look for other causes of interference.

The Octa Capture's chassis has a floating ground, as Mr Anderton pointed out.

Is your computer plugged in to a wall socket that has a good clean ground? Have you ever measured that socket's resistance to ground? Be careful if you start doing that stuff... if you know what you are doing it is a safe procedure and I will not lecture... if you don't know how to do it ask someone who does for safe help.

If hooking up the Octacapture ground strap did help some what, then I suggest that you go old school and actually hook that ground connection up to the wall socket rather than the computer chassis.

You may have seen how the little "ground lift" adapters sometimes come with ground tabs for screwing to the wall receptacles face plate mounting screw?

Try connecting the octa capture in a similar manner.

In other words get it connected straight to ground and not to the computer chassis, which is also acting like a receiving antenna even if it is grounded. 

This will be the same ground the computer sees so it shouldn't exasperate a ground loop and it will allow the Octacapture chassis to work as a shield as effectively as it may. 



best regards,
mike

I am making progress! I have discovered that the problem is ONLY pesent when I have audio cables plugged into the Kurzweil (and octa, of course). Interestingly (to me) the Kurweil does not even have to be powered on for noises to appear at the monitors. If I unplug the audio cables from the Kurz - SILENCE! - even if I have Dim Pro running and using my Remote SL for midi input. Therefore, I have to conclude that the audio cables from the Kurz are acting like antennae for RF interference. I have tried every audio cable in my arsenal (nearly all are unbalanced but there was one short pair of balanced cables). Some are better than others, none are perfect. The balanced cables I thought might be the solution but they are no better than average. That said, they are probably pretty cheap balanced cables. I really don't even know what I ever bought them for. So, unless someone has a better suggestion, my next step will be to get some decent balanced cables and see what happens! Once again, thanks for all of the suggestions!

You dont have any of the cables routed next to power cables or the monitors do you?

The only other thing Ive seen that hasnt been mentioned is a similar prob noted with dual monitors, one monitor had developed a prob causing a similar noise prob and switching to one monitor and swapping monitors and cables proved to find which one was bad creating the noises you describe.

Time to summarize. Over the past 10 or 12 days I have totally taken my system apart and reassembled. I have looked inside the computer and found a massive tangle of wires but nothing I can really do anything about because it is a very tight mini-tower case. I have changed over to all balanced cables for audio. I have removed the Octa from the same cabinet that holds the PC. I have paid attention to cable nmanagement and minimized power and audio cables in proximity to one another. And STILL I have noise. As mentioned earlier, grounding the Octa to the PC did help somewhat. Also unplugging audio outs from the Kurz silences everything but iis obviously not a great solution. Also, grounding the Octa to the Kurz chassis does nothing BUT grounding it to the metal on the outside of the balanced audio cables at the Kurz outputs results in SILENCE! (better than grounding to PC). So, maybe it's not rf picked up by the cables but some sort of grounding issue between the Kurz and the Octa?? (Obviously I am ot an electrical engineer!). For now, I am grounding the Octa to the audio cables at the Kurz which sounds good but looks weird! I remain open to other, better solutions!