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

Is the Octacapture very close to your computer box?

What sort of analog audio cables are you using to get to the 4328's?

Are the power cables for the gear coiled up and near the analog cables?

Have you tried a really nice USB cable?


Lot's of parts inside a computer act like a radio transmitter.

It seems like you've done a lot of good troubleshooting... it's discouraging to think that you still need to do more... but that's where you are at.


Does the computer itself have a nice clean connection to ground or is there some sort of ground lift or cheap power strip in between it and a solid wall outlet.

Good luck.


best regards,
mike

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.   

Thanks for your replies. I realize that this problem has absolutely nothing to do with Sonar as I mentioned that it occurs with Sonar shut down. I am thinking that you are both onto the cause on the basis of proximity issues, I posted this in the Sonar forum also and that consideration was brought up there as well. I have not been using balanced cables - so that might be the whole issue. I noticed in the JBL manual that they are fussy about balanced cables. I always thought that was more of an issue with long runs and signal loss than RF interference. Guess I was wrong and will be fixing that problem first. The USB the octa uses is proprietary (by virtue of an extra deep port on the unit, regular USBs don't quite fit) and it seems pretty heavy duty. I will also be working on cable management though I don't think the "spaghetti" is too bad. Also may have to move the octa or the computer. I mentioned in the other forum that I at first thought I wasn't going to have a problem with the Octa and have thought that the problem may have actually developed when I racked it in the same cabinet the XPS is in. If all else fails I'll be opening the XPS box to see where the cables are. I don't use the internal audio or XPS headphone jack but maybe the MOBO USB cables could be picking up noise somewhere. Ill post back with results.

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

I probably shoudn't have said proprietary but I think that the plug on it is longer than standard. When I first set it up I didn't use the cable in the box and I couldn't get my cable to stay in because it was hitting the housing on the back panel before it fully engaged the socket. Now you've got me thinking about it and I'll have to recheck.

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.

I didn't use the USB cable that came with the Octa-Capture.  I already had a USB cable run from my equipment rack to the PC that I wasn't using so I just used that.

I don't have my unit grounded and no problems.

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

Thanks Mike, That'll be my next step!