[PlanetCCRMA] Sound (is it sound if you cant hear it?) above, 22kHz

[Spec]

>Message: 4
>Date: Tue, 1 Mar 2005 16:59:49 -0800
>From: Tracey Hytry <shakti@bayarea.net>
>To: planetccrma@ccrma.Stanford.EDU
>Subject: Re: [PlanetCCRMA] Sound (is it sound if you cant hear it?) above
> 22kHz
>Organization: Aurinia
>  
>
>>Anyone got any suggestions on best PSU's/cases/case mods and eliminating 
>>sound card/computer self noise (even above 23kHz).
>>
>>Thanks
>>Paul
>>    
>>
>I've had various other problems that have pointed to the power supply on machines before;  and now I'm starting to wonder if they are something to be much more carefull about.
>
>  
>
yep, put the old psu in and it seems better on self noise on cards, the 
onboard is now -90db and AP is -110db. (well not very scientific tests 
as far as levels go) but the psu makes that horrible audible whine in 
the room (small room so possibly worse), think I'll have to get a better 
case and PSU this one is flimsy and probably quite resonant.  one of 
these days....

>Again, I really can't help you that much here.
>
>I do have a little request.  If you do the audio test of the supply with the mic again could you stop the fan on the supply for a few seconds to verify that the noise is from the switching of the supply?
>
>  
>
yep noise is from psu, only when powering seagate barracuda 60gb. fan 
stopped, one psu is worse than another and actually hisses when computer 
powered off and wails with it on.  Sold a dud I think on that one, but 
other one is quiet except when powering hard disks, read some other 
posts about seagate and psu whine, but no solutions....

>Now that I think about it, maybe the old(snap a ferite(balum) noise suppessor around the noisy cables trick might help?  This all will only help electrical noise inside that may get to the sound card, but every bit helps.
>
>Tracey
>
>  
>
maplins seem to do ferrites will have to check that out see if it cuts 
HF emf on the dc power lines in the computer and soundcard selfnoise.  
Is it OK just to clip these round all the cores of multicore cables as a 
bundle?