[PLUG] Audio noise

Dick Steffens dick at dicksteffens.com
Fri Jan 23 17:11:55 PST 2015

On 01/23/2015 11:57 AM, Ken Stephens wrote:
> Dick Steffens wrote:
>> Watched some recordings this evening with the new power supply in my
>> MythTV system. There is some odd noise that is most prevalent while
>> watching recordings. While still present, it's less noticeable with live
>> TV. I tuned in a golf tournament so there would be segments of quiet
>> program, and I could hear the light buzzing. With the front end closed I
>> listened to some music with Movie Player. I didn't hear the noise. It
>> doesn't make sense to me that a program could cause the problem, but
>> I've asked the MythTV list if there anything in MythTV that could be
>> involved in creating this noise.
>> My assumption is that when I put in the new power supply one of the
>> cables is now somewhere it wasn't before. I'll open it up again tomorrow
>> afternoon and see if I can reroute things.
>> Other hints of things to look at are appreciated.
> Dick,
> Check your CPU fan.  The program (active pixel changing) could be
> causing a higher cpu load that would require your cpu fan to speed up to
> cool.  Some systems don't start the fan until the processor heats to a
> certain temperature.

Thanks for the insight. It does not appear to be the fan. The fan does 
not rev up most of the time. The old power supply would start full speed 
some of the time when it was powered up, and never spin down. Restarting 
solved that issue. This has not happened (yet) with the new power 
supply. As far as cpu load, a good bit of the picture processing is 
supposed to be handled by the nVidia card, which has its own fan.

I spent a good bit of the afternoon dressing cables, which I should have 
done a long time ago. That seems to have reduced the problem, but not 
eliminated it entirely. On the other hand, dressing the cables, paying 
attention to separating audio from power cables, may have reduced the 
problem back to where it was before yesterday's PS replacement. It is 
possible that we didn't notice it too much before. And with the cables 
dressed this afternoon, it is much less noticeable than last night. So, 
it's possible we're back to "normal" now.

We'll see how it sounds this evening.


Dick Steffens

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