INTERACT FORUM

Devices => PC's and Other Hardware => Topic started by: dean70 on November 21, 2012, 03:59:22 pm

Title: Power supply for HTPC
Post by: dean70 on November 21, 2012, 03:59:22 pm
I am currently running an AMD A8-3850 based system via a Corsair HX450 PSU. I have currently 2 internal WD green hdds for data and an SSD for the OS drive.

The system runs fine when using the digial outs (either HDMI or SPDIF from sound card for 2 channel). I run an Asus Essense ST card and if I use the analog outs, I get a fair amount of audible background noise, which I assume is from the hard drives. The 4 pin Molex connector for the sound card is daisy chained from the single power cable that feeds all molex and sata power connectors.

I was thinking of swapping the PSU for a Seasonic X-400 which is a modular design with tight regulation and separate sata/molex power cables. It is a bit of a crapshoot as to whether it will solve my analog interference issues, but has anyone had this issue and successfully solved it?

I am waiting on delivery of a H6 expansion card and intend to run direct from sound card to power amp. The audio quality and detail is a noticable improvement over the HT receiver I currently use (dispite the backgound noise).
Title: Re: Power supply for HTPC
Post by: pcstockton on November 21, 2012, 06:37:04 pm
That might be the wrong question for this group.  Just guessing....  "A computer, nor its setup, can affect sound quality of analog outs" is mostly what comes out of any kind of hifi/amp/preamp/WAV vs FLAC discussion around here.
Title: Re: Power supply for HTPC
Post by: jmone on November 21, 2012, 08:53:36 pm
I found I was getting a lot of noise on analogue and for me the answer was better 3.5mm shielded cables with ferrite cores between the DAC (and prior to that the Sound Card) Analogue Speaker Out to the PC Speaker Amp and from there the Speakers. 

The cables are nothing outrageous but did a great job of suppressing all the noise that was being picked up from (I guess) all the other cables jammed behind the PC.  These were the cables I replaced all the cheapies with --> http://www.ebay.com.au/sch/2010lucial/m.html?_nkw=&_armrs=1&_from=&_ipg=&_trksid=p3686
Title: Re: Power supply for HTPC
Post by: InflatableMouse on November 22, 2012, 01:06:30 am
Is it interference or a grounding issue?

The Asus Essence is actually very good and I'm a bit surprised you're hearing background noise. I have one myself and I've done nothing special to prevent it. I think I had to split my molex too from something, Im not sure what exactly anymore. I think from the fans and fancontroller.
Title: Re: Power supply for HTPC
Post by: dean70 on November 22, 2012, 05:10:18 am
I just gave it another try and it is now a faint noise pulse that seems to be tied to hdd activity. When the drive is accessed, there is a series of noise pulses that settle when the hdd light stops. This is with MC sitting idle & nothing playing - set the receiver to the analog inputs and can hear it. Setting the receiver back to the SPDIF connection from the same card & it is silent (can be toggled from the remote). The noise seems to be not as loud as it was originally and the receiver is running with no attenuation (0db) to power amps - hopefully be able to get to the point where I can cut the receiver out of the chain and run direct to power amps.




Title: Re: Power supply for HTPC
Post by: dean70 on December 06, 2012, 01:24:21 am
Finally received the H6 expansion card and Seasonic X-460 modular PSU - let the fun begin. Have researched a number of potential solutions if the PSU swap doesnt fix it.

edit: hooked it up on the bench in the original configuration with PC speakers and there is no audible background noise  ?  Maybe it was an interaction between the PC and Receiver which was placed directly on top of the PC?
Title: Re: Power supply for HTPC
Post by: pcstockton on December 06, 2012, 10:30:25 am
Maybe it was an interaction between the PC and Receiver which was placed directly on top of the PC?

Yes, besides a PC's cheap switch-mode power supply polluting your mains, and vibrations galore, there is also plenty RFI to deal with.  Think about how a cell phone will interfere with radio in the car.  I would try to power the PC from another socket/fuse and keep that puppy as far away as possible from your hifi.

A dedicated streamer comes to mind.  The Squeezebox Touch is a good value.

Good luck,
Patrick
Title: Re: Power supply for HTPC
Post by: dean70 on December 07, 2012, 05:29:33 am
Connected directly to power amps (Emotiva) and there is absolutely no background noise or hiss.  ;D



Title: Re: Power supply for HTPC
Post by: dean70 on December 08, 2012, 01:47:07 am
Now that I have the sound card sorted, just need to restore the 12v remote trigger functionality I had through the receiver to power up the amps.

Looking at these: http://www.relaypros.com/Relay/Device/R210RS#.UMLvz3dUqDM to switch the amps on when pc boots (could even be an MC plugin to control the device).