Ok i tried building a quite PC and it is .. BUT this annoying hiss coming out of my speakers .. let me start with this..I have a PC-based recording studio with a very specific problem. a consistant hiss through my monitors and than I am getting a sort of scratching noise through the speakers when i scroll web pages , etc It seems like it is coming from the motherboard, but I can't tell for sure. Below are my specs. I am tempted to buy a new MBD but if anyone has any other sugggestion i am willing to try as i am stumped.. Or if anyone knows if MBD noted below could just be a noisy board..? I had a gigabyte prior and it was nice and quite .. but was in a rush to upgrade my pc to an i7 and this was the only one in stock ....

Antec Preformance One P183 V3 Case
Sea Sonic x650 Gold Power supply
Intel Core i7-2600K
Asus P8P67 WS Revolution LGA 1155 -REV B3
WD VelociRaptor 150GB
EVGA GTX 570
Lite-On 24x CD/DVD RW Drive
8GB (2x4GB) Kingston Memory DDR3

** I recently added a SoundBlaster Xfi (titanium - the stereo phile one not gaming) which seemed to make it not as prevelant but its still there ... (disabled on board sound (realtek))
***I have the PC plugged into a monster power surge protector

Hi and Welcome to SPCR!

It's possible it's the mobo, but it could be a variety of things. This:



leads me to think of where the rfi noise may be coupling into your system:
- are you using a wireless mouse? Does the problem go away if you use a wired mouse? Does the problem go away if you plug your wired mouse into a different USB connector?
- does the problem diminish/go away if you turn off your monitor? recheck the monitor connection to the gfx card. Is the monitor plugged into the same surge protector? If not, do so.
- do you have an old graphics card you can substitute and see if the problem goes away.

or, a bad ground path perhaps leads to coupling:
- pull the mobo power connection and reattach, same for the gpu.
- A little more work for this and a tad more obscure...try assembling the mobo and gpu outside of the case (put the mobo on a wood or other non-conductive surface) and see if the problem goes away. If so, check and make sure the case/mobo standoffs are set up correctly and only making contact w the mobo where they should be.

That's all of the non-mobo sources I can think of - then again I'm on my 1st cup of coffee.

A friend had an issue with hiss on his speakers and solved with GROUND LOOP ISOLATOR FOR 3.5 MM APPLICATIONS, personally i havent try so idk, but he swears it did the trick.

I would try different speakers and different cables (not speaker wire cables, but between the audio output on PC and the speaker line-in). It might help if the cable was better shielded (hard to find with 2.5 mm or 3.5 mm connecters). But there may also be a fundamental problem with the speakers (not the drivers, but the internal wiring in the speaker).

I had a ground loop problem with a car audio system, but it was more a hum than a hiss. I refused to let the car audio installer put on a ground loop isolator, because I read somewhere that it degraded audio quality to some degree (but not eveyone may notice).

Two more things - yeah, it's possible it's an impedance mismatch between the speakers and the PC audio or the speakers are too inefficient for the PC audio. This can accentuate noise problems that you might not see otherwise. However, using a sound card to drive it....hmm. Try routing the PC audio line out to am external reciever/amp to drive the speakers.

Ground loop isolators are basically a 1:1 transformer. So your audio frequency response is then flavored by however well they made the balun. It may migitate the problem, but not find the root cause and you have to see if it colors the sound.

thanks for the replies ... the speakers are KRK monitors and I am using RCA out L/R shielded cables ... mouse is wireless ... did not even think of that .. will try a wired one .. ALSO i noticed this ... on reboot when its at the win7 spalsh screen (before the actuall desk top).. you hear the hiss , than it goes away for a sec, hear it again, than it goes away than into the desktop hiss ..... found that kind of odd but has me pointing my finger at the MBD again .. going to try the wireless mouse ... If unsuccessful can someone reccomend me a quite 1155p67 mbd ?

Thanks Again
Dave

PS Great forum and information on the site ... i built the pc based on some of the stuff i read here .. except the MBD .. LOL

I just checked the KRK website, and most of their monitors use balanced 10K inputs (not sure which model you have). Balanced inputs are only designed to be driven from a pre-amp (or sound card in the case of a PC) which has balanced outputs. Balanced line-level cabling is pretty standard on professional gear. Standard line level outputs used on consumer grade equipment would be a significant impedance mis-match for a speaker expecting balanced inputs.

If you google you can probably find a sound card with balanced outputs. You may be able to find an adapter (powered) that converts the line-out signal to balanced outputs (with an appropriate balanced cable) for input into your monitor speakers "if" they do in fact require balanced inputs.

Found this on KRK Trouble Shooting web page [my comments in brackets]:

"Check the connections between the signal source and the monitor. The monitors Neutrik(r) Combo connector is a completely balanced system [this means 10K impedance]. If you're connecting an unbalanced output to the monitor, be sure that you're using PIN 2 for signal and have PIN 1 and PIN 3 tied together at the source end."
http://www.krksys.com/krk-trouble-shooting.html

If you are going to stay with your current sound card, I would check out the user manual for the speaker so you understand the above suggestion and see if you can make it work OK.

you are talking about the XLR in, the RCA is unbalanced ..