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High pitched interference noise on ALC892

post #1 of 7
Thread Starter 

Hi guys, I’ve been reading through head fi for a while now for advice on headphone and speaker choices. Great community and knowledge source you guys have here. This is my first post, and it’s about a problem other posts on the net have covered but don’t seem to work in my case.


I got a pair of M-Audio AV40s connected to my Realtek ALC892 onboard sound (Asrock Z68 PRO) via a cheap but decent (I think) mini jack to RCA cable. On high volume and when there’s no music playing, I hear a high pitched chirping sound from the speakers when I move my Razer USB mouse around.


I’ve tried muting all the other inputs and outputs but this doesn’t work. Also tried plugging the mouse in a different port but same thing.


The PC is plugged into a 1000 watt AVR though I think both the PC and AVR have the normal two prong plugs


One thing that did work is plugging the speakers into my PC case’s headphone port. There’s no chirping noise but just a shhhh sound when the speakers volume is cranked up. I guess this is normal though?


This set up is actually alright but do I actually get worse quality from the headphone port on the case? I want to find a proper solution. Hope you guys could help.


Any pro tips on getting the most out of my AV40s would be awesome too!

Edited by jacked - 6/5/12 at 1:42am
post #2 of 7

It is the lack of isolation of the DAC on your soundcard that is most likely the cause.  I worked around this by using an external DAC like the Total Bithead.  It uses USB for the audio interface as well as power which is greatly isolated away from the other power sources in your PC.  I call what you are hearing the "bleep bloops" because if you listen carefully you can actually hear the clocks in your PC.  Hearing the mouse when it moves is also common.


Unfortunately this is a common problem with onboard / soundcards.  They are so close to so many components that are spewing EMF and noise that it is really hard to get away from the problem.  The Bithead or any other decent external DAC will almost certainly cure your problem.


With my Bithead at near full volume I hear virtual silence.  The dreaded bleep bloops are gone.


The other thing it could be, just in case I missed something, is ground loop interference.  Make sure that your PC and M-Audio Speakers have the three pronged plugs and they are both plugged into the same outlet.  This will ensure they use the exact same ground which should greatly reduce ground loop interference.


Check that the sockets on your PC and speakers, where the power cord plugs in, have three posts.  From your description it looks like you are lacking adequate grounding all around if both the PC and speakers do not have the third grounding post.


Let us know what you find.

post #3 of 7

Originally Posted by NA Blur View Post


The other thing it could be, just in case I missed something, is ground loop interference.


If the interference only appears on one jack, but not the other, that is the more likely explanation. But ground loops can be (and often are) present in the PC itself, especially with badly designed motherboard audio, or the front panel connectors. In my experience, computer noise issues are very often grounding related.

post #4 of 7
Thread Starter 

Thanks for the input guys. I have a couple of questions though.


Will using PC and speaker plugs with three prongs make a difference if I plug them into an AVR which is plugged into the wall with only two prongs?


Also, aren't USB DACs like Total Bithead designed to work with headphones and not active speakers like the AV40s? Would these DACs like the FiiO ones work well in the set up?


How does the E9 compare to the E17 for this function? If it were to use the DAC for my desktop "permanently" wouldn't the E17 be not suitable since it has its own battery. Which of the FiiOs / other DACs would you recommend?


Thanks again and more power!

post #5 of 7

If you plug a grounded cable into anything without the grounding plug, and it does not have an external ground like a separate wire coming out of it, then the device will no longer be grounded.


As to the DAC question.  A DAC is not going to drive your speakers it rather turns the 1's and 0'1 from digital media into an analog signal that your amp can then amplify to feed your power hungry speakers.  You would go PC to DAC via USB then DAC into AMP via stereo y-splitter, and finally amp into speakers with normal means.  You will not be driving your speakers with the DAC, that really does not make any sense.  The amp will be doing that.


An external USB DAC should do a much better and cleaner job at turning those fast 1's and 0's into analog signals.  It made a huge difference for me when I first went from noisy on-board sound to the BIthead.


The Bithead is an amp and a DAC so I can see why you were confused.  You can use the BIthead as a DAC and a preamp for your main speaker driving amp.  This way the signal is not only cleaned up quite a bit, but will be a little amplified prior to hitting your speaker amp making it not work quite as hard to power your speakers.


That was my mistake and I can see why that was confusing.


PC--->Bithead--->Speaker Amp--->Speaker Wires--->Speakers

Digital Signal--->Analog and amplified --->Signal Carrier--->Sound generator


I hope that helps.

post #6 of 7
Thread Starter 

Got that. You explained that pretty clearly.


I can get a used FiiO E10 for about $60, maybe less. Would you recommend this to use with my M-Audio AV40s?

For listening to 320kbps MP3s, some FLAC, watching movies and playing video games, would I hear an improvement?


Im pretty impressed with the AV40s connected to my onboard sound if it wasn't for the high pitched sound (connected to PC speaker out) or hiss (connected to headphone out) at high volume (which i don't really crank it up to)


Thanks again!

post #7 of 7

I do not have personal experience with the E10.  I can say that I have seen many issues with FiiO lower end products lately being posted here at head-fi.  I avoid recommending them especially since I have not used them.  I use the Total Bithead and have done so for almost 6 years.  The quality just cannot be beat as far as toughness and build.


I think the E10 will work fine.

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