Quieting speakers and UPS

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Quieting speakers and UPS

Post by catalinr » Wed Oct 04, 2006 4:08 am

After building a nice and quiet system out of carefuly selected components (thanks SPCR!) I had a nasty surprise: two parts I bought without thinking they could make any unwanted noise, did.

1. UPS: APC Back-UPS CS 650

Emits a strong buzzing sound when turned on and powering the PC, even the A/C is on.

2. Speakers: Altec Lansing MX5021

When powered, but with no sound coming from the PC, subwoofer is buzzing just like the UPS. And the speakers HISS!

Even worse, these speakers don't have "hard turn off" button, only a soft turnoff one. This is for remote on/off command. The standby cuts off the speakers hiss but the woofer buzz is still there.

No idea how to quite these two mofo's. Changing them is not possible as there is no budget for it (they weren't cheap!). So any suggestions would help....


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Post by croddie » Wed Oct 04, 2006 6:27 am

Speaker noise can be caused by noisy amplification and noisy line outs. If you would consider going with a stereo separates system then I can give some advice. Otherwise identify the problem by unplugging the speakers and seeing if the hiss is still there, and replace speakers or sound card as necessary.

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Post by chrono » Wed Oct 04, 2006 12:46 pm

I think the sound card would be the likely source of the hissing noise. Could be the speakers.. but, not so likely. Maybe try another pair of speakers to see if they make the hiss too. The buzz from the subwoofer could just be the subwoofer though. I know some subs do that, (mine does and its a home theater sub, but its not very noticeable). Could possibly be the sound card though, ahah. So! It's hard to find the source of the problem, unless you can get another pair of speakers / sub in and see if they make the same noises or not.

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Post by catalinr » Wed Oct 04, 2006 1:01 pm

The sound card is a Creative X-Fi Music.

Thanks for the "testing by elimination" idea. I will borrow some other speakers and test every part of the audio sistem, including the cables.

I have integrated sound on the mobo, too.

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Post by croddie » Wed Oct 04, 2006 5:56 pm

catalinr wrote:The sound card is a Creative X-Fi Music.
In that case the problem most likely is with the speakers, noisy amplification almost certainly.

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Post by flarkit » Mon Oct 09, 2006 8:03 am


I bought the MX5021's a few weeks ago and also discovered the identical hiss/hum on the sub, even when powered off on the control-pod.

Many audiophile sites suggest that this is a "ground-loop hum", which is occurs between the sub-woofer's built-in power-supply and its amplifier. If so, this can be eliminated by using a ground-loop isolator, which is freely available from audio/electronics specialty stores.

The only issue which is keeping me away from trying this though, is the fact that there are various types of these and one needs to additionally buy a set of adaptor cables to allow you to insert the isolator between the soundcard-output (typically a 3.5mm stereo socket) and the sub-woofer's 3.5mm input. I'm hesitant to dive in and get the equipment, only to discover that the isolator is actually meant for a car's audio, or for a home-theater setup.

So far, the stunning sound quality (just using NF4 onboard sound) and the fact that the hiss is inaudible during games or when playing music, has meant that I have no serious need to take these steps.


BTW catalinr: I'm planning to get an X-Fi Xtrememusic for these speakers. How has your experience been?

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