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Noise from Speakers

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jimkfmak 發表於 2008-5-8 23:18:39 | 顯示全部樓層 |閱讀模式
Hi Everybody

In the past, I had got a sony surround amp, I heard some noise (士..士........ 聲) from 高音單元 of speakers after the amp was powered on but no any audio signal input.
Now, I have get a new marantz surround amp,  but I still heard some noise (士... 聲) from 高音單元 of speakers.
My amp, speakers and sacd player are new, they are not more than 1 year.
Why ? Is the problem at amp, speakers, or cable, or electric power ? Is the noise from 220V ?

Please fix it. Thank you very much.

Jim
alant 發表於 2008-5-9 00:18:59 | 顯示全部樓層
May be ground loop problem. Read the passage as below for your self-explanation.

Reference passage
If you experience a hum through the speakers,  the first is the source. If there is an excessive amount of buzz or noise from the loudspeaker, it may be caused by a ground loop, a light dimmer in the home, poor AC power, or any number of causes. The quickest way to determine where to start your search is to simply turn the preamplifi er, integrated, receiver or Control Amplifier off, disconnect the audio cables between it and the sources, and see if the hum goes away when you turn the preamplifier, integrated, receiver or Control Amplifier back on. If it does, it’s most likely a ground loop or buzz from a dimmer.

If this doesn’t solve the problem, follow these easy hum busting tips.  The easiest way to figure out where ground loop problems lie is by the process of elimination. You need to determine where the hum or buzz is coming from within your system.  If the hum/buzz goes away when you remove the inputs to the power amp, your next step will be to reconnect the amp and move further down the chain. If you were working with a receiver or an integrated amplifi er, you will need to jump to step 4. If you have a preamp, or processor that is feeding the power amp, your next step would be to disconnect all inputs to the preamplifi er or processor. Once If you have to replace the AC module If the trigger isn’t working If you have hum these are disconnected, and the preamp or processor is connected only to the power amplifier, turn the system on and again, listen for hum. Should the hum now appear, it is a problem with your preamp or processor or their interaction with the power amp. Before returning the preamp or processor to the manufacturer, try a cheater plug to break a ground loop. Cheater plugs are simple devices that convert a three prong AC plug into a two prong AC plug and in the act of converting three prongs, to two prongs, they disconnect the ground from the wall socket. Try one of these on the preamp, or the power amp, or both.

If you determine that there is still no hum present when the preamp, processor or receiver is connected with no inputs, then selectively begin plugging in your various inputs one at a time. After each connection, check for hum until you discover the humming culprit. VCR’s, surround processors, and any device that is connected to a television cable or satellite dish can cause a loud buzz and should always be suspect. If, by the process of elimination described above, you determine it is a component like a VCR that is causing the hum/buzz to occur, and using a cheater plug or removing the ground pin on a PS xStream Power Cable doesn’t help matters, it may be necessary to isolate the cable connection (CATV) with an isolation transformer. This inexpensive device is available at most Wal Mart, Radio Shack or department store type outlets and is sometimes called a ‘matching transformer’. If you have problems fi nding one, call your local cable TV company for advice. The matching transformer will be placed between the cable TV cord and the VCR, TV or processor.

Just remember, take the system down to its simplest level of connection. Find a way to hook the system up with as many pieces of the system missing or not connected. Keep it simple and get it to the point where the hum’s gone. Then start adding back components one at a time until the hum returns.  Finding the problem is 9/10th of the work in finding a solution.

Reference document (page #7 If you have hum) at http://www.psaudio.com/documents/quintet_duet_manual.pdf


Hope it helpful!

B. regards,
alant
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