Whenever we turn a light on or off, an electrical sound can be heard from the PC speakers. I assume we have a faulty connection somewhere. Any suggestion as to the best place to start. Is it more likely to be the lighting circuit? I suspect the answer is that it could be anywhere but just thought I'd ask!
Don't worry about it. PC speakers are of such piss poor quality they respond to anything like the slightest amount of RF energy. Trust me I'm a radio comms engineer:))
I missread the PC bit thought it was a hifi problem. As others have said it is high frequency "noise" causing the problem could try a plug in mains filter although.......maybe not worth the cash..
Even if he *did* have a UPS, there is no need to run speakers from it. As a general rule, you want to put the minimum of equipment on a UPS to maximise the run time when on batteries. Also, many UPSs don't filter the mains much, JUST provide backup power when the mains goes out. You have to get a decent UPS for this feature.
Also, UPSs are NOT a replacement for backups. Even with a top-of-the-range UPS your hard drive can still fail and lose all your data.
True. Talking about "speakers" is misleading, because the problem is definitely not in the loudspeakers themselves, but most probably in the amplifiers (a stereo pair) that drive them, and/or their power supply.
However, before running away down that path, we need to take a step back, and ask the OP:
Does any other audio device in the house (TV, mains-powered radio, hi-fi) show the same problem when you switch things on and off? Do the lights flicker?
If not, it's highly unlikely to be a major fault in your mains wiring.
Small disturbances on the mains are normal, whenever you switch anything on and off. What seems to be abnormal is that your amp/speakers are very sensitive to them.
Assuming the answer to the first set of questions was No, then try to narrow it down further.
Borrow a completely different set of speaker/amps and power supply from another PC. Is the problem still there, or is it specific to your set?
Aside from the specific problem you reported, is the audio background dead quiet, hum-free and undistorted? Or is the sensitivity to mains switching part of a wider problem?
There are two connections to the speaker/amps system: the mains power supply and the audio input from the PC. The electrical noise could be getting in either way, so:
Unplug the audio input lead from the PC. If the problem is still there, the interference is coming in through the power supply.
If the problem goes away when you unplug the audio lead, it could be either at the PC end, in the lead or its connectors, or the amplifier end (though I'd bet on the last two).
Given the answers to these questions, several people here might be able to help you further.
On Fri, 27 Aug 2004 08:25:54 GMT, "Alan" wrote: [snip]
I agree Alan. No need at all to run speakers through the UPS although, unless they are meaty speakers, their current drain would be minimal.
A UPS that doesn't filter the mains is not much use as to my mind any good quality unit will do this. I also agree that a UPS is not a replacement for a backup. But, many people do not backup as often as they ought and I was envising the (increasingly common) problem of mains spikes. When I worked in IT support, I was amazed by the number of times a PC/server went belly up and on opening the case, literally half of the components had blown off the motherboard and other cards. Needless to say the hard drive was toasted and much of these cases could have been avoided by the mains being filtered for spikes.
On Fri, 27 Aug 2004 08:25:54 GMT, "Alan" wrote: [snip]
I agree Alan. No need at all to run speakers through the UPS although, unless they are meaty speakers, their current drain would be minimal.
A UPS that doesn't filter the mains is not much use as to my mind any good quality unit will do this. I also agree that a UPS is not a replacement for a backup. But, many people do not backup as often as they ought and I was envising the (increasingly common) problem of mains spikes. When I worked in IT support, I was amazed by the number of times a PC/server went belly up and on opening the case, literally half of the components had blown off the motherboard and other cards. Needless to say the hard drive was toasted and much of these cases could have been avoided by the mains being filtered for spikes.
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