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I have an old Creative Inspire 5.1 surround system hooked up to the computer I use with a movie projector. The speaker system has recently begun to give off a weird sort of discharge sound, and it really does sound like a very deep "whoomph", lasting about half a second. The sound appears to come from all speakers, not just one of them, and it happens mostly when the computer isn't playing a sound but I've also heard it while watching a movie.
What can cause such a sound? It sounds like some sort of power build-up that is released at uneven intervals.
Update:
- I wielded a screwdriver and inspected the subwoofer's electronics. I remember an old motherboard once died of bad capacitors and thought this might be part of the problem here, too. A visual inspection of the capacitors and the electronics board in general didn't reveal any problems though, so the bad-caps hypothesis is ruled out.
- The computer is ruled out as well because the speakers go "whoomph" even when not connected to any source.
- That leaves the 220->110V transformer as possible cause, and I can't definitely rule out the subwoofer electronics either. Testing the transformer for this phenomenon is simply not practical, and I have no further means to test the speaker electronics. It seems I can't pursue this any further; sadly I might have to replace the speaker system entirely.
Some techie details about my setup:
The subwoofer acts as a connection hub, so all cables go from there -- 5 speakers, 1 volume/power control, and 3 "stereo walkman" cables to the computer (no digital audio signal). The computer is configured to use a 5.1 speaker system. (Computer-related details have been removed after I ruled out the computer as root cause. Check the post history if you're curious.)
The only special thing is that the trusty old Creative 5.1 set is 110V but my house is on 220V, so I've always had the speakers powered via a 220V->110V transformer. This was never a problem, but perhaps age is catching up (I bought it in Japan 12 years ago!). I don't have a spare transformer to test, nor any other 110V equipment, so it's difficult to test whether the transformer is at fault.
Torben Gundtofte-Bruun
Posted 2014-07-27T18:41:24.140
Reputation: 16 308
I have owned one of these. Good set of speakers for that time. The only thing I can think of is the transformer. Have you tried replacing that one? – LPChip – 2014-07-27T19:07:33.850
No, it's near impossible to find a transformer here, and they're quite costly so I'm hoping the problem is elsewhere. But I mentioned it because it might be part of the problem, yes. – Torben Gundtofte-Bruun – 2014-07-27T19:12:44.753
Can you test the transformer with something else? such as a lightbulb or such? If that goes brigher with the same kind of frequency, you know its the problem. – LPChip – 2014-07-27T19:14:24.977
This relic is the only 110V equipment I own. Also, there is no regular interval for this. It might be 10 minutes, an hour, anything. – Torben Gundtofte-Bruun – 2014-07-27T19:17:22.177
A simple lightbulb will run on V110 and V220. The only exception is that the light is less shiney. Unless the plug is actually different too. That would change things. – LPChip – 2014-07-27T19:21:09.833
Yeah, the transformer offers a US/JP socket but we have different plugs in Europe. I would need to sacrifice some parts to build a plug. Still a good idea (I feel silly for thinking of that dim 110V bulb thing!) but I want to explore other causes first. I'll update my post to include these comments. – Torben Gundtofte-Bruun – 2014-07-27T19:23:55.830
Okay. Keep us posted. If you find out it is the transformer, it wouldn't hurt to look into the costs to replace your speakerset. There are good speakersets now that outperform this one by far for a price less than a new transformer. For example, the Creative Inspire T20 II is amazing for its price. – LPChip – 2014-07-27T19:29:57.867
Uh, that Creative Inspire T20 are not 5.1 surround, so not what I'd need in my humble home cinema. @Dave, good idea! I have an old stereo set left over, I can try those. – Torben Gundtofte-Bruun – 2014-07-27T19:35:40.083
Can you use different speakers to prove it is the set up, AND a different media source. Also, maybe record the noise on your phone And post it some where online and public so we can hear it in action! – Dave – 2014-07-27T20:09:59.420
Since you wrote the computer has changed: I guess a ground loop would cause continuous buzzing—but it's not my expertise. Still then: are both the computer and the subwoofer connected to the same wall outlet? (As an aside: if you are to replace the transformer, then I'd open the subwoofer to see what transformer is inside. Internally, it won't be using 110V. Maybe there's even a way to set it 220V, inside the subwoofer. And replacing that transformer will take out two possible causes, and that transformer is more complicated.)
– Arjan – 2014-07-27T20:51:13.403Yes, all on same wall outlet, although only the pc has a ground plug; neither the transformer nor the subwoofer have that (standard US plug). – Torben Gundtofte-Bruun – 2014-07-27T20:52:49.137
Any chance the computer is going into some power safe mode? Or screen saver, something like that, which then somehow also wakes itself again...? – Arjan – 2014-07-27T21:02:46.733
@LPChip, which transformer are you referring to? I doubt the 220-110V transformer is a very sophisticated device (just a lot of wire around a magnetic core), and I wonder if that can cause any strange behaviour. But the internal transformer will also include components that transform AC into DC, which in my guess might be the culprit, if it's not the computer. But I'm no expert. – Arjan – 2014-07-27T21:43:43.907
Maybe there's something in the Windows Event Viewer? And as for "it happens mostly when the computer isn't playing a sound but I've also heard it while watching a movie" — when it happens during playback, is the movie loaded from a harddisk, or streamed? (Streaming might very well use the harddisk too, but maybe not as much, hence maybe it's the harddisk that is going into some power saving and then causing some interference? Again, I guess it's not very likely. I'm just thinking out loud, just in case; no need to respond if not applicable...) – Arjan – 2014-07-28T16:57:43.853
Ubuntu Linux doesn't have a Windows Event Viewer :) The media is on disk, played with VLC or Plex Media Center. The HDD does not power down, it's always on. – Torben Gundtofte-Bruun – 2014-07-28T17:12:23.553