[kami]

Hi all
I dare asking a non 3d related question here ...
I got a surround system plugged to my computer for music and films of course.
Now, my problem is: every time someone switches a light on or off in the house, I can here hear it! Sometimes it's just a gentle click, but sometimes it's quite loud.
I've plugged it into a simple power strip with an on/off switch.
The worst feeback sound I get, when I cut the power for the speaker system by switching it off on the power strip.
I'm wondering
A - if this can do harm to my speakers
or
B - how I can avoid this noise.

Surely by switching them off with their own power switch, but then they'll stay in standby and still take some energy. And I want to be able to shut down all my devices with one switch.

Can somebody give me any advice?
Thanks, kami

[ivox3]

Hi all
I dare asking a non 3d related question here ...
I got a surround system plugged to my computer for music and films of course.
Now, my problem is: every time someone switches a light on or off in the house, I can here hear it! Sometimes it's just a gentle click, but sometimes it's quite loud.
I've plugged it into a simple power strip with an on/off switch.
The worst feeback sound I get, when I cut the power for the speaker system by switching it off on the power strip.
I'm wondering
A - if this can do harm to my speakers
or
B - how I can avoid this noise.

Surely by switching them off with their own power switch, but then they'll stay in standby and still take some energy. And I want to be able to shut down all my devices with one switch.

Can somebody give me any advice?
Thanks, kami

Sorry if you read my original reply, ..I had to delete it because I'm taking a different tact.

I'll just start with some questions:

Where do you live ? 110v or 220V? ..grounded outlets?

How loud is the pop in the speakers when you flip the switch on the strip? If it's scary loud,..for now, ..just be sure to keep the volume low and you should be fine.

Is there a general hum from the speakers ? ...whether someone has a light on in the house or not ...?

[mtripoli]

Are you using a UPS with your computer? They usually have an outlet on them that is not backed up when the power goes off but is still filtered. This can be usefull in these situations. Also, if you use a UPS (which anyone really should be using) then plug the outlet strip into the non-backed up outlet. This forces anything plugged in to the power strip to use the same hot-neutral-ground configuration (unless you force the plug in backwards, which takes alot of force so unlikely).

On the same note of a UPS; there is a certain amount of free protection using a UPS for more than the backup. The outlets use transient protection for things like lightning strikes and such. If if the battery is not working the filtering is. Better to take out a UPS than the computer and such plugged in. I have a few "dead" UPS's that I use on non-critical things just for the protection afforded.

I'm not sure how much of this is a ground loop. Usually ground loops would exhibit hum in the sound. If there is no hum I'd be suspect of a ground loop.

Expense of the system. Most likely what you are hearing is the output capacitors of the system discharging when turning off abrubtly. Even low cost systems use a "pop circuit" to control the output when you switch them off with the power switch. If there is a sudden loss then it can't work.

I agree with you on the current draw when things are "turned off"; it's one of my pet peeves. I use CFL throughout the house, most of the times candles instead of lights, on and on... however, I'd look at the actual current draw of the items in stand-by and see what the actual draw is. A good rule of thumb is to see if the wall-wart or unit is warm to the touch. If it is then in my estimation it's drawing too much and should be shut-down at the source. If not its most likely a good design and not contributing much to your power bill.

Good luck.

[mtripoli]

How loud is the pop in the speakers when you flip the switch on the strip? If it's scary loud,..for now, ..just be sure to keep the volume low and you should be fine.

Is there a general hum from the speakers ? ...whether someone has a light on in the house or not ...?

"Pop" is independant of the volume of the system. The capacitors block the DC level of the output. Regardless of how loud the system is playing if the power is shut off the DC is discharged throuh the speakers. This is a very common problem in design of an amplifier. Many passive and active designs exist for preventing the pop. As I said, most amplifiers use some kind of soft-shutdown or disconnection of the speakers during shutdown.

[ivox3]

Thanks Mike .. yeah, I was just trying to determine if he had hum as well as the pop. I thought that if there was a some level of voltage differential that maybe it was causing the pop. But now that I reflect back a little ... I know what your talking about with cap discharge -- an unpleasant little pop.

Do you think that something simple like replacing switches with slide type on/off mechanisms would alleviate anything ? ...just a thought.

[kami]

thank you guys so far. sorry if I didn't understand everything completely. the text is way beyond my english level

to answer the questions first:
yeah, the pop is independent of the volume. and there is a slightly humming, when the device is turned. only noticeable if its very silent
I live in a flat in switzerland, so 220v
and I'm not sure if the plug has grounding. I'll check it when I come home.
I don't use UPS. I've heard of it, but never looked at it closely. It's a system that protects your computer from rebooting because of a short power off?

To elaborate my situation a bit. I use my computer to listen to music (speaker system is a logitech z550 for around 300$) and often I listen before going to sleep. I set my computer on timer to shut down some hour later. until lately the speakers always ran all night, taking power, sometimes waking me up with a "pop" .
now, I've bought a master/slave power strip, so whenever my computer shuts down, all other devices are switched off.
but the pop they make now, while taken off power is "scary loud"

thank you very much for your help!

PS: there is no grounding on the cable

[m-Que]

Well, don't know if it's bad or not, but I can here this 'CLICK' sound too on my surround system, but only when someone switches the lights on/off in the room next to mine - these 2 rooms are connected with one central electric cable, so I guess that's the reason why. If you live in a flat, it's quite possible that you hear it every time someone uses the switch in your flat, since there's probably one central cable for every single flat. I've been having my surround system for almost 3 years now and it still works perfectly, so I guess there's nothing to be worried about

And yes, when I turn off the surround system (I use a switch on the back of the box) I can hear a 'boom' sound.

I just hope I got you right and we speak of the same thing

PS: The worst sound I get is when I turn on the video/music and forget that I forgot to turn on the surround system. So I switch it on with the video/music already playing, and the surround system makes a 'BOOOM' sound. (I hate when this happens )

[mtripoli]

The type of switch in the system doesn't make a difference. It's a function of the DC voltage in the output circuit. Many older systems (and in fact a newer Sony I have have relays in the output just for this problem). There are all sorts of ways of doing this. The most recent is a slewing circuit built into the IC so that the voltage ramps up and down to prevent this.

Over time (time?) the pop could have a detrimental effect on the speakers. I have couple of systems that do the same thing (most notably the cheaper stuff that has the amplifiers in the sub-woofer box. Lot's of stored energy in this circuit.

A UPS is a battery backup system. If you can I'd get one and just for peace of mind. It won't help with the popping however given the info you've given (sorry).

A slight "hum" is evident in any amplifier that is turned up very loud with no sound playing. THe hum most likely is 50-60Hz. being injected into the signal from some outside source. It can also just be noise in the electronics for many reasons.

A question I overlooked before; the lights being switched on/off in the other room; are they fluorescent? These are notorious for generating spikes on the electrical lines. These have starter circuits that charge/discharge. Air conditioners as well. Incandescents warm up as they are turned on and generally don't cause the spike in the line (stupid note: incandescents rarely just "burn out". Typically it's when the AC voltage is at a high point of the sine wave and you switch the light on "cold". This burns out the filament. If you leave a light on all the time the bulb will last longer {vs. higher electric bill}).

As for the 220VAC. It uses two 110 (120) hot lines and a neutral. Unless it has a 4-pin plug it won't have a ground. However the two hot lines *should* sum to zero if you look a the phase of the current (yeah I know, STFU now). It's not uncommon however that someone has unevenly distributed the AC so one line is out of phase with the other. Here in the US where both 220-240 is used with 110.

[kami]

You know a lot of stuff about electricity I'm glad, I asked this here ...
I think I understand more clearly what causes these pops (the very abrupt difference of power). And you are right, fluorescent lights cause the most noticeable noise.
One point I did not understand though: what can I do against it? Or is there even anything I can do?

[mtripoli]

Getting rid of the spike generated from fluorescents is tough. Most newer types use an electronic ballast (the circuit that gets the tube going). These generate horrible spikes. The older transformer type less so. In my estimation it would be a very tough job isolating the circuit so that it doesn't conduct the spike.

I used to have one of the master controlled outlet strips you describe for pretty much the same use.

As for the pop; again, I think you're pretty much stuck with it.

[kami]

thank you for your help.
maybe I'll have to consider buying a new music system in the near future then. It's really pretty annoying, even when listening to music. And I'll have to take it off the master/slave thingy.
But this thread really helped me understand the reasons behind it... I'll be more careful what I buy in future.