Speaker noises

March 31, 2005 3:02 PM

Speakers. I have a new set of computer speaker. I'm really happy with them, except they make a loud popping noise anytime I or any of my neighbors turn off a light. (I live in an apartment building.) So I have two questions: Is this harmful to the speakers? Is there anything I can do to eliminate those noises?
posted by epimorph to technology (15 comments total)

I have the same problem, with different causes.

I get popping whenever I'm about to receive a call on my cell phone, and during a call if I place the phone too near the speakers. It's like a foretelling of a phone call when I hear the popping.

Lately I've been getting the popping for no reason whatsoever, which always makes me think I'm about to get a call. Extra annoying in that I don't just have popping, I'm conditioned to reach for my cell phone every time it happens.

So, my belief is that the speakers are very sensitive to any outside interference and I'm just going to have to bear it.
posted by Four Flavors at 3:28 PM on March 31, 2005

that pop is a spike caused by the other items on the same circuit as they shut off. if you have your speakers plugged directly into a wall, try something like a surge protector (which i'm not sure will do the trick as well) or a filter.

in fact, try plugging into different outlets/surge protectors in the nearby area and see if it still happens.

as for the cellphone "ticking" noise, that is interference from the cell's transmission. incoming and outgoing messages both trigger this interference, as do sync and other signals (which are sent even when your phone isn't being spoken on [correct me if i'm wrong, engineers]). I get them with pro studio monitors and generics as well, so just keep the phone away from them cones.
posted by plexiwatt at 4:01 PM on March 31, 2005

I have the same thing happening as Four Flavors, my cell (Sony Ericsson T226) will cause my speakers to pop some, it'll also cause interference on my regular landline if the cell is between the handset and the base.

'Course, my cell's a piece of crap, that's always been my explanation but its nice to know I'm not the only one experiencing this. And it does this when its not plugged into any wall or outlet at all.
posted by fenriq at 4:27 PM on March 31, 2005

It's two different problems, the popping from the light switch is a power surge issue. The cell phone noises are from RF interference.

The computer speakers are probably powered, right? I'm suprised that the transformer reacts so much a change in the supply power. It should keep a steady supply of DC power converted frmo the AC wall power. A surge protector should help, although those are usually set to take care of large surges, not the little variations from turning lights on and off.

The cell phone noise is from the signals sent from your phone to the cell towers. This creats EMI (electromagnetic interference) issues when it couples with the speaker wires, which act like big antennas and amplify the signals that ride on them. Try keeping the wires as short as possible and (obviously) far away from emitters like cell phones. You can also get better shielded cables, which have a metallic braid and a ground path to each end of the connector so that the signal will ride the shield to ground instead of on the signal wires.

To experiment with the phone interference, try wrapping one wire in aluminum foil and leave one bare. You can see how much effect a little bit of shielding will have.

Back to the original question about the light switches, it is possible that the speakers could be damaged if the transformer is bad (which is sounds like).
posted by jonah at 4:43 PM on March 31, 2005

This is a line noise problem, as previously mentioned.

The way to fix it is to buy the cheapest UPS (Uninterruptible Power Supply) you can find and plug the speakers into it.

The UPS is meant to carry a device through a power outage, but it also serves as a line conditioner, meaning that you get a nice, even (and constant) sine wave from it that won't make your speakers pop.

Yes, you can buy seperate line conditioners, but they tend to be more expensive than a cheap UPS, and you get more bang for your buck with a UPS anyway.

I would start Here, and This one would do just fine.
posted by SlyBevel at 4:51 PM on March 31, 2005

Whoops, forgot the cell phone part.

As also previously stated, this is an EMI problem (Electromagnetic Interference).

It's too late to fix with your current speakers, but the next time you buy new speakers, you'll want to make sure that they're magnetically shielded.

M'kay?
posted by SlyBevel at 4:54 PM on March 31, 2005

I already have the speakers plugged into a surge protector. I'll try a UPS next.

Thank you.
posted by epimorph at 5:05 PM on March 31, 2005

cell phone / speaker popping thread from way back

epimorph - it occurs to me to try a UPS as well, but it depends on how it works. If it incorporates a line conditioner, you're in better shape, but it's possible that entry level models are engineered without one. The electronics to switch to battery and count on the PC power supply, or, in your case, the AC adapter to fill the minute gap is a lot cheaper than engineering in a line conditioner. I'd say check out the unit you plan to try, especially since it's going to cost you $50-80 at a bare minimum to even experiment (unless you can borrow one cheap - you're a resourceful man, I'd suggest that route).

Incidentally, are they connected to your PC? Or something else? It's obvious enough where the electical disturbance originates, but it's possible, for example, that your PC's power supply is on its last legs and is creating the disturbance itself, in response to the lightswitch flipping.

You've got to work to find the problem by a process of elimination. It's possible only one outlet in the room presents the problem in the first place. Try another audio source and see if there's any difference. It also goes without saying to try another surge protector as well.
posted by scarabic at 6:31 PM on March 31, 2005

A surge protector--no matter how good--won't do the trick, because it only protects you from a surge.

A surge is extra power. That's not the same as dirty power. Your problem isn't too much electricity, it's messy electricity.

That's why I'm recommending a line comditioner. It's a device that takes a dirty power line (all over the place on an oscilloscope) and cleans it up (a lovely sine pattern on the scope).
posted by SlyBevel at 7:24 PM on March 31, 2005

Conditioner.

Can't type, dammit.
posted by SlyBevel at 7:25 PM on March 31, 2005

After a bit of experimenting, I'm sure the PC itself has nothing to do with it. I've also tried different power outlets, to no avail. So, a UPS it is. Though, I'm a little worried by what jonah said, especially in light of the fact that the old speakers I have don't behave this way. Could it be that the speakers are defective?
posted by epimorph at 10:24 PM on March 31, 2005

A cheap thing to try would be to get some of those cheap ferrite EMI-suppression cores and thread the speaker wires through them. Probably wouldn't help with the power-line related noise but might reduce the cell-phone noise.

Re "magnetic shielding" my understanding is that that's intended to protect against much lower frequencies than are involved here (things like TV or monitor deflection coils). I could be wrong, and I suppose a magnetically-shielded speaker might be better engineered to resist other kinds of interference as well.
posted by hattifattener at 10:38 PM on March 31, 2005

It really sounds like the transformer is defective. A power conditioner might not do the trick.

Your speakers run on DC (Direct Current), while the wall electricity is AC (Alternating Current). If you look at the transformer (the big boxy thing that is either at the plug or in between the wall socket and the speaker), it will say what the output voltage is. It is possible to find replacement transformers, but be very careful to get the same rating with voltage and current.

If it is possible, I would exchange the speakers and try the new ones, especially if your old ones didn't have a problem. Also, if your old speakers have the same Voltage/Amp ratings, you could swap the transformers as long as the interface is the same.

I realize that this is a bit confusing, feel free to email me if you want some additional advice.
posted by jonah at 9:14 AM on April 1, 2005

Eh. I give up. I've got a massive background in electronics and I know what I'm talking about, but whatever.
posted by SlyBevel at 10:36 AM on April 1, 2005

SlyBevel, I don't think I'm arguing with you, no need to give up. My main point is that these are consumer electronics, made cheaply (comparatively) and that to buy an external power conditioner should not be necessary. I imagine that having to buy a separate conditioner would be a significant percentage of the speaker purchase price.

We condition power all the time with EMI and Ripple filters when you need very clean power, but the transformer should make the speakers work. If it was just an issue with dirty power, wouldn't you expect constant noise on the line instead of a pop when an event (light switch) occurs?

What makes me think that it is a speaker related problem also is the fact that this issue wasn't seen with the previous parts. In my engineering work, I try to isolate down to what changed when the problem arose. In this case, it looks like the speaker power supply to me.
posted by jonah at 2:35 PM on April 1, 2005