Ferrite Cores to Reduce Speaker Buzzing?

[RxBrad]

So, the power supply for the LEDs in my cab's marquee is causing a buzzing noise in the Logitech X-140 speakers in my cab. 

The buzzing goes away if I unplug the LED power supply.  It comes back when I plug the power supply back in -- even if I plug it into a different outlet.  It appears that the physical proximity (about 1.5-2ft) of the power supply to my speakers is causing the buzzing. (I have the power supply and speaker wires moved as far apart as I can get them in my cab).

Thinking about snapping some ferrite cores onto some cables to hopefully reduce the noise.  How do I go about doing this?  Attach them to the 3.5mm PC-to-speakers audio cable?  To the power supply cord?  To the speakers' power cord?  Should I attach the ferrite core to one end, or both of the cables?  If just one end, which one?

[Generic Eric]

I used your subject line as a search query and found a product link to amazon.

Black plastic enclosed ferrite core for 1/2" AC power cords. Easy to install, simply snap around cord.

Now what does a guy do about the sound from the speaker when you put your cell phone too close?  Anything to be done about that besides moving it?

[RxBrad]

Yup, I planned on buying some from Amazon.  I just wanted to know which cables to snap them onto, and how many I should use.

[vwalbridge]

I'd be very interested to hear if the ferrite cores solve you problem or even reduce it.

Any time I've used a ferrite core, it provided zero relief on the noise/feedback.

Noise in speakers is almost always a ground loop, or (more likely in this case) poorly insulted speaker wire.

[Generic Eric]

Yup, I planned on buying some from Amazon.  I just wanted to know which cables to snap them onto, and how many I should use.

Sure.

1, or at least one at a time.  I would place one as close to the power input on the speaker system.  Then, move it closer to see if there is any difference.

If you want to go nuts, play a 1khz tone.  That way you are listening to a consistent sound.  Also, it might be worth while to check the speaker wire connections.

[RxBrad]

The speakers have a pretty distinct 60Hz hum going on right now which is actually pretty easy to hear, even if there's no sound being broadcast through the speakers.  It's even there if I unplug the audio cable from the PC in my cab.

There's a Radio Shack down the street from work.  I'll see if I can grab some ferrite cores on my way home.

EDIT: And I have a ground loop isolator hooked up to the bluetooth receiver in my car.  Will give that a try, too.

[lilshawn]

Now what does a guy do about the sound from the speaker when you put your cell phone too close?  Anything to be done about that besides moving it?

get a phone NOT using a CDMA/EDGE network.  had that problem with my phone as well...changed to a provider that uses OFDM like a 4G/LTE network and haven't heard a peep.

[Generic Eric]

Here is a nice primer

[yotsuya]

Now what does a guy do about the sound from the speaker when you put your cell phone too close?  Anything to be done about that besides moving it?

get a phone NOT using a CDMA/EDGE network.  had that problem with my phone as well...changed to a provider that uses OFDM like a 4G/LTE network and haven't heard a peep.

Get your phone away from your arcade cabinet.

[RxBrad]

Bought four ferrite cores, placed them in several different configurations on the speaker connection wire, speaker power wire, and LED power wire. Didn't affect the buzzing at all.

Also tried the ground loop isolator. Again, no luck (which I suspected, as the buzzing was present even with the speaker wire unplugged).

So, I'm just returning this particular LED power supply and trying another one.

[lilshawn]

your problem is caused by the mosfet switches in your LED lighting causing noise in the power brick while they switch. it's also the varrying voltages used in LED lighting that throw the regulators inside the power brick off. this issue is being exasperated by the amplifier driving the speakers since it needs super clean power and super clean audio to produce clean output. the problem is your low audio input side is being affected not the high speaker side.

if you peel the speaker apart you'll see nice shielded cable enter the cabinet... soldered onto a board and then splayed out all over a great big antenna they call the circuit board. this is going to pick up all kinds of junk. switching mosfets switch off and on and everytime it does, it clips the power causing a spike or a dip in the power.

you are either going to have to find a better less noisy power supply, a better less noisy LED controller, or a better shielded audio system.

as a test, try powering your LED system from a 12 volt battery and see how your sound...sounds. if it's the same,  it's your LED controller radiating noise. if it's gone, your power brick is the fault.

it could be a combination of both.