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Radio interference with PC speakers

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Anonymous
a b B Homebuilt system
October 28, 2004 6:15:57 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

I was just wondering if anyone has ever experienced radio interference with PC
speakers. At first I thought that it was just static, but if I listen carefully
I can actually hear a local station through speaker, and only the left one at
that! I suspect that the problem is that the speaker is poorly shielded, but
it's just weird that it's one particular station instead of pure static.
Anonymous
a b B Homebuilt system
October 28, 2004 6:15:58 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Ed Coolidge wrote:

> I was just wondering if anyone has ever experienced radio interference
> with PC speakers.

Not my PC speaker but my component stereo system used to pick up (probably
through the turntable cartridge) a paging system from the hospital that was
around the corner where I used to live.

> At first I thought that it was just static, but if I
> listen carefully I can actually hear a local station through speaker,
> and only the left one at that! I suspect that the problem is that the
> speaker is poorly shielded,

PC speakers, especially low cost ones, aren't usually shielded at all,
being low frequency (audio) devices that don't generate any interfering EMI.

Magnetically 'shielded', yes, to prevent distorting the CRT, but not EMI.

> but it's just weird that it's one particular
> station instead of pure static.

Not as weird, or unusual, as you may think. Just guessing but it's probably
a strong local AM station as AM is super easy to demodulate. All it takes
is a rectifier, low pass filter, and some amplification: all rather
'natural' aspects of a typical transistor audio amp.

That won't 'tune' a station, though, which is why it'll only 'work' for
something local with sufficient power in the area to surpass background
noise; plus enough signal so that the amp can make it audible.

That's why it's more common on amps with a phono input: a lot more gain.
Anonymous
a b B Homebuilt system
October 28, 2004 6:15:58 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

"Ed Coolidge" <semi_DELETE_THIS_charm@earthlink.net> wrote in message
news:xDYfd.9982$5i5.9798@newsread2.news.atl.earthlink.net...
>I was just wondering if anyone has ever experienced radio interference with
>PC speakers. At first I thought that it was just static, but if I listen
>carefully I can actually hear a local station through speaker, and only the
>left one at that! I suspect that the problem is that the speaker is poorly
>shielded, but it's just weird that it's one particular station instead of
>pure static.

My bass amp used to pick up Spanish radio in my dorm room. (Too bad I don't
speak spanish, I guess.)
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Anonymous
a b B Homebuilt system
October 28, 2004 7:52:19 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

David Maynard wrote:

> Ed Coolidge wrote:
> Not as weird, or unusual, as you may think. Just guessing but it's
> probably a strong local AM station as AM is super easy to demodulate.
> All it takes is a rectifier, low pass filter, and some amplification:
> all rather 'natural' aspects of a typical transistor audio amp.
>
> That won't 'tune' a station, though, which is why it'll only 'work' for
> something local with sufficient power in the area to surpass background
> noise; plus enough signal so that the amp can make it audible.
>
> That's why it's more common on amps with a phono input: a lot more gain.
>

Actually it's FM. There are several stations in the area and I'm not sure which
is closest. Usually when you say that you're hearing voices people tell ya to
see a shrink! It's good to know that I'm not going crazy. ;) 
Anonymous
a b B Homebuilt system
October 28, 2004 8:55:19 AM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

Ed Coolidge wrote:

> David Maynard wrote:
>
>> Ed Coolidge wrote:
>> Not as weird, or unusual, as you may think. Just guessing but it's
>> probably a strong local AM station as AM is super easy to demodulate.
>> All it takes is a rectifier, low pass filter, and some amplification:
>> all rather 'natural' aspects of a typical transistor audio amp.
>>
>> That won't 'tune' a station, though, which is why it'll only 'work'
>> for something local with sufficient power in the area to surpass
>> background noise; plus enough signal so that the amp can make it audible.
>>
>> That's why it's more common on amps with a phono input: a lot more gain.
>>
>
> Actually it's FM.

So much for my guessing ;) 

> There are several stations in the area and I'm not
> sure which is closest.

Well, it depends on the power output too. The strongest should be the one,
unless there's something in the amp acting as a semi 'tuner'.

> Usually when you say that you're hearing voices
> people tell ya to see a shrink! It's good to know that I'm not going
> crazy. ;) 

Man, you should have heard the voices in the hospital pager. Louder than
the music, it was. And preceded by an ear splitting beep-bleep-blurp.

Dern near had a heart attack the first time that kicked on.
October 28, 2004 2:04:41 PM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

On Thu, 28 Oct 2004 02:15:57 GMT, Ed Coolidge
<semi_DELETE_THIS_charm@earthlink.net> wrote:

>I was just wondering if anyone has ever experienced radio interference with PC
>speakers. At first I thought that it was just static, but if I listen carefully
>I can actually hear a local station through speaker, and only the left one at
>that! I suspect that the problem is that the speaker is poorly shielded, but
>it's just weird that it's one particular station instead of pure static.

maybe soldering a small bypass capacitor (few nF) to PC speakers vol.
pot could cure that symptom...
--
Regards, SPAJKY ®
& visit my site @ http://www.spajky.vze.com
"Tualatin OC-ed / BX-Slot1 / inaudible setup!"
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Anonymous
a b B Homebuilt system
October 28, 2004 5:33:55 PM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

> Ed Coolidge <semi_DELETE_THIS_charm@earthlink.net> wrote:
> >I was just wondering if anyone has ever experienced radio interference
with PC
> >speakers. At first I thought that it was just static, but if I listen
carefully
> >I can actually hear a local station through speaker, and only the left
one at
> >that! I suspect that the problem is that the speaker is poorly shielded,
but
> >it's just weird that it's one particular station instead of pure static.
>
>
Not the computer speakers. My home stereo speakers pickup police car
broadcasts as they drive by. Even when the receiver is turned off!
Anonymous
a b B Homebuilt system
October 28, 2004 9:53:02 PM

Archived from groups: alt.comp.hardware.pc-homebuilt (More info?)

In article <xDYfd.9982$5i5.9798@newsread2.news.atl.earthlink.net>, Ed
Coolidge says...
> I was just wondering if anyone has ever experienced radio interference with PC
> speakers. At first I thought that it was just static, but if I listen carefully
> I can actually hear a local station through speaker, and only the left one at
> that! I suspect that the problem is that the speaker is poorly shielded, but
> it's just weird that it's one particular station instead of pure static.
>
Actually it is more to do with the length of the speaker cable. It acts
as an antenna and the frequency it'll pick up depends on the length of
the cable.

Try getting a ferrite rod and wrapping the speaker cable round it a few
times.


--
Conor

Opinions personal, facts suspect.
August 11, 2012 3:03:17 AM

I used an old speaker magnet (ironic), doubled the wire over and looped it through the hole in the middle over and over until i ran out of length. This worked because the wire causing the radio signal was the one from the volume control to the subwoofer and they are close by eachother in my configuration, so most of the wire could be wound in the magnet. It may not sound like it's working until you finish and put it down, because for me, the signal boost from me touching it is enough to overcome the efect of the magnet.
!