I'm asking this question on the rec.audio forums because there seem to be a
lot of technical experts who have helped with these kind of problems in the
past.
Anyway I am bashing my head against the wall because my computer speakers
(Altec Lansing ACS45 2 speakers & sub) which worked fine at my apartment,
now emit a very annoying hum/buzz whenever they have power. I thought the
speakers or built-in amp was broken, so I purchased some new speakers
(fairly cheap Cyber Acoustics ones, also 2 + sub), only to find the exact
same problem with them!
Here are the symptoms and results of my testing so far:
0. My ACS45 speakers always did have a bit of static 'snow' whenver turned
on, but it was barely noticable when I lived in my apartment.
1. Speakers emit buzz/hum whenever they are plugged into AC and are turned
on. You can also faintly hear a radio station or other music. This buzz/hum
does not change with volume adjustment, nor does being connected to my
computer's soundcard affect it. In fact, I plugged them into the AC outlet
in my kitchen and found the exact same noise. Playing with the wires'
orientation does affect the noise somewhat.
2. When I tried them at my neighbour's house, the buzz/hum was NOT present..
3. When I try them in my unfinished basement (plugs are near the main wiring
panel), the buzz/hum was also NOT present.
4. Using a ferrite bead/core which I stole off a modem line that came with
my laptop, had almost no effect.
5. I do have an APC surge suppressor, but it's a fairly cheap one that I
don't think does much noise filtering.

At first I suspected a 'ground loop' problem but I don't think it's that
because it happens when my speakers are attached to nothing except AC power.
I still suspect noise in my electrical lines, which goes away in the
basement because so close to the main house wiring & ground? I also suspect
Radio Interference, as there is a radio tower nearby. This would explain the
music heard in the background, and going to the basement (below ground)
might offer some shielding. Although it doesn't explain why the problem
doesn't exist at my next-door neighbour's house.

Sorry for the long explanation. Right now I'm thinking of doing two things:
getting some higher quality speakers, and getting a higher quality surge
suppressor with at elast 70db of EMI/RFI reduction.

Thanks for any help or suggestions as I am having a very hard time with
this!
Mike

"Mike & Kristen" wrote ...
I'm asking this question on the rec.audio forums because
there seem to be a lot of technical experts who have helped
with these kind of problems in the past.
Anyway I am bashing my head against the wall because
my computer speakers (Altec Lansing ACS45 2 speakers
& sub) which worked fine at my apartment, now emit a very
annoying hum/buzz whenever they have power. I thought the
speakers or built-in amp was broken, so I purchased some
new speakers (fairly cheap Cyber Acoustics ones, also 2 +
sub), only to find the exact same problem with them!

You might want to have your house wiring checked.
You could have a faulty ground or something. This could
have actual safety implications far beyond annoying noise
in your computer speakers.

Here are the symptoms and results of my testing so far:
0. My ACS45 speakers always did have a bit of static 'snow'
whenver turned on, but it was barely noticable when I lived
in my apartment.

The generally-accepted term for this is "hiss". Like what you
hear on an FM receiver between stations. People will know
what you are talking about if you use the proper terms.

Most of these cheap computer speakers with built-in amplifiers
have some amount of audible hiss. Goes with the territory.

1. Speakers emit buzz/hum whenever they are plugged into
AC and are turned on. You can also faintly hear a radio station
or other music. This buzz/hum does not change with volume
adjustment, nor does being connected to my computer's
soundcard affect it. In fact, I plugged them into the AC outlet
in my kitchen and found the exact same noise.

This is what makes me think something may be wrong with
your power mains wiring. Have it checked by a quallified
(licensed) electrician.

Playing with the wires' orientation does affect the noise
somewhat.

Are you SURE that you are using the proper SHIELDED
wires?

2. When I tried them at my neighbour's house, the buzz/hum
was NOT present..

Again, another symptom that points to a systemic problem in
your house wiring that is not present in your neighbor's house.

3. When I try them in my unfinished basement (plugs are near
the main wiring panel), the buzz/hum was also NOT present.

Could be because...
a) These plugs are wired properly ("after-market" improvement?)
b) You are more shielded from the nearby transmitter.

4. Using a ferrite bead/core which I stole off a modem line
that came with my laptop, had almost no effect.

Depends on where you put it (power lead, signal leads, etc.),
and depends on what is design characteristics are. Most likely
designed to "snub" sharp wavefronts from digital signals, not
to surpress 60Hz hum (or broadcast radio waves).

5. I do have an APC surge suppressor, but it's a fairly cheap
one that I don't think does much noise filtering.

Not clear whether any of these tests were WITH or WITHOUT
this surge surpressor. Does in/out make any difference?

At first I suspected a 'ground loop' problem but I don't think
it's that because it happens when my speakers are attached
to nothing except AC power.

Good observation. I would agree. (Assuming you have the proper
*shielded* audio wires going to the input of the speaker amp).

I still suspect noise in my electrical lines, which goes away
in the basement because so close to the main house wiring &
ground?

I would suspect bad mains grounding rather than noise (or causing
the noise).

I also suspect Radio Interference, as there is a radio tower nearby.
This would explain the music heard in the background, and going
to the basement (below ground) might offer some shielding.

Are you getting increased interference in any other equipment?
Phones, radio, TV, cable, etc? In the US, the people transmitting
are obligated to help you eliminate any RFI. Dunno if it is the
same in Canadia?

Although it doesn't explain why the problem doesn't exist at
my next-door neighbour's house.

Did they EVER have a similar problem? Did they already solve
the same problems you are now seeing? Where are they relative
to the transmitting tower?

Sorry for the long explanation. Right now I'm thinking of
doing two things:
getting some higher quality speakers,

Don't commit yourself to buying ANYthing until you show that
it will actually WORK in your situation. You have already
proved that it is UNLIKELY to be the fault of the speaker by
trying two different speakers.

and getting a higher quality surge suppressor with at elast
70db of EMI/RFI reduction.

I wouldn't put too much hope in those things unless you can
actually show that it works in YOUR situation. They are
largely marketing gimmicks.

I'd certainly investigate the transmitting tower more before
throwing any more money at potential bandages. Who is
transmitting? Is it the same radio station whose music you
hear in the interference? have any of your neighbors had
similar problems with RFI? What is the age of your house
(specifically the wiring)? Was it inspected when you bought
it?

Hi Richard, thanks for you quick response. Sorry if I a bit lacking in audio
terms and knowledge. Some responses for you:
Playing with the wires' orientation does affect the noise
somewhat.

Are you SURE that you are using the proper SHIELDED
wires?
The ACS45 has shielded wires, playing with those wires' orientation doesn't
have any effect. The new speakers I bought (which I've sinced returned)
didn't have shielded wires; playing with those ones did affect the noise.

5. I do have an APC surge suppressor, but it's a fairly cheap
one that I don't think does much noise filtering.

Not clear whether any of these tests were WITH or WITHOUT
this surge surpressor. Does in/out make any difference?
The surge suppressor does not seem to make any difference.

I'd certainly investigate the transmitting tower more before
throwing any more money at potential bandages. Who is
transmitting? Is it the same radio station whose music you
hear in the interference? have any of your neighbors had
similar problems with RFI? What is the age of your house
(specifically the wiring)? Was it inspected when you bought
it?
I'm not sure who broadcasts through the nearby (~ 400 yards/meters) tower.
The music is faint so it's hard to tell what station it may be.
The house is less than a year old, and it was inspected by a city
electrician when built (we purchased the house from a builder).
My neighbour did mention having problems with a self-powered subwoofer
picking up what might have been RFI. He changed its location in the house
and that solved the problem. My house is between his and the tower, although
there are also umpteen houses between me and the tower.

"Mike & Kristen" wrote ...
The house is less than a year old, and it was inspected by a city
electrician when built (we purchased the house from a builder).

Doesn't mean there might still be a problem. Inspectors aren't
perfect. Especially if you bought the house new, it has no history.

Can you plug an extention cord into the basement plug
and move the speakers around (even upstairs). That would
do a differential diagnosis whether it was the plug or the
location. (And other similar differential experiments.)

My neighbour did mention having problems with a self-
powered subwoofer picking up what might have been RFI.
He changed its location in the house and that solved the
problem.

It sure sounds like you're in the "RFI Zone"

My house is between his and the tower, although
there are also umpteen houses between me and the tower.

How many of THEM have had RFI problems?

That's a good idea about the extension cord. I will give it a try.

Good news, I purchased some new speakers today (Logitech X-220) and they are
much better, hiss is not detectable unless you put your ear right to the
speaker, and no buzz or radio station! I guess you get what you pay for.

I do still plan to try and diagnose the problem with the old speakers, I
will ask more neighbours about RFI and possibly give my builder a call about
the wiring (house is under full warranty for another 2 months). The really
funny thing was I was able to determine what radio station I was picking up,
it was "VIBE 98.5" an R&B station here in Calgary.


"Richard Crowley" wrote in message
...
"Mike & Kristen" wrote ...
The house is less than a year old, and it was inspected by a city
electrician when built (we purchased the house from a builder).

Doesn't mean there might still be a problem. Inspectors aren't
perfect. Especially if you bought the house new, it has no history.

Can you plug an extention cord into the basement plug
and move the speakers around (even upstairs). That would
do a differential diagnosis whether it was the plug or the
location. (And other similar differential experiments.)

My neighbour did mention having problems with a self-
powered subwoofer picking up what might have been RFI.
He changed its location in the house and that solved the
problem.

It sure sounds like you're in the "RFI Zone"

My house is between his and the tower, although
there are also umpteen houses between me and the tower.

How many of THEM have had RFI problems?