[Paul[_12_]]

I live in an apartment in Washington, DC. I've been here for 9 years,
and never had this problem until a couple of months ago. Often times,
when i turn on/off a light switch or the vacuum, i will hear a loud
"POP" eminate from my home theater and/or computer speakers. It does
not happen every time i flip a switch. Only about half of the time. I
also notice it when maintenance plugs in their vacuum cleaner in the
hallway (the a/c outlet is right outside my door). Once the
appliance has been turned on, i notice no buzzing or interference.
It's only the initial turn-on/off that makes the speakers pop.

1. Can this problem damage my equipment in any way (speakers, amp,
computer)?
2. Is there anything i can do about it?

Since i live in an apartment, i can't go playing with their wiring. I
would imagine the only thing i can do is some sort of stop-gap
measure. I have surge protectors in use on all my computer & home
theater equipment. What about line conditioners, or voltage
stabilizers? I know Monster Cables make things that cost up to $1000
or more for "cleaning dirty power" (whatever that means).

I know a good deal about home theater stuff, but not the greatest
knowledge about electrical basics. So, please be gentle. But any
advice or counsel would be greatly appreciated. Thanks.

[Ethan Winer]

Paul,

when i turn on/off a light switch or the vacuum, i will hear a loud "POP"
eminate from my home theater and/or computer speakers.

I agree with Bob to verify your wiring. Then if the wiring is good, buy or
build an RFI filter as described he

http://www.ethanwiner.com/dimmers.html

--Ethan

[Richard Crowley]

"Paul" wrote ...
I live in an apartment in Washington, DC. I've been
here for 9 years, and never had this problem until a
couple of months ago.

Has anything changed? Have you replaced incandescent
lamps with CFL (or other such changes or "improvements"?)
Are the maintenance people using a new/different kind of
vacuum cleaner, etc? Is the FBI bugging one of your
neighbors?

Or maybe what has changed is that a power wiring joint is
getting loose. (Like where the branch circuit connects to the
curcuit beaker, etc.) This was a big problem with buildings
from the era where they were using aluminum wiring.

1. Can this problem damage my equipment in any way
(speakers, amp, computer)?

Yes, if you have your amplifier turned up loud enough for
the transient spike to damage the speaker. No way of
guessing whether it might be harmful to your computer
without making some measurements.

2. Is there anything i can do about it?

As Mr. Morein and Mr. Winer have suggested, evaluation
and filtering are likely solutions.

Since i live in an apartment, i can't go playing with their
wiring.

But if some power wiring joints are coming loose, they are a
potential fire hazard. "Blowing the whistle" may keep your
building from burning down.

I would imagine the only thing i can do is some sort
of stop-gap measure.

I would feel much more comfortable discovering what
changed to cause the problem to start after years of
quiet.

I have surge protectors in use on all my computer & home
theater equipment. What about line conditioners, or voltage
stabilizers?

Your "surge protectors" may provide some minimal
protection, but they are not "fliters" in any meaningful
way. Simple transients such as you seem to be describing
may be handled with a good filter and not require the
"bigger-guns" such as line conditioners or stabilizers.

I know Monster Cables make things that cost up to $1000
or more for "cleaning dirty power" (whatever that means).

It means they make a lot of money at your expense.
I'm not sure I would use that junk even if you gave it
to me for free.

[Paul[_12_]]

Well, as far as what has changed, i can't say that i know anything has
changed, in terms of wiring. The building was built back in the '50s,
and their attitude about this building seems to be "If it hasn't
caused a flood or fire, then it MUST be fine." I live in a very nice
neighborhood, too.

As for the vacuum cleaner, i think it's about as old as the building.

My equipment has been upgraded over the 9 years, but i don't think
i've really acquired MORE equipment, just better equipment.

Since the problems only occurs about half the time, perhaps it's when
more people are using their own equipment. Maybe the times when the
problem is occurring is when more people are using more electricity.
About half of the residents in this building are transients...meaning,
they live here for 2 or 3 years after college/grad school, then move
on. So, perhaps each new tenant that moves out (or dies) brings a
new, younger tenant with more gizmos to eat up my juice. Would that
make sense?

My lighting situation hasn't changed. I should have explained that i
never got any pops when i would turn on my normal incandescent lamps.
(Although my dad has switched to using those energy saver bulbs in his
house, i don't really like the strange dim glow they give off. I'm
still using incandescents.) It is only when i would use the wall
switch to turn on those crappy overhead fluorescent lights that are in
the closet, bathroom, kitchen, etc. Perhaps those take a bigger drain
on power.

I will go to the hardware store and get an outlet tester, and see what
happens.

Thanks everyone for your responses. Hopefully, i'll be able to figure
this out.

Paul

[w_tom]

On Dec 8, 4:43 pm, Paul wrote:
Well, as far as what has changed, i can't say that i know anything has
changed, in terms of wiring. The building was built back in the '50s,
and their attitude about this building seems to be "If it hasn't
caused a flood or fire, then it MUST be fine." I live in a very nice
neighborhood, too.

As for the vacuum cleaner, i think it's about as old as the building.

My equipment has been upgraded over the 9 years, but i don't think
i've really acquired MORE equipment, just better equipment. ...

First, none of your replies address the problem.

Second, building wiring is not relevant here. The surge protector
claims to do what? Read its spec numbers. It claims to do nothing
you are asking. Monster Cable is for the many who know by only
spending money. A $1000 part from Monster Cable, based upon how
Monster does pricing, is sold by others at a profit for maybe $75.
Everything from Monster Cable is for consumers who somehow want to fix
things without even knowing the problem. Spend massive bucks on
things that do not even claim to eliminate noise or the typically
destructive surge? Richard Crowley is partially right. Monster does
not claim to eliminate noise and they don't claim to protect from
surges that typically cause electronics damage. Monster Cable example
applies to how one would solve this problem - through money at it.

Instead, back up. First learn. All appliances create noise when
powered off. And all better equipment has internal circuits that make
noise and surges irrelevant. You stated something about upgrading to
better equipment. Is it? Is it better only because it was more
expensive - ie products from Monster Cable? Does newest equipment
have inferior noise and surge suppression circuits?

The problem is with your equipment - either internal circuits or how
the equipment is interconnected. Some standard procedures used to
avoid such problems include single point chassis grounds, powering
everything from a common source, and how signaling is interconnected.

Long before trying to fix anything, first identify the problem. For
example, first setup the vacuum so that is can reproduce the problem
consistently. And yes, due to reasons electrical (where on a sine
wave that the switch opens), then sometimes it will and will not
create larger noise spikes. But first make the vacuum (or other
device) noise generation reproducible. Then strip your system down to
determine what (when eliminated) does not suffer from noise. Remove
one item. Then test. Reconnect that item. Remove another item.
Then test. Experiment long before trying to solve anything.

Then test again from the other side. For example, with only
amplifier and speakers, and with volume up high, then is noise
heard? Add one peripheral and test again. What peripherals makes no
noise when disconnected AND makes noise when connected (no other
wiring changes made)?

Learn what the problem is; where it resides; what component has such
bad filtering as to carry spikes into the system. Don't even think
for one minute about solving anything. Always identify all problem(s)
first. Do fixes later. It could be a problem due to to component
combinations. Or multiple components each could be letting noise in.

As another noted, Monster Cable lives fat and happy on the naive who
assume more money means better or who always want to solve problems
with 'magic' boxes such as surge protectors.

Normally, if one appliance causes noise, then the reason for that
noise is solved inside the appliance. But you detect noise from
anything including the hall vacumm that is definitely powered on
another circuit. Therefore your stereo system does not or no longer
has standard filtering that makes noise and spikes irrelevant. But
again, how do you know the newer components are better? Where are the
manufacture spec numbers that say so?

Reason why you must not touch building wiring? Well what might you
do? Fix the wiring without having first identified the problem?
Building wiring (and that silly three light tester recommended by
another) is not a solution. Typically there is no problem with wiring
even from the 1950s - except when some human creates problems by
trying to fix things. Wiring does not create problems by being old.
It creates problems by being repaired by one who would fix things
without first learning what the problem is.

Ignore nonsense so often assumed about old wiring. Why is your
entertainment system suddenly so compromised as to not stop the most
trivial of electrical noise? That is your question. What has the
human changed? And why does the human know the new equipment is
'better'? Price? That naivity is why Monster Cable can sell a $50
item for $1000.

Long before trying to fix anything, first, identify the problem.
Your post says you are seeking a solution without first identifying
the problem. Monster Cable and other surge protector manufacturers
love (profits massively from) those kind of people. People who buy
solutions to problems that were not first identified is a market ripe
for scams.

[Chronic Philharmonic]

"Paul" wrote in message
...
I live in an apartment in Washington, DC. I've been here for 9 years,
and never had this problem until a couple of months ago. Often times,
when i turn on/off a light switch or the vacuum, i will hear a loud
"POP" eminate from my home theater and/or computer speakers. It does
not happen every time i flip a switch. Only about half of the time. I
also notice it when maintenance plugs in their vacuum cleaner in the
hallway (the a/c outlet is right outside my door). Once the
appliance has been turned on, i notice no buzzing or interference.
It's only the initial turn-on/off that makes the speakers pop.

Power supplies are normally designed to keep the noise from coming in
through the line cord (regulation and filtering do that, if they're working
right, and most equipment won't work at all if they're not). Do you get a
pop when you turn off your home theater? - Turning off the power is about
the biggest transient you could get.

1. Can this problem damage my equipment in any way (speakers, amp,
computer)?

Probably only if you got angry enough to start hitting it with a baseball
bat.

2. Is there anything i can do about it?

You should try to arrange it so that your entire entertainment system is
powered from the same outlet, assuming it doesn't overload the circuit.
Otherwise, you might need to look at the possibility of audio isolation
transformers in the audio lines running between equipment powered from
different circuits. They help reject common-mode noise and prevent current
from flowing in the ground leads. They range in price and quality. See
http://docs.info.apple.com/article.html?artnum=86655. They have links to
some suppliers.

Since i live in an apartment, i can't go playing with their wiring. I
would imagine the only thing i can do is some sort of stop-gap
measure. I have surge protectors in use on all my computer & home
theater equipment. What about line conditioners, or voltage
stabilizers? I know Monster Cables make things that cost up to $1000
or more for "cleaning dirty power" (whatever that means).

IMHO, with the possible exception of an uninterruptible power supply (which
itself has limited and very specific utility), the built-in power supply
should provide all the power conditioning you could ever need.

I know a good deal about home theater stuff, but not the greatest
knowledge about electrical basics. So, please be gentle. But any
advice or counsel would be greatly appreciated. Thanks.

[Paul[_12_]]

w_tom, (this reply just for you)

i appreciate your response in trying to help me out, but you seem
awfully angry with me. I think largely, it's because you made some
completely incorrect assumptions about what i was trying to say.
Again, i do appreciate the advice, as it seems you know a lot about
electrical stuff. As stated in my original post, i don't. Which is
why i asked for advice.

You wrote to me...

----"You stated something about upgrading to better equipment. Is
it? Is it better only because it was more expensive - ie products
from Monster Cable? Does newest equipment have inferior noise and
surge suppression circuits."

If i read you correctly, you're assuming i upgraded equipment to try
to solve my problem. On the contrary, i was responding to another
poster's question. He asked me if my set-up had changed while in the
apt. As my response, i stated that over 9 years, i have upgraded
various components at various times. (as opposed to adding a host of
additional components). The kind of upgrading i mean is to a better
amp with more inputs, better sound (from component to DVI, etc), as
well as to different sounding speakers, DVD player w/more options, or
simply to replace a broken component. But that's over the course of 9
years. Saying i upgraded has NOTHING TO DO with trying to solve the
problem.

That all having been said, ALL my home theater equipment i currently
have is the same i've had for more than 2 years, and NONE of it has
changed in those last 2 years or so. Remember, the problem only
started a couple months ago.

Also, regarding Monster Cables, I simply used their brand name as an
example, stating the types of products they were selling. If you
couldn't tell by the tone of my words "whatever that means" at the end
of mentioning their products, it was meant to imply a bit of suspicion
as to their viability. Nevertheless, the point was only to say that
those types of products are out there (regardless of who makes them),
and was wondering as to what exactly they do. Besides, i'm not trying
to improve an imagined "deficiency" (which i think is what some of
those products are designed for). I'm trying to solve an actual,
audible problem.

Obviously, solving the problem comes after identifying the problem.
But i felt that was implied in the initial post. By stating what was
happening, i assumed people would know (which the rest of the
responders seemed to) that i was trying to identify the problem first.
Then, inform me of possibilities, followed by solution attempts. For
instance, once poster suggested a voltage meter. That would go toward
identifying the problem first...as you said. But, since i don't know
what's causing the problem, i was hoping to get advice on this board
from others who might be able to lead me in the right direction. If i
knew exactly what the cause of the problem was, i probably wouldn't
need as much help in solving it.

As for saying how "none of my responses had anything to do with the
problem," i'm assuming you're just not following the thread, because
all i was doing was answering questions other posters had asked
me...the vacuum thing, the age of the building, what's changed, etc).
All of that was in response to other's questions.

And as far as the vacuum in the hallway, the outlet that maintenance
plugs into IS connected to my outlet in my apartment. The one in the
hallway is directly opposite one in my apartment wall. I would assume
they are connected to the same circuit. Why wouldn't they be?
They're directly across from each other, about 4 inches apart.

The popping is so sporadic, that it's difficult to identify exactly
when. Granted, i can do as you suggest, and run a series of tests, as
for what is turned on, and which switches cause the most noise.
However, conditions of the setup are almost always the the same. I
almost always have every component on at once (tv, dvd, dvr, and
receiver). It is during those time when it randomly happens, and then
the next time, it doesn't. Sooooooo...that begs the question Tom.
Are you suggesting that part of my equipment is broken, and not
functioning as it had before the problem?

[w_tom]

First let's get this nonsense out of the way. Any peceived tone is
only an assumption. If I was angry, then I would say so. Did I? No.
It's not posted. Then it does not exist. However I am blunt about
solving problems - especially of a three light tester that will
somehow identify a noise problem.

That vacuum must be plugged into the same receptacle as your
entertainment system and still never create noise. Put that transient
into perspective. Others assumed a large transient. The numbers.
Large as in single digit volts. 120 volts spikes to 125 volts and
causes a loud pop? Is one component of the system designed
defectively OR are multiple components somehow improperly connected?

The popping is so sporadic, that it's difficult to identify
exactly when.
Nothing new when solving noise problems. Making a rare noise
repeatable is essential and often difficult. Noise from an appliance
is somehow carried electrically into your system. Which is the
incoming and which is the outgoing wire (both are required for noise
to exist)? A spike that the power supply for every component should
eliminate. A spike so small as to be called noise. Is the noise
being carried into your system via the safety ground wire (as GregS
mentions)? Safety ground bypasses the power supply and filtering. But
then what is the outgoing electrical path? Again, this is why the
problem must be repeatable so that is can be traced to a component or
a unique interconnection of components.

In testing, remember some concepts. Signal grounds are not same as
the safety ground even though both may be connected. Only signal
ground should interconnect components. Chassis (safety) ground may
interconnect chassis. But must remain separate from signal grounds.
Another example to better understand what testing must discover - or
why that testing must be meticulous about what and when anything is
disconnected or changed.

Why does noise happen one time and not another? AC sine wave
repeats every 16 milliseconds. At what point during that sine wave
does a disconnect occur? If switch opens at the right time, then
noise is created. When not, no noise. So your testing device may
only create one spike every (what) five power offs. Tedious? Of
course. EMC testing may be tedious.

Monster Cable was cited as an example of a 'magic box' solution.
Monster Cable is selling the same solution as in other lower price
'magic boxes'. For example, assume the hall vacuum creates a massive
10 volt spike on 120 VAC. 120 volts plus 10 is 130 volts. The
Monster Cable protection may state 330 volts on its box. That means
doing nothing until voltage exceeds 330 volts. Where is that number
that claims a solution? Meanwhile, it connects your system directly
to AC mains with nothing between a wall receptacle and system except
the 'magic box's circuit breaker.

To actually filter noise, well, those products are available from
Brickwall, Surgex, and Zerosurge. View prices for filters that
actually do what others recommend. That assumes noise is entering on
black or white wire; not via green 'safety ground' wire. Green wire
bypasses the filtering.

This noise does not always occur. Well, that implies some filtering
is sufficient when the noise is less. Question remains whether one
component is missing sufficient filtering or whether signal
interconnections are compromising that filtering. Has something
inside your equipment failed? Maybe. But we are far from even asking
that question yet. First establish what is and is not necessary to
create (recreate) noise. Trace noise to some unique part or
combinations of parts. We know this. Component design should make
noise irrelevant.

Finally, speculated is one wiring problem, more common in newer
buildings, that creates electrical noise. Some take the easy way by
wiring wall receptacles with each wire pushed in the back rather than
wrapped around a side screw. When the plug is removed from the
receptacle, then that rear wire intermittently disconnects. Noise
created by 120 volts dropping to zero during receptacle movement.
Short power loss. No problem for lights. But a problem for
electronics that may be connected farther down that circuit. A
problem not due to old wiring. In this example, a problem directly
traceable to a human who did not wrap each wire around the receptacle
screw. One can quickly identify this unique problem by removing
receptacle cover plate - visual inspection. That wire should be
obviously wrapped around each side mount screw so that all wires
remain firmly connected.

This 'speculated' noise problem would occur when a hall vacuum power
cord is removed from the wall receptacle and when other appliances
down that circuit are drawing current. Again, is finding this problem
easy? Of course not. But that is why we find (recreate) the problem
long before solving it (ie. buying Monster Cable or other solutions).

Recently traced a problem over many months that was finally located
in a furnace system. Not even on the same circuit. Not always
reproducible. Solution found by first identifying the source or
unique configuration that makes the noise problematic. EMI/RFI
intermittent problems are often that difficult. 'Magic box' solutions
that are not expensive are usually wasted money. Many expensive
'magic boxes' (ie Monster Cable) do almost nothing - are the same
inexpensive device selling for massive profit. Stick to facts.

On Dec 10, 1:34 am, Paul wrote:
You wrote to me...

----"You stated something about upgrading to better equipment. Is
it? Is it better only because it was more expensive - ie products
from Monster Cable? Does newest equipment have inferior noise and
surge suppression circuits."

If i read you correctly, you're assuming i upgraded equipment to try
to solve my problem. On the contrary, i was responding to another
poster's question. He asked me if my set-up had changed while in the
apt. As my response, i stated that over 9 years, i have upgraded
various components at various times. (as opposed to adding a host of
additional components). The kind of upgrading i mean is to a better
amp with more inputs, better sound (from component to DVI, etc), as
well as to different sounding speakers, DVD player w/more options, or
simply to replace a broken component. But that's over the course of 9
years. Saying i upgraded has NOTHING TO DO with trying to solve the
problem.

That all having been said, ALL my home theater equipment i currently
have is the same i've had for more than 2 years, and NONE of it has
changed in those last 2 years or so. Remember, the problem only
started a couple months ago.

Also, regarding Monster Cables, I simply used their brand name as an
example, stating the types of products they were selling. If you
couldn't tell by the tone of my words "whatever that means" at the end
of mentioning their products, it was meant to imply a bit of suspicion
as to their viability. Nevertheless, the point was only to say that
those types of products are out there (regardless of who makes them),
and was wondering as to what exactly they do. Besides, i'm not trying
to improve an imagined "deficiency" (which i think is what some of
those products are designed for). I'm trying to solve an actual,
audible problem.

Obviously, solving the problem comes after identifying the problem.
But i felt that was implied in the initial post. By stating what was
happening, i assumed people would know (which the rest of the
responders seemed to) that i was trying to identify the problem first.
Then, inform me of possibilities, followed by solution attempts. For
instance, once poster suggested a voltage meter. That would go toward
identifying the problem first...as you said. But, since i don't know
what's causing the problem, i was hoping to get advice on this board
from others who might be able to lead me in the right direction. If i
knew exactly what the cause of the problem was, i probably wouldn't
need as much help in solving it.

As for saying how "none of my responses had anything to do with the
problem," i'm assuming you're just not following the thread, because
all i was doing was answering questions other posters had asked
me...the vacuum thing, the age of the building, what's changed, etc).
All of that was in response to other's questions.

And as far as the vacuum in the hallway, the outlet that maintenance
plugs into IS connected to my outlet in my apartment. The one in the
hallway is directly opposite one in my apartment wall. I would assume
they are connected to the same circuit. Why wouldn't they be?
They're directly across from each other, about 4 inches apart.

The popping is so sporadic, that it's difficult to identify exactly
when. Granted, i can do as you suggest, and run a series of tests, as
for what is turned on, and which switches cause the most noise.
However, conditions of the setup are almost always the the same. I
almost always have every component on at once (tv, dvd, dvr, and
receiver). It is during those time when it randomly happens, and then
the next time, it doesn't. Sooooooo...that begs the question Tom.
Are you suggesting that part of my equipment is broken, and not
functioning as it had before the problem?

[dizzy]

Paul wrote:

w_tom, (this reply just for you)

i appreciate your response in trying to help me out, but you seem
awfully angry with me. I think largely, it's because you made some
completely incorrect assumptions about what i was trying to say.
Again, i do appreciate the advice, as it seems you know a lot about
electrical stuff. As stated in my original post, i don't. Which is
why i asked for advice.

w_tom is a troll who, apparently, googles for "surge" issues on a
daily basis.

[Paul[_12_]]

Chronic, thanks for your thoughts. Much appreciated.

Regarding your suggestions. I already have all my home theater
components going into a single surge suppressor, which is in turn,
plugged into one outlet. My computer equipment is also plugged into
it's own surge suppressor, and then plugged into a different outlet.
So, i already have that covered.

I don't get a pop when i turn on/off my system. I used to work at a
comedy club, and whenever anyone turned off the amps there, the
speakers would always make a pop. So, i'm sure i know what you mean.
But after doing some testing, as Tom suggested, it's only happening
when i turn the overhead lights on (wall switches), or when
maintenance turns on/off the vacuum in the hallway (which plugs into
an outlet right outside my wall, opposite an outlet IN my apartment. I
assume they're connected). Remember, i get pops from my home theater
speakers AND my computer speakers.

I know once, several years ago, i blew a fuse or a circuit in my apt
(i don't remember why), and ALL the power in my apartment went out.
When i got the power back, it was one switch that turned everything
back on. I assume that means that my entire apartment is on a single
circuit. But that's just a guess.

I did test the equipment, with certain things off, but i couldn't get
it to happen every time. I had to run sporadic tests during the day,
because either it would happen over and over again in one sitting, or
not at all. The only consistency was if it happened once, it would do
it again if repeated it immediately after. If i waited a couple
hours, it may, or may not return. In fact, the problem seems to be
happening a lot less over the last few days than it had before.
Again, nothing has changed in two years, but perhaps the problem is
fixing itself. If it is, perhaps it does have to do with something
outside my control. (other tenants, etc). Then again, Tom may yell at
me again.

Thanks everyone who has given me advice.

paul

[Chronic Philharmonic]

"Paul" wrote in message
...
Chronic, thanks for your thoughts. Much appreciated.

Regarding your suggestions. I already have all my home theater
components going into a single surge suppressor, which is in turn,
plugged into one outlet. My computer equipment is also plugged into
it's own surge suppressor, and then plugged into a different outlet.
So, i already have that covered.

I guess that you have no audio connections between your computer and your
home theater.

I don't get a pop when i turn on/off my system. I used to work at a
comedy club, and whenever anyone turned off the amps there, the
speakers would always make a pop. So, i'm sure i know what you mean.
But after doing some testing, as Tom suggested, it's only happening
when i turn the overhead lights on (wall switches), or when
maintenance turns on/off the vacuum in the hallway (which plugs into
an outlet right outside my wall, opposite an outlet IN my apartment. I
assume they're connected). Remember, i get pops from my home theater
speakers AND my computer speakers.

Do they pop at the same time?

I know once, several years ago, i blew a fuse or a circuit in my apt
(i don't remember why), and ALL the power in my apartment went out.
When i got the power back, it was one switch that turned everything
back on. I assume that means that my entire apartment is on a single
circuit. But that's just a guess.

Even if every outlet is on the same circuit, it is still better to power a
system from a single outlet if possible. If not, you might have to resort to
audio isolation transformers or balanced isolation amplifiers. Professional
equipment uses balanced inputs and outputs for just this reason. In large
studios and concert venues, it is often not possible to power everything
from the same outlet.

I did test the equipment, with certain things off, but i couldn't get
it to happen every time. I had to run sporadic tests during the day,
because either it would happen over and over again in one sitting, or
not at all. The only consistency was if it happened once, it would do
it again if repeated it immediately after. If i waited a couple
hours, it may, or may not return. In fact, the problem seems to be
happening a lot less over the last few days than it had before.
Again, nothing has changed in two years, but perhaps the problem is
fixing itself. If it is, perhaps it does have to do with something
outside my control. (other tenants, etc). Then again, Tom may yell at
me again.

This is mysterious. It defies analysis, based on what I know about your
system. Do you have any wireless audio components, such as wireless
satellite speakers? Speaking of wireless, of course AM radio is extremely
susceptible to impulse noise, which is one of the reasons why it cannot be
considered a high-fidelity medium. FM is less susceptible, but not immune.

Another possible source of ground-induced noise is your cable television
connection. That includes the cable modem on your computer, if you have one.
You might try to find out if your cable provider can bond the cable to a
ground inside your apartment, or better yet, provide ground isolation. If it
doesn't degrade your signal too much, back-to-back balun transformers might
help.

Beyond that, I'm really out of suggestions.

[GregS[_3_]]

In article , Paul wrote:
I live in an apartment in Washington, DC. I've been here for 9 years,
and never had this problem until a couple of months ago. Often times,
when i turn on/off a light switch or the vacuum, i will hear a loud
"POP" eminate from my home theater and/or computer speakers. It does
not happen every time i flip a switch. Only about half of the time. I
also notice it when maintenance plugs in their vacuum cleaner in the
hallway (the a/c outlet is right outside my door). Once the
appliance has been turned on, i notice no buzzing or interference.
It's only the initial turn-on/off that makes the speakers pop.

1. Can this problem damage my equipment in any way (speakers, amp,
computer)?
2. Is there anything i can do about it?

Since i live in an apartment, i can't go playing with their wiring. I
would imagine the only thing i can do is some sort of stop-gap
measure. I have surge protectors in use on all my computer & home
theater equipment. What about line conditioners, or voltage
stabilizers? I know Monster Cables make things that cost up to $1000
or more for "cleaning dirty power" (whatever that means).

I know a good deal about home theater stuff, but not the greatest
knowledge about electrical basics. So, please be gentle. But any
advice or counsel would be greatly appreciated. Thanks.

One thing, if any of your equipment uses ground, and especially if
you have a cable hooked up, ground noise can develop. An RFI filter
does not filter ground usually. I would not recommend bypassing a 3
prong plug, but if the cable is not grounded properly, and isolator
can help regardless.

greg