Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!

Pinot Grigio pinotgrigio@somewhere wrote:
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.

Entirely normal.
Most likely poor quality speakers.

I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!

This is due to your amplifier not having a capacitor blocking high frequency
noise from other noisy appliuances connected to the same ring main.


There is no easy answer to this it can often happen with fridges also.

The best place to start is with your hifi.

Regards

Jim

"Pinot Grigio" pinotgrigio@somewhere wrote in message
...
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!

On 26 Aug 2004 21:06:52 GMT, Ian Stirling
wrote:

Pinot Grigio pinotgrigio@somewhere wrote:
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.

Entirely normal.
Most likely poor quality speakers.

I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!


That's strange, that a spike is getting through your UPS to the PC.
Maybe a cheap UPS.

You do have a UPS (or even a mains filter) on the mains to your PC,
don't you?

Actually, I think I already know the answer to that one, hehe!

Please add the following costs:-
New PC = £
Several hours of your time = £
Loss of all that data you meant to back up but didn't = £

Now compare to :-
New UPS cost = £60 to £100

Never ceases to amaze me that people don't use them.

Still, I have my hat, some mayo and a little salt ready and waiting to
be eaten if the OP tells me that the PC (and speakers) are fed from a
UPS.

Rob


Replace 'spam' with 'org' to reply

vivienne wykes wrote:
This is due to your amplifier not having a capacitor blocking high frequency
noise from other noisy appliuances connected to the same ring main.


There is no easy answer to this it can often happen with fridges also.

The best place to start is with your hifi.

???

How is starting with the hifi going to help his clicking PC speakers?


--
Grunff

In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)
--
Tony Sayer

In message , Pinot
Grigio writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!

It may be the switch contacts are "dirty"

It also depends on at which point in the mains cycle you are switching

you might have inadequate rf filtering somewhere

Personally, I'd learn to live with it

--
geoff

That's strange, that a spike is getting through your UPS to the PC.
Maybe a cheap UPS.

You do have a UPS (or even a mains filter) on the mains to your PC,
don't you?

Actually, I think I already know the answer to that one, hehe!

Please add the following costs:-
New PC = £
Several hours of your time = £
Loss of all that data you meant to back up but didn't = £

Now compare to :-
New UPS cost = £60 to £100

Never ceases to amaze me that people don't use them.


Where the hell did a UPS come into it?

Cheap speakers, poor filtering, bad cable management.

nuff said

I missread the PC bit thought it was a hifi problem.
As others have said it is high frequency "noise" causing the problem could
try a plug in mains filter although.......maybe not worth the cash..

V
"vivienne wykes" wrote in message
. uk...
This is due to your amplifier not having a capacitor blocking high
frequency
noise from other noisy appliuances connected to the same ring main.


There is no easy answer to this it can often happen with fridges also.

The best place to start is with your hifi.

Regards

Jim

"Pinot Grigio" pinotgrigio@somewhere wrote in message
...
Whenever we turn a light on or off, an electrical sound can be heard
from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!

In message , tony sayer
writes
In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)


Shock horror

--
geoff

Mike Odd wrote:

Cheap speakers, poor filtering, bad cable management.

nuff said

What about a new light switch?
carbon build up on contacts could be making problem worse.
At a guess.

--
http://gymratz.co.uk
The Worlds best Gym & Fitness Equipment Supplier!
http://fitness-equipment-uk.net
Up to 1/3rd cheaper than Argos & John Lewis !!

"Kalico" wrote in message
...
....
That's strange, that a spike is getting through your UPS to the PC.
Maybe a cheap UPS.

You do have a UPS (or even a mains filter) on the mains to your PC,
don't you?

Actually, I think I already know the answer to that one, hehe!

Please add the following costs:-
New PC = £
Several hours of your time = £
Loss of all that data you meant to back up but didn't = £

Now compare to :-
New UPS cost = £60 to £100

Never ceases to amaze me that people don't use them.

Many people who do use them never bother to test whether they will actually
work when the mains fails.

Colin Bignell

???

How is starting with the hifi going to help his clicking PC speakers?

If he turns it up enough, it will drown out the clicking.

Dave

--

Some people use windows, others have a life.

Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)

Thats the time to worry, when ' experts' tell you not to worry g.

Dave

--

Some people use windows, others have a life.

"tony sayer" wrote in message
...
In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)
--
Tony Sayer


I would have thought that the 'problem' is an amplifier one rather than
speakers.

"Kalico" wrote in message
...
On 26 Aug 2004 21:06:52 GMT, Ian Stirling
wrote:

Pinot Grigio pinotgrigio@somewhere wrote:
Whenever we turn a light on or off, an electrical sound can be heard
from
the PC speakers.

Entirely normal.
Most likely poor quality speakers.

I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!


That's strange, that a spike is getting through your UPS to the PC.
Maybe a cheap UPS.

You do have a UPS (or even a mains filter) on the mains to your PC,
don't you?

Actually, I think I already know the answer to that one, hehe!

Please add the following costs:-
New PC = £
Several hours of your time = £
Loss of all that data you meant to back up but didn't = £

Now compare to :-
New UPS cost = £60 to £100

Never ceases to amaze me that people don't use them.

Still, I have my hat, some mayo and a little salt ready and waiting to
be eaten if the OP tells me that the PC (and speakers) are fed from a
UPS.

Rob


Replace 'spam' with 'org' to reply

Even if he *did* have a UPS, there is no need to run speakers from it. As a
general rule, you want to put the minimum of equipment on a UPS to maximise
the run time when on batteries.
Also, many UPSs don't filter the mains much, JUST provide backup power when
the mains goes out. You have to get a decent UPS for this feature.

Also, UPSs are NOT a replacement for backups. Even with a top-of-the-range
UPS your hard drive can still fail and lose all your data.

Alan.

Handy Andy wrote:

"tony sayer" wrote in message
...
In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)
--
Tony Sayer


I would have thought that the 'problem' is an amplifier one rather than
speakers.

True. Talking about "speakers" is misleading, because the problem is
definitely not in the loudspeakers themselves, but most probably in the
amplifiers (a stereo pair) that drive them, and/or their power supply.

However, before running away down that path, we need to take a step
back, and ask the OP:

* Does any other audio device in the house (TV, mains-powered radio,
hi-fi) show the same problem when you switch things on and off? Do the
lights flicker?

If not, it's highly unlikely to be a major fault in your mains wiring.

Small disturbances on the mains are normal, whenever you switch anything
on and off. What seems to be abnormal is that your amp/speakers are very
sensitive to them.

Assuming the answer to the first set of questions was No, then try to
narrow it down further.

* Borrow a completely different set of speaker/amps and power supply
from another PC. Is the problem still there, or is it specific to your
set?

* Aside from the specific problem you reported, is the audio background
dead quiet, hum-free and undistorted? Or is the sensitivity to mains
switching part of a wider problem?

There are two connections to the speaker/amps system: the mains power
supply and the audio input from the PC. The electrical noise could be
getting in either way, so:

* Unplug the audio input lead from the PC. If the problem is still
there, the interference is coming in through the power supply.

* If the problem goes away when you unplug the audio lead, it could be
either at the PC end, in the lead or its connectors, or the amplifier
end (though I'd bet on the last two).

Given the answers to these questions, several people here might be able
to help you further.


--
Ian White
Abingdon, England

On Fri, 27 Aug 2004 08:25:54 GMT, "Alan"
wrote:
[snip]

Even if he *did* have a UPS, there is no need to run speakers from it. As a
general rule, you want to put the minimum of equipment on a UPS to maximise
the run time when on batteries.
Also, many UPSs don't filter the mains much, JUST provide backup power when
the mains goes out. You have to get a decent UPS for this feature.

Also, UPSs are NOT a replacement for backups. Even with a top-of-the-range
UPS your hard drive can still fail and lose all your data.

Alan.

I agree Alan. No need at all to run speakers through the UPS
although, unless they are meaty speakers, their current drain would be
minimal.

A UPS that doesn't filter the mains is not much use as to my mind any
good quality unit will do this. I also agree that a UPS is not a
replacement for a backup. But, many people do not backup as often as
they ought and I was envising the (increasingly common) problem of
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.
Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Replace 'spam' with 'org' to reply

On Fri, 27 Aug 2004 08:25:54 GMT, "Alan"
wrote:
[snip]

Even if he *did* have a UPS, there is no need to run speakers from it. As a
general rule, you want to put the minimum of equipment on a UPS to maximise
the run time when on batteries.
Also, many UPSs don't filter the mains much, JUST provide backup power when
the mains goes out. You have to get a decent UPS for this feature.

Also, UPSs are NOT a replacement for backups. Even with a top-of-the-range
UPS your hard drive can still fail and lose all your data.

Alan.

I agree Alan. No need at all to run speakers through the UPS
although, unless they are meaty speakers, their current drain would be
minimal.

A UPS that doesn't filter the mains is not much use as to my mind any
good quality unit will do this. I also agree that a UPS is not a
replacement for a backup. But, many people do not backup as often as
they ought and I was envising the (increasingly common) problem of
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.
Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Replace 'spam' with 'org' to reply

In uk.d-i-y, Kalico wrote:

............. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.
Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Umm, this sounds like spectacular component failure of something storing
rather more energy than yer average (or even two-standard-deviations-above
average!) mains spike carries - maybe your PC/server supplier had a
dodgy batch of hefty electrolytics, *and* had them mounted - unusually -
direct on the board rather than enclosed in a bought-in power supply? Or
maybe you had a lot of lightning strikes in your part of the world? Not to
belittle the value of UPSen - my home machines and their less power-hungry
peripherals typically sit behind one, as much for the convenience of a
single power button to turn off all the little bits of kit as for the
power conditioning and keep-goingness of the UPS - but the type of failure
you mention is atypical, and unlikely to have been prevented by a
(consumer-grade) UPS...

Stefek

In article , Handy Andy
bodgityourself.net@?.? writes

"tony sayer" wrote in message
...
In article , Pinot
Grigio pinotgrigio@somewhere.? writes
Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!


Don't worry about it. PC speakers are of such **** poor quality they
respond to anything like the slightest amount of RF energy. Trust me I'm
a radio comms engineer)
--
Tony Sayer


I would have thought that the 'problem' is an amplifier one rather than
speakers.



It works like this. The chip amp that is in the PC speakers more often
than not responds to frequencies way beyond the audio spectrum and
usually well into the radio spectrum. The speaker leads act as aerials
and bring all manner of RF "noise" back into the amp unit in the PC
speakers where it gets demodulated and then presents as audio, hence the
noise.

You may well find that same thing happens if you use your mobile phone
close to them as well. You may well have noticed this effect if your
mobile rings when using your land based phone which is about as bad for
picking up RF "rubbish".

The Yamaha ones on my PC right in front of me now are quite good for
this sort of thing......
--
Tony Sayer

"Dave Plowman (News)" wrote in message ...
In article ,
Pinot Grigio pinotgrigio@somewhere wrote:
Whenever we turn a light on or off, an electrical sound can be heard
from the PC speakers. I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be
the lighting circuit? I suspect the answer is that it could be anywhere
but just thought I'd ask!

Are the speakers driven off a separate amplifier fed from the mains?

Is it all lights or just one and if its one is it a flourescent light.
These can often cause arcing at the switch contact, ruin the switch
and then generate lots of RF energy that will probably be picked up by
the amplifier/speakers

Kalico wrote:
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.

Well in 30 years or so of working with computers I've never ever seen
that. I've seen the odd, single, fried component but that's all.

Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Hmm, they'd have to be ***** big spikes to have the effect of "literally
half of the components had blown off the motherboard and other cards".
A direct lightning strike could have that sort of effect but they're
pretty rare.

We had a very severe over voltage at our previous house, it was due to
a failed neutral at the sub-station. It blew a few lamp bulbs and
the microwave. The only effect on the (several) PCs in our house was
to make two of the switched mode power supplies fail, neither failed
spectacularly, the just died quietly and silently.

You have to do something really serious to get any sort of damaging
overvoltage through a PC power supply, it will die itself before
anything of great consequence gets beyond it.

--
Chris Green

On 27 Aug 2004 12:18:28 GMT, wrote:

Kalico wrote:
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.

Well in 30 years or so of working with computers I've never ever seen
that. I've seen the odd, single, fried component but that's all.

Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Hmm, they'd have to be ***** big spikes to have the effect of "literally
half of the components had blown off the motherboard and other cards".
A direct lightning strike could have that sort of effect but they're
pretty rare.

We had a very severe over voltage at our previous house, it was due to
a failed neutral at the sub-station. It blew a few lamp bulbs and
the microwave. The only effect on the (several) PCs in our house was
to make two of the switched mode power supplies fail, neither failed
spectacularly, the just died quietly and silently.

You have to do something really serious to get any sort of damaging
overvoltage through a PC power supply, it will die itself before
anything of great consequence gets beyond it.

Well, I guess you are right because the ones I saw were all at the
same site of a very large factory with some pretty heavy machinary and
furnaces working 24/7. I have to say I was amazed to see it, but the
cases were like rattles with all the bits at the bottom of them.


Replace 'spam' with 'org' to reply

"Kalico" wrote in message
...
....
Well, I guess you are right because the ones I saw were all at the
same site of a very large factory with some pretty heavy machinary and
furnaces working 24/7. ...

I would also think it likely that they had some heavy duty arc welding
equipment.

Colin Bignell

wrote in message ...
Kalico wrote:
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.

Well in 30 years or so of working with computers I've never ever seen
that. I've seen the odd, single, fried component but that's all.

Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Hmm, they'd have to be ***** big spikes to have the effect of "literally
half of the components had blown off the motherboard and other cards".
A direct lightning strike could have that sort of effect but they're
pretty rare.

We had a very severe over voltage at our previous house, it was due to
a failed neutral at the sub-station. It blew a few lamp bulbs and
the microwave. The only effect on the (several) PCs in our house was
to make two of the switched mode power supplies fail, neither failed
spectacularly, the just died quietly and silently.

You have to do something really serious to get any sort of damaging
overvoltage through a PC power supply, it will die itself before
anything of great consequence gets beyond it.

--
Chris Green

There has been an issue with certain cheap low esr electrolitics, that
wern't and boiling, this could explain your server melt down

Never saw that myself when I was doing PC support. Not sure what value a
UPS alone is if you're backing up. Cost of UPS vs. cost of components
broken by spike vs. likelyhood of said spike occuring over the lifetime of
components.

As I remember UPS's never tended to be too reliable - lot's of expensive
battery problems.



"Kalico" wrote in message
...
On Fri, 27 Aug 2004 08:25:54 GMT, "Alan"
wrote:
[snip]

Even if he *did* have a UPS, there is no need to run speakers from it. As
a
general rule, you want to put the minimum of equipment on a UPS to
maximise
the run time when on batteries.
Also, many UPSs don't filter the mains much, JUST provide backup power
when
the mains goes out. You have to get a decent UPS for this feature.

Also, UPSs are NOT a replacement for backups. Even with a
top-of-the-range
UPS your hard drive can still fail and lose all your data.

Alan.

I agree Alan. No need at all to run speakers through the UPS
although, unless they are meaty speakers, their current drain would be
minimal.

A UPS that doesn't filter the mains is not much use as to my mind any
good quality unit will do this. I also agree that a UPS is not a
replacement for a backup. But, many people do not backup as often as
they ought and I was envising the (increasingly common) problem of
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.
Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Replace 'spam' with 'org' to reply

Pinot Grigio wrote:

Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.

Even when off?

I assume we have a faulty connection somewhere.

I wouldn't.

Any suggestion as to the best place to start.

Decemt PC speakers?


Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd ask!


Try a new light switch, a mains filter on the speakers or new speakers.

vivienne wykes wrote:

This is due to your amplifier not having a capacitor blocking high frequency
noise from other noisy appliuances connected to the same ring main.

capacitors conduct high frequencies, not block them....


There is no easy answer to this it can often happen with fridges also.

The best place to start is with your hifi.

Regards

Jim

"Pinot Grigio" pinotgrigio@somewhere wrote in message
...

Whenever we turn a light on or off, an electrical sound can be heard from
the PC speakers.
I assume we have a faulty connection somewhere.
Any suggestion as to the best place to start. Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd

ask!

"Kalico" wrote in message
...
On Fri, 27 Aug 2004 08:25:54 GMT, "Alan"
wrote:
[snip]

Even if he *did* have a UPS, there is no need to run speakers from it. As
a
general rule, you want to put the minimum of equipment on a UPS to
maximise
the run time when on batteries.
Also, many UPSs don't filter the mains much, JUST provide backup power
when
the mains goes out. You have to get a decent UPS for this feature.

Also, UPSs are NOT a replacement for backups. Even with a
top-of-the-range
UPS your hard drive can still fail and lose all your data.

Alan.

I agree Alan. No need at all to run speakers through the UPS
although, unless they are meaty speakers, their current drain would be
minimal.

A UPS that doesn't filter the mains is not much use as to my mind any
good quality unit will do this. I also agree that a UPS is not a
replacement for a backup. But, many people do not backup as often as
they ought and I was envising the (increasingly common) problem of
mains spikes. When I worked in IT support, I was amazed by the number
of times a PC/server went belly up and on opening the case, literally
half of the components had blown off the motherboard and other cards.
Needless to say the hard drive was toasted and much of these cases
could have been avoided by the mains being filtered for spikes.

Repeated power failures can cause extensive damage- no spikes. I had a 10mA
trip in a new office that had not had computers in it before. The PC kept
tripping it and eventually the board, processor, FD and DVD drives failed. I
was blamed for using a kettle! New PC and new trip (30mA) and it's been
fine.

Peter Scott

"The Natural Philosopher" wrote in message
...
Pinot Grigio wrote:

Whenever we turn a light on or off, an electrical sound can be heard
from
the PC speakers.

Even when off?

I assume we have a faulty connection somewhere.

I wouldn't.

Any suggestion as to the best place to start.

Decemt PC speakers?


Is it more likely to be the
lighting circuit?
I suspect the answer is that it could be anywhere but just thought I'd
ask!
You can get small ferrite rings to reduce spikes and HF interference. You
thread the signal cable through the ring a few times. As someone said
earlier capacitors pass HF, so inductors block them. By winding the witres
round you make a low value inductor.

Peter Scott

Peter Scott wrote:
You can get small ferrite rings to reduce spikes and HF interference.
You thread the signal cable through the ring a few times. As someone
said earlier capacitors pass HF, so inductors block them. By winding
the witres round you make a low value inductor.

Certainly you can, but that isn't an appropriate response to the OP's
problem.

Normal mains wiring and normal PC sound systems don't have that problem,
so what the OP has is a definite *fault*. What you do with faults is
find them, and then fix them.

There is a place for added ferrite rings and such (and I know it well) -
but that place is not here.


--
Ian White
Abingdon, England

In article ,
Ian White wrote:
Certainly you can, but that isn't an appropriate response to the OP's
problem.

Normal mains wiring and normal PC sound systems don't have that problem,
so what the OP has is a definite *fault*. What you do with faults is
find them, and then fix them.

Most external PC sound systems use an external amp too - and this is far
more likely to be the source of the problem through an inadequately
filtered power supply. PCs themselves generally have a well filtered PS
for obvious reasons.

--
*I love cats...they taste just like chicken.

Dave Plowman London SW
To e-mail, change noise into sound.

Ian White wrote:
Peter Scott wrote:
You can get small ferrite rings to reduce spikes and HF interference.
You thread the signal cable through the ring a few times. As someone
said earlier capacitors pass HF, so inductors block them. By winding
the witres round you make a low value inductor.

Certainly you can, but that isn't an appropriate response to the OP's
problem.

Normal mains wiring and normal PC sound systems don't have that problem,
so what the OP has is a definite *fault*. What you do with faults is
find them, and then fix them.

Out of 3 systems I know of, 2 do.

The problem is a design one. Almost all suggestions have been right
off track. Theres nothing you can do about it unless you mod the
design on the audio side, or buy some decent kit.

This is uk.d-i-y not sci.electronics.

Regards, NT

In article ,
N. Thornton wrote:
The problem is a design one. Almost all suggestions have been right
off track. Theres nothing you can do about it unless you mod the
design on the audio side, or buy some decent kit.

You can buy plug in mains filters.

This is uk.d-i-y not sci.electronics.

It would be sad to exclude simple electronics.

However, it would help the the OP actually read the replies and answered
the points arising.

If the same thing happens when using headphones direct from the
computer, then I doubt external filtering on its supply will help. But
if it stops, then the fault lies with the external sound system.

--
*I went to school to become a wit, only got halfway through.

Dave Plowman London SW
To e-mail, change noise into sound.

James Salisbury wrote:

wrote in message ...

You have to do something really serious to get any sort of damaging
overvoltage through a PC power supply, it will die itself before
anything of great consequence gets beyond it.

--
Chris Green

There has been an issue with certain cheap low esr electrolitics, that
wern't and boiling, this could explain your server melt down

Can you say that in English please!

--
Chris Green

In message , writes
James Salisbury wrote:

wrote in message ...

You have to do something really serious to get any sort of damaging
overvoltage through a PC power supply, it will die itself before
anything of great consequence gets beyond it.

--
Chris Green

There has been an issue with certain cheap low esr electrolitics,

I think he meant low ESR electrolytics which didn't have a low ESR, as
for the boiling, he's probably talking about the cup of tea required to
enhance the effect of the sharp intake of breath

that
wern't and boiling, this could explain your server melt down

Can you say that in English please!


--
geoff

Dave Plowman (News) wrote:
In article ,
N. Thornton wrote:
The problem is a design one. Almost all suggestions have been right
off track. Theres nothing you can do about it unless you mod the
design on the audio side, or buy some decent kit.

You can buy plug in mains filters.

This is uk.d-i-y not sci.electronics.

It would be sad to exclude simple electronics.

However, it would help the the OP actually read the replies and
answered the points arising.

If the same thing happens when using headphones direct from the
computer, then I doubt external filtering on its supply will help. But
if it stops, then the fault lies with the external sound system.

I get exactly the same on my computer speakers, it's especially evident
when the humidistat fan in the bathroom spends 20 seconds or so deciding
whether or not to switch off.

If I put my hand near, or touch, the very thin (2mm maybe) signal cable
which takes the audio from PC to speakers while this is happening, then
the effect stops. If I remove the signal cable from the speakers, the
effect stops.

The cable is basically acting as an aerial!

I keep meaning to either replace the cable with one with better quality
screening, or maybe put a ferrite core on it. But it's not a major
problem.