I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis

Dennis wrote:
I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis
Make sure, that both your computer and your stereo are connected
to ground. The netfilter in your computer will otherwise dump a
filtercurrent along your audio path ground.

"Sjouke Burry" wrote in message
...

Make sure, that both your computer and your stereo are connected
to ground. The netfilter in your computer will otherwise dump a
filtercurrent along your audio path ground.

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

--
James T. White

Sounds like ground loop hum. Try plugging your stereo into the same outlet
or power bar as your computer and see if it goes away.


"Dennis" wrote in message
...
I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis

Dennis wrote:

I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis
If you have cable TV in any way connected to either your stereo or
computer (e.g. via a cable modem), disconnect it and see whether
the hum stops. If it does, you know the culprit.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

On 2006-01-03, Dennis wrote:
I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

what about with the computer turned off (but plugged in)?

if it's still there the noise is comiing from the cabling (called a gound
loop)

one thing that helps sometimes is to ensure that the sterio and all the
devices that are connected to it and (subwoofer, DVD player) and any devices
that are connected to them... are all connected to the same electrical outlet
(and to the same filter if any)

if that helps there's a relatively inexpensive device called a audio
isolating transformer that'll probably kill the hum and let you return the
power cabling to its original configuration.

another option would be to go with a non-conductive connection (like fibre
optic if your sterio and sound card support it)

Bye.
Jasen

In article ,
Dennis wrote:
I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Sounds like you've got a ground loop. You could try removing the screen
connection on the interconnect. Or buy a transformer designed to prevent
ground loops from a car audio place.

--
*Modulation in all things *

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

"James T. White" wrote in message
...
"Sjouke Burry" wrote in message
...

Make sure, that both your computer and your stereo are connected
to ground. The netfilter in your computer will otherwise dump a
filtercurrent along your audio path ground.

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Alan


--
James T. White

R you sure of that statement ?
"Alan Holmes" wrote in message
...


But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Alan


--
James T. White

In article ,
Alan Holmes wrote:
More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Neither. The hum you hear in the UK is actually 100 Hz.

--
*I believe five out of four people have trouble with fractions. *

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

Alan:
Gee.... what about Canada, Japan.... and other countries beside the USA that
run 60 Hz power???
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"Alan Holmes" wrote in message
...

"James T. White" wrote in message
...
"Sjouke Burry" wrote in message
...

Make sure, that both your computer and your stereo are connected
to ground. The netfilter in your computer will otherwise dump a
filtercurrent along your audio path ground.

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Alan


--
James T. White

"sofie" wrote in message
...
Alan:
Gee.... what about Canada, Japan.... and other countries beside the USA
that
run 60 Hz power???

Only backward countries use 60 Hz!(:-)

Alan

--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -



"Alan Holmes" wrote in message
...

"James T. White" wrote in message
...
"Sjouke Burry" wrote in message
...

Make sure, that both your computer and your stereo are connected
to ground. The netfilter in your computer will otherwise dump a
filtercurrent along your audio path ground.

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Alan


--
James T. White

"kip" wrote in message
.. .
R you sure of that statement ?

Not 100%, no!

Alan

"Alan Holmes" wrote in message
...


But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Alan


--
James T. White

Something you might try (although you didn't hear it from me) is completely
disconnecting the ground pin on your computer. You didn't mention what kind
of computer you're using, but if it's a laptop, grounding isn't too
essential. (In fact, having a permanently lifted [broken off, actually]
ground pin on mine has several times saved my laptop from almost certain
major damage when connected to equipment with a ground fault - a common
problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio (I
know, not the best choice, but it was sitting around...). All of the audio
I/O is via an external high-quality device, but ground loop hum was killing
me, *even though everything was plugged into the same outlet strip*.
Breaking off the computer's power supply ground pin completely solved the
problem.
--
Mark
"I prefer heaven for climate, hell for company."


"Dennis" wrote in message
...
I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis

Mark Moulding wrote:

Something you might try (although you didn't hear it from me)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In other words, you recognize what a bad idea this is.

is completely
disconnecting the ground pin on your computer. You didn't mention what kind
of computer you're using, but if it's a laptop, grounding isn't too
essential. (In fact, having a permanently lifted [broken off, actually]
ground pin on mine has several times saved my laptop from almost certain
major damage when connected to equipment with a ground fault - a common
problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio (I
know, not the best choice, but it was sitting around...). All of the audio
I/O is via an external high-quality device, but ground loop hum was killing
me, *even though everything was plugged into the same outlet strip*.
Breaking off the computer's power supply ground pin completely solved the
problem.
--
Mark
"I prefer heaven for climate, hell for company."


"Dennis" wrote in message
...

I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis






--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

CJT:
Some years ago when I was in the pro-audio installation business for an on
the road entertainment company, us installation techs would always carried
about a dozen "u-ground" 3 wire to 2 wire ground adapters in our tool boxes
so the ground could be temporarily "lifted" on various pieces of gear to
eliminate ground loops and the subsequent hum problems. (don't cut off
ground pins on the plugs of equipment) Usually the problem would originate
because remote equipment was on a different circuit from the breaker box and
was located some distance from the main head-end gear.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"CJT" wrote in message
...
Mark Moulding wrote:

Something you might try (although you didn't hear it from me)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In other words, you recognize what a bad idea this is.

is completely
disconnecting the ground pin on your computer. You didn't mention what
kind
of computer you're using, but if it's a laptop, grounding isn't too
essential. (In fact, having a permanently lifted [broken off, actually]
ground pin on mine has several times saved my laptop from almost certain
major damage when connected to equipment with a ground fault - a common
problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio (I
know, not the best choice, but it was sitting around...). All of the
audio
I/O is via an external high-quality device, but ground loop hum was
killing
me, *even though everything was plugged into the same outlet strip*.
Breaking off the computer's power supply ground pin completely solved
the
problem.
--
Mark
"I prefer heaven for climate, hell for company."


"Dennis" wrote in message
...

I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis






--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

In article ,
sofie wrote:
Some years ago when I was in the pro-audio installation business for an
on the road entertainment company, us installation techs would always
carried about a dozen "u-ground" 3 wire to 2 wire ground adapters in our
tool boxes so the ground could be temporarily "lifted" on various pieces
of gear to eliminate ground loops and the subsequent hum problems.
(don't cut off ground pins on the plugs of equipment) Usually the
problem would originate because remote equipment was on a different
circuit from the breaker box and was located some distance from the main
head-end gear.

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You
*really* shouldn't mess with safety earths.

--
*Why is a boxing ring square?

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

"Dave Plowman (News)" wrote in message

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You
*really* shouldn't mess with safety earths.
*Why is a boxing ring square?
Dave Plowman London SW
- - - - - - - - - - - - - - - -

"crikey"

exclamation UK OLD-FASHIONED INFORMAL
an expression of surprise

sofie wrote:
"Dave Plowman (News)" wrote in message

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You
*really* shouldn't mess with safety earths.
*Why is a boxing ring square?
Dave Plowman London SW

- - - - - - - - - - - - - - - -

"crikey"

exclamation UK OLD-FASHIONED INFORMAL
an expression of surprise


YIKES!

Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work "crikey"
until today.
How about up in Canada ?? Have you?
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"Ken Weitzel" wrote in message
news:RvAvf.32637$tl.7033@pd7tw3no...


sofie wrote:
"Dave Plowman (News)" wrote in message

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You
*really* shouldn't mess with safety earths.
*Why is a boxing ring square?
Dave Plowman London SW

- - - - - - - - - - - - - - - -

"crikey"

exclamation UK OLD-FASHIONED INFORMAL
an expression of surprise


YIKES!

sofie wrote:
Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work "crikey"
until today.
How about up in Canada ?? Have you?

Hi Sofie...

Been in the UK many times as well, but not in the last 20 years...
would like to once more if I can. Never heard crikey, either, neither
there or here in Canada.

My favorite expression I heard there was from someone I was doing a
bit of a job with. I made a foolish mistake, and he accused me of
"dropping a clanger"

Ken

In article ,
sofie wrote:
I have traveled the world over..... been to the UK many times on
business trips, personal vacations, etc.... but I had never heard the
work "crikey" until today. How about up in Canada ?? Have you?

It's an old expression and I was trying to be polite as a visitor to a non
UK newsgroup.

Otherwise I'd have said ******** or ****e. ;-)

--
*No sentence fragments *

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

Dave Plowman (News) wrote:

In article ,
sofie wrote:

I have traveled the world over..... been to the UK many times on
business trips, personal vacations, etc.... but I had never heard the
work "crikey" until today. How about up in Canada ?? Have you?


It's an old expression and I was trying to be polite as a visitor to a non
UK newsgroup.

Otherwise I'd have said ******** or ****e. ;-)

FWIW, I've heard crikey used in the U.S. many times (but I don't recall
hearing it in the U.K. during the year +/- I lived there). Perhaps it's
a regional thing.

--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

I knew that would raise some rabble. Yes, of course I recognize the
potential (so to speak) problems with opening the safety ground connection.
However, a few interesting points exist in this particular situation:

- The device is a laptop, and there is no direct connection from the ground
pin through the (double-insulated) AC adapter/charger to the laptop chassis,
so it's really not much of a "safety" ground.

- There are two small value (10 nF) caps from each side of the power line to
the ground terminal inside the adapter, presumably as an RFI suppression
measure.

- All of the audio equipment involved was plugged into the *same* outlet
strip - it seems highly unlikely that there'd be much of ground loop within
the 6" or so of 16 gauge wire separating the plugs

- Finally (and this is really no excuse), my house is old enough that I'm
not convinced that all of the three prong outlets have their ground pin
connected to anything at all. It's not so old that it's knob-and-tube, but
the outlets were originally two prong, and I think that many were just
replaced with three-prong as placebos, without pulling a ground wire. At
least the garage (with the concrete floor and the power tools) is wired
correctly...
--
Mark
"I prefer heaven for climate, hell for company."



"sofie" wrote in message
...
CJT:
Some years ago when I was in the pro-audio installation business for an on
the road entertainment company, us installation techs would always carried
about a dozen "u-ground" 3 wire to 2 wire ground adapters in our tool
boxes
so the ground could be temporarily "lifted" on various pieces of gear to
eliminate ground loops and the subsequent hum problems. (don't cut off
ground pins on the plugs of equipment) Usually the problem would
originate
because remote equipment was on a different circuit from the breaker box
and
was located some distance from the main head-end gear.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"CJT" wrote in message
...
Mark Moulding wrote:

Something you might try (although you didn't hear it from me)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
In other words, you recognize what a bad idea this is.

is completely
disconnecting the ground pin on your computer. You didn't mention what
kind
of computer you're using, but if it's a laptop, grounding isn't too
essential. (In fact, having a permanently lifted [broken off,
actually]
ground pin on mine has several times saved my laptop from almost
certain
major damage when connected to equipment with a ground fault - a common
problem in my line of work.)

In my case, I'm also using a laptop for a home music recording studio
(I
know, not the best choice, but it was sitting around...). All of the
audio
I/O is via an external high-quality device, but ground loop hum was
killing
me, *even though everything was plugged into the same outlet strip*.
Breaking off the computer's power supply ground pin completely solved
the
problem.
--
Mark
"I prefer heaven for climate, hell for company."


"Dennis" wrote in message
...

I'm running the output of my computer to my stereo aamplifier.
I'm getting an annoying 60Hz hum through both speakers. This
occurs with all inputs and outputs muted. If I unplug the plug from
the back of the computer the hum stops. Help please,

Dennis






--
The e-mail address in our reply-to line is reversed in an attempt to
minimize spam. Our true address is of the form .

Mark Moulding wrote:

I knew that would raise some rabble. Yes, of course I recognize the
potential (so to speak) problems with opening the safety ground connection.
However, a few interesting points exist in this particular situation:

- The device is a laptop, and there is no direct connection from the ground
pin through the (double-insulated) AC adapter/charger to the laptop chassis,
so it's really not much of a "safety" ground.

- There are two small value (10 nF) caps from each side of the power line to
the ground terminal inside the adapter, presumably as an RFI suppression
measure.

- All of the audio equipment involved was plugged into the *same* outlet
strip - it seems highly unlikely that there'd be much of ground loop within
the 6" or so of 16 gauge wire separating the plugs

- Finally (and this is really no excuse), my house is old enough that I'm
not convinced that all of the three prong outlets have their ground pin
connected to anything at all. It's not so old that it's knob-and-tube, but
the outlets were originally two prong, and I think that many were just
replaced with three-prong as placebos, without pulling a ground wire. At
least the garage (with the concrete floor and the power tools) is wired
correctly...
--
Mark

Hi...

As a side issue, there are testers available for only a couple of
dollars that you can plug into your outlets that will (by way of three
neon lamps) easily tell you whether or not ground exists, and if
hot/neutral are reversed.

Just mentioned it wondering if it might not increase your comfort level.

Ken

"Dave Plowman (News)" wrote in message
...
In article ,
Alan Holmes wrote:
More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Neither. The hum you hear in the UK is actually 100 Hz.

How do you work that out?

Alan


--
*I believe five out of four people have trouble with fractions. *

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

"sofie" wrote in message
...
Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work
"crikey"
until today.

You obviously haven't lived!(:-)

Used to be an everyday exclamation

Alan

How about up in Canada ?? Have you?
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"Ken Weitzel" wrote in message
news:RvAvf.32637$tl.7033@pd7tw3no...


sofie wrote:
"Dave Plowman (News)" wrote in message

Crikey. You'd have been shot in the UK. ;-)

1:1 repcoils are the correct way with balanced pro audio gear. You
*really* shouldn't mess with safety earths.
*Why is a boxing ring square?
Dave Plowman London SW

- - - - - - - - - - - - - - - -

"crikey"

exclamation UK OLD-FASHIONED INFORMAL
an expression of surprise


YIKES!

On 2006-01-06, sofie wrote:
Ken:
I have traveled the world over..... been to the UK many times on business
trips, personal vacations, etc.... but I had never heard the work "crikey"
until today.
How about up in Canada ?? Have you?

dunno about there in in Australia and New Zealand it's heard occasionally.

my (aging) Concise Oxoford dictionary dosen't specifty that it's unique to
any place.

Bye.
Jasen

"Alan Holmes" wrote in message
...

"Dave Plowman (News)" wrote in message
...
In article ,
Alan Holmes wrote:
More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Neither. The hum you hear in the UK is actually 100 Hz.

How do you work that out?

Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
120 Hz for the same reason. Most objects, including speakers, really don't
radiate that well at 50 - 60 Hz fundamental, but can and do radiate pretty
well at some of the higher harmonics.

Karl Uppiano wrote:
"Alan Holmes" wrote in message
...

"Dave Plowman (News)" wrote in message
...

In article ,
Alan Holmes wrote:

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Neither. The hum you hear in the UK is actually 100 Hz.

How do you work that out?


Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
120 Hz for the same reason. Most objects, including speakers, really don't
radiate that well at 50 - 60 Hz fundamental, but can and do radiate pretty
well at some of the higher harmonics.



I always thought the 60Hz caused core laminations, coil windings, etc to
smack into each other at both peaks of the waveform, hence the 120Hz
sound from a 60Hz source. I could be off on the process, but I do know
that if I use a sound editor on my computer to produce a 120Hz sine wave
it sounds just like the 60Hz hum from transformers.

"James Sweet" wrote in message
news:48jwf.13937$ya4.5646@trnddc03...
Karl Uppiano wrote:
"Alan Holmes" wrote in message
...

"Dave Plowman (News)" wrote in message
...

In article ,
Alan Holmes wrote:

More precisely, make sure that your stereo amplifier and your computer
are connected to the same ground. Even a few millivolts of AC
difference in ground potentials can cause lots of 60 Hz hum.

But only if you live in the US of A, if you live in other parts of the
world, it will be 50 hertz.

Neither. The hum you hear in the UK is actually 100 Hz.

How do you work that out?


Second harmonic of 50 Hz. A lot of the hum you hear in the US is actually
120 Hz for the same reason. Most objects, including speakers, really
don't radiate that well at 50 - 60 Hz fundamental, but can and do radiate
pretty well at some of the higher harmonics.

I always thought the 60Hz caused core laminations, coil windings, etc to
smack into each other at both peaks of the waveform, hence the 120Hz sound
from a 60Hz source. I could be off on the process, but I do know that if I
use a sound editor on my computer to produce a 120Hz sine wave it sounds
just like the 60Hz hum from transformers.

Yeah, I think a magnet or buzzer (like in an old alarm clock) will be
attracted by both peaks of a 50 or 60 Hz input, and oscillate at the second
harmonic.