Just a word in case anyone has an idea here. I use a computer as a source on
my hi fi, but when I plug in the monitor lead I get an earth loop. IE loud
nasty buzzing on that input. the problem is a loop as unplugging the earthed
items of the system apart from one, say, a mixer and the monitor, then it
goes away as the only earth is then via the computer, or unearth the
computer and earth the psu on the monitor etc, well you get the drift. Even
unplugging a video lead from a set top box to the monitor reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so I'm
a bit out of ideas here.

Brian

--
From the Sofa of Brian Gaff Reply address is active

On Saturday, October 13, 2012 5:40:12 PM UTC+1, Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source on

my hi fi, but when I plug in the monitor lead I get an earth loop. IE loud

nasty buzzing on that input. the problem is a loop as unplugging the earthed

items of the system apart from one, say, a mixer and the monitor, then it

goes away as the only earth is then via the computer, or unearth the

computer and earth the psu on the monitor etc, well you get the drift. Even

unplugging a video lead from a set top box to the monitor reduces it.

Now its really not safe to start unwiring 13amp maiins plugs earths, so I'm

a bit out of ideas here.



Brian

Earth the computer, and connect the other appliance earth wires to the pc case isntead


NT

On 13/10/12 17:40, Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source on
my hi fi, but when I plug in the monitor lead I get an earth loop. IE loud
nasty buzzing on that input. the problem is a loop as unplugging the earthed
items of the system apart from one, say, a mixer and the monitor, then it
goes away as the only earth is then via the computer, or unearth the
computer and earth the psu on the monitor etc, well you get the drift. Even
unplugging a video lead from a set top box to the monitor reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so I'm
a bit out of ideas here.

Brian


Look for a hi-fi isolation transformer and connect it via that. They're
available on Ebay and many other good outlets ! You'll need to insert
phono plugs in both left and right sides, but it saves mesing about with
the electrics.

Andy C

Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source on
my hi fi, but when I plug in the monitor lead I get an earth loop. IE loud
nasty buzzing on that input. the problem is a loop as unplugging the earthed
items of the system apart from one, say, a mixer and the monitor, then it
goes away as the only earth is then via the computer, or unearth the
computer and earth the psu on the monitor etc, well you get the drift. Even
unplugging a video lead from a set top box to the monitor reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so I'm
a bit out of ideas here.

An isolation transformer in each audio path between the computer and the
Hi-fi will definitely do it. They can be bought from just about any pro
audio supplier. They may be sold as a ground lifter.

Other than that, you need to use a star earthing system, with all the
earth connections on the Hi-fi and computer system going directly to a
single point. Something like plugging everything into extension strips
all connected to the same socket might help. It might even be something
as daft as a loose earth wire on the ring main between the sockets
you're using, or the two sockets you're using being on two different rings.

--
Tciao for Now!

John.

Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source on
my hi fi, but when I plug in the monitor lead I get an earth loop. IE loud
nasty buzzing on that input. the problem is a loop as unplugging the earthed
items of the system apart from one, say, a mixer and the monitor, then it
goes away as the only earth is then via the computer, or unearth the
computer and earth the psu on the monitor etc, well you get the drift. Even
unplugging a video lead from a set top box to the monitor reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so I'm
a bit out of ideas here.

Brian

Can you just plug all the mains plugs into one of those six-way or
eight-way sockets?

Bill

In article ,
Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a
source on my hi fi, but when I plug in the monitor lead I get an earth
loop. IE loud nasty buzzing on that input. the problem is a loop as
unplugging the earthed items of the system apart from one, say, a mixer
and the monitor, then it goes away as the only earth is then via the
computer, or unearth the computer and earth the psu on the monitor etc,
well you get the drift. Even unplugging a video lead from a set top box
to the monitor reduces it. Now its really not safe to start unwiring
13amp maiins plugs earths, so I'm a bit out of ideas here.

Easiest solution is an audio isolation transformer (one per channel)
between computer and amp - removes the DC path from the audio.

They're often needed on car sound systems where an external amp or two is
needed so a place that sells those should have them - or Ebay, of course.

--
*How much deeper would the oceans be without sponges? *

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

"Dave Plowman (News)" wrote in message
...
In article ,
Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a
source on my hi fi, but when I plug in the monitor lead I get an earth
loop. IE loud nasty buzzing on that input. the problem is a loop as
unplugging the earthed items of the system apart from one, say, a mixer
and the monitor, then it goes away as the only earth is then via the
computer, or unearth the computer and earth the psu on the monitor etc,
well you get the drift. Even unplugging a video lead from a set top box
to the monitor reduces it. Now its really not safe to start unwiring
13amp maiins plugs earths, so I'm a bit out of ideas here.

Easiest solution is an audio isolation transformer (one per channel)
between computer and amp - removes the DC path from the audio.

They're often needed on car sound systems where an external amp or two is
needed so a place that sells those should have them - or Ebay, of course.

--
*How much deeper would the oceans be without sponges? *

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

A suggestion for suitable transformers are these ones from Rapid, and CPC
have similar too.

http://www.rapidonline.com/Electrica...34-002-88-2141

They are actually intended for telecom applications, and are speced at only
200 to 4k accordingly, but actually have a much wider freq response. I've
used them in various applications similar to yours, and found them to be a
sensible and low cost (£4ish) solution.

Charles F

I'd presumably need one for input and one for output on the puter though.
I'm thinking the biggest hum increase is always when I connect the monitor
lead, and the hum goes higher in frequency as well, so I'm wondering if it
might not be being induced from the signals for the monitor. I need to have
a think about this.
Brian

--
From the Sofa of Brian Gaff Reply address is active
"Andy Cap" wrote in message
o.uk...
On 13/10/12 17:40, Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source
on
my hi fi, but when I plug in the monitor lead I get an earth loop. IE
loud
nasty buzzing on that input. the problem is a loop as unplugging the
earthed
items of the system apart from one, say, a mixer and the monitor, then
it
goes away as the only earth is then via the computer, or unearth the
computer and earth the psu on the monitor etc, well you get the drift.
Even
unplugging a video lead from a set top box to the monitor reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so
I'm
a bit out of ideas here.

Brian


Look for a hi-fi isolation transformer and connect it via that. They're
available on Ebay and many other good outlets ! You'll need to insert
phono plugs in both left and right sides, but it saves mesing about with
the electrics.

Andy C

Already done that and it made no difference, except that it took me half a
day to disentangle them all etc.. grin.

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Bill Wright" wrote in message
...
Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a source
on my hi fi, but when I plug in the monitor lead I get an earth loop. IE
loud nasty buzzing on that input. the problem is a loop as unplugging the
earthed items of the system apart from one, say, a mixer and the
monitor, then it goes away as the only earth is then via the computer, or
unearth the computer and earth the psu on the monitor etc, well you get
the drift. Even unplugging a video lead from a set top box to the monitor
reduces it.
Now its really not safe to start unwiring 13amp maiins plugs earths, so
I'm a bit out of ideas here.

Brian

Can you just plug all the mains plugs into one of those six-way or
eight-way sockets?

Bill

On 14/10/12 09:28, Brian Gaff wrote:
I'd presumably need one for input and one for output on the puter though.
I'm thinking the biggest hum increase is always when I connect the monitor
lead, and the hum goes higher in frequency as well, so I'm wondering if it
might not be being induced from the signals for the monitor. I need to have
a think about this.
Brian


Not quite sure what you're trying to do. I play stuff from the PC into
an amp and used to suffer the same hum but putting an isolation
transformer in the lead eliminated it completely. If you're also trying
to import a signal from the amp into the PC, then yes, I guess you'd
need to break that too, else you've got the same earth loop in place.

Andy C

On Sunday, October 14, 2012 5:13:06 AM UTC+1, Charles Fearnley wrote:
"Dave Plowman (News)" dave wrote in message

...

In article ,

Brian Gaff Briang1 wrote:

Just a word in case anyone has an idea here. I use a computer as a

source on my hi fi, but when I plug in the monitor lead I get an earth

loop. IE loud nasty buzzing on that input. the problem is a loop as

unplugging the earthed items of the system apart from one, say, a mixer

and the monitor, then it goes away as the only earth is then via the

computer, or unearth the computer and earth the psu on the monitor etc,

well you get the drift. Even unplugging a video lead from a set top box

to the monitor reduces it. Now its really not safe to start unwiring

13amp maiins plugs earths, so I'm a bit out of ideas here.



Easiest solution is an audio isolation transformer (one per channel)

between computer and amp - removes the DC path from the audio.



They're often needed on car sound systems where an external amp or two is

needed so a place that sells those should have them - or Ebay, of course.



--

*How much deeper would the oceans be without sponges? *



Dave Plowman London SW

To e-mail, change noise into sound.



A suggestion for suitable transformers are these ones from Rapid, and CPC

have similar too.



http://www.rapidonline.com/Electrica...34-002-88-2141



They are actually intended for telecom applications, and are speced at only

200 to 4k accordingly, but actually have a much wider freq response. I've

used them in various applications similar to yours, and found them to be a

sensible and low cost (£4ish) solution.



Charles F

madness!


NT

In article ,
wrote:
A suggestion for suitable transformers are these ones from Rapid, and
CPC have similar too.

http://www.rapidonline.com/Electrica...34-002-88-2141

They are actually intended for telecom applications, and are speced at
only 200 to 4k accordingly, but actually have a much wider freq
response. I've used them in various applications similar to yours,
and found them to be a sensible and low cost (£4ish) solution.

madness!

What do you mean? Laptops are hardly going to have the highest of fi audio
circuits and these transformers can be perfectly ok. They are cheap
because they are made in huge quantities.

--
*Why is it that most nudists are people you don't want to see naked?*

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

In article , Dave Plowman (News)
scribeth thus
In article ,
Brian Gaff wrote:
Just a word in case anyone has an idea here. I use a computer as a
source on my hi fi, but when I plug in the monitor lead I get an earth
loop. IE loud nasty buzzing on that input. the problem is a loop as
unplugging the earthed items of the system apart from one, say, a mixer
and the monitor, then it goes away as the only earth is then via the
computer, or unearth the computer and earth the psu on the monitor etc,
well you get the drift. Even unplugging a video lead from a set top box
to the monitor reduces it. Now its really not safe to start unwiring
13amp maiins plugs earths, so I'm a bit out of ideas here.

Easiest solution is an audio isolation transformer (one per channel)
between computer and amp - removes the DC path from the audio.

They're often needed on car sound systems where an external amp or two is
needed so a place that sells those should have them - or Ebay, of course.


You might try an external USB connected sound card that sometimes can
eliminate humm loop problems...

--
Tony Sayer

http://www.rapidonline.com/Electrica...ansformer-Vtx-
134-002-88-2141



They are actually intended for telecom applications, and are speced at only

200 to 4k accordingly, but actually have a much wider freq response. I've

used them in various applications similar to yours, and found them to be a

sensible and low cost (£4ish) solution.



Charles F

madness!


NT

Well not that good for audio. If you do decide transformer isolation is
the way to go then there are better ones that don't cost that much
more;!...

http://www.rapidonline.com/Electrica...ansformer-Vtx-
101-1604-88-2139

Or RS have the Oxford electronic components range which are around a
tenner each..

http://uk.rs-online.com/web/c/power-...transformers/a
udio-transformers/?searchTerm=audio+transformers&page-offset=20&sort-
by=P_breakPrice1&sort-order=asc&view-type=List&applied-dimensions=429496
5433&lastAttributeSelectedBlock=Brand&sort-option=Price

--
Tony Sayer

On Sunday, October 14, 2012 12:54:32 PM UTC+1, Dave Plowman (News) wrote:
In article ,

meow2222 wrote:

A suggestion for suitable transformers are these ones from Rapid, and

CPC have similar too.



http://www.rapidonline.com/Electrica...34-002-88-2141



They are actually intended for telecom applications, and are speced at

only 200 to 4k accordingly, but actually have a much wider freq

response. I've used them in various applications similar to yours,

and found them to be a sensible and low cost (£4ish) solution.



madness!



What do you mean? Laptops are hardly going to have the highest of fi audio

circuits and these transformers can be perfectly ok. They are cheap

because they are made in huge quantities.

There is a far cheaper simpler and better quality way to do it. A phone transformer with freq response down to 300Hz and up to who knows what is an awful solution. Laptop line level output spec is far beyond such things.

You can of course do all sorts, I've even used mains transformers for audio.. But a far better simpler cheaper quicker solution exists.


NT

In article ,
wrote:
What do you mean? Laptops are hardly going to have the highest of fi
audio

circuits and these transformers can be perfectly ok. They are cheap

because they are made in huge quantities.

There is a far cheaper simpler and better quality way to do it. A phone
transformer with freq response down to 300Hz and up to who knows what is
an awful solution. Laptop line level output spec is far beyond such
things.

That is only saying it meets the spec for telephone lines. As was said
they considerably exceed it. If you want a decent repcoil specifically
made for high quality audio, expect to pay many times that amount.

You can of course do all sorts, I've even used mains transformers for
audio. But a far better simpler cheaper quicker solution exists.

And a mains isolation transformer costs what? Talk about taking a
sledgehammer to crack a nut.

--
*When I'm not in my right mind, my left mind gets pretty crowded *

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

"tony sayer" wrote in message
...

http://www.rapidonline.com/Electrica...ansformer-Vtx-
134-002-88-2141



They are actually intended for telecom applications, and are speced at
only

200 to 4k accordingly, but actually have a much wider freq response.
I've

used them in various applications similar to yours, and found them to be
a

sensible and low cost (£4ish) solution.



Charles F

madness!


NT

Well not that good for audio. If you do decide transformer isolation is
the way to go then there are better ones that don't cost that much
more;!...

http://www.rapidonline.com/Electrica...ansformer-Vtx-
101-1604-88-2139

Or RS have the Oxford electronic components range which are around a
tenner each..

http://uk.rs-online.com/web/c/power-...transformers/a
udio-transformers/?searchTerm=audio+transformers&page-offset=20&sort-
by=P_breakPrice1&sort-order=asc&view-type=List&applied-dimensions=429496
5433&lastAttributeSelectedBlock=Brand&sort-option=Price

--
Tony Sayer

Well, everybody is right that you can get better audio transformers at
higher prices than the Rapid telecom ones mentioned.

In a previous life I was part of the sound staff at one of the big five ITV
companies, and as a sideline made an assortment of small
talkback/communications gear for them, when the real maintenance dpt
couldn't be bothered with the hassle of one offs and very short runs. I used
the transformers mentioned to balance audio inputs and outputs, as a cost
effective solution, as I needed a lot of them. I was getting -3db points at
around 50hz and 18khz - not quite hi-fi, but perfectly adequate, and the
gear sounded very clean. No one ever complained!

Since then I have balanced PC's in and out with these too, and they work (
and sound) fine.

Thanks to Dave P for your sensible support!

Charles F

"Charles Fearnley" wrote in
message ...

"tony sayer" wrote in message
...

http://www.rapidonline.com/Electrica...ansformer-Vtx-
134-002-88-2141



They are actually intended for telecom applications, and are speced at
only

200 to 4k accordingly, but actually have a much wider freq response.
I've

used them in various applications similar to yours, and found them to
be a

sensible and low cost (£4ish) solution.



Charles F

madness!


NT

Well not that good for audio. If you do decide transformer isolation is
the way to go then there are better ones that don't cost that much
more;!...

http://www.rapidonline.com/Electrica...ansformer-Vtx-
101-1604-88-2139

Or RS have the Oxford electronic components range which are around a
tenner each..

http://uk.rs-online.com/web/c/power-...transformers/a
udio-transformers/?searchTerm=audio+transformers&page-offset=20&sort-
by=P_breakPrice1&sort-order=asc&view-type=List&applied-dimensions=429496
5433&lastAttributeSelectedBlock=Brand&sort-option=Price

--
Tony Sayer

Well, everybody is right that you can get better audio transformers at
higher prices than the Rapid telecom ones mentioned.

In a previous life I was part of the sound staff at one of the big five
ITV companies, and as a sideline made an assortment of small
talkback/communications gear for them, when the real maintenance dpt
couldn't be bothered with the hassle of one offs and very short runs. I
used the transformers mentioned to balance audio inputs and outputs, as a
cost effective solution, as I needed a lot of them. I was getting -3db
points at around 50hz and 18khz - not quite hi-fi, but perfectly adequate,
and the gear sounded very clean. No one ever complained!

Since then I have balanced PC's in and out with these too, and they work
( and sound) fine.

Thanks to Dave P for your sensible support!

Charles F

Final thought - to make their use entirely clear - I would (obviously) NOT
put these in a broadcast audio chain, but for general use they can be very
useful, and cheap enough to have a few in the spares box.

Charles F

On Sunday, October 14, 2012 2:37:23 PM UTC+1, Dave Plowman (News) wrote:
In article ,

meow2222 wrote:

What do you mean? Laptops are hardly going to have the highest of fi

audio



circuits and these transformers can be perfectly ok. They are cheap



because they are made in huge quantities.



There is a far cheaper simpler and better quality way to do it. A phone

transformer with freq response down to 300Hz and up to who knows what is

an awful solution. Laptop line level output spec is far beyond such

things.



That is only saying it meets the spec for telephone lines. As was said

they considerably exceed it. If you want a decent repcoil specifically

made for high quality audio, expect to pay many times that amount.

It may much exceed it at the high end, but it won't at the low, doing so would be a waste or iron & money.


You can of course do all sorts, I've even used mains transformers for

audio. But a far better simpler cheaper quicker solution exists.



And a mains isolation transformer costs what? Talk about taking a

sledgehammer to crack a nut.

Indeed. Be sensible and reroute the mains earth, like every class I separates hifi system does.


NT

You can of course do all sorts, I've even used mains transformers for

audio. But a far better simpler cheaper quicker solution exists.



And a mains isolation transformer costs what? Talk about taking a

sledgehammer to crack a nut.

Indeed. Be sensible and reroute the mains earth, like every class I separates
hifi system does.


NT

How exactly will you do that then?..

--
Tony Sayer

Final thought - to make their use entirely clear - I would (obviously) NOT
put these in a broadcast audio chain, but for general use they can be very
useful, and cheap enough to have a few in the spares box.


Well I'd hope not;(, yes the other would be fine for Talkback and such
applications. We don't as yet know quite what quality the OP expects if
he's complaining about Humm then I expect his aspirations are higher
then we'd prolly expect!...


Charles F



--
Tony Sayer

In article ,
wrote:
That is only saying it meets the spec for telephone lines. As was said

they considerably exceed it. If you want a decent repcoil specifically

made for high quality audio, expect to pay many times that amount.

It may much exceed it at the high end, but it won't at the low, doing so
would be a waste or iron & money.


Well, Charles Fearnley has actually measure one and I'd not dispute his
findings based on what I've heard of them. Adequate for other than true
Hi-Fi use.

You can of course do all sorts, I've even used mains transformers for

audio. But a far better simpler cheaper quicker solution exists.



And a mains isolation transformer costs what? Talk about taking a

sledgehammer to crack a nut.

Indeed. Be sensible and reroute the mains earth, like every class I
separates hifi system does.

May not be so easy where a computer is involved. If its audio output
screen is connected to mains ground.

BTW, I've seen 'separates' systems where each component had a mains ground
via a three pin lead and plug, and that connected to the signal ground.
The result was a hum loop. As supplied. It was a long time ago, though.

--
*If you lived in your car, you'd be home by now *

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

On Monday, October 15, 2012 10:52:39 AM UTC+1, tony sayer wrote:
You can of course do all sorts, I've even used mains transformers for



audio. But a far better simpler cheaper quicker solution exists.







And a mains isolation transformer costs what? Talk about taking a



sledgehammer to crack a nut.



Indeed. Be sensible and reroute the mains earth, like every class I separates

hifi system does.





NT



How exactly will you do that then?..

As already mentioned, earth appliance 1, and reroute each other appliance's mains earth connection to appliance 1's case.


NT

On Monday, October 15, 2012 11:04:27 AM UTC+1, Dave Plowman (News) wrote:
In article ,

meow2222 wrote:

That is only saying it meets the spec for telephone lines. As was said
they considerably exceed it. If you want a decent repcoil specifically
made for high quality audio, expect to pay many times that amount.

It may much exceed it at the high end, but it won't at the low, doing so
would be a waste or iron & money.

Well, Charles Fearnley has actually measure one and I'd not dispute his
findings based on what I've heard of them. Adequate for other than true
Hi-Fi use.

Do you the results?


You can of course do all sorts, I've even used mains transformers for
audio. But a far better simpler cheaper quicker solution exists.

And a mains isolation transformer costs what? Talk about taking a
sledgehammer to crack a nut.

Indeed. Be sensible and reroute the mains earth, like every class I
separates hifi system does.

May not be so easy where a computer is involved. If its audio output
screen is connected to mains ground.

I don't see any difficulty there, you simply make the pc the directly earthed appliance, and reroute other appliance earths to a point on its case.


BTW, I've seen 'separates' systems where each component had a mains ground

via a three pin lead and plug, and that connected to the signal ground.

The result was a hum loop. As supplied. It was a long time ago, though.

NT

In article ,
wrote:
May not be so easy where a computer is involved. If its audio output
screen is connected to mains ground.

I don't see any difficulty there, you simply make the pc the directly
earthed appliance, and reroute other appliance earths to a point on its
case.

You may not see any difficulty in that - but I'll bet others will. And
what happens if you wish to move any of it, etc?

Transformers in the audio connector leads are the easy - and safe - way to
do things. Messing about with mains earths isn't - unless you know what
you're doing. Although you could first try simply removing the screen
connection at one end of the interconnecting audio cable(s)

--
*I was once a millionaire but my mom gave away my baseball cards

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

In article ,
wrote:
Well, Charles Fearnley has actually measure one and I'd not dispute
his findings based on what I've heard of them. Adequate for other
than true Hi-Fi use.

Do you the results?

Read his post.

--
*I didn't fight my way to the top of the food chain to be a vegetarian.

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

On Mon, 15 Oct 2012 13:23:09 +0100, Dave Plowman (News) wrote:

In article ,
wrote:
May not be so easy where a computer is involved. If its audio output
screen is connected to mains ground.

I don't see any difficulty there, you simply make the pc the directly
earthed appliance, and reroute other appliance earths to a point on its
case.

You may not see any difficulty in that - but I'll bet others will. And
what happens if you wish to move any of it, etc?

Transformers in the audio connector leads are the easy - and safe - way
to do things. Messing about with mains earths isn't - unless you know
what you're doing. Although you could first try simply removing the
screen connection at one end of the interconnecting audio cable(s)

Yes, that's what I've done in the past and it's (mostly) worked.



--
Use the BIG mirror service in the UK:
http://www.mirrorservice.org

*lightning protection* - a w_tom conductor

On Monday, October 15, 2012 1:32:41 PM UTC+1, Dave Plowman (News) wrote:
In article ,

meow2222 wrote:

Well, Charles Fearnley has actually measure one and I'd not dispute

his findings based on what I've heard of them. Adequate for other

than true Hi-Fi use.



Do you the results?



Read his post.

Charles didn't say what his test results were, or link to them. The mfr's spec of 300Hz-4k +/- 0.2dB is very insufficient.


NT

On Monday, October 15, 2012 1:32:41 PM UTC+1, Dave Plowman (News) wrote:
In article ,

meow2222 wrote:

May not be so easy where a computer is involved. If its audio output

screen is connected to mains ground.



I don't see any difficulty there, you simply make the pc the directly

earthed appliance, and reroute other appliance earths to a point on its

case.



You may not see any difficulty in that - but I'll bet others will. And

what happens if you wish to move any of it, etc?

No difficulty there either


Transformers in the audio connector leads are the easy - and safe - way to

do things. Messing about with mains earths isn't - unless you know what

you're doing. Although you could first try simply removing the screen

connection at one end of the interconnecting audio cable(s)

Its trivial to know what youre doing, just connect the appliance earth wire to the pc case instead.


NT

In article ,
wrote:
Do you the results?



Read his post.

Charles didn't say what his test results were, or link to them. The
mfr's spec of 300Hz-4k +/- 0.2dB is very insufficient.


From: Charles Fearnley
Subject: Earth loops
Date: Sun, 14 Oct 2012 16:50
Newsgroups: uk.d-i-y

I used the transformers mentioned to balance audio inputs and outputs, as
a cost effective solution, as I needed a lot of them. I was getting -3db
points at around 50hz and 18khz - not quite hi-fi, but perfectly
adequate, and the gear sounded very clean.

--
*"I am " is reportedly the shortest sentence in the English language. *

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

In article ,
wrote:
Its trivial to know what youre doing, just connect the appliance earth
wire to the pc case instead.


That sounds like you *don't* know what you're doing. If you are using the
PC as a safety mains earth for other equipment the connection needs to be
to where the PC itself is grounded - not just anywhere on the case. This
probably means opening up the PS.

However, that is still a bad idea. To make sure the flexible cord earth
isn't overloaded in event of multiple faults, the supply to the other
equipment should be taken from the PC too.

So basically a bodge.

--
*Save the whale - I'll have it for my supper*

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

On Monday, October 15, 2012 6:52:22 PM UTC+1, Dave Plowman (News) wrote:
In article ,
meow2222 wrote:

Its trivial to know what youre doing, just connect the appliance earth

wire to the pc case instead.


That sounds like you *don't* know what you're doing. If you are using the

PC as a safety mains earth for other equipment the connection needs to be

to where the PC itself is grounded - not just anywhere on the case. This

probably means opening up the PS.

That's not true at all. Standard PCs have a metal case with the earthed psu screwed to the case with 4 screws. Its very much earthed, via a very low R path.


However, that is still a bad idea. To make sure the flexible cord earth

isn't overloaded in event of multiple faults, the supply to the other

equipment should be taken from the PC too.

That's not true either. As long as you run the equipment from one supply circuit, which is trivially achieved by using a multiway extension lead, there's no issue.


NT

So basically a bodge.

hardly

In article ,
wrote:
That sounds like you *don't* know what you're doing. If you are using
the

PC as a safety mains earth for other equipment the connection needs to
be

to where the PC itself is grounded - not just anywhere on the case.
This

probably means opening up the PS.

That's not true at all. Standard PCs have a metal case with the earthed
psu screwed to the case with 4 screws. Its very much earthed, via a very
low R path.

Still needs to have the earth connected correctly. Not just anywhere on
the case. Cases have removable lids...


However, that is still a bad idea. To make sure the flexible cord earth

isn't overloaded in event of multiple faults, the supply to the other

equipment should be taken from the PC too.

That's not true either. As long as you run the equipment from one supply
circuit, which is trivially achieved by using a multiway extension lead,
there's no issue.

But can you be sure it will all be run from the same extension lead?

--
*Where there's a will, I want to be in it.

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

In article ,
wrote:
Its not unearthing, and afaik not messing about. Its standard practice with hifi systems, has been for many decades.

Hi- Fi systems (separates) where no earth is provided other than at the
amp must conform to the regs for this type of equipment if used as a stand
alone. So are double insulated. You can't rely on the interconnect screen
to carry enough current in event of a fault.

--
*On the other hand, you have different fingers*

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

How exactly will you do that then?..



As already mentioned, earth appliance 1, and reroute each other appliance's

mains earth connection to appliance 1's case.





NT



Do you really think thats wise to un-earth or rather to mess around with

the earthing of a laptop?..



Or the amp system its connected to?..

Its not unearthing, and afaik not messing about. Its standard practice with hifi
systems, has been for many decades.


NT

Do you think its good advice to tell an obvious novice to start messing
around with any mains earthing arrangements on his laptop?..


--
Tony Sayer

On Tuesday, October 16, 2012 11:29:04 AM UTC+1, tony sayer wrote:

Do you think its good advice to tell an obvious novice to start messing

around with any mains earthing arrangements on his laptop?..

No-one has told anyone to mess around


NT

In article ,
scribeth thus
On Tuesday, October 16, 2012 11:29:04 AM UTC+1, tony sayer wrote:

Do you think its good advice to tell an obvious novice to start messing

around with any mains earthing arrangements on his laptop?..

No-one has told anyone to mess around


NT

Well wasn't it you who was suggesting the removal of Earths?..

--
Tony Sayer

On Wednesday, October 17, 2012 10:28:15 AM UTC+1, tony sayer wrote:
In article ,
meow2222 scribeth thus
On Tuesday, October 16, 2012 11:29:04 AM UTC+1, tony sayer wrote:

Do you think its good advice to tell an obvious novice to start messing
around with any mains earthing arrangements on his laptop?..

No-one has told anyone to mess around

Well wasn't it you who was suggesting the removal of Earths?..

No, I suggested rerouting the earth connection, as a huge number of hifis already do.


NT

In article ,
scribeth thus
On Wednesday, October 17, 2012 10:28:15 AM UTC+1, tony sayer wrote:
In article ,
meow2222 scribeth thus
On Tuesday, October 16, 2012 11:29:04 AM UTC+1, tony sayer wrote:

Do you think its good advice to tell an obvious novice to start messing
around with any mains earthing arrangements on his laptop?..

No-one has told anyone to mess around

Well wasn't it you who was suggesting the removal of Earths?..

No, I suggested rerouting the earth connection, as a huge number of hifis
already do.


NT

The earth connection .. where exactly then are you removing that?...

--
Tony Sayer

In article ,
wrote:
On Wednesday, October 17, 2012 10:28:15 AM UTC+1, tony sayer wrote:
In article ,
meow2222 scribeth thus
On Tuesday, October 16, 2012 11:29:04 AM UTC+1, tony sayer wrote:

Do you think its good advice to tell an obvious novice to start
messing around with any mains earthing arrangements on his laptop?..

No-one has told anyone to mess around

Well wasn't it you who was suggesting the removal of Earths?..

No, I suggested rerouting the earth connection, as a huge number of
hifis already do.


Please describe these 'hifis' One make and model will do.

--
*Despite the cost of living, have you noticed how it remains so popular?*

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