In article ,
Nick Gorham wrote:
I use an amplifier which has no speaker relay protection systems.
Therefore, when it is unplugged, it can still deliver power to the
speakers, for as long as the main capacitor banks can supply it. The
main filter caps total 250,000uF. This means the amplifier can
deliver a handful of Watts for several seconds. Plugging and
unplugging the amp from the 240VAC mains supply is inaudible to all
listeners. Therefore, there can never be any difference between power
cords.



Ahh, thats because your capacitors are already filled from the corrupted
supply :-)

Thanks for the first good laugh of the day. ;-)

--
*A fine is a tax for doing wrong. A tax is a fine for doing well.

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

Trevor Wilson wrote:
I use an amplifier which has no speaker relay protection systems. Therefore,
when it is unplugged, it can still deliver power to the speakers, for as
long as the main capacitor banks can supply it. The main filter caps total
250,000uF. This means the amplifier can deliver a handful of Watts for
several seconds. Plugging and unplugging the amp from the 240VAC mains
supply is inaudible to all listeners. Therefore, there can never be any
difference between power cords.

Is there not another angle to look at (says he throwing fuel on the
cynical fire...) and that is when the mains power supply is noisey.
While I can appreciate a mains cable ain't going to make any difference
with a clean power supply, to what extent do these noise reducing mains
cables with their ferrite rings and platted cables reduce an
interference that may be inherent in the supply? Of course an amp that
removes all such interference before the amp power lines will not show
any difference, but will a hifi component with a less than optimally
design power supply benefit from a "noise reducing" cable?

"David Lodge" wrote in message
ps.com...
Trevor Wilson wrote:
I use an amplifier which has no speaker relay protection systems.
Therefore,
when it is unplugged, it can still deliver power to the speakers, for as
long as the main capacitor banks can supply it. The main filter caps
total
250,000uF. This means the amplifier can deliver a handful of Watts for
several seconds. Plugging and unplugging the amp from the 240VAC mains
supply is inaudible to all listeners. Therefore, there can never be any
difference between power cords.

Is there not another angle to look at (says he throwing fuel on the
cynical fire...) and that is when the mains power supply is noisey.

**Sure. However, a power cord is not even going to appraoch the capabilities
of a decent power supply, in removing mains bourne crap.

While I can appreciate a mains cable ain't going to make any difference
with a clean power supply, to what extent do these noise reducing mains
cables with their ferrite rings and platted cables reduce an
interference that may be inherent in the supply?

**All of which can easily be placed inside the amplifier, if there is a
problem. Moving this hardware to the outside is wasteful, inefficient and
costly.

Of course an amp that
removes all such interference before the amp power lines will not show
any difference, but will a hifi component with a less than optimally
design power supply benefit from a "noise reducing" cable?

**Perhaps. Ironically, cheap, crappy amplifiers (i.e.: The ones which suffer
from mains borne noise) are not likely to be used with expensive power
cords.


--
Trevor Wilson
www.rageaudio.com.au

In article om, David
Lodge wrote:


Is there not another angle to look at (says he throwing fuel on the
cynical fire...) and that is when the mains power supply is noisey.

This is why amplifier designers tend to pay attention to ensuring the amp
has a decent PSU, and has some level of inherent noise rejection. They also
live in the real world. Indeed, the mains supply in many factories or labs
can be even worse than domestic mains in terms of the interference added to
the basic mains waveforms.

While I can appreciate a mains cable ain't going to make any difference
with a clean power supply, to what extent do these noise reducing mains
cables with their ferrite rings and platted cables reduce an
interference that may be inherent in the supply?

Depends. Those that have 'ferrite coatings' would be likely to have almost
no effect on anything except the seller's bank balance. Correct use of
rings, etc, may help in some cases, but this isn't "mains cables" any more.
We are moving into the different topic of "mains filters".


Of course an amp that removes all such interference before the amp power
lines will not show any difference, but will a hifi component with a
less than optimally design power supply benefit from a "noise reducing"
cable?

If the amp and its PSU let through interference, then a filter can help.

FWIW my experience is that some items do produce audible 'clicks' at times
which are mains injected. Reason follows from the above: PSU and rail
rejection not adequate. This can be dealt with by using a mains filter, not
an expensive mains cable. Alternatively, change the item for something else
that has a better PSU and/or amp stages with better rail rejection.

Above said, my experience is also that most items I've used don't have this
problem - or at least it became rarer some decades ago as the designs and
components improved.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

Jim Lesurf wrote:
FWIW my experience is that some items do produce audible 'clicks' at times
which are mains injected. Reason follows from the above: PSU and rail
rejection not adequate. This can be dealt with by using a mains filter, not
an expensive mains cable. Alternatively, change the item for something else
that has a better PSU and/or amp stages with better rail rejection.

That all make sense (both what I quoted above and what I didn't), so is
it fair to say:
- mains filtering devices can provide a degree of noise reduction, but
whether you'll hear a difference or benefit from it depends on the
level of noise in the first place, and the extent to which your amp (or
source component) filters out the noise anyway
- Good main cables themselves are likely to provide a benefit only if
they replace a cable which is difficient in delivering the required
power. Once its sufficient (as I suspect most standard cables are),
there's no additional benefit to be gained by replacing them with
"better" cables.

In article . com,
David
Lodge wrote:
Jim Lesurf wrote:
FWIW my experience is that some items do produce audible 'clicks' at
times which are mains injected. Reason follows from the above: PSU and
rail rejection not adequate. This can be dealt with by using a mains
filter, not an expensive mains cable. Alternatively, change the item
for something else that has a better PSU and/or amp stages with better
rail rejection.

That all make sense (both what I quoted above and what I didn't), so is
it fair to say: - mains filtering devices can provide a degree of noise
reduction, but whether you'll hear a difference or benefit from it
depends on the level of noise in the first place, and the extent to
which your amp (or source component) filters out the noise anyway

Yes. If you find whilst listening to your audio system that you can hear
occasional 'clicks' which seem to come from things like light switches,
fridge motors, etc, then a mains filter may help eliminate these. However
this isn't much to do with fancy mains cables, or the more mysterious and
subtle changes which some sellers of cables describe. Just about having a
PSU/amp that doesn't let mains-carried interference get onto the output of
the amp..

- Good main cables themselves are likely to provide a benefit only if
they replace a cable which is difficient in delivering the required
power. Once its sufficient (as I suspect most standard cables are),
there's no additional benefit to be gained by replacing them with
"better" cables.

That is my exprience. It is also my understanding of the relevant physics,
etc. My main pun concerns with mains cables are safety, and that they
have no basic flaws/problems like non-ohmic (dirty) contacts. Nothing
fancy.

Slainte,

Jim

--
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Audio Misc http://www.st-and.demon.co.uk/AudioMisc/index.html
Armstrong Audio http://www.st-and.demon.co.uk/Audio/armstrong.html
Barbirolli Soc. http://www.st-and.demon.co.uk/JBSoc/JBSoc.html

"Jim Lesurf" wrote in message

In article
om,
David Lodge wrote:


Is there not another angle to look at (says he throwing
fuel on the cynical fire...) and that is when the mains
power supply is noisey.

This is why amplifier designers tend to pay attention to
ensuring the amp has a decent PSU, and has some level of
inherent noise rejection. They also live in the real
world. Indeed, the mains supply in many factories or labs
can be even worse than domestic mains in terms of the
interference added to the basic mains waveforms.

While I can appreciate a mains cable ain't going to make
any difference with a clean power supply, to what extent
do these noise reducing mains cables with their ferrite
rings and platted cables reduce an interference that may
be inherent in the supply?

The biggest EMI filter in most power supplies is the power
transformer. If its optimized for efficiency at 60 Hz, its
likely to be a good rejector of higher frequencies.

"Arny Krueger" wrote in message
...
"Jim Lesurf" wrote in message


While I can appreciate a mains cable ain't going to make
any difference with a clean power supply, to what extent
do these noise reducing mains cables with their ferrite
rings and platted cables reduce an interference that may
be inherent in the supply?

The biggest EMI filter in most power supplies is the power transformer. If
its optimized for efficiency at 60 Hz, its likely to be a good rejector of
higher frequencies.



I beg to differ. Frequencies above 50/60Hz can find their way across/through
that transformer, even when an electrostatic screen is present. It's a very
complex subject.

Any decent amplifier will have good rejection of any crap likely to be
picked up or conducted by ALL the cables going to it (speakers, inputs and
mains).

Graham Holloway
www.accuphon.co.uk

"Arny Krueger" wrote in message
...
"Jim Lesurf" wrote in message

In article
om,
David Lodge wrote:


Is there not another angle to look at (says he throwing
fuel on the cynical fire...) and that is when the mains
power supply is noisey.

This is why amplifier designers tend to pay attention to
ensuring the amp has a decent PSU, and has some level of
inherent noise rejection. They also live in the real
world. Indeed, the mains supply in many factories or labs
can be even worse than domestic mains in terms of the
interference added to the basic mains waveforms.

While I can appreciate a mains cable ain't going to make
any difference with a clean power supply, to what extent
do these noise reducing mains cables with their ferrite
rings and platted cables reduce an interference that may
be inherent in the supply?

The biggest EMI filter in most power supplies is the power transformer. If
its optimized for efficiency at 60 Hz, its likely to be a good rejector of
higher frequencies.

**You'd be wrong. Particularly in the case of most toroidal types. An
efficient, close coupled power transformer can exhibit an excellent HF
response.


--
Trevor Wilson
www.rageaudio.com.au