Ok, as promised, results of tests with various filters, power cables etc...

First test on my own system, Arcam DV-79, AVR-250, Mordaunt-Short Avant
908/905C/903S speakers, B&W ASW-1000 sub, Audio Innovations Silver
Bi-Wire speaker cable.

As promised, I've been loaned an Isotek power cable (£60) in order to
carry out these tests. I was also loaned an Isotek power distribution
block (not sure of price, I think they're about £150).

For comparison, I also used a standard IEC mains cable, and an IEC cable
with a filtered plug.

I normally have my system plugged in via a Masterplug surge protected
and RFI-filtered 4-way distribution block, £8 trade or £20 retail.

For a test track I decided to use "So Far Away", from Dire Straits'
"Brothers In Arms" CD. The version in question is the SBM remaster.

Two other people were also present. One person was unsure, the other was
a complete sceptic.

First things first, I plugged the DVD player and amplifier into an
unfiltered block. I then played the test track.

I then switched power cables on the DVD player to use the Isotek, and
played the track again. This made no difference whatsoever - which is to
be expected, as the DVD player is merely acting as a transport. I
switched cables back again and played the test track to be sure, and
indeed there was no difference.

I then switched the power cable on the amplifier to use the Isotek
cable. Immediately there was an improvement in dynamics, percussion in
particular had much more presence and depth.

I switched back to the standard IEC cable and listened again to ensure
that there was in fact a difference and that I wasn't imagining things.
The sound seemed flat after switching back.

Next I tried the standard cable with filtered plug. This again made
quite a dramatic difference to dynamics. Perhaps not quite so much as
the Isotek cable, but that may be the psychological bit coming into
play. But maybe not, as later tests showed.

I then brought filtered mains distribution blocks into play, and tried
various combinations of esoteric and generic branded filters, unfiltered
cables etc.

What I discovered (and the two other people in the room also heard quite
clearly) was that a filtered distribution block makes a difference, but
there did not appear to be any audible difference between the Isotek
block at £150 or the Masterplug block. Both have RFI filtering and surge
protection, the Isotek has a metal case, the Masterplug is plastic. But
none of us could hear a difference between them.

Also, the Isotek cable sounded exactly the same when plugged into an
unfiltered or filtered block. The generic filtered cable sounded
slightly better when connected via an RFI filtered block.

The combination of generic filtered cable and Masterplug filtered block
sounded as good as using the £60 Isotek cable. Both sounded
significantly better than using an unfiltered cable.

So on this basis I would recommend the Masterplug filtered 4-way block,
£8 from CPC or anything up to £20 retail, along with a filtered plug on
the IEC cable (costs about £3.50 from CPC, not sure about retail).

However, the next part of the test was interesting. We then went around
to a friend's house, who has a similar setup to mine - Arcam CD73, A90,
B&W DM603 speakers, QED speaker cables (not sure which one, but nice and
thick).

We then performed the same series of tests, and obtained a similar set
of results. However, the differences on his system weren't anywhere near
as dramatic as on mine.

So we then shut down and unplugged his PC, in the next room but on the
same ring main, and repeated the experiments.

This time the differences were negligibly small. We heard a tiny
improvement when using either the Isotek or generic filtered cables, and
a similar improvement when using the filtered mains blocks. This time we
didn't hear any difference between a filtered and unfiltered IEC cable
when used with a filtered block.

We plugged the PC back in and fired it up again, and repeated several
times for consistency. Once again the results with filtered mains were
much more noticeable when the PC was turned on.

So, in summary:

If you don't have any computer equipment (or anything with switch-mode
power supplies) on the same ring main as your hi-fi, buy a Masterplug
RFI filtered 4-way strip, if for no other reason than it incorporates
surge protection, so will protect your kit against voltage spikes.
(Believe me, I've seen quite a few PSUs fried by this type of thing.) If
it makes it sound better then that's a bonus. If it doesn't, well, at
least you know your equipment is protected.

If you have one or two PCs in the house that aren't left on all the
time, get the RFI filtered block. Try using a filtered IEC cable and
listen, if it makes a difference then keep using it.

If you've got a miniature version of Docklands Telehouse in your attic
or spare room, stick an RFI filtered 4-way block in, then use filtered
power cables from that. It's also probably worth putting filtered cables
on your PCs and other items with SMPSUs, as then you'll tackle the
problem at source (and additionally protect *that* expensive equipment
from spikes).

In the meantime, I appear to have "won" an Isotek power cable worth £60.
They want the distribution block back, but they've said I can hang on to
the power cable for now. Might try opening up the plug and see exactly
what type of filter they've put in...

--
Glenn Richards Tel: (01453) 845735
Squirrel Solutions http://www.squirrelsolutions.co.uk/

IT consultancy, hardware and software support, broadband installation

In article , Glenn Richards wrote:
[...]
I then switched the power cable on the amplifier to use the Isotek
cable. Immediately there was an improvement in dynamics, percussion in
particular had much more presence and depth.

I switched back to the standard IEC cable and listened again to ensure
that there was in fact a difference and that I wasn't imagining things.
The sound seemed flat after switching back.

Next I tried the standard cable with filtered plug. This again made
quite a dramatic difference to dynamics. Perhaps not quite so much as
the Isotek cable, but that may be the psychological bit coming into
play. But maybe not, as later tests showed.
[...]

Did you measure anything objectively with instruments? Anything at all?
Doesn't it ever cross your mind how remarkable it is that after the mains
current has travelled all those miles underground and overhead, the last
few feet can make such a difference? Are you sure you're really hearing
what you think you're hearing?

Rod.

On Mon, 20 Mar 2006 00:51:28 -0000, Roderick Stewart
wrote:

Did you measure anything objectively with instruments? Anything at all?
Doesn't it ever cross your mind how remarkable it is that after the mains
current has travelled all those miles underground and overhead, the last
few feet can make such a difference? Are you sure you're really hearing
what you think you're hearing?

He's suggesting that a filtered power lead can reduce interference
from an adjacent computer. Not that it's improving the mains supply
as such.

Glenn Richards wrote:

What I discovered (and the two other people in the room also heard quite
clearly) was that a filtered distribution block makes a difference, but
there did not appear to be any audible difference between the Isotek
block at £150 or the Masterplug block. Both have RFI filtering and surge
protection, the Isotek has a metal case, the Masterplug is plastic. But
none of us could hear a difference between them.


What you discovered was that a particular amplifier sounded better to three
people under certain circumstances, no more, no less.

Ian

In article 441e64e4.0@entanet, Ian Bell wrote:
Glenn Richards wrote:

What I discovered (and the two other people in the room also heard
quite clearly) was that a filtered distribution block makes a
difference, but there did not appear to be any audible difference
between the Isotek block at £150 or the Masterplug block. Both have
RFI filtering and surge protection, the Isotek has a metal case, the
Masterplug is plastic. But none of us could hear a difference between
them.


What you discovered was that a particular amplifier sounded better to
three people under certain circumstances, no more, no less.

Not quite. It was 'discovered' that they had this opinion... However the
'test' as reported shows no signs of being reliable beyond that.

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

In article , Glenn Richards
wrote:
Ok, as promised, results of tests with various filters, power cables
etc...

[snip]

First things first, I plugged the DVD player and amplifier into an
unfiltered block. I then played the test track.

I then switched power cables on the DVD player to use the Isotek, and
played the track again. This made no difference whatsoever - which is to
be expected, as the DVD player is merely acting as a transport. I
switched cables back again and played the test track to be sure, and
indeed there was no difference.

You presumably were aware thoughout of what arrangement was in use. You
also seem to have only done this a few times, not many times to form
abody of data on which any meaningful statistical analysis could be
carried out.

I then switched the power cable on the amplifier to use the Isotek
cable. Immediately there was an improvement in dynamics, percussion in
particular had much more presence and depth.

....or at least that was the impression of those involved.


[snip]

What I discovered (and the two other people in the room also heard quite
clearly) was that a filtered distribution block makes a difference, but
there did not appear to be any audible difference between the Isotek
block at £150 or the Masterplug block. Both have RFI filtering and surge
protection, the Isotek has a metal case, the Masterplug is plastic. But
none of us could hear a difference between them.

The problem is that no-one else at this point can tell if your opinions
have any weight or not since your test method may not be reliable, and
you give no data which others could uses to assess the validity or
statistical reliability of what you report.

If you wish to obtain valid results which can be used as a reliable guide
then you would at least have to:

A) Do some tests where the results can be shown to depend *only* on the
sounds being produced. i.e. ensure that those involved don't know which of
the items being compared are in use at any point when having to make
decisions.

B) Do the tests enough times to allow the results to be assessed for level
of statistical significance.

It might also help if you'd tried actually measuring or examining the
output from the system to see if you could find any changes that might
account for the opinions you formed.

It would also help to take measures to check for, or control the risk
of interpreting an effect due to some other cause as being due to
what you may incorrectly assume. e.g. ensure that you have enough
test runs to deal with alterations in listening position (acoustics)
and reverse ordering to deal with psycho- or physio- adaptions due
to immdiately previous experiences.

In this particular case, it would have been useful to repeat the tests
in your friend's house, with someone else in another room either having
the PC (alleged to be the source of assumed 'interference') on or off,
and have you say which was the case simply by listening. If you could
do this repeatedly and get the answer correct then that would be a
useful result. But if you know the PC is on or off when listening, then
it is not really very useful.

Alas, in the absence of the above, the report you make tells us about the
opinions of those involved, but does not tell us if the cables, etc,
actually did anything to the output of the system. Nor if this had
anything to do with 'filtering'.

IIUC it has been explained on more than one occasion in the past that such
'tests' do need to be carried out in an appropriate manner if we wish the
results to have any reliability as evidence. It therefore seems a shame
that you seem not to have done this. The result is that your opinions
may or may not be well-founded, and no-one can tell which since either
possibility will seem equally probable to anyone other than yourself.

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

In the meantime, I appear to have "won" an Isotek power cable worth £60.
They want the distribution block back, but they've said I can hang on to
the power cable for now. Might try opening up the plug and see exactly
what type of filter they've put in...


Yes, see what's adding in extra resistance and or inductance.

Don't fancy doing it all again with a storage scope across the mains to
see what's happening to the waveform and voltage?, to see if the
filters/power cords etc are seriously affecting the mains power
increasing the source impedance etc, into the units under test?........

--
Tony Sayer

In article , Roderick
Stewart writes
In article , Glenn Richards wrote:
[...]
I then switched the power cable on the amplifier to use the Isotek
cable. Immediately there was an improvement in dynamics, percussion in
particular had much more presence and depth.

I switched back to the standard IEC cable and listened again to ensure
that there was in fact a difference and that I wasn't imagining things.
The sound seemed flat after switching back.

Next I tried the standard cable with filtered plug. This again made
quite a dramatic difference to dynamics. Perhaps not quite so much as
the Isotek cable, but that may be the psychological bit coming into
play. But maybe not, as later tests showed.
[...]

Did you measure anything objectively with instruments? Anything at all?
Doesn't it ever cross your mind how remarkable it is that after the mains
current has travelled all those miles underground and overhead, the last
few feet can make such a difference? Are you sure you're really hearing
what you think you're hearing?


Perhaps he is hearing/imaging some change. Course if I stuck some
inductance resistance into the mains on my amp etc, I would expect it
the behave differently, wouldn't expect it to behave any better tho!..

BTW was there any RF present to speak of when U were doing all this?...
Rod.


--
Tony Sayer

"tony sayer" wrote in message
...
In the meantime, I appear to have "won" an Isotek power cable worth £60.
They want the distribution block back, but they've said I can hang on to
the power cable for now. Might try opening up the plug and see exactly
what type of filter they've put in...


Yes, see what's adding in extra resistance and or inductance.

Don't fancy doing it all again with a storage scope across the mains to
see what's happening to the waveform and voltage?, to see if the
filters/power cords etc are seriously affecting the mains power
increasing the source impedance etc, into the units under test?........

--
Tony Sayer


I was about to say exactly the same thing as Tony. I don't doubt that Glenn
and his chums thought that they heard some difference - and perhaps they
did. I'm certainly not going to join the " it's all just a load of ********
" brigade on this BUT, if adding in filtering ahead of the equipment really
DID produce a difference, then in order to evaluate the true validity of the
perceived improvement, we would need to know exactly what the filters were
filtering against, and how effectively. A high bandwidth storage scope would
be a satisfactory way of doing this. If the filters are indeed removing
mains-injected hash from a single computer's power supply, then firstly, you
would have to question if that computer's power supply and input filtering,
were working correctly. If there is sufficient level to have a siginificant
enough effect to hear, being introduced by this computer, then it would
almost certainly be operating outside of it's CE approval ( assuming that
it's got one ). Strictly speaking, if it hasn't, and is introducing hash to
the mains supply, you render yourself liable to prosecution ...

Secondly, if the computer is within spec regarding its emmissions, then you
would have to question why an expensive amplifier is being affected to a
degree that you can hear, by such a low level of mains borne noise ? If this
is indeed the case, and the amp is CE approved, then it should not respond
to such low levels, introduced through its mains port. Indeed, if you
contact the manufacturer and ask nicely, they might be able to produce a
copy of the CE test report for you, or at least tell you what figures were
achieved for noise immunity.

Either way, if you want to progress this discussion further, in a sensible
way, we need to see some objective test results as to what the filters were
doing, otherwise, this thread will just degenerate into another long string
of insults and taunts and challenges, that are meaningless, and time
wasting, and do nothing for the credibility of the group.

Arfa

On Sun, 19 Mar 2006 23:42:23 +0000, Glenn Richards
wrote:

Ok, as promised, results of tests with various filters, power cables etc...

First test on my own system, Arcam DV-79, AVR-250, Mordaunt-Short Avant
908/905C/903S speakers, B&W ASW-1000 sub, Audio Innovations Silver
Bi-Wire speaker cable.

As promised, I've been loaned an Isotek power cable (£60) in order to
carry out these tests. I was also loaned an Isotek power distribution
block (not sure of price, I think they're about £150).

For comparison, I also used a standard IEC mains cable, and an IEC cable
with a filtered plug.

I normally have my system plugged in via a Masterplug surge protected
and RFI-filtered 4-way distribution block, £8 trade or £20 retail.

For a test track I decided to use "So Far Away", from Dire Straits'
"Brothers In Arms" CD. The version in question is the SBM remaster.

Two other people were also present. One person was unsure, the other was
a complete sceptic.

First things first, I plugged the DVD player and amplifier into an
unfiltered block. I then played the test track.

I then switched power cables on the DVD player to use the Isotek, and
played the track again. This made no difference whatsoever - which is to
be expected, as the DVD player is merely acting as a transport. I
switched cables back again and played the test track to be sure, and
indeed there was no difference.

I then switched the power cable on the amplifier to use the Isotek
cable. Immediately there was an improvement in dynamics, percussion in
particular had much more presence and depth.

I switched back to the standard IEC cable and listened again to ensure
that there was in fact a difference and that I wasn't imagining things.
The sound seemed flat after switching back.

Next I tried the standard cable with filtered plug. This again made
quite a dramatic difference to dynamics. Perhaps not quite so much as
the Isotek cable, but that may be the psychological bit coming into
play. But maybe not, as later tests showed.

I then brought filtered mains distribution blocks into play, and tried
various combinations of esoteric and generic branded filters, unfiltered
cables etc.

What I discovered (and the two other people in the room also heard quite
clearly) was that a filtered distribution block makes a difference, but
there did not appear to be any audible difference between the Isotek
block at £150 or the Masterplug block. Both have RFI filtering and surge
protection, the Isotek has a metal case, the Masterplug is plastic. But
none of us could hear a difference between them.

Also, the Isotek cable sounded exactly the same when plugged into an
unfiltered or filtered block. The generic filtered cable sounded
slightly better when connected via an RFI filtered block.

The combination of generic filtered cable and Masterplug filtered block
sounded as good as using the £60 Isotek cable. Both sounded
significantly better than using an unfiltered cable.

So on this basis I would recommend the Masterplug filtered 4-way block,
£8 from CPC or anything up to £20 retail, along with a filtered plug on
the IEC cable (costs about £3.50 from CPC, not sure about retail).

However, the next part of the test was interesting. We then went around
to a friend's house, who has a similar setup to mine - Arcam CD73, A90,
B&W DM603 speakers, QED speaker cables (not sure which one, but nice and
thick).

We then performed the same series of tests, and obtained a similar set
of results. However, the differences on his system weren't anywhere near
as dramatic as on mine.

So we then shut down and unplugged his PC, in the next room but on the
same ring main, and repeated the experiments.

This time the differences were negligibly small. We heard a tiny
improvement when using either the Isotek or generic filtered cables, and
a similar improvement when using the filtered mains blocks. This time we
didn't hear any difference between a filtered and unfiltered IEC cable
when used with a filtered block.

We plugged the PC back in and fired it up again, and repeated several
times for consistency. Once again the results with filtered mains were
much more noticeable when the PC was turned on.

So, in summary:

If you don't have any computer equipment (or anything with switch-mode
power supplies) on the same ring main as your hi-fi, buy a Masterplug
RFI filtered 4-way strip, if for no other reason than it incorporates
surge protection, so will protect your kit against voltage spikes.
(Believe me, I've seen quite a few PSUs fried by this type of thing.) If
it makes it sound better then that's a bonus. If it doesn't, well, at
least you know your equipment is protected.

If you have one or two PCs in the house that aren't left on all the
time, get the RFI filtered block. Try using a filtered IEC cable and
listen, if it makes a difference then keep using it.

If you've got a miniature version of Docklands Telehouse in your attic
or spare room, stick an RFI filtered 4-way block in, then use filtered
power cables from that. It's also probably worth putting filtered cables
on your PCs and other items with SMPSUs, as then you'll tackle the
problem at source (and additionally protect *that* expensive equipment
from spikes).

In the meantime, I appear to have "won" an Isotek power cable worth £60.
They want the distribution block back, but they've said I can hang on to
the power cable for now. Might try opening up the plug and see exactly
what type of filter they've put in...

Well, this would all be a little more convincing if the changes you
"observed" were ones concerned with symptoms that might possibly be
addressed by cleaner power. These would be essentially (as Dave
Plowman pointed out), an absence of clicks from devices like
thermostats.

What you present here amounts to "I used Cillit Bang to clean my sink,
and yes, I was three inches taller as a result".

So no, yet again you have presented us with some nonsensical
pseudo-science to support something imaginary that you and your
friends convinced yourselves had happened.

d

Pearce Consulting
http://www.pearce.uk.com