Mains filters
 

"Don Pearce" wrote in message
...
On Thu, 16 Mar 2006 10:39:13 +0200, "Iain Churches"
wrote:


"Glenn Richards" wrote in message
t.uk...
Just a quick straw poll...

What are people's opinions of mains filters, upgraded power cables etc?

Have been doing some investigation and there may actually be something
in
this. Not talking Russ Andrews style £250 mains cables here, more like
sticking a plug with a filter onto a standard IEC lead, and possibly
using
one of those Masterplug RFI filtered 4-way blocks.

Has anyone done any serious experimentation on this? I did hear a quite
convincing demonstration at the Sound & Vision show in Bristol a few
years
ago, but the mains there is probably a lot dirtier than your typical
home
installation.

What myself and a few others have figured out is that the level of RFI
introduced onto your ring main by something like the switching PSU in a
typical PC is quite high.

Opinions, people?


Hello Glenn. A couple of days ago, I popped in for 30 secs to
an audio demo at a local dealership to take him some audition
material. He was demonstrating a mains filter unit. He had a
tunable RF gadget with a small inbuilt speaker which he plugged
into a wall socket. Radio transmissions and very loud hash could
clearly be heard. Then he plugged the gadget into one of the
filtered outlets. Silence.


It had a filter in it - what would you expect? This has nothing
whatever to do with audio noise.

The unit was about 4U in height, and had ten mains outlets
on the rear panel.

I was there for only a few seconds, (car parked on a yellow
line) The dealer has promised me some literature.

Regards to all
Iain



Don't be conned; there is no need.

d

Hi Don. I have a feeling you are right. In many years of large
recording sessions, with hundreds of cables and interconnects
I have never seen a mains filter unit in use.

When I get the literature about the mains filter perhaps we can
discuss this further. Glenn's post is IMO and interesting one.
If there is a ghost to be laid to rest here, thsis is a good time
and a good place to do it.

Iain

Mains filters
 

In article , Glenn Richards
wrote:
Don Pearce wrote:

Glen,, please give it a rest. You aren't funny any more and this is
all becoming just a little boring.

And herein lies the problem with this group.

I ask a serious question, expecting some sensible responses, and instead
all I get are sarcastic comments.

The theory is sound anyway, if sticking an LCR filter across the mains
input does indeed reduce the noise floor.

I note the "if" qualifier in the above statement. :-)

The problem is that you also need to know the source and load impedances in
between which you are fitting any filter. e.g. if the load is essentially a
short, then a shunt capacitance across it won't do much.

The problem is that the source impedance can be expected to vary with
location and frequency, and that the load impedance can be expected to vary
during the mains cycle. Also, if you change the source impedance seen by
the PSUs in the units you are trying to 'protect' you might cause some
problems to become worse, not better.

As reducing the noise floor (by whatever means) improves dynamics.

This makes the unstated assumption that the PSU isn't already ensuring the
'noise' from the mains is - at the output of the unit - already so low as
to be inaudible.

[snip]

So, I repeat. If you've got a lot of electrically noisy equipment on the
same ring main as the hi-fi (eg switching power supplies in PCs etc)
that's kicking out a lot of RF interference on the ring main, would it
not follow that eliminating (or at least greatly reducing) this noise,
and therefore providing a clean power feed to the amplifier and other
equipment, would lower the noise floor?

It may do so *if* the noise was previously at an audible level. It is easy
enough to measure the output of a unit to look for signs of this - although
simply listening and finding you can't actually hear anything may be a
useful guide.

The key point is that the designer of the equipment may well be sensible
enough to know he/she lives in the real world, and will already have:

1) Designed the unit with a PSU that rejects mains interference to a
suitable degree.

2) Designed the circuits in the unit so as to reject fluctuations on the
power rails, and correctly references itself to the defined system ground
level.

Once again, I'm not for a moment advocating spending £250 on something
from Russ Andrews. What I'm actually talking about is getting a standard
IEC lead for a couple of quid, then fitting a filtered 13A plug to it,
also for a couple of quid. At trade prices in single quantities this
will cost less than a fiver (which is actually less than you pay for a
standard IEC cable at places like PC World).

So, would someone like to provide a serious answer now?

There is unlikely to be any harm in buying and using some simple mains
filters. Although note the caution I give above.

FWIW I use 'RS' filtered blocks on the systems I use. The primary reason
being that the Quad 34's I use are prone to picking up 'clicks' from the
mains, and these filters dispose of the problem. As does the TV I use as a
display in the living room.

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

Mains filters
 

On Thu, 16 Mar 2006 10:58:37 +0200, "Iain Churches"
wrote:

Don't be conned; there is no need.

d

Hi Don. I have a feeling you are right. In many years of large
recording sessions, with hundreds of cables and interconnects
I have never seen a mains filter unit in use.

When I get the literature about the mains filter perhaps we can
discuss this further. Glenn's post is IMO and interesting one.
If there is a ghost to be laid to rest here, thsis is a good time
and a good place to do it.

Iain


The problem is that this is a ghost that has been laid now many times,
and every so often somebody comes along and insists on digging it up
again, usually with some piece of pseudo science to back it up, as
Glenn has. You are then torn - do you explain the engineering and
science to somebody who is clearly not equipped to understand it, or
simply tell them not to be stupid? Unfortunately, with Glenn the first
option has been shown not to work.

d

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

Mains filters
 

In article , Iain Churches
writes

"Glenn Richards" wrote in message
.uk...
Just a quick straw poll...

What are people's opinions of mains filters, upgraded power cables etc?

Have been doing some investigation and there may actually be something in
this. Not talking Russ Andrews style £250 mains cables here, more like
sticking a plug with a filter onto a standard IEC lead, and possibly using
one of those Masterplug RFI filtered 4-way blocks.

Has anyone done any serious experimentation on this? I did hear a quite
convincing demonstration at the Sound & Vision show in Bristol a few years
ago, but the mains there is probably a lot dirtier than your typical home
installation.

What myself and a few others have figured out is that the level of RFI
introduced onto your ring main by something like the switching PSU in a
typical PC is quite high.

Opinions, people?


Hello Glenn. A couple of days ago, I popped in for 30 secs to
an audio demo at a local dealership to take him some audition
material. He was demonstrating a mains filter unit. He had a
tunable RF gadget with a small inbuilt speaker which he plugged
into a wall socket. Radio transmissions and very loud hash could
clearly be heard. Then he plugged the gadget into one of the
filtered outlets. Silence.

The unit was about 4U in height, and had ten mains outlets
on the rear panel.

I was there for only a few seconds, (car parked on a yellow
line) The dealer has promised me some literature.

Regards to all
Iain





Yes please publish it here for all the see, and see also what snake oil
he used to do that with.

Total bollockx!.....
--
Tony Sayer

Mains filters
 

Don Pearce wrote:

I ask a serious question, expecting some sensible responses, and
instead all I get are sarcastic comments.
No, you were trolling.

No, I was asking a serious question.

As reducing the noise floor (by whatever means) improves dynamics.
And this I have tested, I've recently been involved in cleaning up
some recordings made about 25 years ago on analogue equipment. This
process involves re-EQ followed by digital noise reduction, and the
results before and after applying the noise reduction are nothing
short of dramatic.
Cleaning up recordings most certainly does *not* involve eq. That
would be changing recordings.

By "cleaning up" I was referring specifically to applying digital noise
reduction. The re-EQ was mentioned simply for completeness, as the
recordings were a bit bass-shy and lacking in sparkle. So a touch of
smiley EQ solves that, followed by noise reduction.

It's rather vital that you EQ before NR though, otherwise the re-EQ
boosts bits that the NR has cut, leading to some interesting pumping
effects...

Read above - you can filter the mains til you turn blue and you won't
change your noise floor by even a milli dB.

On an average setup in an average domestic residence I'm sure that's the
case. Unfortunately I have a dozen or so PCs, all with switching power
supplies, sat in the next room, spewing RF onto the ring main. Which in
theory could be affecting the sound... at least in theory.

Turn your amplifier on, with no music playing and listen. Leave the
volume control in the normal listening position and sit in your
listening chair. What can you hear? Anything? Of course not. And what
little hiss there is comes from the front end of the amplifier. None
of it comes from the mains.

You can't hear much above 20kHz. But signals at frequencies above this
will affect what you do hear, harmonics, interaction etc. Why do you
think there's been so much work done on DVD-A, SACD etc, using sample
rates of 96kHz or even 192kHz, rather than 44.1?

Good old Russ Andrews - he has successfully conned £250 out of you.

Read my earlier postings. Currently I'm just using a standard IEC cable,
running into a surge protected (not even an RFI filtered) 4-way strip.
Surge protected for obvious reasons... I don't want a rogue power spike
frying 2 grand's worth of kit.

Now wise up and stop waving your stupidity like a flag of honour.

You are Stewart Pinkerton and I claim my five pounds.

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

IT consultancy, hardware and software support, broadband installation

Mains filters
 

Don't be conned; there is no need.

d

Hi Don. I have a feeling you are right. In many years of large
recording sessions, with hundreds of cables and interconnects
I have never seen a mains filter unit in use.

Nope pro audio people are a tad less neurotic then Joe hi-fi public!....

When I get the literature about the mains filter perhaps we can
discuss this further. Glenn's post is IMO and interesting one.
If there is a ghost to be laid to rest here, thsis is a good time
and a good place to do it.

Iain



--
Tony Sayer

Mains filters
 

Don Pearce wrote:

The problem is that this is a ghost that has been laid now many times,
and every so often somebody comes along and insists on digging it up
again, usually with some piece of pseudo science to back it up

Just a thought...

If I were to replace my Ethernet cables with triple-shielded OFC, and
use a £250 IEC cable to connect my PC to the mains, do you think it
would lower the noise floor in this group?

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

IT consultancy, hardware and software support, broadband installation

Mains filters
 

On Thu, 16 Mar 2006 09:10:30 +0000, Glenn Richards
wrote:

Don Pearce wrote:

I ask a serious question, expecting some sensible responses, and
instead all I get are sarcastic comments.
No, you were trolling.

No, I was asking a serious question.

As reducing the noise floor (by whatever means) improves dynamics.
And this I have tested, I've recently been involved in cleaning up
some recordings made about 25 years ago on analogue equipment. This
process involves re-EQ followed by digital noise reduction, and the
results before and after applying the noise reduction are nothing
short of dramatic.
Cleaning up recordings most certainly does *not* involve eq. That
would be changing recordings.

By "cleaning up" I was referring specifically to applying digital noise
reduction. The re-EQ was mentioned simply for completeness, as the
recordings were a bit bass-shy and lacking in sparkle. So a touch of
smiley EQ solves that, followed by noise reduction.

It's rather vital that you EQ before NR though, otherwise the re-EQ
boosts bits that the NR has cut, leading to some interesting pumping
effects...

Read above - you can filter the mains til you turn blue and you won't
change your noise floor by even a milli dB.

On an average setup in an average domestic residence I'm sure that's the
case. Unfortunately I have a dozen or so PCs, all with switching power
supplies, sat in the next room, spewing RF onto the ring main. Which in
theory could be affecting the sound... at least in theory.

Turn your amplifier on, with no music playing and listen. Leave the
volume control in the normal listening position and sit in your
listening chair. What can you hear? Anything? Of course not. And what
little hiss there is comes from the front end of the amplifier. None
of it comes from the mains.

You can't hear much above 20kHz. But signals at frequencies above this
will affect what you do hear, harmonics, interaction etc. Why do you
think there's been so much work done on DVD-A, SACD etc, using sample
rates of 96kHz or even 192kHz, rather than 44.1?

Good old Russ Andrews - he has successfully conned £250 out of you.

Read my earlier postings. Currently I'm just using a standard IEC cable,
running into a surge protected (not even an RFI filtered) 4-way strip.
Surge protected for obvious reasons... I don't want a rogue power spike
frying 2 grand's worth of kit.

Now wise up and stop waving your stupidity like a flag of honour.

You are Stewart Pinkerton and I claim my five pounds.

That is the end of that then. You are not an engineer - you have never
been an engineer and you can never be an engineer.

So for goodness sake stop posting stuff that is trying to sound like
engineering when it is in fact unmitigated balls. I already told you,
it is no longer funny. Stick to whatever it is you know about.

d

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

Mains filters
 

On Thu, 16 Mar 2006 09:14:39 +0000, Glenn Richards
wrote:

Don Pearce wrote:

The problem is that this is a ghost that has been laid now many times,
and every so often somebody comes along and insists on digging it up
again, usually with some piece of pseudo science to back it up

Just a thought...

If I were to replace my Ethernet cables with triple-shielded OFC, and
use a £250 IEC cable to connect my PC to the mains, do you think it
would lower the noise floor in this group?

Not while you are posting, it wouldn't. Stop now and lower the noise
floor by 20dB.

d

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

Mains filters
 

tony sayer wrote:

I've never ever had a problem with dodgy mains and audio equipment
apart from a very many years ago now when early solid state amps were
around and for that matter haven't been able to affect my system at
all with locally generated RF fields, except with the exception of
the QUAD ESL's where you can trigger the protection with an RF
signal.

Nice!

The main reason I was asking... as I said in an earlier post, because I
work from home I've got about a dozen PCs sitting in the next room, on
the same ring main as the hi-fi. Which makes one wonder just how much
crap is getting onto the mains.

I would generally be of the opinion that if you've got a "normal" setup
at home (one PC, turned on when needed) filtering etc probably wouldn't
make a difference. But when you're sat next door to a scaled down
version of Telehouse you probably do want some filtering.

I'm currently using a standard Masterplug 4-way surge strip for obvious
reasons, but you can get an RFI filtered version for about £8 trade.
Which is about 2 quid more than the unfiltered surge protected version,
so as I'm going to need another surge strip shortly, I might well "risk"
a couple of quid. If it doesn't make any difference, it doesn't matter,
it's less than the cost of a pint.

Nope, its just another area where people like Russ A sell all manner
of exotic junk to the feeble minded to con them out of their moolah,
and if he gets away with it, more fool them!.......

This is the problem with places like Russ Andrews. *If* upgrading the
mains cable makes a difference, it'll be the filtered plug that does it.
Which you can buy for a couple of quid, and fit to a standard IEC or
figure 8 cable, or even chop off the moulded plug and fit to the captive
lead on cheaper kit. Although if it's the filtering that makes the
difference, just use one of those Masterplug surge/RFI strips and leave
the moulded plug.

So you can get exactly the same improvement (if there is one - while I'm
convinced on speaker cables and interconnects I'm still a little
sceptical about power cables) with less than a tenner's worth of bits as
you can with a £250 cable, how many bottles of snake oil are Russ
Andrews bundling with that cable?

The biggest problem with the snake oil merchants of course is that it
makes everyone sceptical of what could possibly be a genuine improvement.

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

IT consultancy, hardware and software support, broadband installation