In article ,
Don Pearce wrote:
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've never heard things like a fridge splat etc which is mains borne? Of
course it depends on the design of the power supply in your amp, etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

--
*I used up all my sick days so I called in dead

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

On Thu, 16 Mar 2006 11:14:28 +0000 (GMT), "Dave Plowman (News)"
wrote:

In article ,
Don Pearce wrote:
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've never heard things like a fridge splat etc which is mains borne? Of
course it depends on the design of the power supply in your amp, etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

No - never heard a thing come through the mains. If I started hearing
stuff now, I wouldn't be buying mains filters - I'd be fixing the
wiring.

d

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

"Dave Plowman (News)" wrote in message
...
In article ,
Don Pearce wrote:
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've never heard things like a fridge splat etc which is mains borne? Of
course it depends on the design of the power supply in your amp, etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

--
*I used up all my sick days so I called in dead

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



If folk happen to have mains borne fridge splats etc. surely employ RC
snubbers at the source (or if it really bad replace those burnt arcing
contacts) rather than going to the expense of filtering the mains for the AV
equipment. I borrowed some hi-fi branded mains filters - read expensive -
before I had a dedicated circuit and in every case they either made no
audible difference or they 'appeared' to be deleterious to the sound
(sighted evaluations of course).

Mike

In article , Dave Plowman (News) wrote:
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've never heard things like a fridge splat etc which is mains borne? Of
course it depends on the design of the power supply in your amp, etc.

I've got a dedicated radial circuit with its own earth feeding my AV
equipment.

I've got all my electrical equipment plugged into the normal wiring that came
with the house, no fancy filters anywhere, nothing special at all, and have
never heard any splats from my loudspeakers since I stopped listening to AM
radio. There's no audible hiss from a normal listening position either, even
if I turn the volume control to its upper endstop. (Normal listening requires
about a quarter turn). My audio and video equipment is not the sort of silly
pretentious stuff that costs a king's ransom, and it's not cheap rubbish
either, just carefully chosen well-designed gear that works.

Rod.

"Dave Plowman (News)" wrote in
message
In article ,
Don Pearce wrote:
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've never heard things like a fridge splat etc which
is mains borne? Of course it depends on the design of the
power supply in your amp, etc.

Most such interference probably does not come in via the power supply or
component power cord.

I've got a dedicated radial circuit with its own earth
feeding my AV equipment.

It's probably the clean ground that's providing any noticable benefit. It's
pretty hard to make up a clean ground with a line cord filter.

In article , Glenn Richards wrote:
The theory is sound anyway, if sticking an LCR filter across the mains
input does indeed reduce the noise floor.

Maybe it would be if it did, but it doesn't, so it isn't. It's nonsense.

Rod.

Roderick Stewart wrote:

The theory is sound anyway, if sticking an LCR filter across the mains
input does indeed reduce the noise floor.
Maybe it would be if it did, but it doesn't, so it isn't. It's nonsense.

That's why I said "if".

--
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:
The theory is sound anyway, if sticking an LCR filter across the mains
input does indeed reduce the noise floor.
Maybe it would be if it did, but it doesn't, so it isn't. It's nonsense.

That's why I said "if".

There isn't really an "if" at all. Sticking an LCR filter across the mains
input will not affect the noise floor in any way whatsoever, so this "theory"
isn not sound, being based on something that isn't true.

Rod.

"Glenn Richards" wrote in
message
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,

No its not. Contrary to some naive beliefs, there is not a direct connection
from your power line to your speaker cable.

Here's a news flash: there is a fair amount of active and passive circuitry
between your power line and your speaker cable.

if sticking an LCR filter
across the mains input does indeed reduce the noise
floor.

It doesn't. For one thing there already is a massive LCR filter accross the
mains input in just about every piece of gear. It's called the power supply.

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

If you want to reduce the noise floor - then why not address the cause of
the noise in the first place? Hint: the source of noise in properly-designed
audio equipment *isn't* leakage from the power line.

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.

Hint: the source of the noise in those old recordings wouldn't have been
helped by power line filters.

This is using Nero Wave Editor (that comes with Nero
Burning ROM), so no fancy expensive software.

You're taking a good idea and running off to China with it.

My question was a serious one, as it's obvious to anyone
with any knowledge of audio that lowering the noise floor
will improve the sound.

Not if the noise floor is already below audibility. And reducing the noise
floor in your stereo will do no good if it is already lower than the noise
floor in the recordings you play.

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?

Flawed premise. Switching power supplies in PCs don't kick a lot of RF
interference into the mains. They have built in line filters that prevent
that from happening. PC's are widely used for audio production and testing.
They generally don't compromise those environments.

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).

Do a sighted evaluation of this idea. I'm sure you'll get positive results.

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

Trust me, if improving sound quality was this easy, it would have been done
all over the place. And in some sense it has - by the plain ordinary power
supplies in regular audio gear.

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