Mains filters
 

On Thu, 16 Mar 2006 10:47:44 +0000, Glenn Richards
wrote:

Sadly there doesn't appear to be a uk.rec.hi-fi where those of us who
can tell the difference between bell wire and 105-strand speaker cable
can have a discussion about which cable sounds best with which
equipment, without the likes of yourselves or Pinkerton (to name but
two) chiming in with "********" or words to that effect. We've got
uk.rec.audio.vinyl now, why not have uk.rec.audio.hi-fi or audiophile as
well?

If you want a private news group where you can promulgate your own
audio mythology without fear of being called an idiot, I suggest you
start it on your own hard drive, and keep it there. Spout your
nonsense in a public forum, though, and expect to be called on it.

Just stop crying for goodness sake - it isn't pretty.

d

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

Mains filters
 

To Tony. You're right. In recent years, the electricity companies have
installed fibre optic links,

Energis.. IIRC used to carry FM broadcast and TV to transmitters.

but I'm fairly sure that when they first
started using this method of communicating amongst themselves, they did make
use of the full distribution network, including the supergrid, but I may be
wrong on that. How much power volts are on the line, shouldn't make any
difference. It's still just a piece of wire, with HF skin effect, to the
comms signal. I believe that with the PLT internet trials, the injection
points were at central substations, so I guess that this must have been
working at up to at least the local 11kV distribution level. Just as an
aside, I think that the grid and supergrid operate at 275kV and 400kV,

Yep 400 kV. Even so it would be interesting to see how they get the RF
on and off the line;-!!! wouldn't go through the trannies too well
unless they were using Russ A MK-IV snake oil of course;-))

not
475kV. I also have a dim recollection of reading somewhere, that the 25kV
overhead lines on the uk rail nework, were also used for HF telemetry, but
again, I could be going off on one there.

Never heard of that?.

Suffering from CRAFTs disease,
don'tcha know ... !! d;~}

Errmm hate to admit I do know;-0

Arfa



--
Tony Sayer

Mains filters
 

On 2006-03-16, Serge Auckland wrote:

"Iain Churches" wrote in message
...

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

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.

A lot of Pro equipment includes a mains filter as part of the IEC mains
socket. I have VDRs fitted to the plugs feeding all my audio and computer
equipment, as I've found it helps reduce the number of unexplained lock-ups,
when only a power cycle will unlock the kit. I only get one or two a year
now, as opposed to one or two a month without them. I do live out in the
sticks, so my supply may well have less urban hash on it, but possibly more
surges.

As an experiment I have been running my audio kit in recent years from
a single supply point across which I have connected (IIRC):

- A couple of 275 V VDRs in parallel between live and neutral;
- A 220 nF class X2 capacitor from live to neitral; and
- A pair of 22 nF class Y2 capacitors from live to earth and neutral to earth.

Actually I am not aware of any audible difference that this makes
compared to the direct connection. I currently am aware of no audible
"splats" from line voltage anomalies but then again I was not aware of
any beforehand.

I was going to try adding inductances in series with L and N and
bring the filter up to the normal IEC socket filter circuit but since
I perceive no improvement from the above I am not inclined to get out
the soldering iron.

An experiment I recently tried was to burn a dithered -105 dBFS tone at
3 kHz onto a CD. I can hear that as well as the -93.3 dBFS dither noise
if I turn up the gain to maximum. So the mains cannot be interfering
with my kit to that extent anyway.

--
John Phillips

Mains filters
 

In article , Glenn Richards
writes
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.

Quite a bit in fact the mains waveform can be a rather distorted and
rarely these days will look like a sine wave, but its not causing any
problems to me and I sleep soundly knowing that:)

Anyway it undergoes quite some more distortion in the mains input
circuits of the average power amp, gets flattened quite a bit;-)


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.

Several PC's and other gubbins..


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.

If it makes you feel better and you !!believe!! brother then spend,
spend, spend,

I'd prefer the 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.

Its all a load of bollockx and anyone who understands electricity can
see that, but if some want to join the Russ A church, then it'll cost
them cos its not for free!..

Like most religions.. but they make people feel better, tho not often
happy...

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?

Christ or Russ knows...

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

Naturally. Does the National gird know that?....
--
Tony Sayer

Mains filters
 

"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

Mains filters
 

In article , Glenn Richards wrote:
Sadly there doesn't appear to be a uk.rec.hi-fi where those of us who
can tell the difference between bell wire and 105-strand speaker cable
can have a discussion about which cable sounds best with which
equipment, without the likes of yourselves or Pinkerton (to name but
two) chiming in with "********" or words to that effect.

If you believe you can hear difference between audio cables, you should
look for something along the lines of uk.rec.hi-fi.ignorant_self_delusion
or start one yourself.

Rod.

Mains filters
 

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.

Mains filters
 

"tony sayer" wrote in message
...
To Tony. You're right. In recent years, the electricity companies have
installed fibre optic links,

Energis.. IIRC used to carry FM broadcast and TV to transmitters.

but I'm fairly sure that when they first
started using this method of communicating amongst themselves, they did
make
use of the full distribution network, including the supergrid, but I may
be
wrong on that. How much power volts are on the line, shouldn't make any
difference. It's still just a piece of wire, with HF skin effect, to the
comms signal. I believe that with the PLT internet trials, the injection
points were at central substations, so I guess that this must have been
working at up to at least the local 11kV distribution level. Just as an
aside, I think that the grid and supergrid operate at 275kV and 400kV,

Yep 400 kV. Even so it would be interesting to see how they get the RF
on and off the line;-!!! wouldn't go through the trannies too well
unless they were using Russ A MK-IV snake oil of course;-))

not
475kV. I also have a dim recollection of reading somewhere, that the 25kV
overhead lines on the uk rail nework, were also used for HF telemetry, but
again, I could be going off on one there.

Never heard of that?.

Suffering from CRAFTs disease,
don'tcha know ... !! d;~}

Errmm hate to admit I do know;-0

Arfa



--
Tony Sayer


I guess you would get it on and off capacitively. Not too difficult to make
a cap of a few decimals of a uF at several hundred kV working, I would have
thought. You'd then use these to bridge any high inductances in the way,
such as tranny windings, and to get the data on and off. Depending on the
frequencies involved, you may actually get away with a few hundred pF.

I'm sure that such caps must have existed when megawatt main UHF TV
transmitter sites, such as Sandy Heath, used valve transmitters at the
bottom of the mast ( perhaps still do ?? ). Also, maybe for use in high
pulse power radar ?

Arfa

Mains filters
 

"Roderick Stewart" wrote in message
om...
In article , Glenn Richards wrote:
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.

Mains is full of crap anyway. Have you ever looked at it with a scope?
Sometimes it looks nothing whatsoever like those neat sinewaves in the
textbooks, but the power supplies in any electronic equipment running from
it will transform it, rectify it, filter it and stabilise it and thereby
turn it into clean DC for the electronics itself because that's what power
supplies do. Filtering the mains will have no additional benefit.

Rod.


That's what power supplies *should* do, Rod ! I've seen many linears in
lower end equipment, though, where the HF bypassing is poor, and spiky crap,
at least, does find its way onto the DC rails, and things like fridge stats
and room stats, and even next door's electric lawnmower motor, do cause
audible disturbance. In such cases, a surge plug or filtered plug or
combination of both plug, may prove beneficial. However, in general, I agree
with everyone else, that once you've got beyond the eighty quid TescoSonic
market, the input and power supply filtering easily take care of any mains
borne crap, and additional external filtering will be a waste of good beer
money.

Arfa

Mains filters
 

Roderick Stewart wrote:

In a conversation I had with a friend, we determined that power
cables are good at carrying low frequencies, and poor at carrying
higher frequencies. So RFI picked up at the substation won't make
it to your house, but interference sources in your house will cause
RFI to reach your kit.
How do you determine the electrical properties of cables by
conversation?

By applying known principles of engineering.

The losses at high frequencies are significantly higher in 2.5mm mains
wiring cable than screened co-ax, if you don't believe me try running a
composite video signal down mains cable (rather than 75ohm co-ax) and
see how far you get.

It's like saying "how can you determine that an Audi Quattro is going to
go around a hairpin bend at 100mph faster than a Ford Fiesta", for example.

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

IT consultancy, hardware and software support, broadband installation