[Iain Churches]

"Eeyore" wrote in message
...


Iain Churches wrote:

"Eeyore" wrote

The only UK maker of serious audio specific test gear was Radford,
later
to become Wayne Kerr Radford, later still dropping the Radford.

Hi Graham. I am getting indignant e.mails by the bucketfull,
People asking: "Have you never heard of Dawe Instruments, Solartron,
Pye Electronics, Levell UK, Farnell, Feedback Electronics etc etc"

Anyone would think it was I who made the above statement:-)

LOL ! Well, I even still have some Levell kit myself (oscillator and
microvoltmeter) but I never considered it to be audio specific nor
especially
well made either as it happens.

About 36 yrs ago I did actually buy a Feedback Instruments sweep generator
for
Studiomaster's R&D lab. In those days before modern automated test gear it
was
quite handy to look a frequency response with.

Feedback are still going strong, with educational establishments as their
main client base, I think. They make a variable phase oscillator with a
separate
meter uint, which is a very quick and accurate way to measure phase
response.
I have one of these.

http://www.fbk.com/test-measurement/vpg608.asp

I have however failed to mention Bruel and Kjaer. I still have a chart
recorder
of theirs here ! Leader Instruments made a kind of asian knock-off of it
too
with inbuilt oscillator as a self-contained response measurement set.

I was thinking about UK based makers.

Sound Technology should have a mention too. They made some very fine test
kit
specifically for audio but seemingly later vanished without trace.

Then again there was Tektronix's excellent SG505 sig-gen and matching
AA501
analyser. Designed by the same guys who went on to become Audio Precision.
Hewlett Packard had an all-in-one audio sig-gen and analyser which I once
used
for a couple of weeks. It was OK but I wasn't especially keen on it.

HP seem to have made a lot of stuff in the UK. I have a distortion analyser
made there,

Audio Precision is still my fave by a long way, although I have some ideas
to
design a remote control surface for the Prism Sound analyser that would
make it
more user friendly.

Don't know their products. I must do a little Googling.

Lastly, a word of loathing for Neutrik's A2. God, I *HATE* that POS. It
seems
they took the UK made Technical Projects self-contained test set and
buggered it
up !

Hmm. Yes. You see the Neutrik everywhere, they must have sold by the
thousands.

Let me know if you need any info about the Ferrograph RTS.

Cheers
Iain

[Arny Krueger]

"Eeyore" wrote in
message
Peter Wieck wrote:

A shielded mains cable *might* be useful against heavy
transients from equipment nearby,

How ?

*might* be useful against noise from switching power-
supplies, *might* be useful against local rF sources
(and if you discount this, you have never experienced CB
interference from truckers with massive (and illegal)
linear amps on their rigs). Operative word in all cases
is *might*.

It'll do nothing about the unscreened cable in the wall
so will have effectively zero impact.

This raises the question of why people are using screened power cables at
all. I suspect they are trying to address very high frequency radiation
which is also being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the shielding could be
effective, even though its attached to possibly unshielded power wiring in
the wall.

[Eeyore]

Arny Krueger wrote:

"Eeyore" wrote
Peter Wieck wrote:

A shielded mains cable *might* be useful against heavy
transients from equipment nearby,

How ?

*might* be useful against noise from switching power-
supplies, *might* be useful against local rF sources
(and if you discount this, you have never experienced CB
interference from truckers with massive (and illegal)
linear amps on their rigs). Operative word in all cases
is *might*.

It'll do nothing about the unscreened cable in the wall
so will have effectively zero impact.

This raises the question of why people are using screened power cables at
all. I suspect they are trying to address very high frequency radiation
which is also being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the shielding could be
effective, even though its attached to possibly unshielded power wiring in
the wall.

Look at the equipment using it. I'm sure it's being used to contain / reduce
EMI. I'd have to check out what's happening. It's simply a myth that having a
screened cable stops the cable radiating (or receiving) like an aerial AIUI.

It seems more likely to me that the screened mains cable may be operating as
some kind of low-pass filter.


Graham

[Arny Krueger]

"Eeyore" wrote in
message
Arny Krueger wrote:

This raises the question of why people are using
screened power cables at all. I suspect they are trying
to address very high frequency radiation which is also
being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the
shielding could be effective, even though its attached
to possibly unshielded power wiring in the wall.

Look at the equipment using it.

Problematical if it radiated EMI.

I'm sure it's being used
to contain / reduce EMI.

Yup.

I'd have to check out what's
happening. It's simply a myth that having a screened
cable stops the cable radiating (or receiving) like an
aerial AIUI.

Then how does it contain/reduce EMI?

It seems more likely to me that the screened mains cable
may be operating as some kind of low-pass filter.

I think that a power cable has to act like a low pass filter for very high
frequency radiated EMI. However, it might radiate some EMI over an inital
short segment. The shield would trap that, even though the EMI is filtered
out by the other end of the cable.


Graham

[Arny Krueger]

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same pair?

AFAIK, it is becasue the higher frequencies DSL works at have more line
loss. For example, my sources say that heavier gauge telephone wire gives
greater DSL range at a given data rate, or a higher data rate for a given
distance.

[John Byrns]

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same pair?

AFAIK, it is becasue the higher frequencies DSL works at have more line
loss. For example, my sources say that heavier gauge telephone wire gives
greater DSL range at a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is obvious, if that
were all there was to it, logic would say that a properly equalized
amplifier would be all that would be needed to make the range of DSL on
a given cable independent of the bit rate, so there must be more to it
than Graham is admitting to? To explore this issue further I asked
Graham "But what is the SNR at 1 MHz vs. 1 kHz?" Graham's answer was
"Quite low !"


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[west[_4_]]

"Eeyore" wrote in message
...


west wrote:

"Eeyore" wrote
west wrote:

This shield ground is to eliminate induced RF interference in the AC
line.

No it isn't. You need to learn what induction is.

I didn't think you were the type inclined to toss out a curt diatribe.
Perhaps you need to learn the conventions of a civilized dialog.

You need to learn the conventions of not talking out of your rectum.

Graham
I'm glad that you didn't waste any time defining who you are, so from now
on I'll know to avoid you and any opinions you might express.

[Eeyore]

west wrote:

"Eeyore" wrote
west wrote:
"Eeyore" wrote
west wrote:

This shield ground is to eliminate induced RF interference in the AC
line.

No it isn't. You need to learn what induction is.

I didn't think you were the type inclined to toss out a curt diatribe.
Perhaps you need to learn the conventions of a civilized dialog.

You need to learn the conventions of not talking out of your rectum.


I'm glad that you didn't waste any time defining who you are, so from now
on I'll know to avoid you and any opinions you might express.

From previous posts of yours I've noticed that you don't like to sully yourself
with technical truths when magical myths will do, so you wouldn't much like what
I'd say anyway.

Graham

[Arny Krueger]

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can accomplish with
line equalization. The limits of practicality depend on the application.
Trans-oceanic telephones cables used very high voltages. Cables that run
through people's houses and backyards can't go there.

To explore this issue
further I asked Graham "But what is the SNR at 1 MHz vs.
1 kHz?" Graham's answer was "Quite low !"

Not a lot of signal.

[John Byrns]

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can accomplish with
line equalization. The limits of practicality depend on the application.
Trans-oceanic telephones cables used very high voltages. Cables that run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Arny Krueger]

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article
, "Arny
Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same
range as voice transmitted from the exchange over the
same pair?

AFAIK, it is becasue the higher frequencies DSL works
at have more line loss. For example, my sources say
that heavier gauge telephone wire gives greater DSL
range at a given data rate, or a higher data rate for
a given distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all
that would be needed to make the range of DSL on a
given cable independent of the bit rate, so there must
be more to it than Graham is admitting to?

I don't think so. There are practical limits to what you
can accomplish with line equalization. The limits of
practicality depend on the application. Trans-oceanic
telephones cables used very high voltages. Cables that
run through people's houses and backyards can't go
there.

I don't know what the signal voltage used on the
Trans-oceanic telephones cables was, but I would be
surprised if it was unusually high.

The repeaters had 60 dB gain. If their outputs were standard line levels,
then their inputs were in the millivolt range. The actual cable loss per
repeater was said to be about 40 dBm or 2100 dB for the entire segment with
51 repeaters.

The high voltage you
are referring to, which I think was several thousand
volts positive at one end of the cable and several
thousand volts negative at the other end of the cable,

2400 volts

was the power source for the repeaters of which there
were a very large number.

51

The repeaters were powered in
series like Christmas tree lights, and IIRC the power
feed was a constant current.

Agreed. But the repeaters were tubed. If they were connected purely in
series, VCC per repeater would only be about 100 volts. But that's not the
quesiton, the signal voltage is the question.

Cables that run through people's houses and backyards
don't have to go there, there is local power available in
the house to power the equipment.

The telephone system equipment is powered centrally, not from subscriber
homes.

[Peter Wieck]

On Jun 2, 10:09 am, John Byrns wrote:
In article ,
"Arny Krueger" wrote:





"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can accomplish with
line equalization. The limits of practicality depend on the application.
Trans-oceanic telephones cables used very high voltages. Cables that run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/- Hide quoted text -

- Show quoted text -

"Bell System" lines receive no power from individual houses. Excepting
the early "Princess" phones which had separate local power for the
lighted dial, and multi-line sets with similar lighted buttons. When
these phones went modular, a very special adaptor was required (for
the princess-style).

Should I be abuse over your error?

Peter Wieck
Wyncote, PA

[John Byrns]

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article
, "Arny
Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same
range as voice transmitted from the exchange over the
same pair?

AFAIK, it is becasue the higher frequencies DSL works
at have more line loss. For example, my sources say
that heavier gauge telephone wire gives greater DSL
range at a given data rate, or a higher data rate for
a given distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all
that would be needed to make the range of DSL on a
given cable independent of the bit rate, so there must
be more to it than Graham is admitting to?

I don't think so. There are practical limits to what you
can accomplish with line equalization. The limits of
practicality depend on the application. Trans-oceanic
telephones cables used very high voltages. Cables that
run through people's houses and backyards can't go
there.

I don't know what the signal voltage used on the
Trans-oceanic telephones cables was, but I would be
surprised if it was unusually high.

The repeaters had 60 dB gain. If their outputs were standard line levels,
then their inputs were in the millivolt range. The actual cable loss per
repeater was said to be about 40 dBm or 2100 dB for the entire segment with
51 repeaters.

The high voltage you
are referring to, which I think was several thousand
volts positive at one end of the cable and several
thousand volts negative at the other end of the cable,

2400 volts

was the power source for the repeaters of which there
were a very large number.

51

The repeaters were powered in
series like Christmas tree lights, and IIRC the power
feed was a constant current.

Agreed. But the repeaters were tubed. If they were connected purely in
series, VCC per repeater would only be about 100 volts. But that's not the
quesiton, the signal voltage is the question.

Cables that run through people's houses and backyards
don't have to go there, there is local power available in
the house to power the equipment.

The telephone system equipment is powered centrally, not from subscriber
homes.

The "OP" was talking about ADSL which I assume works in a similar
fashion to DSL, my DSL modem is powered from my house, not the central
office. My telephone isn't powered from the central office either, it
is powered from a utility connection to a vault under, well nearly
under, the local tennis court where the RT is located.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[John Byrns]

In article . com,
Peter Wieck wrote:

On Jun 2, 10:09 am, John Byrns wrote:
In article ,
"Arny Krueger" wrote:





"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can accomplish
with
line equalization. The limits of practicality depend on the application.
Trans-oceanic telephones cables used very high voltages. Cables that run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/- Hide quoted text -

- Show quoted text -

"Bell System" lines receive no power from individual houses. Excepting
the early "Princess" phones which had separate local power for the
lighted dial, and multi-line sets with similar lighted buttons. When
these phones went modular, a very special adaptor was required (for
the princess-style).

Should I be abuse over your error?

You are welcome to if you first explain what my error is? The "OP" was
talking about ADSL, so I was referring to my AT&T DSL modem which is
powered from my home with electricity I provide for it.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Peter Wieck]

On Jun 2, 9:22 pm, John Byrns wrote:
In article . com,
Peter Wieck wrote:





On Jun 2, 10:09 am, John Byrns wrote:
In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can accomplish
with
line equalization. The limits of practicality depend on the application.
Trans-oceanic telephones cables used very high voltages. Cables that run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/-Hide quoted text -

- Show quoted text -

"Bell System" lines receive no power from individual houses. Excepting
the early "Princess" phones which had separate local power for the
lighted dial, and multi-line sets with similar lighted buttons. When
these phones went modular, a very special adaptor was required (for
the princess-style).

Should I be abuse over your error?

You are welcome to if you first explain what my error is? The "OP" was
talking about ADSL, so I was referring to my AT&T DSL modem which is
powered from my home with electricity I provide for it.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/- Hide quoted text -

- Show quoted text -

And you made a blanket statement. The ADSL unit you have at home is
powered by your mains, yes. However, what gives between it and the
"switch" is 100% powered by the Company. Keep in mind that part of the
"Bell System" tariffs is that _NO_ external power sources are applied
to their lines for security and operational safety purposes. Imagine
the situation if somehow straight line-voltage found a way into the
Phone Lines.....

And exactly why I used the Princess Phone analogy. The princess had a
light which was powered from a local source, but much care was taken
to make sure that the source could not impinge on the line. The
electronics in the ADSL are local-power. The signal is "Bell System"
power.

Peter Wieck
Wyncote, PA

[John Byrns]

In article . com,
Peter Wieck wrote:

On Jun 2, 9:22 pm, John Byrns wrote:
In article . com,
Peter Wieck wrote:

On Jun 2, 10:09 am, John Byrns wrote:
In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can
accomplish
with
line equalization. The limits of practicality depend on the
application.
Trans-oceanic telephones cables used very high voltages. Cables that
run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.

"Bell System" lines receive no power from individual houses. Excepting
the early "Princess" phones which had separate local power for the
lighted dial, and multi-line sets with similar lighted buttons. When
these phones went modular, a very special adaptor was required (for
the princess-style).

Should I be abuse over your error?

You are welcome to if you first explain what my error is? The "OP" was
talking about ADSL, so I was referring to my AT&T DSL modem which is
powered from my home with electricity I provide for it.

And you made a blanket statement. The ADSL unit you have at home is
powered by your mains, yes. However, what gives between it and the
"switch" is 100% powered by the Company. Keep in mind that part of the
"Bell System" tariffs is that _NO_ external power sources are applied
to their lines for security and operational safety purposes. Imagine
the situation if somehow straight line-voltage found a way into the
Phone Lines.....

And exactly why I used the Princess Phone analogy. The princess had a
light which was powered from a local source, but much care was taken
to make sure that the source could not impinge on the line. The
electronics in the ADSL are local-power. The signal is "Bell System"
power.


Peter, you are playing the old internet game of putting words in
someone's mouth and then claiming they made an error because the words
you put in their mouth were in error. You are taking my statement
completely out of its original context and also trying to ascribe some
"blanket" meaning to it that it never had.

This thread was originally about "Shielded mains cable", as is typical
of internet threads, topic drift occurred and the issue of phone line
bandwidth was brought into the discussion. At that point Eeyore/Graham
commented that phone lines had a bandwidth of at least 1 MHz, citing the
example of ADSL as proof. At that point I asked what the signal to
noise ratio of a phone line was at 1 MHz, and also why the range of DSL
was less than the range of voice. Someone answered that the attenuation
of a phone line was greater at 1 MHz than at voice frequencies, so the
range of DSL less than range of voice signals, dodging the issue of
signal to noise ratio. Thinking there might be more involved than
simply attenuation, I attempted to draw out all the issues relating to
signal to noise ratio by asking the question, if attenuation were all
there was to it, wouldn't it be true that "a properly equalized
amplifier would be all that would be needed to make the range of DSL on
a given cable independent of the bit rate, so there must be more to it
than Graham is admitting to?" At that point Arny Krueger commented "I
don't think so. There are practical limits to what you can accomplish
with line equalization. The limits of practicality depend on the
application. Trans-oceanic telephones cables used very high voltages.
Cables that run through people's houses and backyards can't go there."
This raised the issue of "high voltages" running "through people's
houses and backyards" to which I responded "Cables that run through
people's houses and backyards don't have to go there, there is local
power available in the house to power the equipment." This is my
statement that you are taking exception to and calling a "blanket"
statement. I guess you could say that is a "blanket" statement in the
sense that "there is local power available in the house to power the
equipment" which is true, but notice I didn't say this "local power" was
used to power all the telephone equipment in a house, just that power
was available. I was simply pointing out that there was no need for the
telephone company to transmit high voltage power through people's back
yards and into their house to power equipment as was done with the
Trans-oceanic telephone cables. My point was that "local" power was
available in the house to power equipment like DSL modems, I made this
statement because that is how my AT&T DSL modem is powered, i.e. from
"local" power I provide, not from "high voltage" transmitted through my
backyard on the telephone cable.

What is your point, are you saying I am wrong when I stated that DSL
modems and the like are powered "locally"? Your statement that "The
signal is 'Bell System' power" is also certainly wrong, or at least half
wrong. The downstream signal may be "Bell System" power, but the
upstream signal is clearly my "local" power.


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Peter Wieck]

On Jun 3, 10:21 am, John Byrns wrote:
In article . com,
Peter Wieck wrote:





On Jun 2, 9:22 pm, John Byrns wrote:
In article . com,
Peter Wieck wrote:

On Jun 2, 10:09 am, John Byrns wrote:
In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message

In article ,
"Arny Krueger" wrote:

"John Byrns" wrote in message


I also meant to ask why DSL doesn't have the same range
as voice transmitted from the exchange over the same
pair?

AFAIK, it is becasue the higher frequencies DSL works at
have more line loss. For example, my sources say that
heavier gauge telephone wire gives greater DSL range at
a given data rate, or a higher data rate for a given
distance.

Yes, the greater loss as the frequency increases is
obvious, if that were all there was to it, logic would
say that a properly equalized amplifier would be all that
would be needed to make the range of DSL on a given cable
independent of the bit rate, so there must be more to it
than Graham is admitting to?

I don't think so. There are practical limits to what you can
accomplish
with
line equalization. The limits of practicality depend on the
application.
Trans-oceanic telephones cables used very high voltages. Cables that
run
through people's houses and backyards can't go there.

I don't know what the signal voltage used on the Trans-oceanic
telephones cables was, but I would be surprised if it was unusually
high. The high voltage you are referring to, which I think was several
thousand volts positive at one end of the cable and several thousand
volts negative at the other end of the cable, was the power source for
the repeaters of which there were a very large number. The repeaters
were powered in series like Christmas tree lights, and IIRC the power
feed was a constant current.

Cables that run through people's houses and backyards don't have to go
there, there is local power available in the house to power the
equipment.

"Bell System" lines receive no power from individual houses. Excepting
the early "Princess" phones which had separate local power for the
lighted dial, and multi-line sets with similar lighted buttons. When
these phones went modular, a very special adaptor was required (for
the princess-style).

Should I be abuse over your error?

You are welcome to if you first explain what my error is? The "OP" was
talking about ADSL, so I was referring to my AT&T DSL modem which is
powered from my home with electricity I provide for it.

And you made a blanket statement. The ADSL unit you have at home is
powered by your mains, yes. However, what gives between it and the
"switch" is 100% powered by the Company. Keep in mind that part of the
"Bell System" tariffs is that _NO_ external power sources are applied
to their lines for security and operational safety purposes. Imagine
the situation if somehow straight line-voltage found a way into the
Phone Lines.....

And exactly why I used the Princess Phone analogy. The princess had a
light which was powered from a local source, but much care was taken
to make sure that the source could not impinge on the line. The
electronics in the ADSL are local-power. The signal is "Bell System"
power.

Peter, you are playing the old internet game of putting words in
someone's mouth and then claiming they made an error because the words
you put in their mouth were in error. You are taking my statement
completely out of its original context and also trying to ascribe some
"blanket" meaning to it that it never had.

This thread was originally about "Shielded mains cable", as is typical
of internet threads, topic drift occurred and the issue of phone line
bandwidth was brought into the discussion. At that point Eeyore/Graham
commented that phone lines had a bandwidth of at least 1 MHz, citing the
example of ADSL as proof. At that point I asked what the signal to
noise ratio of a phone line was at 1 MHz, and also why the range of DSL
was less than the range of voice. Someone answered that the attenuation
of a phone line was greater at 1 MHz than at voice frequencies, so the
range of DSL less than range of voice signals, dodging the issue of
signal to noise ratio. Thinking there might be more involved than
simply attenuation, I attempted to draw out all the issues relating to
signal to noise ratio by asking the question, if attenuation were all
there was to it, wouldn't it be true that "a properly equalized
amplifier would be all that would be needed to make the range of DSL on
a given cable independent of the bit rate, so there must be more to it
than Graham is admitting to?" At that point Arny Krueger commented "I
don't think so. There are practical limits to what you can accomplish
with line equalization. The limits of practicality depend on the
application. Trans-oceanic telephones cables used very high voltages.
Cables that run through people's houses and backyards can't go there."
This raised the issue of "high voltages" running "through people's
houses and backyards" to which I responded "Cables that run through
people's houses and backyards don't have to go there, there is local
power available in the house to power the equipment." This is my
statement that you are taking exception to and calling a "blanket"
statement. I guess you could say that is a "blanket" statement in the
sense that "there is local power available in the house to power the
equipment" which is true, but notice I didn't say this "local power" was
used to power all the telephone equipment in a house, just that power
was available. I was simply pointing out that there was no need for the
telephone company to transmit high voltage power through people's back
yards and into their house to power equipment as was done with the
Trans-oceanic telephone cables. My point was that "local" power was
available in the house to power equipment like DSL modems, I made this
statement because that is how my AT&T DSL modem is powered, i.e. from
"local" power I provide, not from "high voltage" transmitted through my
backyard on the telephone cable.

What is your point, are you saying I am wrong when I stated that DSL
modems and the like are powered "locally"? Your statement that "The
signal is 'Bell System' power" is also certainly wrong, or at least half
wrong. The downstream signal may be "Bell System" power, but the
upstream signal is clearly my "local" power.

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/- Hide quoted text -

- Show quoted text -

John:

Your equipment, exactly as the light in the Princess Phone is locally
powered. And that is exactly as far as it goes. The ADSL Modem induces
a signal onto the "Bell System" powered line, but does not add any
power to that line from any local source. That is the point... and
with some thought, that is why it is rather obvious why a digital
signal would not have near as much range as an analog signal due to
cliff effects if nothing else.

Peter Wieck
Wyncote, PA

[John Byrns]

In article .com,
Peter Wieck wrote:

John:

Your equipment, exactly as the light in the Princess Phone is locally
powered.

True, I don't believe I stated otherwise.

And that is exactly as far as it goes.

Not quite.

The ADSL Modem induces
a signal onto the "Bell System" powered line, but does not add any
power to that line from any local source.

Wrong, the signal power transmitted by my DSL modem into the "Bell
System" phone line comes from my "local" power source, not from a "Bell
System" power source, and it adds power to the line.

I think you need to study up on how DSL works, it sounds like you are
being confused by the way "Bell System" POTS Telephones work.

When I was a young boy my Grandmother had a "General Telephone"
Telephone at her summer home which operated differently than a "Bell
System" Telephone, all the power for speech and signaling delivered by
the phone to the line came from "local" sources, so all phones don't
even operate in the same way with respect to power sources.

That is the point... and
with some thought, that is why it is rather obvious why a digital
signal would not have near as much range as an analog signal due to
cliff effects if nothing else.

Huh, could you elaborate on that, it sounds like complete nonsense at
first blush, am I missing something? What are "cliff effects", it
sounds like something to do with college exams?


Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

[Peter Wieck]

On Jun 3, 5:42 pm, John Byrns wrote:
In article .com,
Peter Wieck wrote:

John:

Your equipment, exactly as the light in the Princess Phone is locally
powered.

True, I don't believe I stated otherwise.

And that is exactly as far as it goes.

Not quite.

The ADSL Modem induces
a signal onto the "Bell System" powered line, but does not add any
power to that line from any local source.

Wrong, the signal power transmitted by my DSL modem into the "Bell
System" phone line comes from my "local" power source, not from a "Bell
System" power source, and it adds power to the line.

I think you need to study up on how DSL works, it sounds like you are
being confused by the way "Bell System" POTS Telephones work.

When I was a young boy my Grandmother had a "General Telephone"
Telephone at her summer home which operated differently than a "Bell
System" Telephone, all the power for speech and signaling delivered by
the phone to the line came from "local" sources, so all phones don't
even operate in the same way with respect to power sources.

That is the point... and
with some thought, that is why it is rather obvious why a digital
signal would not have near as much range as an analog signal due to
cliff effects if nothing else.

Huh, could you elaborate on that, it sounds like complete nonsense at
first blush, am I missing something? What are "cliff effects", it
sounds like something to do with college exams?

Regards,

John Byrns

--
Surf my web pages at, http://fmamradios.com/

Yikes... exactly how does your ADSL modem "add power" to the "Bell
System" lines?

Cliff Effects: Digital signal 'falls off a cliff' when it degrades
beyond use. Analog signal degrades on a more-or-less linear basis.
Pretty elementary stuff.

Peter Wieck
Wyncote, PA

[west[_4_]]

Eyeso why do you qualify your contention further on down the thread?
Clever subject switching, but not unnoticeable, asshole doubletalker.

"Eeyore" wrote in message
...


west wrote:

"Eeyore" wrote
west wrote:
"Eeyore" wrote
west wrote:

This shield ground is to eliminate induced RF interference in
the AC
line.

No it isn't. You need to learn what induction is.

I didn't think you were the type inclined to toss out a curt
diatribe.
Perhaps you need to learn the conventions of a civilized dialog.

You need to learn the conventions of not talking out of your rectum.


I'm glad that you didn't waste any time defining who you are, so from
now
on I'll know to avoid you and any opinions you might express.

From previous posts of yours I've noticed that you don't like to sully
yourself
with technical truths when magical myths will do, so you wouldn't much
like what
I'd say anyway.

Graham

[west[_4_]]

There's eyesore's strawman...changing the topic to not embarrass herself.

"Eeyore" wrote in message
...


Iain Churches wrote:

Here in Europe, many
studios are using tube power amps, mic preamps and outboard
processing also.

!!!

Maybe the antique 'boutique' stuff.

Graham

[west[_4_]]

What the heck does that have to do with shielded AC lines, asshole eyesore?

"Eeyore" wrote in message
...


Iain Churches wrote:

"Eeyore" wrote
Iain Churches wrote:

Here in Europe, many
studios are using tube power amps, mic preamps and outboard
processing also.

!!!

Maybe the antique 'boutique' stuff.

Studios provide what clients ask for. Simple as that.
Market research is an important factor in any successful
business.

You don't need to do much research to know that Teletronix / Urei optical
compressors are much liked.
http://www.barryrudolph.com/mix/bombfactory.html

These days you can get them as digital plug-ins though.

[west[_4_]]

Hey stupid, ever hear of twisted pair? Know the narrow bandwidth your
working with? Stay out of topics you know nothing about. There's no twisted
pair that can attenuate that bull****.

"Eeyore" wrote in message
...


Iain Churches wrote:

One guy a retired German broadcast engineer told me that it
was standard practice in analogue equipment racks for *all*
cables to be screened with RF shields.

Typical Germanic overkill ! :~)

Have you ever considerd why your phone line doesn't hum appreciably
despite
consisting of maybe 7 km of unscreened wire ?

Graham

[Eeyore]

west wrote:

Eyeso why do you qualify your contention further on down the thread?
Clever subject switching, but not unnoticeable, asshole doubletalker.

Bugger off you know-nothing pontificating nitwit.

I'm sick of the likes of you pulluting the world with your idiot know-nothing
stupid jibes.

Graham

[west[_4_]]

"Arny Krueger" wrote in message
. ..
"Eeyore" wrote in
message
Arny Krueger wrote:

This raises the question of why people are using
screened power cables at all. I suspect they are trying
to address very high frequency radiation which is also
being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the
shielding could be effective, even though its attached
to possibly unshielded power wiring in the wall.

Look at the equipment using it.

Problematical if it radiated EMI.

I'm sure it's being used
to contain / reduce EMI.

Yup.

I'd have to check out what's
happening. It's simply a myth that having a screened
cable stops the cable radiating (or receiving) like an
aerial AIUI.

Then how does it contain/reduce EMI?

If you notice, eyesore doesn't offer any plausible explanation for his
disagreement. Even though I and many manufacturers like GE, Phillips,
Siemens used this technique for over 20 years on sophisticated medical
systems, some costing over a million dollars, it means nothing to eyesore. I
believe he's another one that simply can not say "I'm wrong and I learned
something today."

west

[Eeyore]

west wrote:

"Eeyore" wrote
Iain Churches wrote:

Here in Europe, many
studios are using tube power amps, mic preamps and outboard
processing also.

!!!

Maybe the antique 'boutique' stuff.

There's eyesore's strawman...changing the topic to not embarrass herself.

There is virtually ZERO *new* tube gear in pro-audio. Such as there is is almost
exclusively in the 'toy box' category such as signal processing equipment
designed to intentionally alter the sound.

Professionals aren't gullible idiots like you. They'll use tube gear to *add
colouration* when it's felt necessary. No professional labours under the
mythical belief that tubes are 'more accurate'.


Graham

[Eeyore]

west wrote:

What the heck does that have to do with shielded AC lines, asshole eyesore?

It's called 'thread drift' you brain dead ****wit.

Graham

[Eeyore]

west wrote:

"Eeyore" wrote in message
Iain Churches wrote:

One guy a retired German broadcast engineer told me that it
was standard practice in analogue equipment racks for *all*
cables to be screened with RF shields.

Typical Germanic overkill ! :~)

Have you ever considerd why your phone line doesn't hum appreciably
despite consisting of maybe 7 km of unscreened wire ?


Hey stupid, ever hear of twisted pair?

You bet.

It doesn't have a screen though does it ?


Know the narrow bandwidth your working with?

DSL signals go just beyond 1MHz down the same telephone cable.

What did you say about narrow bandwidth ?


Stay out of topics you know nothing about.

Bwahahahahahahahaha !

Precious !

Graham

[Eeyore]

west wrote:

"Arny Krueger" wrote
"Eeyore" wrote
Arny Krueger wrote:

This raises the question of why people are using
screened power cables at all. I suspect they are trying
to address very high frequency radiation which is also
being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the
shielding could be effective, even though its attached
to possibly unshielded power wiring in the wall.

Look at the equipment using it.

Problematical if it radiated EMI.

I'm sure it's being used
to contain / reduce EMI.

Yup.

I'd have to check out what's
happening. It's simply a myth that having a screened
cable stops the cable radiating (or receiving) like an
aerial AIUI.

Then how does it contain/reduce EMI?

If you notice, eyesore doesn't offer any plausible explanation for his
disagreement. Even though I and many manufacturers like GE, Phillips,
Siemens used this technique for over 20 years on sophisticated medical
systems, some costing over a million dollars, it means nothing to eyesore. I
believe he's another one that simply can not say "I'm wrong and I learned
something today."

So you can tell us all about B, H and E fields then can't you ?

Graham

[Iain Churches]

"Arny Krueger" wrote in message
...
"Eeyore" wrote in
message
Peter Wieck wrote:

A shielded mains cable *might* be useful against heavy
transients from equipment nearby,

How ?

*might* be useful against noise from switching power-
supplies, *might* be useful against local rF sources
(and if you discount this, you have never experienced CB
interference from truckers with massive (and illegal)
linear amps on their rigs). Operative word in all cases
is *might*.

It'll do nothing about the unscreened cable in the wall
so will have effectively zero impact.

This raises the question of why people are using screened power cables at
all. I suspect they are trying to address very high frequency radiation
which is also being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the shielding could be
effective, even though its attached to possibly unshielded power wiring
in the wall.

Hi Arny. I am grateful to John Woodgate of the ISCE for the answer:

"The screen may be intended to reduce emissions *from* the cable,
rather than improving immunity. A Class D amplifier, is very likely to
interfere with AM radio reception, yours or in adjacent houses. This
happens even if the emission standard, EN 55013, (or EN 55103-1
for a professional product) is met, because the amplifier is quite close
to the receiver."

Regards to all
Iain

[Eeyore]

Iain Churches wrote:

"Arny Krueger" wrote
"Eeyore" wrote
Peter Wieck wrote:

A shielded mains cable *might* be useful against heavy
transients from equipment nearby,

How ?

*might* be useful against noise from switching power-
supplies, *might* be useful against local rF sources
(and if you discount this, you have never experienced CB
interference from truckers with massive (and illegal)
linear amps on their rigs). Operative word in all cases
is *might*.

It'll do nothing about the unscreened cable in the wall
so will have effectively zero impact.

This raises the question of why people are using screened power cables at
all. I suspect they are trying to address very high frequency radiation
which is also being reduced by the inductance and capacitance over the
length of the power cable. This would explain why the shielding could be
effective, even though its attached to possibly unshielded power wiring
in the wall.

Hi Arny. I am grateful to John Woodgate of the ISCE for the answer:

"The screen may be intended to reduce emissions *from* the cable,
rather than improving immunity. A Class D amplifier, is very likely to
interfere with AM radio reception, yours or in adjacent houses. This
happens even if the emission standard, EN 55013, (or EN 55103-1
for a professional product) is met, because the amplifier is quite close
to the receiver."

Exactly.

That's what I'd expect.

Graham

[Sander deWaal]

Chris Hornbeck said:


Clamp-on ferrite chokes are cheap insurance too.


And not nearly as effective as real EMC measures inside the box.
Clamp-on ferrites have the disadvantage of the necessary air gap,
thereby reducing the effect.

I use shielded mains cables on all things digital to prevent radiation
*out*, not *in*.

--

- Maggies are an addiction for life. -

[Sander deWaal]

robert casey said:


We don't use that kind of 'zip cord' here in the UK. An outer jacket is required
for a mains lead for safety. As such I'm sure it would be easy to make twisted
pair power leads for use from wall socket / plugboird to equipment.


I've seen those power cords on stuff from Asia. Blue and brown wires
inside a jacket. It should take twisting as well, though it will want
to untwist itself until the jacket takes the "set".


Be very careful with twisting a cable like this, you might pull the
core out of the connectors.

--

- Maggies are an addiction for life. -

[Sander deWaal]

Eeyore said:


None of these companies was notable for high spec audio test gear. They
did make general test equipment for sure but nothing to associate them
specifically with pro-audio or hi-fi.


One used to see lots of Marconi and Racal,


I never have myself. A slightly different era perhaps ?


I still have this set, it even gets used every now and then:

http://img526.imageshack.us/img526/8092/marconiaq9.jpg

Nothing like the feel of real ceramic rotary switches and wirewound
pots (though my PC with USB preamp and Smaart/RMAA/Cooledit works both
faster and more precise).

--

- Maggies are an addiction for life. -

[Eeyore]

Sander deWaal wrote:

Eeyore said:

None of these companies was notable for high spec audio test gear. They
did make general test equipment for sure but nothing to associate them
specifically with pro-audio or hi-fi.

One used to see lots of Marconi and Racal,

I never have myself. A slightly different era perhaps ?

I still have this set, it even gets used every now and then:

http://img526.imageshack.us/img526/8092/marconiaq9.jpg

Nothing like the feel of real ceramic rotary switches and wirewound
pots (though my PC with USB preamp and Smaart/RMAA/Cooledit works both
faster and more precise).

Did you know that early Neve consoles used Marconi knobs ?

Graham

[Eeyore]

Sander deWaal wrote:

Chris Hornbeck said:

Clamp-on ferrite chokes are cheap insurance too.

And not nearly as effective as real EMC measures inside the box.
Clamp-on ferrites have the disadvantage of the necessary air gap,
thereby reducing the effect.

I use shielded mains cables on all things digital to prevent radiation
*out*, not *in*.

Exactly.

For the dimwits who keep pestering about it........

The reaon it's a waste of time screening the mains cable on typical audio
equipment is that it's not a point that's particularly *susceptible* to
inteference.

Graham

[west[_4_]]

Is there any concern for eyesore's sickness ...anybody? Always remember, you
struck the first blow.

west

"Eeyore" wrote in message
...


west wrote:

Eyeso why do you qualify your contention further on down the thread?
Clever subject switching, but not unnoticeable, asshole doubletalker.

Bugger off you know-nothing pontificating nitwit.

I'm sick of the likes of you pulluting the world with your idiot
know-nothing
stupid jibes.

Graham

[west[_4_]]

Eyeso what's unnatural is using a basic switching device for an
amplifier. What's unnatural is pushing then pulling down a signal. Your
absolutely off base when you say tubes are unnatural. Your natural world is
antiseptic, no art, no music, no beauty.
west

"Eeyore" wrote in message
...


west wrote:

"Eeyore" wrote
Iain Churches wrote:

Here in Europe, many
studios are using tube power amps, mic preamps and outboard
processing also.

!!!

Maybe the antique 'boutique' stuff.

There's eyesore's strawman...changing the topic to not embarrass
herself.

There is virtually ZERO *new* tube gear in pro-audio. Such as there is is
almost
exclusively in the 'toy box' category such as signal processing equipment
designed to intentionally alter the sound.

Professionals aren't gullible idiots like you. They'll use tube gear to
*add
colouration* when it's felt necessary. No professional labours under the
mythical belief that tubes are 'more accurate'.


Graham

[Eeyore]

west wrote:

Always remember, you struck the first blow.

My pleasure

[Eeyore]

west wrote:

Eyeso what's unnatural is using a basic switching device for an
amplifier.

What switching device ?