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July 28, 2005 2:06:41 PM

Archived from groups: rec.audio.tech (More info?)

I read an article in the latest Skeptic magazine on Audio scams. The
author states that there is no reason to pay more than $3/foot for
speaker cable and interconnects. Does anyone have evidence to
contradict this? What about the connectors attached to the cable?

Dan

More about : audio cable

Anonymous
July 28, 2005 2:06:42 PM

Archived from groups: rec.audio.tech (More info?)

"Dan" wrote ...
>I read an article in the latest Skeptic magazine on Audio
> scams. The author states that there is no reason to pay
> more than $3/foot for speaker cable and interconnects. Does anyone have
> evidence to contradict this?

Does anyone have any evidence to show that expensive
cable really DOES sound better? (Hint: No)

I would never pay as much as $3/ft for speaker cable.
That is outrageous. Even complex 14-conductor TV
camera cable doesn't cost that much!

> What about the connectors attached to the cable?

What kind of connectors do you use on speaker cable?
Anonymous
July 28, 2005 3:27:45 PM

Archived from groups: rec.audio.tech (More info?)

"Dan" <dan@nospam.com> wrote in message
news:5w6Ge.3$0B5.2008@news.uswest.net

> I read an article in the latest Skeptic magazine on Audio
> scams. The author states that there is no reason to pay
> more than $3/foot for speaker cable and interconnects.

Seems plenty high of a price to allow for more than enough
quality.

> Does anyone have evidence to contradict this?

Such evidence will prove to be highly elusive.

> What about the connectors attached to the cable?

Hi fi speaker cables generally require no connectors. 12
gauge finely stranded wire runs under $0.50 per foot in
hardware and home improvement stores.

Good shielded speaker cable or interconnect cable costs less
than $0.50 per foot. Good RCA connectors are still under
$2.00. A typical 3 foot cable can thus be assembled for
under $7.50 or bought pre-assembled for under $5.00.
Related resources
Anonymous
July 28, 2005 9:36:02 PM

Archived from groups: rec.audio.tech (More info?)

>I read an article in the latest Skeptic magazine on Audio scams. The
>author states that there is no reason to pay more than $3/foot for
>speaker cable and interconnects. Does anyone have evidence to
>contradict this? What about the connectors attached to the cable?

I tend to agree, although I question whether a flat $NN/foot is the
right way to look at it.

High-quality, flexible, well-shielded interconnect stereo interconnect
cable need not cost more than a dollar a foot (and it's probably less
than $0.25 per foot in bulk). Good terminations aren't all that
expensive, either - a few dollars per pair will get you some very
serviceable RCAs.

Speaker cable, also, need not be expensive. I usually consider 10-12
gauge stranded pair to be a good choice. As long as it's of
sufficiently heavy gauge to have low resistive losses, flexible enough
to be placed in your room conveniently, and uses a stable insulation
polymer that doesn't outgas chlorine vapor and turn the copper green
(which happens with some cheap PVC), I see little need for anything
fancier. As an example here, Belden 8477 is a 4-wire, 12-gauge
high-conductivity copper cable intended for speaker applications - you
can use two wires in parallel for each side of the signal and get the
equivalent of a 9-gauge pair (with lower inductance). Newark sells it
for $261.04 for a 500-foot spool - that's about half a buck a foot.

From what I've seen in the trade ads, I believe that a lot of the
"technical" claims used to justify the alleged superiority of boutique
cables are either completely nonsensical, or are technically valid but
irrelevant when the cables are used in a stereo system (any difference
these cables make are far below the human perceptual threshold and far
below the level of other effects in the system).

That's not to say that boutique cables with fancy claims are _bad_
cables. They probably aren't. They're probably just fine. They just
aren't audibly superior to cables costing a tenth as much.

I've heard, a number of times, that audio dealerships *love* these
cables. They're usually a fairly easy sell (playing on buyers'
insecurities and desire for "the best"), and they have a high profit
margin... often higher than the whole rest of the sale!

--
Dave Platt <dplatt@radagast.org> AE6EO
Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
Anonymous
July 29, 2005 1:30:33 AM

Archived from groups: rec.audio.tech (More info?)

On Thu, 28 Jul 2005 10:06:41 -0500, Dan <dan@nospam.com> wrote:

>I read an article in the latest Skeptic magazine on Audio scams. The
>author states that there is no reason to pay more than $3/foot for
>speaker cable and interconnects.

Three dollars per foot is still a really high price.

>Does anyone have evidence to
>contradict this?

Is there any evidence to support it?

>What about the connectors attached to the cable?
>
>Dan

-----
http://www.mindspring.com/~benbradley
Anonymous
July 29, 2005 4:26:14 AM

Archived from groups: rec.audio.tech (More info?)

On Thu, 28 Jul 2005 08:42:05 -0700, Richard Crowley <richard.7.crowley@intel.com> wrote:


>"Dan" wrote ...
>>I read an article in the latest Skeptic magazine on Audio
>> scams. The author states that there is no reason to pay
>> more than $3/foot for speaker cable and interconnects. Does anyone have
>> evidence to contradict this?

>Does anyone have any evidence to show that expensive
>cable really DOES sound better? (Hint: No)

It depends on what you mean by "sound better". Most "audiophile" cables are so
amazingly mediocre that they can barely handle frequencies above about 12khz
giving audiophiles that "warm" (muffled) sound that helps their CDs sound like
their familiar worn out LPs. And of course, there's that special feeling of
pride that comes from having spent too much.

I still get a chuckle over the idea of thousand dollar power cords.

Anything more than about a buck a foot or $5/connector is a serious ripoff. It
doesn't take much to make a cable vanishingly clean compared to the rest of the
audio chain.
Anonymous
July 29, 2005 10:54:10 AM

Archived from groups: rec.audio.tech (More info?)

"AZ Nomad" <aznomad@PmunOgeBOX.com> wrote in message
news:slrndeittb.e3r.aznomad@ip70-176-155-130.ph.ph.cox.net
> On Thu, 28 Jul 2005 08:42:05 -0700, Richard Crowley

> It depends on what you mean by "sound better". Most
> "audiophile" cables are so amazingly mediocre that they
> can barely handle frequencies above about 12khz
> giving audiophiles that "warm" (muffled) sound that
> helps their CDs sound like
> their familiar worn out LPs.

Nahh. Most audiophile cables are just pretty good cable
doctored up to look expensive.

> And of course, there's that
> special feeling of
> pride that comes from having spent too much.

Agreed.

> I still get a chuckle over the idea of thousand dollar
> power cords.

I've read some audiophiles hooting and holloring about the
alleged benefits of shielded IEC power cables. Recently I
hung a bunch of florescent fixtures that needed power cables
added. So, I grabbed a bunch of old PC IEC power cables that
were stacking up in the dust and stripped one end off of
them and wired em up. They were all shielded.

> Anything more than about a buck a foot or $5/connector is
> a serious ripoff.

Agreed.

> It doesn't take much to make a cable vanishingly clean
> compared to the rest of the audio chain.

Agreed.
Anonymous
July 29, 2005 1:40:07 PM

Archived from groups: rec.audio.tech (More info?)

The NRC, among a number of research groups found that for speaker cable, any
large gauge fine strand cable will work for speaker wire. Extensive testing
was done under controlled conditions.

Good quality wire in the AWG # 10 to 14 range can be found for about $0.60
to about $1.20 per foot on the average. We did some tests using AWG # 12
Captire. This is heavy duty flexible electrical wire. There was no audible
difference between the Captire, and the very expensive wire that we tested
from the audio store.

The connectors can also be over priced from many dealers. A connector that
costs only a few dollars should be okay.

See if you can borrow some high prices speaker wire that has no added
chokes, or filters in it, and also get some Captire. Connect them both up
through an A/B switch arrangement to the same set of speakers. Put on some
critical music. While the music is playing, switch from one side to the
other. I doubt you will hear any difference. I have repeated this type of
test myself, on many occasions.

Every time, I make a comment like this, I get a lot of flames. But, most are
from the dealers who want to sell the expensive wire, and some are from
people who want to believe that their expensive wire is justified.

--

JANA
_____


"Dan" <dan@nospam.com> wrote in message
news:5w6Ge.3$0B5.2008@news.uswest.net...
I read an article in the latest Skeptic magazine on Audio scams. The
author states that there is no reason to pay more than $3/foot for
speaker cable and interconnects. Does anyone have evidence to
contradict this? What about the connectors attached to the cable?

Dan
Anonymous
July 29, 2005 1:40:08 PM

Archived from groups: rec.audio.tech (More info?)

"JANA" wrote ...
> Good quality wire in the AWG # 10 to 14 range can be found
> for about $0.60 to about $1.20 per foot on the average.
....
> Every time, I make a comment like this, I get a lot of flames.
> But, most are from the dealers who want to sell the expensive
> wire, and some are from people who want to believe that their
> expensive wire is justified.

Precisely. Well said.
Anonymous
July 29, 2005 10:23:00 PM

Archived from groups: rec.audio.tech (More info?)

"AZ Nomad" <aznomad@PmunOgeBOX.com> wrote in message

>
> It depends on what you mean by "sound better". Most "audiophile" cables
> are so
> amazingly mediocre that they can barely handle frequencies above about
> 12khz
> giving audiophiles that "warm" (muffled) sound that helps their CDs sound
> like
> their familiar worn out LPs. And of course, there's that special feeling
> of
> pride that comes from having spent too much.

That's odd. I've never noticed the cheapest most horrible cables being
remoterly down at 12K, let alone supposedly audiophool ones.

>
> I still get a chuckle over the idea of thousand dollar power cords.

It doesn't make me chuckle - it makes me angry.

geoff
Anonymous
July 29, 2005 10:23:01 PM

Archived from groups: rec.audio.tech (More info?)

On Fri, 29 Jul 2005 18:23:00 +1200, "Geoff Wood"
<geoff@nospam-paf.co.nz> wrote:

>
>"AZ Nomad" <aznomad@PmunOgeBOX.com> wrote in message
>
>>
>> It depends on what you mean by "sound better". Most "audiophile" cables
>> are so
>> amazingly mediocre that they can barely handle frequencies above about
>> 12khz
>> giving audiophiles that "warm" (muffled) sound that helps their CDs sound
>> like
>> their familiar worn out LPs. And of course, there's that special feeling
>> of
>> pride that comes from having spent too much.
>
>That's odd. I've never noticed the cheapest most horrible cables being
>remoterly down at 12K, let alone supposedly audiophool ones.

It's virtually impossible to accidentally make cable that bad. An
audible change in frequency response is clearly no accident.
Scott has written about "high-end" speaker cable having unusually
high induictance and capacitance (possibly such components built into
the connectors?), enough so that it DOES affect the sound. This gives
the manufacturers 'evidence' that their cables really are 'better'
(sound different).

>> I still get a chuckle over the idea of thousand dollar power cords.
>
>It doesn't make me chuckle - it makes me angry.

I can understand that reaction, but of all the injustices in the
world, "Audiophool Cable" isn't really that big. I've never heard of
anyone going hungry because someone sold them expensive speaker cable.
You might as well go against the White Van Speakers sellers in the
vacant parking lot, how record labels treat artists, or if you really
want to be a hero, go after spammers.

>geoff
>

-----
http://www.mindspring.com/~benbradley
Anonymous
July 30, 2005 1:53:29 AM

Archived from groups: rec.audio.tech (More info?)

On Thu, 28 Jul 2005 10:06:41 -0500, Dan <dan@nospam.com> wrote:

>I read an article in the latest Skeptic magazine on Audio scams. The
>author states that there is no reason to pay more than $3/foot for
>speaker cable and interconnects. Does anyone have evidence to
>contradict this? What about the connectors attached to the cable?

Connectors are absolutely essential. Though I've never understood
why the audiophools don't insist on soldered connections, bypassing
plugs and sockets entirely. They could insist on gold-plated solder
and boutique soldering guns if it wasn't satisfyingly expensive
enough.
July 30, 2005 5:16:44 PM

Archived from groups: rec.audio.tech (More info?)

"Geoff Wood" <geoff@nospam-paf.co.nz> wrote in
news:42e9cb3f$1@clear.net.nz:

>
> "AZ Nomad" <aznomad@PmunOgeBOX.com> wrote in message
>
>>
>> It depends on what you mean by "sound better". Most "audiophile"
>> cables are so
>> amazingly mediocre that they can barely handle frequencies above
>> about 12khz
>> giving audiophiles that "warm" (muffled) sound that helps their CDs
>> sound like
>> their familiar worn out LPs. And of course, there's that special
>> feeling of
>> pride that comes from having spent too much.
>
> That's odd. I've never noticed the cheapest most horrible cables
> being remoterly down at 12K, let alone supposedly audiophool ones.
>
> geoff
>
>

Agreed. I measured a bunch of 25 foot long cables a while back. The worst
of them had a frequency response well beyond 50kHz and only because it was
more than triple the typical shunt capacitance per foot of cable you'd
likely find in a system.

-Bruce
Anonymous
July 30, 2005 5:39:08 PM

Archived from groups: rec.audio.tech (More info?)

On Sat, 30 Jul 2005 13:16:44 GMT, Bruce <xxx@yyy.zzz> wrote:

>Agreed. I measured a bunch of 25 foot long cables a while back. The worst
>of them had a frequency response well beyond 50kHz and only because it was
>more than triple the typical shunt capacitance per foot of cable you'd
>likely find in a system.
>
>-Bruce

I've got news for you. Every one of those cables has a useful
frequency response to well beyond 1GHz. The cable has yet to be made
that doesn't manage at least 100MHz without undue attenuation.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 3:53:43 PM

Archived from groups: rec.audio.tech (More info?)

If they were _really_ serious they would want welded, not soldered,
connections with the small oxypropane or oxyhydrogen equipment common
in the jewelry trade.

The continued omnipresence of IEC and RCA connectors on allegedly high
end equipment belies the lie of high end audio as strongly as anything
else.
Anonymous
July 31, 2005 7:19:45 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ed82b9.60031781@text.usenet.plus.net...
> I've got news for you. Every one of those cables has a useful
> frequency response to well beyond 1GHz. The cable has yet to be made
> that doesn't manage at least 100MHz without undue attenuation.

What a blanket statement without any mention of source impedance, load
impedance, cable length, or what constitutes undue attenuation!

I've yet to see a standard audio cable that is useful at 1 Ghz frequencies.
I have seen "undue attenuation" at 50kHz with some source/load/cable
combinations however.

Fortunately most cables are quite adequate in the *audio* band.

MrT.
Anonymous
July 31, 2005 7:19:46 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 15:19:45 +1000, "Mr.T" <MrT@home> wrote:

>
>"Don Pearce" <donald@pearce.uk.com> wrote in message
>news:42ed82b9.60031781@text.usenet.plus.net...
>> I've got news for you. Every one of those cables has a useful
>> frequency response to well beyond 1GHz. The cable has yet to be made
>> that doesn't manage at least 100MHz without undue attenuation.
>
>What a blanket statement without any mention of source impedance, load
>impedance, cable length, or what constitutes undue attenuation!
>
>I've yet to see a standard audio cable that is useful at 1 Ghz frequencies.
>I have seen "undue attenuation" at 50kHz with some source/load/cable
>combinations however.
>
>Fortunately most cables are quite adequate in the *audio* band.
>
>MrT.
>
My statement was about cables - as was the one I was responding to,
and it stands exactly as I wrote it.

Your comments about terminal impedances are spot on, of course, and it
is these and not the cables that limit frequency response. Of course
audio engineers seldom consider this, hence comments about cables with
poor frequency response. If they would only use 600 ohm cables with
600 ohm terminations (both ends please) there would never be another
gripe about frequency response - they would be essentially flat,
however long.

So just choose an appropriate cable based on the impedances in use - a
nice woven litz to suit 8 ohm speakers perhaps, and all is well.

A cable which matches the impedance of its terminations has NO
capacitance and NO inductance as far as the system is concerned.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 8:34:49 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ec6c8e.28196609@text.usenet.plus.net...
> A cable which matches the impedance of its terminations has NO
> capacitance and NO inductance as far as the system is concerned.

I'm not sure what you mean by this. The distributed impedances still exist,
and cause signal loss. Any reputable cable has specs for loss per metre at
it's intended range of frequencies, when properly terminated.

MrT.
Anonymous
July 31, 2005 8:34:50 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 16:34:49 +1000, "Mr.T" <MrT@home> wrote:

>
>"Don Pearce" <donald@pearce.uk.com> wrote in message
>news:42ec6c8e.28196609@text.usenet.plus.net...
>> A cable which matches the impedance of its terminations has NO
>> capacitance and NO inductance as far as the system is concerned.
>
>I'm not sure what you mean by this. The distributed impedances still exist,
>and cause signal loss. Any reputable cable has specs for loss per metre at
>it's intended range of frequencies, when properly terminated.
>
>MrT.
>

I mean exactly what I say. A cable that matches its terminating
impedances looks like a delay - nothing more. It you measure it as a
load on a source in such a condition, you will see a resistance equal
to the terminating resistance. You will see neither inductance nor
capacitance.

As for the loss, sure there will be some, but it will be down to
resistance only. The will be no reactive losses caused by shunt
capacitance or series inductance.

Loss per metre can be specified of course, but I have measured many
cables and even the very worst of them had less than 1dB per metre at
1GHz. At audio frequencies it was almost impossible to measure a loss
unless you looked really carefully at an entire reel. Matching is
everything.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 8:34:51 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" wrote in ...
> Loss per metre can be specified of course, but I have measured many
> cables and even the very worst of them had less than 1dB per metre at
> 1GHz. At audio frequencies it was almost impossible to measure a loss
> unless you looked really carefully at an entire reel. Matching is
> everything.

The telephone industry would strongly disagree with that
philosophhy. (And has for ~100 years).
Anonymous
July 31, 2005 9:15:09 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ed715d.29427718@text.usenet.plus.net...
> As for the loss, sure there will be some, but it will be down to
> resistance only. The will be no reactive losses caused by shunt
> capacitance or series inductance.

Please explain why the loss increases with frequency then?

> Loss per metre can be specified of course, but I have measured many
> cables and even the very worst of them had less than 1dB per metre at
> 1GHz. At audio frequencies it was almost impossible to measure a loss
> unless you looked really carefully at an entire reel. Matching is
> everything.

Just how many audio systems have you seen with impedance matched
inputs/outputs ?

MrT.
Anonymous
July 31, 2005 9:15:10 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 17:15:09 +1000, "Mr.T" <MrT@home> wrote:

>
>"Don Pearce" <donald@pearce.uk.com> wrote in message
>news:42ed715d.29427718@text.usenet.plus.net...
>> As for the loss, sure there will be some, but it will be down to
>> resistance only. The will be no reactive losses caused by shunt
>> capacitance or series inductance.
>
>Please explain why the loss increases with frequency then?
>
Because the resistive loss of both the dielectric insulator and the
copper is frequency dependent. The copper suffers from skin effect
which reduces the effective area as frequency rises, and the
dielectric has an electric moment which increases the effective
"stiffness" and lossiness of the dipoles as frequency rises. They both
appear as entirely resistive factors, and have negligible effect at
frequencies below a few MHz.

>> Loss per metre can be specified of course, but I have measured many
>> cables and even the very worst of them had less than 1dB per metre at
>> 1GHz. At audio frequencies it was almost impossible to measure a loss
>> unless you looked really carefully at an entire reel. Matching is
>> everything.
>
>Just how many audio systems have you seen with impedance matched
>inputs/outputs ?
>
>MrT.
>
Professional audio systems used to be built properly, with 600 ohm
source and load impedances for all equipment, which would then be
connected together with 600 ohm cable. You could run signals literally
for miles with no frequency response unflatness. The analogue
telephone system still maintains this standard.

Unfortunately, some know-nothing "engineer" in some studio somewhere
discovered that if he removed the 600 ohm resistor at the input of a
piece of gear, he got himself 6dB extra signal level for free. Since
then it has routinely been the practice not to have this fitted, and
now here we are discussing unflatness of cables. One man's stupidity
and an entire industry's ignorance has caused all this.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 9:15:11 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ee7e30.32711218@text.usenet.plus.net
> On Sun, 31 Jul 2005 17:15:09 +1000, "Mr.T" <MrT@home>
> wrote:

>> Just how many audio systems have you seen with impedance
>> matched inputs/outputs ?

Pretty much none.

> Professional audio systems used to be built properly,
> with 600 ohm source and load impedances for all
> equipment, which would then be connected together with
> 600 ohm cable.

Telephone cable is different from the audio cables generally
used in studios. Frankly, I'm not sure that even most
telephone cable has a 600 ohm characteristic impedance. In
fact, I'm pretty sure that it doesn't.

A 600 ohm cable would have a fairly small conductor and a
comparitively large thickness of insulator. This sounds like
legacy telephone cable I remember seeing in the 1950s war
surplus and the like.

Modern telephone cable is solid 22-28 gauge wire with
relatively thin insulation, much like CAT-5 network wiring.
CAT-5 is typically 24 guage wire with thin insulation and
110 ohm characteristic impedance.

>You could run signals literally for miles
> with no frequency response unflatness. The analogue
> telephone system still maintains this standard.

It turns out that the characteristic impedance of most
balanced studio cables is around 110 ohms. The impedance
that was chosen for AES-3 and AES/EBU digital lines is 110
ohms, based on actual measurements of typical studio mic
cables. A typical modern mic cable is composed of 22 or 24
gauge twisted pair with fairly thin insulation.
Anonymous
July 31, 2005 9:15:11 PM

Archived from groups: rec.audio.tech (More info?)

Don Pearce wrote:

> Professional audio systems used to be built properly, with 600 ohm
> source and load impedances for all equipment, which would then be
> connected together with 600 ohm cable. You could run signals literally
> for miles with no frequency response unflatness. The analogue
> telephone system still maintains this standard.

Are you sure about this? Doesn't it require a very odd cable to maintain
a 600 ohm characteristic impedance down to 50 Hz or so?
What are the LCR values required?

--
Eiron

I have no spirit to play with you; your dearth of judgment renders you
tedious.
Anonymous
July 31, 2005 9:15:12 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 07:17:11 -0400, "Arny Krueger" <arnyk@hotpop.com>
wrote:

>It turns out that the characteristic impedance of most
>balanced studio cables is around 110 ohms. The impedance
>that was chosen for AES-3 and AES/EBU digital lines is 110
>ohms, based on actual measurements of typical studio mic
>cables. A typical modern mic cable is composed of 22 or 24
>gauge twisted pair with fairly thin insulation.
>
Then that is how they should be matched.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 9:15:12 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 12:30:47 +0100, Eiron <e1ron@hotmail.com> wrote:

>Don Pearce wrote:
>
>> Professional audio systems used to be built properly, with 600 ohm
>> source and load impedances for all equipment, which would then be
>> connected together with 600 ohm cable. You could run signals literally
>> for miles with no frequency response unflatness. The analogue
>> telephone system still maintains this standard.
>
>Are you sure about this? Doesn't it require a very odd cable to maintain
>a 600 ohm characteristic impedance down to 50 Hz or so?
>What are the LCR values required?

All cables have an impedance that rises as you move down towards 50Hz,
but the wavelength is increasing at the same time, so the impedance is
nothing like as important. As for 600 ohm cables, they used to be
pretty common "back in the day", but they are pretty bulky and are no
longer terribly common. As Arny pointed out twisted pair is typically
something like 110 ohms, so that is the matching impedance you need
for optimum flatness.

As for keeping a low impedance load resistor on a line level input, it
is a good idea for another reason, which is that you never need fear
unwanted hum on an open input.

d

Pearce Consulting
http://www.pearce.uk.com
July 31, 2005 10:11:14 PM

Archived from groups: rec.audio.tech (More info?)

donald@pearce.uk.com (Don Pearce) wrote in
news:42ed82b9.60031781@text.usenet.plus.net:

> On Sat, 30 Jul 2005 13:16:44 GMT, Bruce <xxx@yyy.zzz> wrote:
>
>>Agreed. I measured a bunch of 25 foot long cables a while back. The
>>worst of them had a frequency response well beyond 50kHz and only
>>because it was more than triple the typical shunt capacitance per foot
>>of cable you'd likely find in a system.
>>
>>-Bruce
>
> I've got news for you. Every one of those cables has a useful
> frequency response to well beyond 1GHz. The cable has yet to be made
> that doesn't manage at least 100MHz without undue attenuation.
>
> d
>
> Pearce Consulting
> http://www.pearce.uk.com

I guess you don't understand the word measured. I got news for you, you're
wrong.

The cables were driven with an HP 200AB and terminated with 10K ohms. They
wre measured with an HP 400 FL....now why don't you go grab some random
cables(including non coaxial) do some measuring.

-Bruce
Anonymous
July 31, 2005 10:14:59 PM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ee7e30.32711218@text.usenet.plus.net...
> Professional audio systems used to be built properly, with 600 ohm
> source and load impedances for all equipment, which would then be
> connected together with 600 ohm cable.

In the days when valves and line transformers were common. Not much benefit
for audio frequencies in most consumer items these days.

Just be glad you don't need to waste your money on exotic cables, others can
waste their money as they see fit. Many people get more enjoyment from the
pursuit of audio nirvana than from actual listening. Let them have their
thrill.

MrT.
Anonymous
July 31, 2005 10:15:00 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 18:14:59 +1000, "Mr.T" <MrT@home> wrote:

>
>"Don Pearce" <donald@pearce.uk.com> wrote in message
>news:42ee7e30.32711218@text.usenet.plus.net...
>> Professional audio systems used to be built properly, with 600 ohm
>> source and load impedances for all equipment, which would then be
>> connected together with 600 ohm cable.
>
>In the days when valves and line transformers were common. Not much benefit
>for audio frequencies in most consumer items these days.
>
No benefit at all for consumer equipment.

>Just be glad you don't need to waste your money on exotic cables, others can
>waste their money as they see fit. Many people get more enjoyment from the
>pursuit of audio nirvana than from actual listening. Let them have their
>thrill.
>
So very true.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
July 31, 2005 10:26:44 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 18:11:14 GMT, Bruce <xxx@yyy.zzz> wrote:

>donald@pearce.uk.com (Don Pearce) wrote in
>news:42ed82b9.60031781@text.usenet.plus.net:
>
>> On Sat, 30 Jul 2005 13:16:44 GMT, Bruce <xxx@yyy.zzz> wrote:
>>
>>>Agreed. I measured a bunch of 25 foot long cables a while back. The
>>>worst of them had a frequency response well beyond 50kHz and only
>>>because it was more than triple the typical shunt capacitance per foot
>>>of cable you'd likely find in a system.
>>>
>>>-Bruce
>>
>> I've got news for you. Every one of those cables has a useful
>> frequency response to well beyond 1GHz. The cable has yet to be made
>> that doesn't manage at least 100MHz without undue attenuation.
>>
>> d
>>
>> Pearce Consulting
>> http://www.pearce.uk.com
>
>I guess you don't understand the word measured. I got news for you, you're
>wrong.
>
>The cables were driven with an HP 200AB and terminated with 10K ohms. They
>wre measured with an HP 400 FL....now why don't you go grab some random
>cables(including non coaxial) do some measuring.
>
>-Bruce

I guess you don't understand measurement. If you are measuring a
cable, you must terminate it with its correct characteristic
impedance. What you have measured is the frequency response of a
network. It is as you have measured it, but don't blame the cable, the
reason you saw the frequency response error is that you got the load
wrong.

d

Pearce Consulting
http://www.pearce.uk.com
Anonymous
August 1, 2005 12:23:10 AM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 18:11:14 GMT, Bruce <xxx@yyy.zzz> wrote:

>The cables were driven with an HP 200AB

A 200AB? How can you use it at 1 MHz and more?

>and terminated with 10K ohms.

Then you don't measure the cables, but the system created by the generator,
the cables and the termination.

>They
>wre measured with an HP 400 FL....

400 FL? Is it a 400 voltmeter?

>now why don't you go grab some random
>cables(including non coaxial) do some measuring.

Been there, done that : Don Perace is correct even if his answer is
incomplete.
Anonymous
August 1, 2005 4:54:33 AM

Archived from groups: rec.audio.tech (More info?)

"Don Pearce" <donald@pearce.uk.com> wrote in message
news:42ee7e30.32711218@text.usenet.plus.net...
> On Sun, 31 Jul 2005 17:15:09 +1000, "Mr.T" <MrT@home> wrote:
>
>>
>>"Don Pearce" <donald@pearce.uk.com> wrote in message
>>news:42ed715d.29427718@text.usenet.plus.net...
>>> As for the loss, sure there will be some, but it will be down to
>>> resistance only. The will be no reactive losses caused by shunt
>>> capacitance or series inductance.
>>
>>Please explain why the loss increases with frequency then?
>>
> Because the resistive loss of both the dielectric insulator and the
> copper is frequency dependent. The copper suffers from skin effect
> which reduces the effective area as frequency rises, and the
> dielectric has an electric moment which increases the effective
> "stiffness" and lossiness of the dipoles as frequency rises. They both
> appear as entirely resistive factors, and have negligible effect at
> frequencies below a few MHz.
>
>>> Loss per metre can be specified of course, but I have measured many
>>> cables and even the very worst of them had less than 1dB per metre at
>>> 1GHz. At audio frequencies it was almost impossible to measure a loss
>>> unless you looked really carefully at an entire reel. Matching is
>>> everything.
>>
>>Just how many audio systems have you seen with impedance matched
>>inputs/outputs ?
>>
>>MrT.
>>
> Professional audio systems used to be built properly, with 600 ohm
> source and load impedances for all equipment, which would then be
> connected together with 600 ohm cable. You could run signals literally
> for miles with no frequency response unflatness. The analogue
> telephone system still maintains this standard.

A radio station where I used work had a telephone loop for a backup studio
transmitter link. The raw loop was far from flat. I used to have to get the
telephone company to come in and equalize the line about once a year. We
could barely keep it in spec out to 8 kHz. The line was terminated at each
end with transformers that went from 600 Ohms to whatever the characteristic
line impedance was (it wasn't 600). We always made sure we terminated our
side of the transformers with 600 Ohms.

Our in-studio gear used the NAB impedance standard, which, IIRC, was not
more than 150 Ohms output, and not less than 7500 Ohms input. That was so
that you could bridge multiple loads (tape recorders, etc.). We never had
any issues with cable frequency response. It was a constant struggle to keep
the tape decks flat to 15 kHz @ 7.5 IPS, but cables were the least of our
worries.

> Unfortunately, some know-nothing "engineer" in some studio somewhere
> discovered that if he removed the 600 ohm resistor at the input of a
> piece of gear, he got himself 6dB extra signal level for free. Since
> then it has routinely been the practice not to have this fitted, and
> now here we are discussing unflatness of cables. One man's stupidity
> and an entire industry's ignorance has caused all this.

I never had the feeling the industry was suffering very much from this
"abomination". I never encountered a cable length where frequency response,
power transfer or line levels were our primary source of difficulty.
Whenever we got into distances where cables were the limiting factor, we
used microwave links.
Anonymous
August 1, 2005 9:59:12 AM

Archived from groups: rec.audio.tech (More info?)

"Bruce" <xxx@yyy.zzz> wrote in message
news:Xns96A49094DCD23xxxyyyzzz@216.77.188.18

> The cables were driven with an HP 200AB and terminated
> with 10K ohms. They wre measured with an HP 400 FL....now
> why don't you go grab some random cables(including non
> coaxial) do some measuring.


Been there done that.

I suspect you were measuring the joint frequency response of
your two pieces of test equipment.

My recollection is that the HP400FL has pretty good
frequency response, but the 200 AB didn't. The 200AB is a
1952 design and actually pretty crude by modern standards,
both design and implementation.

http://www.hp.com/hpinfo/abouthp/histnfacts/museum/earl...

The 400FL came about 20-30 years later. I think I even own
one - stored away someplace.

To make measurements of cables with equipment like this, one
should use a differencing approach. Measure the length of
cable at some frequency, and then swap in a very short
length (inches) of cable. Calculate the difference in
response and attribute the difference to the longer cable.
Anonymous
August 1, 2005 3:04:19 PM

Archived from groups: rec.audio.tech (More info?)

On Sun, 31 Jul 2005 12:30:47 +0100, Eiron <e1ron@hotmail.com> wrote:

>Are you sure about this? Doesn't it require a very odd cable to maintain
>a 600 ohm characteristic impedance down to 50 Hz or so?
>What are the LCR values required?

What was the characteristic impedance of a single copper cable strung
on telegraph poles?
Anonymous
August 1, 2005 3:05:56 PM

Archived from groups: rec.audio.tech (More info?)

On 31 Jul 2005 11:53:43 -0700, "Bret Ludwig" <bretldwig@yahoo.com>
wrote:

> The continued omnipresence of IEC and RCA connectors on allegedly high
>end equipment belies the lie of high end audio as strongly as anything
>else.

Are you sure that's what you mean? Belies the lie?
Anonymous
August 2, 2005 12:53:58 PM

Archived from groups: rec.audio.tech (More info?)

"Eiron" <e1ron@hotmail.com> wrote in message
news:3l3r46F10edknU1@individual.net...
> Don Pearce wrote:
>
>> Professional audio systems used to be built properly, with 600 ohm
>> source and load impedances for all equipment, which would then be
>> connected together with 600 ohm cable. You could run signals literally
>> for miles with no frequency response unflatness. The analogue
>> telephone system still maintains this standard.
>
> Are you sure about this? Doesn't it require a very odd cable to maintain
> a 600 ohm characteristic impedance down to 50 Hz or so?
> What are the LCR values required?

Odd ? No, it is closest to the natural characteristic impedence of the
cables used for telephone systems. however telephones are only require to
have a 'bass response' down to 400Hz ! .

As telephones were once exclusively passive devices, maximum power
transfer (ie best possible impedence matching) was essential, and still is
when that last 0.5 dB is sought. The same applies to open wire and cable
(not coax) FDM transmission systems.

geoff
Anonymous
August 2, 2005 12:57:21 PM

Archived from groups: rec.audio.tech (More info?)

"Laurence Payne" <lpayne1NOSPAM@dsl.pipexSPAMTRAP.com> wrote in message
news:9vsre1h5ridnd4235lfke7n02meuhhp16d@4ax.com...
> On 31 Jul 2005 11:53:43 -0700, "Bret Ludwig" <bretldwig@yahoo.com>
> wrote:
>
>> The continued omnipresence of IEC and RCA connectors on allegedly high
>>end equipment belies the lie of high end audio as strongly as anything
>>else.
>
> Are you sure that's what you mean? Belies the lie?


Yeah, it underlines the surrealism of the underlying metaphor very well

geoff
!