Acoustic Research RF cables

[Lee]

Okay, I know that RF cables are meant for video, not audio.
But the video newsgroups seemed to be full of noise, and I
suspect many audiophiles watch television every now and
then, so here goes. When I look at the plug end of an RF
cable, I can see some differences between brands. The
really cheap cables, and even some medium priced cables,
have the inner wire surrounded by very little white plastic
insulation material. I've seen some cables where the inner
wire can touch the metal portion of the plug with just a little
movement. If I look at a Monster cable, there is a substantial
amount of white plastic insulation, and it fills the cavity so
the inner wire cannot move at all. To quote Martha Stewart,
this is a good thing. What about Acoustic Research cables?
From online photos (I cannot seem to find one to see in
person) AR cables look nice and fat (good insulation), and
have the knurled ends to turn (instead of the hexagonal ends
which aren't as easy to turn), but I cannot see inside the plug
to see the white insulation. Anyone own an AR cable?

Lee

[Richard Crowley]

"Lee" wrote ...
> Okay, I know that RF cables are meant for video, not audio.
> But the video newsgroups seemed to be full of noise, and I
> suspect many audiophiles watch television every now and
> then, so here goes. When I look at the plug end of an RF
> cable, I can see some differences between brands. The
> really cheap cables, and even some medium priced cables,
> have the inner wire surrounded by very little white plastic
> insulation material. I've seen some cables where the inner
> wire can touch the metal portion of the plug with just a little
> movement. If I look at a Monster cable, there is a substantial
> amount of white plastic insulation, and it fills the cavity so
> the inner wire cannot move at all.

Most of us just use cables to conduct signals from one place
to the other. Those who like looking at and fondling cables
more likely prefer "Monster" and other "boutique" brands at
rip-off prices. If you can't see/hear the difference in the signal,
it's not worth the money. Period.

[Michael Squires]

>Most of us just use cables to conduct signals from one place
>to the other. Those who like looking at and fondling cables
>more likely prefer "Monster" and other "boutique" brands at
>rip-off prices. If you can't see/hear the difference in the signal,
>it's not worth the money. Period.

The really cheap cables can have enough capacitance to cause changes
in frequency reponse with some amps/preamps with long cables.

I needed about 30' between
a preamp and the power amps and wound up making cables from surplus
coax cable, a military type with Teflon insulation, silver-plated
shield, and a very low capacitance per foot.

Cables were measured on a GR 1650 impedance bridge, if anyone cares.

Mike Squires
--

Mike Squires ) 317 233 9456 (w) 812 333 6564 (h)
546 N Park Ridge Rd., Bloomington, IN 47408

[Bob-Stanton]

"Lee" > wrote in message ink.net>...
> Okay, I know that RF cables are meant for video, not audio.
> But the video newsgroups seemed to be full of noise, and I
> suspect many audiophiles watch television every now and
> then, so here goes. When I look at the plug end of an RF
> cable, I can see some differences between brands. The
> really cheap cables, and even some medium priced cables,
> have the inner wire surrounded by very little white plastic
> insulation material. I've seen some cables where the inner
> wire can touch the metal portion of the plug with just a little
> movement. If I look at a Monster cable, there is a substantial
> amount of white plastic insulation, and it fills the cavity so
> the inner wire cannot move at all. To quote Martha Stewart,
> this is a good thing. What about Acoustic Research cables?
> From online photos (I cannot seem to find one to see in
> person) AR cables look nice and fat (good insulation), and
> have the knurled ends to turn (instead of the hexagonal ends
> which aren't as easy to turn), but I cannot see inside the plug
> to see the white insulation. Anyone own an AR cable?
>
> Lee

I don't want to spoil your fun, but RF cables require a termination
equal to the characteristic impedance of the cable itself. Your
speakers are not 75 Ohms! RF cables won't act as "RF cables" into an
8 Ohm load. You can buy speaker wire with 8 Ohms characteristic
impedance.

I know this has been said hundreds of times before but, nothing beats
Home Depot's 12 gage speaker wire.

Bob Stanton

[Lee]

> I don't want to spoil your fun, but RF cables require a termination
> equal to the characteristic impedance of the cable itself. Your
> speakers are not 75 Ohms! RF cables won't act as "RF cables"
> into an 8 Ohm load. You can buy speaker wire with 8 Ohms
> characteristic impedance.

I never mentioned anything about speakers, but you assumed I
wanted to use video cables as speaker wire. Do you always
answer questions that weren't asked?

Lee

[Bob-Stanton]

"Lee" > wrote in message k.net>...
> > I don't want to spoil your fun, but RF cables require a termination
> > equal to the characteristic impedance of the cable itself. Your
> > speakers are not 75 Ohms! RF cables won't act as "RF cables"
> > into an 8 Ohm load. You can buy speaker wire with 8 Ohms
> > characteristic impedance.
>
> I never mentioned anything about speakers, but you assumed I
> wanted to use video cables as speaker wire. Do you always
> answer questions that weren't asked?
>
> Lee

Are you always such a **** head?

Bob Stanton

[Richard Crowley]

> You can buy speaker wire with 8 Ohms characteristic impedance.

Talk about your snake-oil hucksterism!!!
There's one born every millisecond.

[TCS]

On 27 Jul 2003 03:52:13 -0700, Bob-Stanton > wrote:
>You can buy speaker wire with 8 Ohms characteristic
>impedance.

Name a *single* example, please. Otherwise it's obvious you're talking
out your ass.

Transmission line effects only come into play if the cable is at least 1/2
wavelength. At audio frequencies, this'll be measured in miles. Do you
typically run 10 miles of speaker wire?

[Richard Crowley]

> Bob-Stanton wrote:
> >You can buy speaker wire with 8 Ohms characteristic
> >impedance.

"TCS" wrote ...
> Name a *single* example, please. Otherwise it's
> obvious you're talking out your ass.

Or Mr. Stanton is quoting know-nothing, schyster,
snake-oil cable salesmen!

Of course it doesn't make any sense technically, but it
would sure sound good to a customer with deep pockets
and shallow knowledge of electronics. (i.e. you typcial
"Monster" et.al. cable customer)

I'm sure even you, "TCS" could come up with a plausible-
sounding line of bull. Something like the "benefit of better
power coupling resulting from proper impedance matching
of the cable" or some such silliness.

[Laurence Payne]

>You can buy speaker wire with 8 Ohms characteristic
>impedance.

What, at audio frequencies? How many miles of cable are we talking
about here? :-)

[Bob-Stanton]

TCS > wrote in message 625.kaosol.net>...
> On 27 Jul 2003 03:52:13 -0700, Bob-Stanton > wrote:
> >You can buy speaker wire with 8 Ohms characteristic
> >impedance.
>
> Name a *single* example, please. Otherwise it's obvious you're talking
> out your ass.
>

How about four examples. Alpha-Core, Goetz, Dunlavy and even Radio
Shack. Ribbon cables, two flat conductors close together, have
characteristic impedances of typically 8 Ohms. Dunlavy specified his
cable's characteristic impedance at 6 Ohms.


> Transmission line effects only come into play if the cable is at least 1/2
> wavelength.

Wrong, transmission line effects occure at all wavelenghts.

For example, a 50 ft length (1.016 E-3 wavelengths) of 100 Ohm
characteristic impedance, speaker wire (such as Home Depot's) will
have a loss of about 0.01 dB at 20kHz, due to the reflection caused by
the impedance mismatch. (At lower frequencies the loss is much less
than 0.01 dB.)

> At audio frequencies, this'll be measured in miles.

At 1000 Hz, 1/2 wavelenght = 93 miles.


> Do you
> typically run 10 miles of speaker wire?


Yes, I do, but the insertion loss is terrible. I'm thinking about
moving the speakers closer to my house.

Bob Stanton

[Bob-Stanton]

"Richard Crowley" > wrote in message >...
> > Bob-Stanton wrote:
> > >You can buy speaker wire with 8 Ohms characteristic
> > >impedance.
>
> "TCS" wrote ...
> > Name a *single* example, please. Otherwise it's
> > obvious you're talking out your ass.
>
> Or Mr. Stanton is quoting know-nothing, schyster,
> snake-oil cable salesmen!
>
> Of course it doesn't make any sense technically, but it
> would sure sound good to a customer with deep pockets
> and shallow knowledge of electronics. (i.e. you typcial
> "Monster" et.al. cable customer)
>

If you go back and reread my message, you will notice I did *not*
recommend buying an expensive 8 Ohm (characteristic impedance),
speaker cable. I mearly mentioned that such cable was available. This
type of cable has only one pratical advantage over regular speaker
cable, it will cause less of a bump when run under a rug.

I recommended Home Depot's 12 gage speaker cable, which has a
characteristic impedance of around 100 Ohms. This is an inexpensive
but very adequite, speaker cable.

Bob Stanton

[Bob-Stanton]

"Lee" > wrote in message news:<cnRUa.23740


> I never mentioned anything about speakers, but you assumed I
> wanted to use video cables as speaker wire. Do you always
> answer questions that weren't asked?
>

Pardon me for not reading your message carefully. I assumed that
because you posted your message in an *audio* group, your message was
somehow related to audio. Perhaps you should look for a group that
more discusses video.

Do you always post your questions to the wrong group?

Bob Stanton

[Richard Crowley]

"TCS" wrote ...
> 0.01DB? Thanks for agreeing with me.

IOW indistinguishable from natural noise and instrument calibration.
Or do you realize that you have just conceded your argument?

[Bob-Stanton]

Laurence Payne > wrote in message >...
> >You can buy speaker wire with 8 Ohms characteristic
> >impedance.
>
> What, at audio frequencies? How many miles of cable are we talking
> about here? :-)

93.1 miles

Bob Stanton

[[email protected]]

Michael Squires > wrote:
>>Most of us just use cables to conduct signals from one place
>>to the other. Those who like looking at and fondling cables
>>more likely prefer "Monster" and other "boutique" brands at
>>rip-off prices. If you can't see/hear the difference in the signal,
>>it's not worth the money. Period.

Concur, spend the money where it matters.

> The really cheap cables can have enough capacitance to cause changes
> in frequency reponse with some amps/preamps with long cables.

Sounds like a case of a preamp with a **** poor line driver stage to me,
I would get it replaced with something competently designed.

> I needed about 30' between
> a preamp and the power amps and wound up making cables from surplus
> coax cable, a military type with Teflon insulation, silver-plated
> shield, and a very low capacitance per foot.

30ft is a long cable? On what planet? I routinely run mic level signals
(which often have source impeadences many times that of a decent line
driver stage) down 100+M (300+ft) mulicores and it all seems to work just
fine.

Now sometimes you can hear a difference in the special case of a ribbon
mic, but for anything with a reasonable amount of drive available (and
anything with a line output should have a reasonable amount of drive
available) 30ft is *NOTHING* .

> Cables were measured on a GR 1650 impedance bridge, if anyone cares.

I really would not sweat the details like this, there are things which make
far larger differences to the quality of reproduction (of audio or video)
then the "wow these cables are really expensive" factor.
Spend the money on better room lighting (for video), better acoustic
treatment, better speakers, better processing......

For video, I normally choose a decent 75ohm cable (then terminate with
50ohm BNC (more mechanically robust, the electrical length of the connector
is neglegable for baseband video)). For long runs a Balun and 110ohm
twisted pair can have some advantages (most buildings are now wired with
lots of CAT5, which can be *really* convinient).

Regards, Dan.
--
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