screening of speaker leads.

[chris]

If you wanted to screen your speaker leads against EMI/RFI pickup, at what
distance from the core of the wire would you put the screening ?

[Arny Krueger]

"chris" > wrote in message
news:wQ%Va.24658$YN5.23420@sccrnsc01

> If you wanted to screen your speaker leads against EMI/RFI pickup, at
> what distance from the core of the wire would you put the screening ?

I'd use coax, which is inherently screened, and really pretty good low
inductance, low capacitance speaker cable. Belden makes some with 11 gauge
copper center conductors and heavy copper braid shield that has enough
conductivity for longer and/or more critical applications.

[GregS]

In article >, "Arny Krueger" > wrote:
>"chris" > wrote in message
>news:wQ%Va.24658$YN5.23420@sccrnsc01
>
>> If you wanted to screen your speaker leads against EMI/RFI pickup, at
>> what distance from the core of the wire would you put the screening ?
>
>I'd use coax, which is inherently screened, and really pretty good low
>inductance, low capacitance speaker cable. Belden makes some with 11 gauge
>copper center conductors and heavy copper braid shield that has enough
>conductivity for longer and/or more critical applications.

I might question the use of coax. Ground current might still present problems.
I would also include a ferrite core at the amp. Electrostatic shielding might not
shield against electromagnetic interference. Not all amps have unbalance outputs.
Some use bridged outputs, requiring a shielded pair for best shielding.

The question about distance, it should not matter. In low impedance transmission lines,
the distance determines the characteristic impedance, but is of no use here.
greg

[Johnd1001]

There exists no credible engineering reason for the use of bi-amping cables,
etc,,

I envite "informed opinion, based upon the teachings of sound engineerinf
teachings, inot commercially induced opinions, regardarging this important
subjuct.

John D 1001 @aol.com

[chris]

"Arny Krueger" > wrote in message
news:h9vWa.28427$Oz4.9089@rwcrnsc54...
> "chris" > wrote in message
> news:mXlWa.36568$uu5.4475@sccrnsc04
>
> > Thanks for the suggestion. belden would be nice to use but I cant get
> > the good stuff in the UK. only yucky foil under thin braid. and the
> > cost of the shipping and importing it from the US is high.
>
> Ever hear of a UK retail supplier named Maplin?
>
> They have a web site at http://www.maplin.co.uk/
>
> Here's a cable from their catalog that has a big thick copper center
> conductor composed of 7 strands of roughly 20 gauge wire, and heavy
copper
> braid.
>
>
http://www.maplin.co.uk/Products/ModuleInfo.asp?Addon=&CartID=03080109583586
> 4&moduleno=257&
>
> "URM67 50 ohm heavy duty RF cable"
>
> according to
>
> http://www.cdt-uk.co.uk/cat3pdfs/Raydex%20Coaxial%20Bro%208.pdf
>
> It has a DC resistance of 10.9 ohms per kilometer, or 0.011 ohms per
meter,
> or 0.0037 ohms per foot which is roughly the same as 12 gauge 2-conductor
> speaker cable.
>

Thanks Arny I forgot about Maplin's -silly me.
I will take a look at it, but I tend to prefer solid wire for the power side
(i've never been too impresed with the mutlistrands ive heard) Im currently
using a litz twisted pair config12*2*24. Which sound nice! - I will say no
more, for fear of "them"

[chris]

I will respond to the wrong thread
Why are people still thinking "DC" when dealing with "AC theory"
only the LCR has changed but since we are dealing with a "perfect wire"
THERE IS NO DIFFERENC in any amount of copper not to mention a perfect
crossover and perfect "air waggerlers" in a perfect anaconic chamber all
driven by a theoretically perfect amplifier.
of course there is no difference
Of course in a perfect world everything works fine- perfect in-fact. just
like the perfect theoretical model that you didn't learn at college.

In fact the world is so perfect that anyone would know the answer to a
perfectly good question. but I guess in a perfect world I would need to ask
the question in the 1st place. but wot the heck this is High-end audio were
the people know stuff about things !!!

"chung" > wrote in message
...
> Johnd1001 wrote:
> > There exists no credible engineering reason for the use of bi-amping
cables,
> > etc,,
> >
> > I envite "informed opinion, based upon the teachings of sound
engineerinf
> > teachings, inot commercially induced opinions, regardarging this
important
> > subjuct.
> >
> > John D 1001 @aol.com
>
> I can think of a scenario where bi-wiring can make an academic
> difference. I have not, however, made any measurements to verify the
theory.
>
> Look at the single cable case. Assume that the bass driver is driven
> into a highly non-linear region. The current flowing into the bass
> driver will have distortion components in it. Let's say that there is a
> 100 Hz tone at the amplifier's output. The current flowing in the
> speaker cable will have harmonic components of 100 Hz, i.e., 200 Hz, 300
> Hz, etc.
>
> Assume that the cable has a finite resistance. That resistance will
> cause voltage components of 200Hz, 300Hz, etc. to appear at the speaker
> end of the cable.
>
> If you assume that the tweeter driver has a response to those
> frequencies, then there may be sound coming out of the tweeter at those
> frequencies.
>
> In the case where there is bi-wiring, the tweeter does not see the
> harmonic voltage components, so there will be much less output from the
> tweeter at those harmonic frequencies.
>
> Also, in the case of a single cable, if there is a high frequency tone
> present at the same time, and if the tweeter is not linear, then the
> high frequency tone may mix with the harmonics of the low frequency
> tone, at the tweeter, to generate tones at NxFh + MxFl, where M and N
> are integers and Fh and Fl are the frequencies of the two tones. For
> instance, if Fh=3K and Fl=100, there may be tones at 3.2KHz, 3.3KHz etc.
> present at the output of the tweeter. At least the magnitudes of those
> mixing products *could* be different depending on whether bi-wire or
> single-wire is used.
>
> In reality, the low impedance of the speaker cable, and the linearity of
> the drivers under normal conditions make these effects very
> insignificant, so that there is no audible difference. But if one were
> to make measurements, there could be differences, depending upon the
> linearity of the drivers.
>
> Note that the differences are due to the non-linearity of the drivers,
> and not that of cables. As far as we can measure, there is no
> non-linearity in copper cables. IOW, if the drivers are perfectly
> linear, there would not be any intermodulation products.
>
> Comments?
>

[Richard D Pierce]

In article <JQlWa.36368$Ho3.6629@sccrnsc03>,
All Ears > wrote:
>You could also add a Zobel RC network, it will effectively short any high
>freq. noise on the speaker cables.

Sorry, "Ears," that is NOT what a "Zobel" network is. Not in the
least.

A "Zobel," so named after one Otto J. Zobel, is network that
implements a complex conjugate of another network. That is, a
circuit might have a non-resistive impedance. A complex
conjugate is a circuit that, combined with the original circuit,
results in a resistive impedance. Be assured that a Zobel
circuit DOES NOT "effectively short any high freq. noise on the
speaker cable." That is NOT what a Zobel does, despite
ill-informed claims by some to the contrary.

A common use for Zobel-type circuits in audio is in speakers. A
driver present a non-resistive impedance. In its most basic
form, the impedance presented by a driver looks like a circuit
consisting of a resistor in series with and inductor inseries
with a parallel RLC resonant circuit (this RLC circuit is the
electrical equivalent of the speakers mechanical resonance).

WIthout a resistive load, it is impossible to achieve certain
response functions from passive crossover filter networks.
However, by applying the kind of circuit Mr. Zobel describes,
the non-resistive load presented by a driver can be made to look
resistive.

But the high-frequency decoupling and bypass circuits used on
the outputs of amplifier ARE NOT, most definitely are not
"Zobel" circuits.

For more details, you might want to take a look at US Patent
1,557,230, granted to Otto. J. Zobel on Octover 13, 1925,
assigned to the American Telephone and Telegraph company, titled
"Complementary Filter." It clearly describes the implementation
of conjugate filters, and clearly does NOT describe what you're
talking about.

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |

[chris]

Hi Arny

thanks for the info I contacted my local Maplin and they also told be about
this stuff
http://www.maplin.co.uk/default.asp?CartID=10957281&userid=newsletter&target
module=30819 what do you think ?
any good ? better or worse than the URM67 ?

"Arny Krueger" > wrote in message
news:h9vWa.28427$Oz4.9089@rwcrnsc54...
> "chris" > wrote in message
> news:mXlWa.36568$uu5.4475@sccrnsc04
>
> > Thanks for the suggestion. belden would be nice to use but I cant get
> > the good stuff in the UK. only yucky foil under thin braid. and the
> > cost of the shipping and importing it from the US is high.
>
> Ever hear of a UK retail supplier named Maplin?
>
> They have a web site at http://www.maplin.co.uk/
>
> Here's a cable from their catalog that has a big thick copper center
> conductor composed of 7 strands of roughly 20 gauge wire, and heavy
copper
> braid.
>
>
http://www.maplin.co.uk/Products/ModuleInfo.asp?Addon=&CartID=03080109583586
> 4&moduleno=257&
>
> "URM67 50 ohm heavy duty RF cable"
>
> according to
>
> http://www.cdt-uk.co.uk/cat3pdfs/Raydex%20Coaxial%20Bro%208.pdf
>
> It has a DC resistance of 10.9 ohms per kilometer, or 0.011 ohms per
meter,
> or 0.0037 ohms per foot which is roughly the same as 12 gauge 2-conductor
> speaker cable.
>

[JF Lagardère]

For what reason would you want to do this? It's useless.
Speaker leads are loaded with a very low impedance (a few ohms).
There is no reason to fear antenna-style interference phenomena with them.

"chris" > wrote in message
news:wQ%Va.24658$YN5.23420@sccrnsc01...
> If you wanted to screen your speaker leads against EMI/RFI pickup, at what
> distance from the core of the wire would you put the screening ?

[All Ears]

Exactely my thoughts as well...

"JF Lagardère" > wrote in message
...
> For what reason would you want to do this? It's useless.
> Speaker leads are loaded with a very low impedance (a few ohms).
> There is no reason to fear antenna-style interference phenomena with them.
>
> "chris" > wrote in message
> news:wQ%Va.24658$YN5.23420@sccrnsc01...
> > If you wanted to screen your speaker leads against EMI/RFI pickup, at
what
> > distance from the core of the wire would you put the screening ?
>

[chris]

"Richard D Pierce" > wrote in message
...
> In article <CEkYa.56109$cF.20345@rwcrnsc53>,
> chris > wrote:
> >Richard
> >
> >Would a zobel network have any value placed outside of a xover unit on a
> >modern speaker?
>
> What do you presume is the purpose of such?

I was asking if using a zobel to correct any imperfections in the impeadance
curve could possibly be of any use. I have no knowledge of zobel devices
in real use, and I was .enquiring as to if you had any experiance of them.

> >and if so would it not be best placed near or at the amps o/p terminals ?
ie
> >to correct the total impeadance of lead and speaker ?
>
> The impedance imposed by all but the most pathologically bad of
> speaker leads is such a TINY part of the total impedance seen by
> the amplifier as to be insignificant.
>
> Further, I would submit that if such a network IS needed, it is
> correcting for a defficiency in the amplifier, and one might
> argue that applying external means of solving the internal
> defficiency of an amplifier is the wrong approach to addressing
> the problem.

I wasnt really thinking of amplifer defficencies but in that respect I agree
(poss best to ditch the amp), but more of where would be the best place to
put the correctig device should one be required.

> >so what are the (overpriced?) "network thinggys" that I hear people put
at
> >the speaker terminals?
>
> Often, they are nothing more than passive tone controls.

So what are they less often ?

[Howard Ferstler]

"chris" > wrote in message >...
> "Richard D Pierce" > wrote in message
> ...
> > In article <CEkYa.56109$cF.20345@rwcrnsc53>,
> > chris > wrote:

> > >so what are the (overpriced?) "network thinggys" that I hear people put
> at
> > >the speaker terminals?

> > Often, they are nothing more than passive tone controls.

> So what are they less often ?

Probably fake filters that do not do anything but make the owner feel
smug about his wires. I remember reading somewhere (quite a long time
ago) where some guys took one of the "thinggys" apart and discovered
that it had no electrical materials in it at all. I think I also read
(again, quite a long time ago) where one contained a high-impedance
resistor hooked between the leads. Given the impedance of a typical
speaker system, that kind of resistor would also effectively not do
anything.

To my way of thinking, devices of that kind are obvious manufacturing
scams.

Howard Ferstler

[Richard D Pierce]

In article >,
chris > wrote:
>"Richard D Pierce" > wrote in message
...
>> In article <CEkYa.56109$cF.20345@rwcrnsc53>,
>> chris > wrote:
>> >Richard
>> >
>> >Would a zobel network have any value placed outside of a xover unit on a
>> >modern speaker?
>>
>> What do you presume is the purpose of such?
>
>I was asking if using a zobel to correct any imperfections in the impeadance
>curve could possibly be of any use. I have no knowledge of zobel devices
>in real use, and I was .enquiring as to if you had any experiance of them.

The main purpose, in the context of speakers, for such conjugate
networks, aka "Zobels," is to provide a resistive load for the
passive crossover. Using standard ladder-type passive filters,
there are entire classes of useful transfer functions which you
simply CANNOT get unless your crossover has a resistive load. So
a "Zobel" is used to make sure that the non-resistive load
typically presented by a driver is converted to a resistive
load.

On the other hand, one often sees a passive network on the
output of power amplifiers. Common forms are a parallel
combination of a resistor and inductor in series with the load,
or a series combination of a resistor and capacitor shunting the
output. These are NOT "Zobel" networks, in that they are NOT
intended as a conjugate circuit for some load. They are there
for the prupose of either decoupling the amplifier or providing
filtering at some very high frequency to increase stability well
outside the audio bandpass.

A lot of people call such circuits "Zobels." They aren't. It's
as simple as that.

>
>> >and if so would it not be best placed near or at the amps o/p terminals ?
>ie
>> >to correct the total impeadance of lead and speaker ?
>>
>> The impedance imposed by all but the most pathologically bad of
>> speaker leads is such a TINY part of the total impedance seen by
>> the amplifier as to be insignificant.
>>
>> Further, I would submit that if such a network IS needed, it is
>> correcting for a defficiency in the amplifier, and one might
>> argue that applying external means of solving the internal
>> defficiency of an amplifier is the wrong approach to addressing
>> the problem.
>
>I wasnt really thinking of amplifer defficencies but in that respect I agree
>(poss best to ditch the amp), but more of where would be the best place to
>put the correctig device should one be required.

But exactly WHAT are you correcting?

>> >so what are the (overpriced?) "network thinggys" that I hear people put
>at
>> >the speaker terminals?
>>
>> Often, they are nothing more than passive tone controls.
>
>So what are they less often ?

Effective. Useful. Needed. Properly designed.

--
| Dick Pierce |
| Professional Audio Development |
| 1-781/826-4953 Voice and FAX |
| |