Oxygen Free Cables - Page 4

I suppose now that you must be using tassie devil gizzards for your
moonlight evening tweaks, there being an accute shortage of hyenas down your way,
but I hear that a lot can be achieved by whisking off a visiting politishun
on fact finding missions for forest policies and boiling the bastard down at
around
election times.

Last time someone tried that they played an RCA copy of Gord Save the Quean,
and it came out sounding like Walking Barkwards to Christmas, Across the Irish
Sea....

Patrick Turner.

Yes, along with other hyped specs like low
capacitance low inductance and such.  "Low resistance"
is the only spec that matters for speaker cable used
in the home.  Oh, if you had runs several kilometers
long you'd start to care about inductance and capacitance,
but nobody's house is that big.  I use power cord
suitable for 15 amp service (AWG #14).  Inexpensive
and effective.

After the wife starts screaming about the money
you wasted....  :-)

**Capacitance is unimportant, but inductance may well be.

  "Low resistance"


**Really? Where did you study electrical engineering? I hope you didn't,
because you can be shown to be wrong, very easily.

  Oh, if you had runs several kilometers


**Several km? Are you certain about that? So-called 'zip' cable has an
inductance of approximately 0.75uH/Metre. At 1kM, with 8 Ohm speakers, the
attenuation will be around 3dB at around 1.5kHz. At 100Metres, the
attenuation (with 'normal' 8 Ohm speakers) will occur within the audible
range. When dealing with VERY difficult speakers:

www.rageaudio.com.au/kappa9.jpg
or
www.rageaudio.com.au/accu.jpg

The attenuation will occur with MUCH shorter cable lengths. As little as 10
Metre cable runs may show some audible degradation.

And, of course, capacitance doesn't matter one whit, with any competently
designed amplifier.

  I use power cord


**For you, perhaps. Do not presume that what works for you, is appropriate
for everyone.



**Yeah, well, they all do that.

Women, can't live with 'em, can't kill 'em.

"Trevor Wilson"


 **  Mr Casey is an expert on work creation  -   following him around usenet
correcting all his asinine postings is almost a full time job.






 **  Even  a 5 metre length of twin wire  ( gauge is irrelevant)  has enough
linear inductance to become quite audible when the load impedance drops to 2
ohms near 17 or 18 kHz  -   as it does with the Quad ESL57.  With "stacked"
ESL57s,  impedance drops to 1 ohm making even as little as 3 metres of heavy
gauge twin lead audible.

BTW   I am not referring to some subtle effect that takes practice to
ear  -   but a very audible  loss of signal that amounts to 1 to 3 dB  @
17 - 18 kHz  !!!

Also, when viewed on a scope, there is serious ringing of a square wave at
audible frequencies  ( 10 to 25 % amplitude  -  depending on cable length )
at the speaker end of the cable that it NOT there at the amp input end.

The ONLY solution I know to cure this is to use a low inductance,
inter-woven cable like Tocord.

Using  5 metre long Tocord leads, with single ESL57s, high frequency loss is
reduced to under 0.5 dB ( resistance loss alone) and ringing all but
disappears.





...........   Phil

Commonly called stalking.

for a 2-wire parallel transmission line, the exact formula for external
inductance for spacing s and conductor diameter d is:

L = 0.4uH*acosh(s/d)

my 2.5mm^2 speaker cable has s=4mm, D = 1.8mm

so L = 0.575uH per metre

I had 10m of the stuff, so 6uH. Thats 0.4 Ohms at 10kHz, which is quite
a bit compared with my 4 Ohm speakers, so I stuck them in series and
ignored it.




absolutely.


when I first connected the speakers in series, in a fit of inspired
stupidity I stuck each speaker as far away as possible from its series
partner. The resultant loop in the cable was huge, and much more than
doubled the inductance.



Bob Pease suggested 64-way ribbon cable, interdigitated. That gets the L
right down. the IDC connections can be troublesome, but a little adaptor
pcb would be trivial

A simple, cheap approach would be a copper stripline. magnetics vendors
often stock copper strip of various thicknesses, and sometimes wrapped
with quite good insulators.

two long strips of 1mm copper, perhaps w = 25mm wide, wrapped in
heatshrink and glued together so separation s = 1mm.

inductance L = u0*s/w = 0.4*pi*1/25 = *50nH* per metre

the DC resistance is about 2*20n[Ohm-m]/25u[m^2] = 1.6mOhm/m

the strip is one skin depth thick at 1mm = 66mm/sqrt(f) so f = 4.4kHz.
For 5 skin depths, 0.2mm = 66mm/sqrt(f) so f = 108kHz. At 20kHz its 2.1
skin depths thick. So the AC resistance Fr is close to 1 over the entire
audio band.

10mm strip will be about 125nH and 4mOhm per metre.

the problem with cutting the strip by hand is jagged edges. and it wont
bend so nice.





Cheers
Terry

**This MIGHT be a cheaper alternative:

http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099

"Trevor Wilson"


http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099



 **  No way has co-ax  got zero linear inductance.



...........  Phil

http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099


**Of course not. Inductance of RG213 is approximately 10% of that of zip
cable. A big step up from 'zip' cable. I would estimate the inductance of
Tocord to be around 4-5 times lower again.

"Trevor Wilson"
 "Phil Allison"

http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099



**  A big step up from figure 8 ( or zip ) cable is simply to tightly twist
the same wires.

 Easy to do and costs nothing.

 Far better idea than using hose thick, hard to bend and terminate co-ax .



.............   Phil

http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099


Phil, what's your opinion on using CAT5 cabling, with the pairs in parallel.
Neat, flexible.

yep.


solid-core would be terrible because the interconnects would break if
you move them.

I use (stranded) CAT5 for a wide variety of things - broadband scope
probes, RS485 wiring etc. Its very handy, precisely because its twisted.
Its impedance is very well controlled, and data is also available from
most manufacturers.

only things are: not much copper area, so limited amps (or parallel
pairs), and most RJ type connections are utter shit - fine for heavily
error corrected networks or voice, but no good for important signals.
especially not with vibration, as they are single-wipe connectors.
decent plugs and sockets help a great deal, but the single-wipe
vibration problem remains.

Cheers
Terry

"Robert Murphy" <okami1,westnet,com,au> wrote in message

http://www.dse.com.au/cgi-bin/dse.storefront/42cc8d9509787e1e273fc0a87f9c0744/Product/View/W2099


**I'm not Phil, but there are a number of problems with the CAT5 cable idea:

* You need A LOT of CAT5 cables to keep resistance low enough for difficult
speakers. There are simply not enough conductors, of low enough resistance,
in a single CAT5 cable. As soon as you start using multiple CAT5 cables, you
start losing some of the advantages.
* Terminating all those conductors is a PITA.
* High power coax will provide adequately low R and L and is easier to
terminate.
* CAT5 conductors are far too loosely bound, IMO. This is where coax and
Tocord are far better choices. Conductors are tightly contained within the
outer sheath.
* CAT5 cables (well, the cheap ones anyway) uses the cheapest, worst, most
lossy insulation material known to mankind. PVC. There are far superior
insulators. Those cables using superior insulators cost more money
(surprise, surprise). Even the CAT5 ones.

CAT5 is designed for very low power levels, whilst Tocord and RG213 are
designed (specifically) for high current applications. As is the best
speaker cable on the planet, BTW - Goertz MI-1. VERY low resistance and VERY
low inductance.

I'm not sure what it is, but there's something dodgy about this analysis.

The Quad manuals say that an ESL is between 30 and 15 ohms from 40Hz to
8KHz.
It should therefore be about 6 ohms at 18KHz.

Ringing suggests a resonance or rising frequency response, which would be
caused by series inductance and the ESL's capacitance, and doesn't fit
with Phil's severe high frequency loss.

I suppose I'd better get measuring, analyzing and plaiting my own cables.

change the oil every 6000km and make sure you lube the chain

"Eiron"



**  The manual is simply not correct.





**  This published graph is close to my own measurements.

     http://www.quadesl.com/quad_main.shtml






**  A sharp HF impedance dip will cause ringing in the drive wave for a
non-zero source impedance.






**  Better to post after doing that than before.

      Lest you make an ass of yourself.




..........    Phil

About 1 1/4 inches?

ROTFLMAO

"Alan Rutlidge" >>>





 *   So I bet was   " Phouc Yu  " when he cleaned out your bank and credit
accounts.




...........   Phil

Thanks, I hadn't seen that impedance graph recently.
Anyone got an equivalent circuit to model the impedance of an ESL?