Why aren't speaker cables Coaxial?

[skeptic2]

I don't buy into the very expensive cable either. But from the skin effect calculation, above 10KHz, the dept get quite thin, so I do believe more pairs of cable with fine strands give you more surface area. This no only lower the resistance, the most important thing ( just my thinking only) is the inductance of the cable. A little increase of inductance might change the phase and attenuation of the highs. Even though ears cannot hear about 10KHz to 15KHz, but I do believe your body feel it. Again, I believe it's the transient that made the sound real.

The resistance for 1 strand of 12 AWG wire 10 feet long is 0.01588 ohms. Four pairs would bring that down to about 8 milliohms round trip. If your receiver has an output impedance of about 10 milliohms, that amount of resistance sounds about right. What I am concerned about however is the crossover network of the speaker itself. I find it difficult to imagine a crossover network that can transform 20 milliohms to 4 ohms and at the same time maintain a relatively constant source impedance and phase over the full range of each speaker. Also for a high end speaker we would not want to alter the original phase relationship between the low medium and high frequencies. I think a crossover network that fails to do all of the above would mask and negate any benefit of low resistance cables. It also seems to me audiophiles should be putting much more attention to the design of the crossover network than to the resistance of the cables.

I believe the hardest sound to produce is glass breaking, crashing of the symbol of the drummer in music, object drops, explosion etc. All these have very sharp transient and very large dynamic range. No matter how good the system, I don't think any recording can come close to capturing these sounds. That is the reason you always can tell a live band out of the recording, and the most obvious is the percussion including drums. To a less degree, sax and other horn instrument. The true sound has the kind of raw edge that the recording cannot produce. Those are the sound that the better the system, the more you get out of it and the more critical the inter-connects are.

This sounds reasonable. In fact I've heard that the attack of a piano note must be clipped in digital recordings because there is not enough dynamic range to capture both that peak and the soft passages.

I did try reverse those uni-directional coax, and I cannot tell the difference in my system, my system is no where belong to the top end, so I am not going to say yes or no. Again, this is only my theory and I am no expert. None of these can be measure by instruments as human ears are much sharper than the instruments.

The problem is the human mind often compensates for deficiencies in speakers and ears.

 

[yungman]

The resistance for 1 strand of 12 AWG wire 10 feet long is 0.01588 ohms. Four pairs would bring that down to about 8 milliohms round trip. If your receiver has an output impedance of about 10 milliohms, that amount of resistance sounds about right. What I am concerned about however is the crossover network of the speaker itself. I find it difficult to imagine a crossover network that can transform 20 milliohms to 4 ohms and at the same time maintain a relatively constant source impedance and phase over the full range of each speaker. Also for a high end speaker we would not want to alter the original phase relationship between the low medium and high frequencies. I think a crossover network that fails to do all of the above would mask and negate any benefit of low resistance cables. It also seems to me audiophiles should be putting much more attention to the design of the crossover network than to the resistance of the cables.


This sounds reasonable. In fact I've heard that the attack of a piano note must be clipped in digital recordings because there is not enough dynamic range to capture both that peak and the soft passages.


The problem is the human mind often compensates for deficiencies in speakers and ears.

I don't have enough experience with crossover network, I don't even dare to touch it. My feeling is the low pass crossover side is no where as critical compare the mid and the tweeter side. I think they really need good capacitors...which I still don't quite buy into yet. I still believe if you need a 10uF, instead of pulling hair to get the best one, use two 4.7uF, one 0.47, one 0.1 high voltage cap ( like 200V that has bigger area and thicker dielectric) to make up the 10uF. This combination should have very low ESR.

Actually I think one of the biggest path of the electronics that contribute to the loss of fidelity is the mic that record the sound! It is just like speakers, nothing is linear about it and the dynamic range is limited also. So far we never talked about human voice. This is because when we listen to concert, singer sing through the mic, what you hear already include the distortion already. Just listen to a person singing without a mic, it is not even close to the voice through the PA system.

 

[jim hardy]

our mind will color our perceptions in accordance with our pride and prejudices...


given that today's speaker standards specify DC resistance of speaker coil to be around 80% 0f nominal z,

ie an 8 ohm speaker has about 6 ohms of resistance

i could never buy into necessity of exotic wire for connecting to them.
so i am skeptical...

but i do relish hearing of you guys' experiments.

I never owned more than 100 watts
and never used anything larger than #16 copper lamp cord.
i believe sound is mostly in quality of magnet structure and cone material.
Enclosure too, of course.

the ear hears via electrochemistry of nerves in the cochlea and i just don't see how that could be sensitive to phase.

carry on, fellows, i am very interested.

old jim

 

[yungman]

our mind will color our perceptions in accordance with our pride and prejudices...


given that today's speaker standards specify DC resistance of speaker coil to be around 80% 0f nominal z,

ie an 8 ohm speaker has about 6 ohms of resistance

i could never buy into necessity of exotic wire for connecting to them.
so i am skeptical...

but i do relish hearing of you guys' experiments.

I never owned more than 100 watts
and never used anything larger than #16 copper lamp cord.
i believe sound is mostly in quality of magnet structure and cone material.
Enclosure too, of course.

the ear hears via electrochemistry of nerves in the cochlea and i just don't see how that could be sensitive to phase.

carry on, fellows, i am very interested.

old jim

Use cheap #12 multi strands, you might be surprised. It is not much more than the #16 in the big picture. You don't need any fancy stuff.

 

[jim hardy]

i think i'll give that a try.

i always speculated that part of this long standing debate lies in transfer function of amplifiers.
modern stereo uses feedback to make a closed loop controlling the voltage across load

whereas in old days the pentode output stage was a controlled current source, (think Norton)
so compared to a modern amp, voltage across load was comparatively free to be the differential of applied current .

I guess your speaker wire impedance is one more term in system transfer function?
It lies in between amp and the speaker's inductance/inertia so is outside the feedback loop..

might that help explain an unexpected sensitivity?
We need Morbius.

old jim

 

[audionut]

having read above, from a sound quality side there is a major improvement to be had
by using coax the only available suitable cable is urm76 or make your own from the articles written back in 1997 july to october wireless world magazine (no longer produced) this was an article written by Cyril bateman who is a electronics design engineer. this will give you all the information you need regarding this subject. the articles are available on line it took me a little while to locate them but worth it.
start with your existing cable, turn up the volume to max (with no music playing !) listen to the noise produced. now connect your urm76 and repeat the above, you will find there is a reduction in noise. now play your preferred music and you will now notice more realism to the music and more detail at the top end and better more accurate bass.

 

[sophiecentaur]

That has no relevance to speaker cables.

Why would you want to connect an amplifier with an output impedance of say 0.01 ohms (if it's a good quality amp) to a speaker with nominal impedance 4 ohms, with a 600 ohm impedance cable?

The characteristic impedance of a transmission line is hardly relevant at audio frequencies. The "600Ω" refers to the source and load impedances of amplifiers used in audio distribution and the choice (way back) was based on state of the art valve amp devices and likely sources of noise and interference. Aamof, to make a transmission line with much more than 200Ω impedance is hard - the spacing between conductors needs to be made impracticably large for audio cable. (RF open-wire feeders are a different matter)

It's the resistance that counts with speaker cables and even then, of the two effects of a high series resistance (frequency response and loudness) it would only be the frequency response that would be relevant (you just turn up the wick if it's too quiet - and, in any case, most good speakers are pretty inefficient by design).

I think most people (enthusiasts) listen to their HiFi via their wallets.

 

[yungman]

having read above, from a sound quality side there is a major improvement to be had
by using coax the only available suitable cable is urm76 or make your own from the articles written back in 1997 july to october wireless world magazine (no longer produced) this was an article written by Cyril bateman who is a electronics design engineer. this will give you all the information you need regarding this subject. the articles are available on line it took me a little while to locate them but worth it.
start with your existing cable, turn up the volume to max (with no music playing !) listen to the noise produced. now connect your urm76 and repeat the above, you will find there is a reduction in noise. now play your preferred music and you will now notice more realism to the music and more detail at the top end and better more accurate bass.

It is very hard for me to buy into there is a difference in noise with speaker cable. I don't have to best audiophile system, I use JM Lab Focal speaker and Acurus power amp, I use 4 pairs of Monster "like" fine stranded 12 gauge cable for each speaker and it compares with expensive speaker cable.

There is no transmission line thing to speak of for speaker cable as Sophiecentaur said. You don't talk transmission line until the length becomes a significant fraction of the wavelength. Until you have a mile of length or more, don't think of tx line.

You want to keep capacitance low and inductance low...of cause resistance low. URM76 has inner diameter less than 1mm, that is small and the resistance comes into play. You might be better off using RG8 that has inner diameter of 2.7mm if you believe coax has some magic. But be aware, RG8 is so stiff you can whip people with that!

If I were to be so nitpick, I would have a two individual cable, spaced it out like the old tv antenna flat cable to minimize coupling capacitance. Then I use like a 22 gauge insulated magnet wire and twist them together to form an 8 gauge cable or two 10 gauge separate cables, one for woofer, the other for the mid and tweeter. This will get rid of any skin effect at 20KHz. This ensure minimal resistance, minimal capacitance and inductance.

Or better yet, use Mono bloc amp and put the amp next to the speaker so you use a very short speaker cable. Then find coax with highest characteristic impedance ( not the impedance, but lower the capacitance to ground) to run from preamp to the Mono Bloc.