Why aren't speaker cables Coaxial?

[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.