The 3 Properties of Wire/Cable

[mzisserson]

Re: The 3 Properties of Wire/Cable

You yourself invited this debate by the nature of the questions you posed in your original post. Specifically question #2 is asking for a subjective opinion on the desirability of any of these properties.

So don't get p!ssed off if your questions don't elicit the response that you are looking for, but instead end up in a debate. People are only trying to answer your questions. After all it is assumed that the reason behind your questions is the pursuit of improved sound quality.

If you are strictly after in depth knowledge of the cause and effect of these properties, I suggest you take an Electrical Engineering course and possibly a Physics course since those questions cannot be answered in a few posts and are beyond the scope of this forum.

I can agree with some of your observation. It will be interesting to see some real, hard data that correlated to audible effect someday.

Yeah sorry guys I had just finished off a bottle of Sake before that - bad idea - but I digress.

I will be taking some EE classes for a degree as soon as I can get out of Uncle Sam's leash, haha. :rolleyes:

I was merely curious to see if what people were hearing is measureable as far as using different speaker cables and interconnects. Also a little bit of research for the future improvements on the crap components I have as of right now. Walmart/RS interconnects, some speaker cable I found somewhere, Free stuff, etc.

I'd really like to build my own set of speaker cables and thought this would be an educational endeavor as well, designing a pair.

Thanks for all the info guys. Let's keep going but keep it sane.

Actually, this has been one of the most sane cable debates in some time! It is actually enjoyable and much has surface with some great education and knowledge. I actually do not think it has one become de-railed.

I am sure if you stared to DIY them and get good measurements/effects/numbers EVERYONE would be waiting with baited breath to hear the results!

[greywarden]

Re: The 3 Properties of Wire/Cable

So I need an LCR meter and some wire

So is capacitance in speaker cables desireable? Essentially each one of the 3 properties can be built into the cable by intelligent design, and not just guessing.

I'll assume that since *usually* higher gauged wire is normally used that it's what is desireable.

And I'll have to figure out what ultimately affects inductance.

[Sydney]

Re: The 3 Properties of Wire/Cable

So is capacitance in speaker cables desireable?

No

Essentially each one of the 3 properties can be built into the cable by intelligent design, and not just guessing.

yes
Like bwaslo mentioned ( post 42 ): A cable design is one of compromise for the intended application and frequency range. Like selection of insulating material etc

And I'll have to figure out what ultimately affects inductance.

For one: the orientation of the conductors with respect to each other.

[greywarden]

Re: The 3 Properties of Wire/Cable

Right on. I'll fiddle around with some designs and get myself an LCR meter, then Report back with my findings.

So where do Dielectrics come into play and how do they effect the cable itself?

[philiparcario]

Re: The 3 Properties of Wire/Cable

Note the source impedance is default to 600 ohms and it uses the equation


Which has 3 variables: d = distance of cable run, Cspec ( capacitance per unit measure provided by the manufacturer ) and Source Impedance:
Plug in the appropriate Source Output Impedance of the appropriate driving device:
For line level sources typical output impedances are in a higher range. For an amplifier it's output impedance is a different low range.
Playing with that calculator you can notice the effects of each of the variables.
I think you can see that each variable has an impact and that the significance of capacitance is tied to Source Impedance.

yes i punched in 6000 ohms and the high freq cutoff was about 4300.

with 600 ohms the high freq cutoff was 43000 not sure


what number to use for ohms in the case of a speaker output from an amp.

that is why I asked the question if 600 ohms was correct for a speaker output from an amp well then the diy cables are going to hurt the rolloff on a 100 meter run only if you can hear above 30000. the diy speakers had higher cap then the example in the link 195 for a meter vs 120 for a meter.

but ohms will affect the qts on a 6ohm speaker 1 ohm of resistance will alter qts quite a bit. for instance on a jordan 92s 1 ohm will change qts from .56 to .64 1.6 ohm will change it to .68

[bwaslo]

Re: The 3 Properties of Wire/Cable

Zout of a decent amp will be in the thousandths of an ohm, pretty much makes that equation explode. For some tube amps and some cheaper class D amps at high freq, Zout can be up to a few ohms.

[Sydney]

Re: The 3 Properties of Wire/Cable

The dielectric constant is how effective a dielectric is at allowing a capacitor to store more charge. It depends on the material the dielectric is made from. Every material has a dielectric constant k. ( Air, plastic, paper, etc ).
The choice of insulation affects capacitance.

http://www.asiinstr.com/technical/Dielectric%20Constants.htm

Phil: a typical solid state amp has a very low impedance ( well below 1 ohm ) a tube amp can be higher.
( what Bwaslo just said )

[greywarden]

Re: The 3 Properties of Wire/Cable

Charcoal has a lower dialectric than teflon haha.

Looks like Cotton is the lowest attainable or sane method of covering wire. 1.3 Dielectric. That's what alot of Headphone guys use to retrofit their cables with.

[ReissM]

Re: The 3 Properties of Wire/Cable

Sydney and Bwaslo both made some very important points that often get forgotten when discussing cable parameters. The input impedance of a pre amp (or Receiver) is often up around 47Kohms. At these high impedance interfaces, capacitance is far more important to minimize than inductance. So your typical RCA interconnect cable from CD player to your pre amp, or pre amp going to your power amp would benefit from a low capacitance cable. The good news is that the majority of coax RCA cables are inherently low enough in capacitance as to not cause any issues below 200KHz simply due to the nature of a coax design geometry.

Now, things are much different when we start discussing low impedance interfaces like power amplifier to loudspeakers. As BWaslo mentioned, a typical solid state amplifier will have nearly zero output impedance... we're talking 0.001 ohms guys. Tube amps can be several orders of magnitude higher, but a reasonable approximation could be made at about 1 ohm depending on the design.

"So what?" you ask. Well... the big thing to remember is that inductance is what you want to minimize when dealing with low impedance interfaces. Again we have good news... typical 12, 14, 16 AWG wire is low enough in inductance as to not cause any audible issues.

Surprisingly, cable Resistance is not the biggest concern for speaker cables. Cable inductance is the key parameter for low Z interfaces like speaker connections. If it were simply about finding low resistance speaker wire, car jumper-cables would be terrific.

P.S. - Back to the high impedance interface for a second. It is possible that a vacuum tube pre amp with an output impedance around 10,000 ohms would be greatly affected by a high capacitance cable... while the exact same cable used with a receiver (output Z about 1 ohm) would not be affected at all in the audible range. This is why some people hear large differences in cables but their friends using the exact same cable can't hear a difference at all in their system. A vacuum tube pre amp's high output impedance will interact with the cable's high capacitance to form a low pass filter... sometimes well below 20KHz, and thus is clearly audible.

So it might not be solely the cable's high capacitance causing problems... the vacuum tube pre amp's high output impedance is partially to blame in this example.

Stick to low capacitance for RCA cables.
Stick to low inductance speaker wire.

Both are easily accomplished at very reasonable prices. No need for extreme $$$$ cables.

The last point I would like to make... During the physical arrangement of your equipment... If you have a choice between these two situations:

1. Long RCA interconnects and short speaker wire.
2. Short RCA interconnects and long speaker wire.

Always choose the first. Lots of math to justify this but I won't bore you any further. Have fun and enjoy the music.

[greywarden]

Re: The 3 Properties of Wire/Cable

Where the hell have you been the past 54 posts?!? Lol.

AWESOME information, there man.

Thanks!