4 conductor cable used as single channel?
Oct 29, 2008 at 3:52 PM Thread Starter Post #1 of 23

wudai_e

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I have some spare Canare mic cables which has 4 conductors inside, and what I'm thinking is using these cables into phono RCA.

Basically what I'm thinking is cut the cables and use 2 for signal and 2 for ground.

These will only be 1-2 feet short ICs and any down side of this configuration?
 
Oct 29, 2008 at 4:42 PM Post #2 of 23

nikongod

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lots of parallel capacitance. keeping the cable short will reduce this, but its still there.

If your source has a higher output impedance too much parallel capacitance can create a low-pass filter that extends into the audible range.
 
Oct 29, 2008 at 5:05 PM Post #3 of 23

wudai_e

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Well I'm using 840C as a Dac and feeding a Onkyo 9555 into a Pair of Polk LSi9s. Sometimes I think my system is too revealing in the highs so I guess a little LPF wouldn't hurt :p, besides 2 feet shouldn't make a difference at all.

Guess I'll go ahead and find out. Thanks for the input.
 
Oct 29, 2008 at 5:16 PM Post #4 of 23

JamesL

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iirc... and I'm no EE, parasitic capacitance is caused when wires carrying different voltages run in parallel.

I personally don't see this being a problem. After all, stranded wire is in a sense, a half dozen or so strands of wires running in parallel.
 
Oct 29, 2008 at 6:27 PM Post #6 of 23

wudai_e

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what do you mean by high and low level? you mean frequency? or gear? or noise?
 
Oct 29, 2008 at 7:09 PM Post #7 of 23

nikongod

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Quote:

Originally Posted by JamesL /img/forum/go_quote.gif
iirc... and I'm no EE, parasitic capacitance is caused when wires carrying different voltages run in parallel.


the strands do carry differnt signals.
one is ground, the other signal.
Quote:

Originally Posted by wudai_e /img/forum/go_quote.gif
what do you mean by high and low level? you mean frequency? or gear? or noise?


voltage and output impedance levels. Pro audio often runs higher "nominal' signal voltages, and STRONGLY avoids high output impedances. both of these things make the pickup of noise and loss of signal in certain gear smaller.
 
Oct 29, 2008 at 9:11 PM Post #10 of 23

nikongod

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Quote:

Originally Posted by apatN /img/forum/go_quote.gif
I'm also interested. So, it's not advisable to use two conductors for signal and two for ground?


I would avoid it.

it makes LOTS of capacatance where it can be harmful. It does reduce inductance, but in "home" applications the inductance of a SIGNAL level cable is of little importance.
Quote:

Originally Posted by digger945 /img/forum/go_quote.gif
I'm interested also.
Would you share with us nikongod, what you think about hookup wire for an amp also.



In the amp? solid core. For signal level I prefer thin stuff when possible.

Try building a few IC's with THIN THIN THIN magnet wire 2 strands of 28 or 30ga wire (1 ground, 1 signal) signal. As an alternate: use thin for signal and something thick for the ground. Just 1 strand of each. 30ga is doable if your careful, 40ga is doable if you just dont care if it breaks and are careful. Ironically, my first attempt at a 40-ga cable broke on my workbench. the second attempt has survived 2 or 3 meets.

If you look around, there are some valid arguments AGAINST solid core wire in interconnects. Specifically it is somewhat delicate. the total parts costs of a "thick and thin" 1M cable is $0.10, with the thin section being replaceable for a penny if you can do the work yourself... recycle some old connectors and give it a shot.
 
Oct 29, 2008 at 9:20 PM Post #11 of 23

apatN

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Sorry if I don't use the right terms but isn't it so that the resistance is bigger in thin wires and that is also one of the tricks to up the ohm on a headphone (beyer for example)? So, if I'm right it would pick up less noise..?

And the reason for a thicker ground is that it 'flows' easier, right?
 
Oct 29, 2008 at 9:46 PM Post #12 of 23

FallenAngel

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The resistance is a bit more in a thin wire than thick, but nowhere near the "ohm" range, more like 0.05 Ohms vs 0.06 Ohms for a reasonble length.

Thicker ground - "flows" easier, don't think so
wink.gif
 
Oct 29, 2008 at 9:48 PM Post #13 of 23

JamesL

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Quote:

Originally Posted by nikongod /img/forum/go_quote.gif
the strands do carry differnt signals.
one is ground, the other signal.



How is it different from a twisted pair with single signal and single ground wire?
Likewise, how is it different from a cardas litz?

I've heard of braiding being used to minimize parallel wiring, but that's usually used for 2-channel cabling.

I think coax cables minimize this effect, as the shielding is distributed 360 degrees, thus canceling out the effect, but on the other hand, i've heard that shielding shouldn't be used to connect the ground.

I'm interested in learning more, as I have some connectors and wire ready at hand.
 
Oct 29, 2008 at 11:14 PM Post #14 of 23

nikongod

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aah, the yin and the yang of life. go too far one way and you tip over. too far the other and you tip over that way. Somewhere in the middle you are stable and can perform well...

Quote:

Originally Posted by apatN /img/forum/go_quote.gif
Sorry if I don't use the right terms but isn't it so that the resistance is bigger in thin wires and that is also one of the tricks to up the ohm on a headphone (beyer for example)? So, if I'm right it would pick up less noise..?


I could be VERY far off, but beyer does not use thinner wire to increase the impedance, but so they can make the voice coils lighter. The extra impedance is a result of the goal: less moving mass.
Quote:

And the reason for a thicker ground is that it 'flows' easier, right?


the idea behind a "thick and thin" cable is mostly in that.

The resistance of 3FT of 40-ga wire is about 10-ohms. certainly FAR more than any practical length of 22-24ga. 3ft of 30ga has much less resistance for that length, but still more than the ground wire.

By making the resistance in the signal wire greater than the ground resistance you can sometimes avoid ground loops by FORCING the ground current through the ground wire. When they are both the same size, the ground current can flow in the signal wire and poof, you have a ground loop.

as far as capacitance is concerned, the thinner wire has less surface area. Capacitance is proportional to distance between the 2 "plates" or wires in this case and surface area. you could increase distance from wire to wire, but then you loose some noise rejection (unless you use the shield as ground as in coax). aah the fun games we play: see the balancing act.
Quote:

Originally Posted by JamesL /img/forum/go_quote.gif
How is it different from a twisted pair with single signal and single ground wire?


if you mean using both wires in a "starquad" cable for a single ended cable, it is very similar, except that the capacatance is far higher.
Quote:

Likewise, how is it different from a cardas litz?


Litz-wire is a technique for making the individual wires, not the "quad"
cardas litz uses several sizes of wire in its core. cardas also individually coats EACH strand to insulate from its neighbors. most other brands use a bunch of one size of wire without coatings. there are some advantages to doing this compared to other stranded wires, but its expensive.
Quote:

I've heard of braiding being used to minimize parallel wiring, but that's usually used for 2-channel cabling.


braiding INCREASES capacitance. BUT if you use a whole bunch of strands you can minimize inductance (at the expense of still more capacitance). This is good for a speaker cable where you want LOW inductance, but are using a power amp which can drive a very reactive load without concern.
Quote:

I think coax cables minimize this effect, as the shielding is distributed 360 degrees, thus canceling out the effect, but on the other hand, i've heard that shielding shouldn't be used to connect the ground.


coax cable minimizes capacitance by using a VERY thin conductor. they also "hold" it a uniform and far distance from the shield. Both things combine to reduce capacitance. I agree, the shield should not be used as an audio ground though.

As a VERY good place to start looking into "thick and thin" cable design is the "anticable." you will need a pencil, or something similar and a decent bit of time. take a couple breaks while winding
wink.gif
 
Oct 30, 2008 at 10:38 AM Post #15 of 23

apatN

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Thanks Nikongod. I heard the voice coils in the Beyer600 are thinner and therefore have a higher ohm.

BTW, there was this one guy in the DIY cable thread. He used a copper wire for audio and two thicker silver wires for ground. He said it was a nice upgrade. What do you think?
 

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