DIY DC power cables

[sockpit]

Slightly off topic but star quad related:

 

my speaker cables our diy, and made from 14 awg, four strand audio quest speaker cable design for in-wall installations.

 

when terminating them, I paired them together (since I'm not biwiring).  Problem is I didn't pair them diagonally.

 

now so far as I can see these four wires are not twisted at all, but just run parallel inside the casing. 

 

Would redoing the pairing so they are diagonally paired make any difference theoretically with speaker wires of this sort?

 

thanks.

[sockpit]

Alex C.

 

I own two of the special DC cables you sell with the JS-2, the star quad 5 footers with oyaide plugs.  Can I assume that since JS designed the JS-2 and sleeps on your couch from time to time that these cables follow the principles generously outlined above?  ?

[sockpit]

1 hour ago, Superdad said:

 

It was the traditional, tie the shield at just one end.  

Oh noooooooooooooooo!

 

Is their merit in clipping the tied end, or is the shield all for nought?

 

Pasted from JS post above:

 

"OK here it is: cable shielding, how to make it work and how almost all cables have it wrong . . . 

 

So what about shielded cables? I hope is now obvious that for shielding to be effective there needs to be a conductive path from one end of the shield to the other. If there is not such a path the only shielding that is going to happen is for high frequencies due to cpacitances involved with the shield.

 

The best way for the shielding to work properly is a separate wire connected to each end of the shield. This is sufficient for shielding from DC to very high frequencies. Note the shield does NOT have to be connected an earth ground, the "ground" of the circuit at either end, or any thing else for that matter. A cable with a shield the is not connected to anything else except itself (ie a separate wire from one end to the other of the shield) will be highly effective in shielding what is inside.

 

Where does this wire need to go? It can be either inside or outside the shield, but if it is inside it can couple to the signal wires inside, so it is usually best to have it outside the shield. Note it has to be insulated from the shield except for the ends where it connects to the shield. It should intersect as little of the external field as possible so it should NOT be tightly spiraled around the cable. Just running along side the shield is best, although a very loose spiral (say one turn per foot) is almost as good.

 

So some ramifications of this: The traditional "connect the shield to one end and let the other end float" is not good, it does not allow a loop so shielding does not happen very well. If you add the external wire connected to the shield at both ends, then you CAN connect one or both sides of the shield to the signal ground or some other ground, but you don't NEED to for effective shielding. You will find that in many cases leaving the shield completely disconnected from the rest of the circuit is the best way to go, you get the benefit of properly working shielding without any interaction of the shield with your system. You may wind wind up with static charges on the shielding so a resistance from the shield to ground may be useful in some cases in order to dissipate static charges.

 

So how come nobody does this? I don't know. My only guess is that cable shielding has been going on long before the actual mechanism for shielding was worked out, thus by the time it was understood, cable shielding was "standard" and nobody ever even thought about analyzing it based on an understanding of how shielding actually works.

 

But shouldn't the big companies know about this? It seems they don't. I have read several app notes from Belden that state that shielding is only effective at high frequencies, at audio frequencies and power supply frequencies (60Hz etc) it is totally ineffective.

 

Audio people are the only ones that seems to at least empirically know about this. Remember phono cartridges and preamps, there is a little green wire that goes from the "ground jack" on the preamp to the tonearm. Everybody assumes that this is to "ground the cartridge" but what it really does is provide a loop from one end of the interconnect shield to the other, it has nothing to do with whether it is "grounded" or not. So if you have (or had) a turntable you were actually taking advantage of this without realizing it.

 

So there you have it, shielding DOES work, but only if you provide a path from one end of the shield to the other. This is effective even if you don't connect the shield to anything else.

 

John S."

 

 

 

[sockpit]

4 hours ago, agladstone said:

Thanks - I think you're correct, perhaps it's time for me to buy a soldering iron and  associated gear and start practicing/ learning how to solder. I can't tell you how many times I've actually said to myself "if only I could solder.....," over the years!!

Just do it.  When I was a kid, probably 7or 8, I got a soldering iron for my birthday.  And some radio shack kit for making a radio.  Now at 55, I still own the iron and used it yesterday to make my own DC cable.  It's a cheap iron, but did the job of tinning and fusing the quad star ends just fine.  Can't believe I've schlepped it with me all these years.  Anyway, soldering isn't all that hard if you're  patient and let the wire get good and hot.

[sockpit]

13 hours ago, watercourse said:

 

I still remember the sound of my 8th grade teacher's voice when I'm tinning and drawing solder up.

 

If I can do it, you can too. of course, everything was easier when lead was around. I also wonder how much higher my IQ would be?

 

I held on to a big roll of lead solder, too