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Old 14th August 2003, 04:37 PM   #1
Kal is offline Kal  Germany
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Default power chord with or without shield

Hello,

as a DIY newbie, I would like to start my DIY-career with something easy such as a power chord.
Are their any new ideas/designs except for the ones found on tnt-audio?
What is important? A high capacitance?
Is a shield really that important, since I heard that a shield slowers the sound?
Thanx
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Old 31st August 2003, 08:30 PM   #2
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You'll find that there is no such thing as a good power cable. The notion that one power cable can sound better than another has precisely no scientific background and is a prime example of the trash that so-called audiophiles spread around. By far the most important aspect of a power cable is its total resistance. Keep this as low as possible by using thick conductors (at least 12awg, thicker for high-powered equipment). Of course, once its resistance becomes equal to that of the rest of the wiring in your home and all the way to your power utility substation, decreasing it further gives no gain.
Ferrite rings wrapped around the cable have a way of removing HF interference from mains lines, but any well-designed piece of equipment will have an equally, if not more effective way of rejecting it.
Keep it thick, and make it look pretty, but don't be fooled into thinking that it will make your system sound better.
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Old 31st August 2003, 09:13 PM   #3
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Default Re: power chord with or without shield

Quote:
Originally posted by Kal
What is important?
Hi Kal

The most important thing is that any cables you use for your homebrew experiments have insulation rated for the voltage you put throught them.
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Old 1st September 2003, 05:48 PM   #4
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Regardless of what certain 'experts' (without the benefit of actual experimentation) oppine, there are valid technical objective measures that will change the subjective capabilities of a powercord.

In the States, it is easy to get a subtantial improvement over the typically supplied OEM stock cord by replacing them with Volex 17604 IEC terminated cords at less than $1/ft. These have 3 14ga cabled wires with plastic fillers to space the shield away from the current carrying wires. This results in far less capacitive coupling to ground than an apparently similar cords (such as those from Unicable that lack the fillers) and will result in very different subjective perceptions. The voltage rating of cords used must be appropriate for your line voltage, i.e. 240vac as opposed to the 120vac here in North America.

Certainly, there is much voodoo associated with aftermarket cords... but there are construction details that change subjective perceptions that correllate to measureable objective measures.

1. As Pinkmouse said, use appropriately rated cords, with a large gauge to minimize both danger and resistance.

2. Minimize capacitive coupling to ground by spacing the shield away from the line and neutral wires, if you use a shield. This is easiest to do, but I'm not familiar with what is available in Europe, but it should be possible to find premade cordage in Europe who's shield is spaced away from the wires

3. Maximize the line to neutral capacitace by using multiple twisted pairs or a star-quad configuration for the line and neutral wires, as that capacitance acts as a noise filter, and those geometries will minimize the effects of external emi and rfi interference, especially if your cord lacks a shield.

And finally, I'd advise you that this forum is probably not the appropriate venue to discuss powercords. AudioAsylum.com cable forum is far more open minded, though I'll caution you that the signal to noise ratio is rather low. Here are two threads discussing high value, easy to build, effective approaches -

http://www.audioasylum.com/audio/cab...ages/7885.html

http://db.audioasylum.com/scripts/t.pl?f=cables&m=24220
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Old 2nd September 2003, 09:41 PM   #5
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Quote:
By far the most important aspect of a power cable is its total resistance
Ohm's law is apparently dangerous knowledge for some. Especially when it becomes the primary tool to debunk myths.
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Old 2nd September 2003, 10:15 PM   #6
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Default Bigger is better for welding and amplifer cables.

A few years ago I walked into a music store and announced to the owner that I wanted to buy some guitar chords.

He says, "sure, how bout a nice new C-sharp."

I said, "no, no these are for an electric guitar."

He then jumps in with, "Oh then you need power chords, I've got a great deal on an open position 2 note movable power chord."

{*** If your as musically clueless as myself a partial explanation of the shop owners pithy wise cracks can be found here:
http://www.cyberfret.com/chords/power/index.php ***}

...This actually happened to me. All I needed was some shielded cables with 1/4" phone plugs. This wise guy decided to drop all the old corny music jokes he could think of on me. I seem to unnaturally attract these people.

I'm a bigger fan of over sizing the conductors of a power chord by at least one gauge than I am of using shielded chords. I figure that if something has been induced onto the power line in the several miles of open cabling before it gets to my audio power supplies that 72 inches of foil and braids aren’t going to help me much.

From some school of hard knocks engineering classes I have however observed that amplifiers tend to draw their power non-linearly or asymmetrically. Making sure that my power supply does not get bogged down by its power cable has seemed to have an audible difference for me. (spose I should try measuring this sometime)

PinkMouse’s observations about the voltage rating of the insulation are very important if you are stepping away from off the spool products.

I’ve jumped into an area of electrical engineering here that I'm not fully qualified in. Others have tried explaining this stuff to me on this site, but I fear they've grown (justifiably) weary of me. There might be some relevant information to AC power cable gauge available buy searching the archives.

-Dave
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Old 2nd September 2003, 10:39 PM   #7
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For the power cable i use Lapp cable, Ölflex shielded 3*1.5 :
http://www.lappcable.com/products/pv...lass_100cy.htm

And a brown, Bakelite - Style plug from KEMA or so.

Others use this cable as XLR cable: http://www.springair.org/index.html?..._11_127711.htm

It looks very pretty, with some imagination you may be able to see one attached to my BZLS: BZLS work in progress
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