Litz braiding and DIY interconnects - AVS Forum
Forum Jump: 
 
Thread Tools
post #1 of 15 Old 02-26-2003, 06:40 PM - Thread Starter
AVS Special Member
 
yubyub's Avatar
 
Join Date: Dec 2001
Location: NY
Posts: 1,515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I've been looking to experiment with some DIY power and audio interconnects.

I've read a good deal of posts/pages which describe using braided wire to form the interconnect. Doing a bit of research reveals this is called Litz braiding.

The part I'm a bit confused about is that while some people recommend stranded wire, others recommend solid core (claiming that stranded wire lessens the effects of the Litz braiding). In fact, here's a page in particular which strongly recommends against stranded wire:

http://home.att.net/~chimeraone/audiolitzwirebraid.html

Can someone give me some background on why/why not stranded might be bad?

-Jon

-Y
"First things first, but not necessarily in that order." - Dr. Who
yubyub is offline  
Sponsored Links
Advertisement
 
post #2 of 15 Old 02-27-2003, 06:27 AM - Thread Starter
AVS Special Member
 
yubyub's Avatar
 
Join Date: Dec 2001
Location: NY
Posts: 1,515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Okay, from what I've read this is the reason:

Litz wire works well because it helps reduce the skin effect. This effect is apparently more important to consider in high frequency (i.e. RF) applications.

The reason why stranded wire shouldn't be used is again due to the skin effect. The idea behind Litz wire is to increase the surface area of the conductor (by using multiple conductors) while reducing the skin effect (which is why each conductor must be insulated from each other).

This, however, brings up two questions:

1) I've seen many designs (including some posted here on AVS) which use Litz wire constructed with stranded wire. Are these designs incorrect, or am I still missing something?

2) All of the info I've found so far claims that Litz wire has most of its benefits in the higher frequency ranges (i.e. RF). If so, then why are there several designs for audio interconnects and power cords using Litz wire? It seems these designs would benefit very little from the Litz design.

Edit:

This site claims "Skin effect can be reduced by using stranded rather than solid wire."

This site claims "...you will find that it doesn’t even become an issue until over 1GHz which is significantly higher then audio, component video and HDTV signals."

This article claims that "It does not matter if a Conductor is 12 Gauge solid Copper, or a Conductor of a 12 Gauge multi-stranded Cable...both will appear as 12-Gauge solid Copper round conductors."

-Jon

-Y
"First things first, but not necessarily in that order." - Dr. Who
yubyub is offline  
post #3 of 15 Old 02-27-2003, 08:41 AM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Skin effect??? In what a 3 foot cable??? I'm sorry you can use up to 16ga with no skin effect at that length...maybe 100 feet you'll experience skin effect problems. Roll off in audio cables is not skin effects , it's a reaction magnetic between conductors...and all types of metals react differently.

Alan Maher

Alan Maher
Perfect Cable
Chili Minora is offline  
post #4 of 15 Old 02-27-2003, 08:59 AM - Thread Starter
AVS Special Member
 
yubyub's Avatar
 
Join Date: Dec 2001
Location: NY
Posts: 1,515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Alan,

What is the purpose of using a Litz type configuration in a power cable which is 1m, then? From what I've read, Litz cables reduce the skin effect - that is their primary "function" if you will. Do Litz cables have other benefits?

Please realize that I'm not trying to attack anyone here; I'm merely trying to learn a bit about this. I was contemplating building one of your power cords, Alan, and decided to do some research on the matter so I could understand what I built.

-Jon

-Y
"First things first, but not necessarily in that order." - Dr. Who
yubyub is offline  
post #5 of 15 Old 02-27-2003, 09:34 AM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Jon-

In my designs stranded cable is used for cable flexibility...it certainly doesn't offer any performance upgrade. Some people claim audible differences between solid and stranded, but it has to do with surface area contact vs any form of skin effect.

Depending which of my designs you built, each offers a different magnetic reaction between the conductors. In the case of the dual twisted design you have 2 things going on. First is the overall size of the ground (8ga). 8ga is used in commercial applications to help filter up to high emi frequencies. Second, keeping the hot and neutral isolated from one another reduces stray magnetic fields that cause 90% of audible noise in a/v components. Now, if you built the 4 wire braid, the inter 8 weave design is another animal. Magnetic Shield Corp who owns the patient on the design, came up with a new way to reduce inductance compared to normal twisted pair conductors. The braid cancels all forms of stray magnetic fields within the geometry. This is the main reason why people claim the soundtstage size grows in depth and width after building the cable. I modified the design to use the same principals as the inter 8 weave, but this time adding the 8ga ground for additional noise filtering up to high emi. In my commercial line I took this design to the next level, but I'm in the process of applying for a patient on the design so please don't ask for additional information at this time.

Alan

Alan Maher
Perfect Cable
Chili Minora is offline  
post #6 of 15 Old 02-27-2003, 09:37 AM - Thread Starter
AVS Special Member
 
yubyub's Avatar
 
Join Date: Dec 2001
Location: NY
Posts: 1,515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Alan,

I believe I understand now. Thanks for taking the time to explain it.

Do you still have a page up with the rest of your DIY designs? I certainly don't want to hamper your patent process, but I'd love to see what else you've come up with.

Again, many thanks.

-Jon

-Y
"First things first, but not necessarily in that order." - Dr. Who
yubyub is offline  
post #7 of 15 Old 02-27-2003, 11:14 AM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
I haven't been involved with diy designs in a long time. My latest effort is a prototype power conditioner design of my new PC3000 (minus a few stages). Maybe you might want to try building one. I'm very pleased with the results. All of my cable designs have moved over to my commercial line. I still offer custom designs.

Both the dual twisted and 4 wire braid have multiple applications of use. Try the 4 wire braid for interconnects. 22ga and 20ga conductors normally offer excellent results for rca and xlr applications (silver is best). The dual twisted can be used as a cross-connected speaker cable. In direct signal applications step up the wire and connector quality. I can always assist in designing these applications.

Alan

Alan Maher
Perfect Cable
Chili Minora is offline  
post #8 of 15 Old 02-27-2003, 12:05 PM
AVS Addicted Member
 
Chu Gai's Avatar
 
Join Date: Sep 2002
Location: NYC area
Posts: 14,967
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 318 Post(s)
Liked: 596
with regards to interconnects, the additional braiding will also increase the capacitance, which can, say for a passive preamp and a longish run, cause a bit of difficulty. nice link to the company. one could also run some canare star quad or mogami microphone cable too.

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
Chu Gai is online now  
post #9 of 15 Old 02-27-2003, 12:12 PM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Yes and no...don't get 3 wire braids, 4 wire braids, and star quads confused. A 4 wire braid design will offer a balanced inductance and capacitance build up to cross cancel each other out.

Alan

Alan Maher
Perfect Cable
Chili Minora is offline  
post #10 of 15 Old 02-27-2003, 12:14 PM - Thread Starter
AVS Special Member
 
yubyub's Avatar
 
Join Date: Dec 2001
Location: NY
Posts: 1,515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
<oh no, here we go again>

-Jon

-Y
"First things first, but not necessarily in that order." - Dr. Who
yubyub is offline  
post #11 of 15 Old 02-27-2003, 12:24 PM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Not really...let me explain. Take a look at Ray Kimbers design of a cable. The distance between the conductors (loose braid) is what causes added capacitance in a cable design. A 4 wire braid (designed properly) doesn't allow for any space gap between conductors. This allows maximum cancellation of inductance and capacitance.

A star quad is a different design. It's basically two twisted pairs (excellent to lower inductance) twisted together. The plastic filler between the wiring controls space gap between the conductors. The gap sneaks a little capacitance into the design.

Keep in mind capacitance is not a bad thing in audio design. But if your looking not to alter the signal then you need to look at other means for signal transfer.

Alan

Alan Maher
Perfect Cable
Chili Minora is offline  
post #12 of 15 Old 02-27-2003, 01:44 PM
AVS Addicted Member
 
Chu Gai's Avatar
 
Join Date: Sep 2002
Location: NYC area
Posts: 14,967
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 318 Post(s)
Liked: 596
so you're stating, if i read it correctly, that the cable such as in the link you provided would have a neglible increase in capacitance and would be less than say the Canare StarQuad?

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
Chu Gai is online now  
post #13 of 15 Old 02-27-2003, 02:29 PM
Senior Member
 
Chili Minora's Avatar
 
Join Date: Jan 2003
Location: Somewhere in the world
Posts: 388
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Yes...

Alan

Alan Maher
Perfect Cable
Chili Minora is offline  
post #14 of 15 Old 02-28-2003, 10:25 AM
AVS Addicted Member
 
Chu Gai's Avatar
 
Join Date: Sep 2002
Location: NYC area
Posts: 14,967
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 318 Post(s)
Liked: 596
They're reply to me was...
Quote:
Sir, The interweave cable consists of 4 colored wires of 24awg each. 24 gauge is approx .027 ohms per foot. The distributed capacitances and inductances are low ( in the range of picofarards and microhenries). Exact values are not known. The cable is not used extensively in the mhz or ghz region and so inductance and cap. is not that big a factor. I don't believe the 90deg weave eliminates these parameters; that pattern is done to minimize pickup coupling....Regards...ms corp
would seem to suggest that the braiding doesn't serve to decrease capacitance rather to act primarily as most twisted pairs do with regards to minimizing external pickups, no?

"I've found that when you want to know the truth about someone that someone is probably the last person you should ask." - Gregory House
Chu Gai is online now  
post #15 of 15 Old 02-28-2003, 02:28 PM
Advanced Member
 
Entropy512's Avatar
 
Join Date: Feb 2003
Location: Owego, NY
Posts: 515
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 0 Post(s)
Liked: 10
Skin effect is something only present at RF, specifically, with RF signals the current only travels on the surface of the conductor, i.e. the "skin".

This is why a silver-plated RF cavity filter made from copper will have the same performance as a solid silver RF cavity filter - Only the surface layer makes any difference.

So, theoretically, solid wire would be better to reduce skin effect and hence decrease the ability of your cable to be an RF transmission line. But the difference is most likely negligible. The geometry of the cable on a large scale is more important than the small-scale geometry (i.e. solid vs. stranded as compared to how your wires are placed with respect to each other.)

Using braided cables for the intention of PASSING RF would be just plain dumb... If you WANT RF to get through (antenna cables, for example), use a proper transmission line such as either twinlead or coaxial cables.

(Why do "top-quality" coax cables use solid conductors? Because solid conductors offer a more accurate surface, resulting in a more consistent impedance along the length of the line.) There's less surface area, but it's a more accurate and unbroken one, and in the GHz range, surface accuracy matters.
Entropy512 is offline  
Closed Thread Tweaks and Do-It-Yourself



Forum Jump: 

Posting Rules  
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off