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Need some expert help with coax cable project

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Posted on June 16, 2017 at 14:52:51
mr.bear
Audiophile

Posts: 4167
Joined: November 13, 2001



Via the secret BearNet, a few nice RCA interconnects have arrived at the Cave- a trio originally intended for "component" video service. The construction is ~6% silver center conductor and silver foil / silver plated braided shield, and silver-plated RCA's already attached. (Audioquest YIQ-3 IIRC). The sound is quite good in my system. I am committed to use these for stereo interconnects.

The issue is this: I painstakingly removed the braid and PVC outer jacket (it tightly covered all 3 cables) to separate the 3 cables. That left the cables wrapped together with some dry, papery, white plastic stuff and under that, each shield is wrapped with a thin transparent plastic insulating scrim (photo). I need to add an outer jacket.

Is anyone conversant with the effect of the outer jacket on cable performance? I assume it's there 99% to insulate and protect the shield from damage. By careful handling and minimal disturbance over time plus protection from environmental exposure, that will be minimised.

I was thinking of wrapping the individual shields in Teflon plumber's tape and Tech-Flex's tightest-woven braid over each, and a binding the ends with a little heat-shrink. That should provide adequate insulation and protection. The material of the braid is PET- Polyethylene Terephthalate.

I'd greatly value your experience with coaxial cable jacket material, particularly if you have determined that there are meaningful audible effects.

Do I want to put a small drain wire in the new jacket somehow?



 

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RE: Need some expert help with coax cable project, posted on June 18, 2017 at 17:33:22
Jon Risch
Bored Member

Posts: 6659
Joined: April 4, 2000
Contributor
  Since:
March 1, 1999
The jacket material does impact the overall sound, but not to a large degree.

It is subtle, and somewhat depends on the actual construction of the cable, whether it is coax, twinax, etc.

In my experience, coax is affected more than other geometries, but this is somewhat dependent on the amount of braid shielding. Since you have "taken the cable apart", the braid can "come loose" and will no longer have the stated percentage of shield coverage per the original specs.

Spacing the PET techflex away with some teflon plumbers tape will help ameliorate the effects of the PET, but not totally.

Good luck with your project, and remember to try and physically constrain the cables mechanically against vibration and relative movement between the materials.





Jon Risch

 

RE: Thanks, Jon, posted on June 18, 2017 at 22:50:32
mr.bear
Audiophile

Posts: 4167
Joined: November 13, 2001
Very helpful advice. I was wondering of there were any DIY cable experimenters here after all. I studied teflon tape and acquired the heavyweight "gas service" yellow PTFE tape from a reliable hardware store here in town. It's Mil-spec and quite a bit thicker than the white stuff and has an excellent dielectric constant (around 2 at 1MHz)

The braid on my cables is nicely restrained by an intact length of ordinary PVC(?) jacket at each end, so it can be carefully handled without coming apart.

Your advice about the physical constraint is very good. I am considering using the thinnest (20-mil) "self-sealing" silicone tape to wrap the cable again after wrapping with the teflon.

What's better than PET for an outermost (essentially decorative) jacket? How about glue-lined heat-shrink tubing- probably polyolefin? Provides the physical restraint.

 

Interesting design info from Belden, posted on June 18, 2017 at 22:57:25
mr.bear
Audiophile

Posts: 4167
Joined: November 13, 2001
Check this website - ideas for inventor-types- detailed comparisons and tech data on various insulation types

 

RE: Thanks, Jon, posted on June 19, 2017 at 15:07:08
Duster
Manufacturer

Posts: 17117
Location: Pacific Northwest
Joined: August 25, 2002
The heavy duty PTFE tape will be fine. A layer of "self-sealing" silicone tape over the PTFE layer is a good idea. Don't be concerned about ordinary PET sleeving, since it won't affect performance in a notable way. Techflex Clean Cut sleeving is my preferred option, since it's easy to work with and has the best look and feel, unless you seek a more decorative look.

 

RE: Thanks, Jon, posted on June 20, 2017 at 19:22:41
Jon Risch
Bored Member

Posts: 6659
Joined: April 4, 2000
Contributor
  Since:
March 1, 1999
If you must cover it up, then yes, the thin wall polyolefin HS is the way to go.

The adhesive lined HS can be very stiff, if you use the silicone rubber tape, this will provide enough physical damping and constraint, then the thin wall polyolefin HS is just a pretty cover a that point.


Jon Risch

 

Only for rank beginners?, posted on June 20, 2017 at 19:36:10
Jon Risch
Bored Member

Posts: 6659
Joined: April 4, 2000
Contributor
  Since:
March 1, 1999
Not detailed enough for the real nitty gritty of high performance DIY audio cables.

Only generalities and industry conventional stuff.

The insulation chart does not provide actual numbers for the dielectric quality as regards DF, DA, etc., and the overall article is aimed more at commercial/industrial style usage.

Of course, if one knew what to look for in the first place, then this article would be superfluous.

Try checking out the link.

The ghost web host .ws has all my old pages, just don't click on anything else there, none of the ads or links not associated with my old pages.

Jon Risch

 

Rank beginners? HEY I RESEMBLE THAT REMARK!!, posted on June 21, 2017 at 12:51:50
mr.bear
Audiophile

Posts: 4167
Joined: November 13, 2001
But I did tease the secret Dr. Jon cookbook out of you! Thanks and I hope I can help you with a structural dynamics matter someday.

 

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