Tuesday, March 23, 2010

Home-brew high end speaker cables

Becoming interested in a few DIY projects seen online I decided to make my own speaker cables to replace some home-made jobbies that I'd been using for about 10 years..

Since I work in the commercial A/V field I have collected a ton of surpluse cable and wire over the years. Having an abundance of CAT5E cable on hand it was a cinch to choose one of the projects that feature use of that sort of cable. The final design of the cable is a distillation of several articles that covered the making of your own speaker cable.

Needing approximatley 15' runs I played out eight 18' strands of CAT5E cable. I then made four twisted pairs out of the 8 strands, twisting counter-clockwise. I then took two twisted pairs and combined them, twisting in clockwise direction. This made two rather thick braids of CAT5E about 16' long, of which I secured the ends with electrical tape.

Next I cut 4 6" long pieces of heavy 1" heat shrink and slid them down the cable ends. Then stripped back about 6" of each of the four strands at each end. Next I un-twisted every pair, sorted them out (stripes and solids) and combined all the solids together and the stripes together. I then twisted each bundle and wrapped with teflon plumbers tape. Next I pushed 3" of red heat-shrink down the "solids" bundle and 3" of black heat-shrink down the "stripes" bundle. Next, shrink the black and red wraps on the bundle ends, pull the 1" x 6" heavy shrink up the cable to cover the transition point where the bundles are seperated out of their CAT5 strands and shrink. I then put some hot glue into this cover between the bundles, heated and pinched together with big needle nose pliers to clamp the shrink together and make "pants" over the transition point and the bundles.

Next I stripped each individual strand of the wire bundles for pos. and neg., trimmed to length and crimped on heavy fork connectors, then soldered with silver content solder. Heat shrink was applied over the connectors for a finished look.

Upon first listen they sounded terrible. But after about 1/2 hour of listening they started to break-in and sound better. Now with about 6 hours on them they sound wonderful! Tighter bass, more texture and detail in the lower registers, better integration of the whole sonic picture and a more even presentation of the frequency range. More detail is heard, more low-level stuff like reverb tails, backing vocals I'd never noticed before, etc.

Since CAT5E cable is rated for 350Mhz it should work fine as an audio cable. Even better is that the positive and negative conductors are all seperated and twisted together in individual pairs, and each individual CAT5 strand is twisted with another, and so on. This results in very low inductance (but rather high capacitance, though that doesn't matter as much as inductance for speaker cable) and low resistance. Also this design eliminated the smearing of signal and skin-effect losses associated with multi-stranded cable because each strand is individually insulated, much like Litz wire.

Anyway, DIY is awesome, and cheap!

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