The idea to use LAN cable was suggested to me by an audiophile friend. I arrived at the exact cable specifications after quite a bit of experimentation. I found out later that TNT audio had also recommended the same basic geometry, so I guess I won't be taking out any patents...
Cat 5 plenum-rated data cable. "LAN cable", as its also known, has four twisted pairs of 24 AWG, bare solid copper. Plenum versions use fluorinated ethylene propylene (FEP) as the insulator. There is no shield.
I tin the bare wire with silver solder, and screw the ends into a double banana plug. Crimped spades would be just as good, if not better, but I like the convenience of banana plugs.
Simply twist two cables together, about 5 cm per twist. All eight conductors of one cable are connected positive, all eight of the other connected negative.
The best starting point seemed to be LAN cable. I'd seen the idea kicked around on rec.audio.opinion, and it looked interesting. A long time ago I tried it, hooked up in the manner prescribed on Usenet: + and - from each twisted pair, one cable per channel. It was very disappointing. Completely dead in both treble and bass, it's one redeeming feature was a clear and detailed midrange. It was not, however, a cable you would consider listening to.
Later on I took it up again, and tried all kinds of configurations until I hit on something that worked. Thus "Endeavour-X".
I've since tried several other Cat 5 cables by different manufacturers. I was quite shocked when I realised just how much difference the jacket material makes. Most brands use a fire-retardant PVC jacket. I've found that the Dataclear with the Halar jacket consistently sounds better.
Electrical data for Endeavour-X :
|Measured inductance, uH/m||Measured capacitance, pF/m||Calculated resistance, ohms/m|
The Endeavour-X cable can be bi-wired by splitting the four pairs of wires into two sets of two pairs each. I think it would be better to run two complete lengths of Endeavour-X, however. Also see the Endeavour-X2 cable.