janpo@relay.EU.net (07/05/90)
In article <4822@uwm.edu> Mike Thome writes: > I'm told that there is at least one company which sells high-end >speaker wires made from ribbon cable... is this true? Would you want >to alternate conductors or group 'em? How 'bout cables made up of a >bunch of twisted pair sets? I've never heard of such a company but I've been playing with the idea of using ribbon or twisted pair cables as speaker wire as well. The idea is that with such cable the inductance of the cable can be reduced significantly. A normal two lead speaker wire can have an inductance of about 1 to 1.4 microHenry depending on the electromagnetic coupling between the individual wires. Two wires carrying the same current but with opposite direction have a coupling factor of one if their magnetic fields cancel each other like in a good coax cable and is zero when their fields don't "see" each other. This inductance seems insignificant relative to the milliHenries of cross-over circuits but it isn't. I use, for example, 5 metres of Monster cable which has an inductance of 5.5 microHenry and KEF 104.II speakers which are 4 ohm resistive over the entire audio frequency range. At 10 kHz the impedance of the cable is about 0.35 ohm which, together with the output impedance of the amp and the resistance of the cable would yield a 1 dB loss and a 5 degrees phase shift! Depending on the cable type the extrinsic cable impedance (I.e. 2*PI*f*L) will exceed the intrinsic cable impedance (Resistance and skin effect) from a few hundred or thousand Hertz. From this point of view it's barely usefull to use Litze wire to reduce the skin-effect but much more usefull to find ways to reduce the inductance of the cable. To achieve a reduction of the inductance you'll have to increase the coupling between the wires. Using coax cable as speaker wire would seem a good idea but this wire has quite a high resistance which would yield poor bass response. A better idea is to use ribbon cable or even better, twisted pair flat cable. When using ribbon cable alternate "hot" wires and return wires for lowest inductance and when using twisted pair one conductor should be the "hot" and the other the return wire. A 64 lead AWG 28 (0.089 mm2) cable would yield a 2.85 mm2 (Sorry, no gauge table available here) cable which is worse than the 4.5 mm2 (?) of my Monster cable but all in all it might well be a better choise. Another advantage of ribbon cable is that you can run it out of sight under the carpet. Jan Postma -- Jan Postma UUCP: ...!mcvax!phigate!philmds!janpo | Piekerje net, Philips I&E DTS Inet: janpo@dts.ine.philips.nl | it komt dochs Eindhoven Phone: +31 (0)40-788015 | oars! The Netherlands Fax: +31 (0)40-786114 |
wb1j+@andrew.cmu.edu (William M. Bumgarner) (07/06/90)
Try Kimber cable-- it is multiple conductors (24 or 48) weaved together to form a thick, round cable. At the ends, you seperate, strip and twist together all conductors of one color... Not only does the stuff sound good, but it looks good too-- impressive, yet not obtrusive. b.bumgarner | Disclaimer: All opinions expressed are my own. wb1j+@andrew.cmu.edu | I officially don't represent anyone unless I NeXT Campus Consultant | explicity say I am doing so. So there. <Thpppt!> "I ride tandem with the random/Things don't run the way I planned them.."