On Sun, May 10, 2009 at 08:42:13AM -0700, Aaron L. wrote: > However, in the sense of diy (and there being some great brains in this room), > I'd love to hear someones thoughts about this article. > > http://www.mcmelectronics.com/content/en-US/diy/baluns > > Scroll down to the yellow number 3. Long unshielded transformer isolated twisted pair cable run for audio ... can work, but the things that would worry me are: 1. electromagnetic interference, or induced audio, ... at a gig I had a twisted pair run parallel to speaker wire once and managed to induce some crosstalk from the output back into the input, and the feedback whistle was very different to audio air mediated feedback, and my mixing position at the back of the building was not enough defense, ouch, 2. radiofrequency interference, you have a long antenna, ... probably not a problem provided your equipment already has RF filtering, if you've ever heard the GSM signalling from a nearby phone on your equipment, then you know what I mean, 3. lightning strike, or telephone circuit fault current from a neighbour ... you have your audio line running in the same sheath as a telephone line, and the telephone line extends out of the house all the way to wherever it is originated ... any lightning strike along that path can raise the voltage on one pair in the sheath, which is harmless to the other pair that you weren't using, since it is not terminated at either end ... terminate it now to a transformer and the transformer sits on the path to ground, 4. codes or regulations, ... some regulatory regimes prohibit this sort of connection for various reasons, including safety of line workers ... who dislike encountering strange voltages while buried up to their ankles in mud next to an open cable termination ... ;-) while it should not happen, it may, if the balun is faulty, or shorts, or is damaged by a prior event that doesn't render it inoperative for audio. -- James Cameron mailto:quozl@xxxxxxxxxxxxx http://quozl.netrek.org/ _______________________________________________ Linux-audio-user mailing list Linux-audio-user@xxxxxxxxxxxxxxxxxxxx http://lists.linuxaudio.org/mailman/listinfo/linux-audio-user
