Post
by momunist » Sat Jan 13, 2007 8:33 am
ditto on what those guys said. it's one of those things people will do because they see people do it and get away with and you will sometimes, but i've also seen it fry a number of cool amps, most recently a really cool old silvertone that belonged to a pal of mine. aside from the problems mentioned above, proper speaker cables are made with unshielded two conductor cable. instrument cables are single conductor with a shield (usually braid or foil) that acts as the ground. this can cause a number of problems when acting as speaker cable. any time you have two conductive surfaces separtated by a dielectric(non conductor such as air, rubber, etc) it forms a capacitor. in an instrument cable, the single conductor with insulation around it then braid around that is no different. therefore, shielded cable is capacitive by nature. and we all know what capacitors do in audio circuits (think tone circuit on your guitar), or at least suffice it say that there's not supposed to be one between your head and your cab (this can make output transfos die). also the purpose of the shielding in an instrument cable is to prevent stray electromagnetic interference from showing up in your audio. this works in an instrument lead because noise hits the shield and is shunted off to ground before it gets to your conductor and messes with your low level high impedance signal. when you use instrument cables in a speaker cable situation, any of that noise picked by the shield that should go to ground goes through the speaker instead and shows up as amplified noise (think spinal tap at the military base). it can be anything from simple hiss to radio stations to horrid awful squealing. but worst of all, as they mentioned above, it's much easier for a braided single conductor cable to become shorted than heavy guage two conductor (think of the crackling you hear when you flex an old guitar cable. when this happens, this also makes output transfos die. sorry if that was long winded or a little off for some of the super techs. but as one of the guys who fixes these things i will simply say yes this is bad and please don't do it.