The logical next question to last week’s Tech Tip about splitting microphone signals between two mixers (see inSync 3/13/01) would have been, “What about Phantom Power? Does it need to be enabled on both mixers or what?” Surprisingly no one outside of Sweetwater asked this question. But, in the interest of being thorough we’ll answer it anyway.
Definitely phantom power should only be supplied from one place. Never enable it on two mixers connected to the same mic. For phantom power to work you need the shield or ground connection between the mic intact. Sometimes when splitting signals using something as simple as a “Y” cable (as was discussed, but not recommended in last week’s Tip) it is necessary to break the shield connection on the line going into one of the mixers to prevent ground loop problems. Obviously then, there is no way that mixer can supply the power so you must use the other one. In cases where both mixers have the shields connected you should simply pick one to supply the power and stick to it. Never use the phantom power in the other mixer. Normally having phantom power enabled on one mixer will not cause problems with the other one, but there are always exceptions so proceed carefully. Only hook up one channel to test it. Better to repair one channel if there is a problem than 24.