Phantastic is a DIY device that checks for the presence of voltages (expected and unexpected) when connecting to a phantom power source.
The purpose is to confirm that a given XLR jack (such as that on a snake in a club) is "cold" before plugging equipment into it that may be damaged by the presence of phantom power (or any other strange power). Devices that send balanced signals into XLR jacks (such as a keyboard or a computer sound interface, using a 1/4" - XLR converter) may be harmed unless the jack is known to be safe (e.g. the sound person didn't turn off phantom power on the correct channel, or strange wiring is afoot, etc.) Also, in cases where phantom power is desired, it was hoped that the tester could indicate the presence of correct phantom power or mis-wired phantom power or other wiring anomalies before risking the device in question. See the main page for more information.