There are, by the way, perfectly good reasons for using +/- 12 (or
even more) volts on long, unshielded, untwisted, unpaired wires
that run from the machine in the air conditioned basement, up into
the ceiling, through chases and drop ceilings next to the 120VAC
wiring and 400V fluorescents, finally to emerge in an office, wrap
around the 90-volt-ring-voltage telephone wires a few times, and
then go to the terminal on the desk.

Can you guess what those reasons might be? :-)

Chris