Samson MPL 1640 - Manual (Page 18)

Grounding Techniques
If you’re using the MPL 1640 in a fixed location such as a recording studio, you
may want to invest the time and money into creating a star ground network. This
is by far the best technique for avoiding grounding problems. It involves using a
formidable ground source such as a cold water pipe or a copper spike driven into
the earth. A thick grounding cable is connected to that source and is then
brought to a central distribution point; from there, individual cables are connected
to each piece of equipment. This setup also requires that you lift the ground plug
of all three-prong AC connectors, so there is the possibility of danger if it is done
incorrectly. We strongly recommend that you contract with a qualified profes-
sional to carry out this or any kind of electrical work.
Another, less common problem you may encounter is that of oscillation (a ringing
tone), which, apart from being annoying, is potentially dangerous to your speak-
ers. This is generally caused either by poor outside wiring or by returning a sig-
nal out of phase (most commonly from an outboard signal processor). If audible
oscillation occurs, try isolating each input signal (by muting all other inputs or by
using the PFL soloing function). If one signal alone is causing the problem, you
should be able to eliminate the oscillation by reversing that signal’s phase (many
signal processors have a switch that allows you to do this).
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