SoundCraft Audio Mixing Console Model Spirit Studio manual Polarity, Grounding and Shielding

	and other equipment which would otherwise show up
	as hum. If the output is driving a device or amplifier
	that has an unbalanced input, connect the -ve(cold) sig-
	nal to the ground at the destination, not at the output of
	your SPIRIT STUDIO console.
Polarity	You will probably be familiar with the concept of polar-
	ity in electrical signals and this is of particular
	importance to balanced audio signals. Just as a bal-
	anced signal is highly effective at cancelling out
	unwanted interference, so two microphones picking up
	the same signal can cancel out, or cause serious deg-
	radation of the signal if one of the cables has the +ve
	and -ve wires reversed. This phase reversal can be a
	real problem when microphones are close together and
	you should therefore take care always to connect pins
	correctly when wiring audio cables.

Source BALANCED TO BALANCED

+

-

GND

LINK

Input

+

-

Source	UNBALANCED TO BALANCED
	+
GND
LINK

Input

+

-

Source UNBALANCED TO UNBALANCED Input

+

GND

LINK

If ground link absent, or mains earth isolated from source ground, then connect shield at both ends

+

Grounding and Shielding

For optimum performance it is vital that all signals are referenced to a solid, noise-free earthing point and that all signal cables have their screens connected to ground. To avoid earth ‘loops’, use balanced connec- tions where possible and ensure that all cable screens and other signal earths are connected to ground only at their source and not at both ends.

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