Crown CROWN K Series, Reference Manual

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Page 28
K-Series Balanced Current Amplifier™
Fig. 4.1
Balanced &
Unbalanced
Input Wiring
–
+
3
1
2
GND
FROM
SOURCE INPUT
BALANCED
+
–
SHIELD
FROM
SOURCE
INPUT
UNBALANCED
+
SHIELD
+
3
1
2
SHIELD
Balancing the Line
A balanced audio circuit typically will have both positive (+)
and negative (–) legs of the circuit that are isolated from the
ground circuit. These balanced legs exhibit identical imped-
ance characteristics with respect to ground, and may also
carry the audio signal at the same level, but with opposite po-
larities. This results in a line that offers excellent rejection of
unwanted noise.
On the other hand, an unbalanced circuit usually holds one
leg at ground potential, while the second leg is “hot.” Unbal-
anced line is less expensive, but is much more susceptible to
noise, and is not usually used in professional applications. For
the cleanest signal, without unwanted hum and buzz, bal-
anced line is always recommended. It is especially helpful if
you have a long cable run (over 10 feet (3 m)), since noise is
easily introduced into long, unbalanced lines.
Getting Rid Of Dr. Hum and Mr. Buzz
If you have noticeable hum or buzz in your system, you may
want to check your cable connections to see if the unwanted
noise is being introduced via a ground loop. To determine the
proper wiring, first check whether the output from your source
is unbalanced or balanced (if you don’t know, refer to the unit’s
back panel or instruction manual). If the source is balanced,
refer to Figure 4.2; if it is unbalanced refer to Figure 4.3. Next,
determine if the source’s power cable is floating (ungrounded,
2-prong) or grounded (3-prong). Finally, if the source in unbal-
anced, check the type of wiring: twin-lead or single coax.