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CE-Series Amps with an Attitude!
4 Other Issues
Balancing the Line
A balanced audio circuit typically will have both positive (+)
and negative (–) legs of the circuit isolated from the ground
circuit. These balanced legs exhibit identical impedance char-
acteristics with respect to ground, and may also carry the au-
dio signal at the same level, but with opposite polarities. This
results in a line that offers excellent rejection of unwanted
noise.
BALANCED
GND
1
–
3
2
+
INPUT
+
–
SHIELD
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.
1/4-inch
Tip
Ring
Sleeve
FROM
INPUT
SOURCE
=
+
=
–
=
UNBALANCED
1
SHIELD
3
2
+
FROM
SOURCE
+
SHIELD
XLR
=
Pin 2
=
Pin 3
=
Pin 1
Fig. 4.1
Balanced &
Unbalanced
Input Wiring
Fig. 4.2
Polarity
Conversions
Page 31
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