Crown Audio STUDIO AMPLIFIER - Manual (Page 16)

Page 16
Studio Reference IIIII & II II II II II
Professional Studio Amplifiers
power cables and power transformers. We also recom-
mend using shielded or twisted pair wire. With loose
wires, use tie-wraps to bundle together each pair of in-
put wires. This helps reduce magnetically-induced
current by minimizing the cross-sectional area be-
tween conductors that could bisect the magnetic field.
Ground loops often occur when the input and output
grounds are tied together. DO NOT CONNECT THE
INPUT AND OUTPUT GROUNDS TOGETHER. Tying
the grounds together can also cause feedback oscil-
lation from the load current flowing in the loop. To
avoid this problem, use proper grounding, isolate the
inputs, and isolate other common AC devices. When
using the input phone jacks, the signal grounds can be
isolated from the AC mains ground with the ground lift
switch located on the amplifier’s back panel (see Fig-
ure 2.2 and Section 4.4).
3.3.5 Output Connection
Consider the rated power-handling capacity of your
load before connecting it to the amplifier. Crown is not
liable for damage incurred at any time due to overpow-
ering. Fusing loudspeaker lines is highly recom-
mended (see Section 3.3.6). Also, please pay close
attention to Section 4.1,
Precautions.
You should always install loudspeaker cables of suffi-
cient gauge (wire thickness) for the length used. The
resistance introduced by inadequate output wiring will
reduce the amplifier’s power to and motion control of
the loudspeakers. The latter problem occurs because
Use Good Connectors
1. Male connectors on loudspeaker cables
should not be exposed to prevent possible
short circuits.
2. Connectors which might accidentally
cause the two channels to be tied together
when making and breaking connections
should not be used. (A common example is
the standard three-wire stereo phone plug.)
3. Connectors which can be plugged into
AC power receptacles should never be used.
4. Connectors having low current-carrying
capacity should not be used.
5. Connectors having any tendency to short
should never be used.
the damping factor decreases as the cable resistance
increases. This is very important because the ampli-
fier’s excellent damping factor can be easily negated
by using insufficient cable.
Use the nomograph in Figure 3.14 and the procedure
that follows to find the recommended wire gauge
(AWG or American Wire Gauge) for your system.
Fig. 3.14 Wire Size Nomograph
40
30
20
15
10
9
8
7
6
5
4
3
2
1
2
5
10
20
50
100
.04
.06
.1
.2
.4
.6
1
2
4
6
10
20
40
5
10
20
50
1
2
100
200
500
1000
2000
5000
8000
5000
1000
500
100
50
10
5
1
.5
.1
.05
.01
#28
#26
#24
#22
#20
#18
#16
#14
#12
#10
#8
#6
#4
#2
#0
#00
#0000
R
LOAD
RESISTANCE
(ohms)
L
R
R
DAMPING
FACTOR
L
S
R
SOURCE
RESISTANCE
(ohms)
S
2-COND.
CABLE
(feet)
COPPER
WIRE
(AWG)
(ohms/1000 ft.)
Example Shown:
R = 8 ohms; R = 0.016 ohms or D.F. = 500;
Cable Length = 10 ft.; answer: #8 wire
L S
1
0.5
200
500
1,000
2,000
20,000
5,000
10,000
.01
.001
.02
.004
.006
.002
.0004
.0006
.0002
0.6
0.7
0.8
1.5
0.9