Connecting The Audio Ins & Outs (Step 3); Mic/Line Inputs; An Audio Input Section; Suggested Audio Input Gain Control Settings - Crown AMB-5 Hardware Installation Manual

IQ Mixer / Multiplexer Hardware Installation
added to the audio lines. Use only the signal
lines which normally connect to pins 2 and 3 of
the XLRs. Note: Because typical mic cables
have high capacitance, the maximum possible
Crown Bus loop distance will be less.
Outside RF interference is seldom a problem for a
Crown Bus loop...especially if shielded twisted-pair
wire is used. However, there are extreme situations
when fiber optic wiring is recommended. For ex-
ample, locating a Crown Bus loop next to an AM
radio transmission line may require fiber optic ca-
bling. An extremely long Crown Bus loop distance
(greater than 10 miles) may also require fiber optic
cabling.
Some examples of twisted pair wiring follow. Figure
3.6 shows point-to-point wiring for the Crown Bus
using two female removable barrier block connec-
tors:
Some IQ components use separate 5-pin and 4-pin
DIN connectors for Crown Bus input and output
wiring. Connecting to them is shown below:
The IQ components in each Crown Bus loop are
wired in series. The output of one IQ component
÷loopsš to the input of the next and so on. This is
shown in Figure 3.9.
AUDIO
IN
1
-10
+
Fig. 3.10 An Audio Input Section
Pro audio Semi-pro or
equipment
equipment
dBm/dBV +4 dBm
dBu +4 dBu
Suggested –4 (L)
Setting
0 dBm = 0.775 VRMS with a 600 ohm load, 0 dBV = 1 VRMS, 0 dBu = 0.775 VRMS
Rev. 0
ADD 25
0
5
FOR MIC
-5
10
15
-12 21
M L P
–
Dynamic Condenser
consumer mic, speech mic, speech
–10 dBV –75 dBV –65 dBV
–8 dBu –73 dBu –63 dBu
+8 (L) +21 (M) +11 (P)
Fig. 3.11 Suggested Audio Input Gain Control Settings
3.3 Connecting the Audio Ins & Outs (Step 3)
IQ mixer/multiplexers have 6 mic/line inputs and
2 stack inputs. (Input 6 of the AMB-5 is dedicated
for ambient sensing and is discussed in Section
3.3.2.) For output, there are two audio channels that
feed two main and two auxiliary bus outputs.

3.3.1 Mic/Line Inputs

Three-terminal removable barrier block connectors
are provided for the audio inputs. Each input has an
input selector switch. Slide it to the left (M) for
microphone signal levels up to +7 dBu (0 dBu =
Microphone
Note: If more than one
input is driven from the same
source equipment, connect only
Floating
one shield at the source
source
equipment chassis.
–
Output
+
2-wire line cord
(or battery power)
Grounded
Shield not connected
source
at this end
–
Output
+
3-wire grounded line cord
(or other ground connection)
Fig. 3.12 Balanced Audio Input Wiring
Hot Dynamic
condenser mic, music condensor
mic, speech mic, music
–45 dBV –55 dBV –25 dBV
–43 dBu –53 dBu –23 dBu
+18 (P) +21 (M)
Shield connected
at both ends
INPUT
+ –
INPUT
+ –
INPUT
+ –
Hot Close-miked Close-miked
dynamic mic, dynamic mic,
bass/drums kick drum,
guitar amp
–15 dBV –5 dBV
–13 dBu –3 dBu
–12 (M)
–2 (P) –12 (M)
+3 (L)
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