6.1.1 Input; 6 IQ Audio In Depth; 6.1 A Closer Look at Audio Signal Wiring- Page 23

Page 23

IQ–AMB-5 / IQ–SMX-6

 Reference Manual

AMB-5 / SMX-6

  IQ Mixer/Multiplexer

6 IQ Audio In Depth

This section provides additional information about
Crown’s IQ System with special guides to aid in the
installation and use of the IQ–AMB-5/IQ–SMX-6. For
more information about any of these topics, contact
the Crown Technical Support Group.

6.1 A Closer Look at Audio Signal Wiring

6.1.1 Input

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 = 0.775 volts). Select
the center position (L) for line level signals up to +32
dBu. Slide it to the right (P) to provide 44 VDC to mics
requiring phantom power.

source. Setting the source signal level to approxi-
mately 0 dBu will provide 20 dBu of headroom in the
input preamp. Some recommended settings are given
in Figure 6.2.

Figures 6.3-4 show the normal wiring for balanced and
unbalanced inputs. It is also possible to parallel the
inputs of multiple units

 to increase the number of mixer

outputs. For example, the inputs of two 6x2 IQ–SMX-6s
can be paralleled to create a 6x4 mixer. This technique
is described in Section 6.1.5.

Fig. 6.2  Suggested Audio Input Gain Control Settings

Figure 6.1 An Audio Input Section

Figure 6.3 Balanced Audio Input Wiring

Each input has a screwdriver-set, calibrated gain con-
trol to compensate for different input source levels. The
slot on the control shaft points to the gain setting. The
settings are labelled for line-level input. Add 25 dB to
the scale if the inputs are switched for microphone
level signals.

Use a screwdriver to adjust the gain pot so that the
input signal level plus gain equals roughly 0 dBu. You
will need to know, or estimate, the level of the input

0 dBm = 0.775 VRMS with a 600 ohm load,  0 dBV = 1 VRMS, 0 dBu = 0.775 VRMS

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