3 features, 1 signal generator, 2 load/output monitoring – Crown Audio IQ-SLM8 User Manual

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IQ–SLM-8 System and Load Monitoring IQ System Component

Reference Manual

3 Features

Many of the features of the

SLM-8 must be configured

with IQ software while the unit is connected to an

System. Please consult your Crown representative or
Crown’s Technical Support Group if you are unfamiliar
with IQ software or

IQ Systems. Once the SLM-8 is

configured, it can function as a stand-alone device
without an

IQ System. This will require the use of the

unit’s AUX input for manually triggering tests.

3.1 Signal Generator

The

SLM-8 includes its own internal signal generator to

provide the required swept sine wave signal for the
tests. When a test is not being conducted, the signal
generator can also be used to produce a steady sine
wave signal for other applications. The signal genera-
tor is configured by the

IQ System and has the follow-

ing parameters:

Sweep Enable:

Enables or disables the generator.

Amplitude:

Sets the output level of the generator. Its

range is –40 dBu to +10 dBu.

Osc Enable:

Immediately turns on or off the signal

generator when a test is not being performed. When
turned on with this control, the generator will output a
fixed sine wave at the frequency specified by the Osc
Frequency parameter.

Osc Frequency:

Sets the frequency in hertz for the

above function. It does not affect the generator when a
test is in progress.

Sweep Resolution:

Sets the frequency step size of the

test sweeps. It can be set to

, and 1

octave steps. If multiple units are synchronized, their
Resolution settings must match.

Sweep Start Freq:

Sets the frequency at which the

generator will start the test sweeps. Although you can
set this parameter in 1 Hz steps, the actual starting
frequency will be equal to the closest octave setting as
determined by the Sweep Resolution parameter. The
lowest possible setting is 20 Hz.

Note: The Sweep Start

and Stop Frequencies of synchronized units must be
set to the same values (see Section 4.10).

Sweep Stop Freq:

Sets the frequency at which the

generator will stop the test sweeps. Although you can
set this parameter in 1 Hz steps, the actual stopping
frequency will be equal to the closest octave setting as
determined by the Sweep Resolution parameter. The
highest possible setting is 22000 Hz (22 kHz).

Note:

The Sweep Start and Stop Frequencies of synchronized
units must be set to the same values (see Section 4.10).

Sweep Sync:

Forces the test generator duration to be

the equivalent of an eight-channel test regardless of
the number of channels actually being tested so mul-
tiple units can be synchronized together. (See Section
4.10.)

3.2 Load/Output Monitoring

The

SLM-8 can monitor both the impedance response

of a load and the frequency response of an output. The
load is usually a loudspeaker. The output can be any
line-level or high-level output. This means you can
monitor the frequency response of a main mixer out-
put, equalizer output or the loudspeaker output of the
amplifier, itself.

These capabilities make it possible to monitor an audio
system in several different ways. The most obvious is
to monitor each amplifier output and each loud-
speaker load to make sure that the loudspeakers are
functioning normally and that they are being fed a
correct signal at a correct level. However, with its ability
to also monitor line-level outputs, you can monitor the
outputs of each component in your audio chain, from
the mixer’s main output(s) to the equalizer, compres-
sor/limiter and crossover network outputs. In this way
you can pinpoint exactly where a change has oc-
curred and greatly speed system troubleshooting.

To prepare the

SLM-8 to monitor a load or an output,

you first determine what the load and output should
normally look like by making a series of tests under a
variety of “normal” operating conditions. Its up to you
to decide what these conditions are. Bear in mind that
some audio systems may measure differently depend-
ing on environmental conditions such as temperature,
humidity, wind and ambient noise. This is noted in the
installation instructions in Section 4.

After determining what measurements of the audio
system should “normally” look like and what the nor-
mal variation in impedance and frequency response
should be, it is time to make some reference measure-
ments and set the pass/fail tolerance for future tests.
This must be done with an

IQ System using the follow-

ing parameters:

Acquire Mode:

Determines which test(s) will be per-

formed for each channel. The choices are:

Off-Pass:

Do not test the channel but report a

“passed” status.

Off-Report:

Do not test the channel but continue to

report the status from the previous test.

Impedance:

Test only the impedance response of

the channel.