MOTU 4pre User Manual download pdf (Page 12)

Pre-recording Steps

Before recording for the first time the output level to the excitation speaker must be set correctly.

1. Turn on the source loudspeaker, but ensure its volume is turned down.

2. On the 4pre, turn down the output by turning the “MAIN” knob all the way down. (This knob

controls the level of the outputs labelled MAIN (channels 1 and 2) on the back of the 4pre).

3. Click the “Play Test Signal” button in the IRIS software. This will play back a series of sweeps.

4. Increase the output levels on the amplifiers and 4pre until the excitation volume in the space is

acceptable. Louder means more signal-to-noise ratio, but be careful not to drive the speaker

into distortion. Wear hearing protection if necessary.

5. Click the “Play Test Signal” button again to stop the test signal. The measurement is now ready

for recording.

Note that the setup steps leading up to this point should only need to be carried out once for a

measurement session.

Record Measurement

The measurement can now be conducted – push the record button. The progress bar will indicate how

far through the excitation is. The recording can be stopped at any time if necessary (the record button

changes to a stop button during a recording).

The room should be as silent as possible during a recording. Be careful not to make noise during the

period of silence following the sweep. If any impulsive noises happen during a recording, stop the

measurement and redo it when the room is silent again.

If something was not connected correctly, or there is too much noise in the recording, the software

should display an error message.

This knob controls

the output level

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MOTU 4pre User Manual Page 12