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11
MODULUS II HOME THEATER SYSTEM
Initial System-Level Setting
The following steps will set the playback level of the system to the
correct level for all tests that follow.
Turn the system volume to minimum.
Cue the R.A.B.O.S.Test CD to Track 2 and press Pause II.This
track will produce band-limited pink noise in both the left and
right channels.
Press
Play ›.With the RSLM positioned as described above,
increase the system volume until the RSLM display indicates –10dB.
See Figure 14.
RSLM indicating the correct system
level to begin tests (–10dB)
When you have completed this
adjustment, press
Pause II.
Setting the Subwoofer Test Level
Each of the following test tracks is about one minute
long.This is normally much longer than required. Press
Pause II
or advance to the next test as soon as you are ready.
This step will set the subwoofer level for measurement purposes.
The objective is to scale the subwoofer’s output to make full use
of the RSLM indicator range. Scaling is optimum when a 0dB
reading is observed on the highest peak without triggering the
over-range indication. Later, you will rebalance the subwoofer to
the main speakers.
The Modulus II subwoofer should be shipped with the three
R.A.B.O.S.controls,
™,£ and ¢, set to fully clockwise positions,
and all measurements should be conducted with their level
controls in this position.Confirm this setting before you begin this
test.The Level Control ª should be set to the mid position (5).
Cue Track 3 and
Pause II.Track 3 continuously steps through all
subwoofer test tones for approximately 1 minute. Each tone will
play just long enough for the RSLM to give a stable reading.
To get accurate measurements, it is necessary to play
the woofers quite loud.The 0dB indication is about 94dB.At this
level, frequencies below 100Hz can cause doors, windows,
furnishings and other objects in the room to vibrate.This
frequently results in clearly audible buzzes and/or rattles that
come and go as each test tone plays. Strong buzzes not only
sound bad, they can cause measurement errors.If you hear a buzz
or rattle during this test, it is highly recommended that you locate
the source and eliminate its effects.This is actually a valuable
room-diagnostic tool.
Press
Play
›
.As Track 3 plays,watch the RSLM carefully.Watch
for peak readings.The peak reading may be no more than a brief
flash. Readjust the subwoofer’s Level Control
ª until the peak
level observed is 0dB without triggering the over-range indication.
See Figure 15.
When finished,press
Pause II.
Performing Low-Frequency Measurements
Read the following instructions fully before beginning tests.
For the following steps, you will need a Measurement Template
and a pencil.
R.A.B.O.S. measurement template
Adjusting the subwoofer levels for a 0dB peak
Too Low
Correct
Level
Too High
FIGURE 14
F
IGURE 15
F
IGURE 16