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Cascade Model Twelve
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 4.
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 levels 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
tr
igger
ing the over-range indication. Later,you will rebalance
the subwoofer to the main speakers.
T
he three R.A.B.O.S. controls,
‚
,
⁄
and
¤
,
should be 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
§
should be
set to the mid position.
Cue
T
r
ack 3 and
P
ause
II
.
T
r
ack 3 continuously steps thr
ough all
subwoofer test tones for approximately 1 minute. Each tone will
play just long enough for the RSLM to give a stable reading.
T
o get accur
ate measur
ements,
it is necessary to pla
y
the subwoofer quite loud.The 0dB indication is about 94dB.At
this level, frequencies below 100Hz can cause doors, windows,
fur
nishings and other objects in the r
oom to vibrate.This
frequently results in clearly audible buzzes and/or rattles that
come and go as each test tone pla
ys
.
Str
ong buzzes not only
sound bad; they can cause measurement errors. If you hear a buzz
o
r 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.
P
ress
P
lay
›
.
As Track 3 plays, watch the RSLM carefully.Watch
f
or peak readings.The peak reading may be no more than a brief
flash. Readjust the subwoofer’s
Level control
§
until the peak
level observed is 0dB without triggering the over-range
indication. See Figure 5.
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.
Figure 6. R.A.B.O.S.Measurement Template
Figure 4. RSLM indicating the
correct system level to
begin tests (–10dB)
Figure 5.Adjusting the subwoofer levels for a 0dB peak
Cascade 12 OM 9/21/05 5:03 PM Page 10