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
Press Play ›. With the RSLM positioned as described above, increase the system volume until the RSLM display indicates
Figure 4. 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 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 triggering the
The three R.A.B.O.S. controls, ‚, ⁄ and B, 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 Track 3 and Pause II. Track 3 continuously steps through all subwoofer test tones for approximately one 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 subwoofer 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
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 ¢ until the peak level observed is 0dB without triggering the
Figure 5. Adjusting the subwoofer levels for a 0dB peak
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
7CASCADE MODEL FIFTEEN