1.Select a new test position: Cue the test track corresponding to the center frequency of the dip. In the first example in Figure 18, you would play Track 13 (56Hz). Press Play ›. You will see a reading very close to what you had before. Now slowly move the RSLM around the area, if possible remaining within about a foot of the original test point. As you move the RSLM, watch the bar graph. You will observe large level fluctuations. Find a position that restores the level to approximately that of the adjacent test points. You may find it helpful to move the RSLM vertically. Dips can be oriented in any axis. The position that restores the level to about that of the adjacent test points is your new test position.
2.Reset the test level: Return to the section “Setting the Subwoofer Test Level” on page 7. Perform the procedure as described.
3.Repeat the measurements: Now that you are familiar with the measurement process, you can go much faster by using Tracks
Your second measurement will no longer exhibit the deep response dip. However, the peak will still be evident. Without the influence of the response dip, the amplitude and center of the peak may have changed. Compare your new data to the examples given in this section of the manual. Follow the instructions for the example that most closely matches your new measurement.
Example 4. Narrow Response
Figure 18. Narrow response
Although it looks as though this system is quite bass-deficient, this is actually indicative of a single, very narrow peak in excess of 10dB high.
Apply the Width Selector as described earlier. Align the center line of the Selector over the center of the peak, as shown in Figure 13. Now adjust the Selector until you have achieved the “best fit.”The slider now points to the correct width setting. In this example, the frequency is 40Hz and the
Determine the appropriate level using the technique described earlier. In this example,
Skip to the “Adjusting the R.A.B.O.S. Equalizer”section on page 14.
Example 5. One or More Narrow Dips
Figure 19. Example of two narrow dips
Response dips can occur at any frequency, sometimes immediately adjacent to the peak you want to correct. In this example, there are two such dips on either side of the peak. Deep response dips such as these are caused by destructive wave interference. Destructive interference dips occur only in one spot within the room. It is not uncommon to completely eliminate their effect by moving the RSLM to a different location. Note that this does not eliminate the dips. We have simply moved away from them. Sometimes only a few inches are required. Do not attempt to correct this condition with equalization. If you encounter dips like this, take the following steps:
13CASCADE MODEL FIFTEEN