Infinity TWELVE Owner's Manual page 16

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
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
27–50.These tracks contain all the test tones necessary for
measurement. However, each test is only about three seconds,
and there is no frequency announcement.The first test is
100Hz. Just place each test mark in order until finished.
Connect the dots.
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
CASCADE MODEL TWELVE
13
› .You will see a
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 best-fit width is
10%. Fill in the Width and Frequency fields provided on the
template.
Determine the appropriate level using the technique described
earlier. In this example, –13dB is indicated. Enter "13"in the
field provided.
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: