Rane AC 23S Guide D'utilisation page 15

Realtime Analyzer
Now, set the output Level controls on the crossover so that the entire speaker system has a uniform, flat response.
Unfortunately, the room in which the speakers are placed can introduce a lot of variables. There are two ways to
address this:
Equalization
With this approach, use the crossover to flatten system response as much as possible without room acoustics
involved. This means setting up the system outside and with the aid of a realtime analyzer and pink noise source,
adjust all of the crossover outputs so that the system is as flat as possible. Once the system is tuned, the crossover is
then locked and never again touched. It is then the job of the system equalizer(s) to normalize or flatten the system to
each different room.
Crossovers + Equalizers
Using this approach, crossover is used at each location to help flatten the system along with the equalizer. Some
even maintain that a good active crossover can work alone like a parametric equalizer in the hands of an expert. This
does require experience, skill, and the right equipment.
Regardless of the method, using some kind of realtime analyzer for this process is extremely important. An
analyzer will save time and provide much better accuracy and consistency than human ears.
See the following sections for recommended ways of setting the crossover output levels.
Setting Levels Using a Realtime Analyzer
NOTE: If you are running two Channels, tune up only one channel at a time.
1. Set all Level controls on the crossover to minimum; leave Delay and Frequency controls as set previously.
2. Place the analyzer microphone at least 15 feet away from the speaker stack, on axis (dead ahead) and about
chest level. Minimize any background noise (fans, air conditioners, traffic, etc.) that could affect the readings.
3. Run pink noise through the system, either through a mixer channel or directly into the crossover. Turn all
amplifier controls at least half way up.
4. We will use the 3-Way mode here as an example—the procedure applies to all configurations. Turn up the
Input Level control(s) on the crossover about half way.
5. Slowly turn up the Low Level control on the crossover, until you hear a healthy level of noise through the low
frequency drivers (it should sound like rumble at this point).
6. Adjust the analyzer controls so the display shows the greatest number of 0 dB indicators below the crossover
point.
7. Now slowly turn up the Mid Level on the crossover until the display shows the same output level average as the
Low frequency section.
8. Repeat this procedure for all crossover frequency sections, lowest to highest, so that the end result is as flat
response as possible on the analyzer display.
IMPORTANT: Compression driver or horn roll-off, bass roll-off, and room acoustics usually cannot be corrected by
the crossover. If, for example, you are adjusting the High frequency controls and observe a decline in frequency
response somewhat above the crossover point, then set the crossover Level control for equal display level near the
crossover point and leave it there. Then use an equalizer or bank of tweeters to correct the roll-off problem. If you are
tuning the system in a room, the room acoustics will greatly influence the system response, as shown by the
analyzer. Check the system response on an analyzer at several other locations and adjust the crossover as
necessary to reach a fixed compromise setting if desired. If you plan to use the analyzer only once to set the
crossover, set up the speaker system in a quiet place outside or in a very large concert theater, and run pink noise at
low levels with closer microphone placement to keep the room acoustics out of the picture as much as possible.
SPL Meter & Tone Generator
The Mute switches on the AC 23S make using an SPL meter an easy and relatively accurate means of tuning a
system, available from a local electronics store. You may also use a sweep or tone generator in place of a pink noise
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