Rane AC 22B (2003 version) - Manual (Page 9)

Manual-
STEP BY STEP PROCEDURE
A 3-Way mode consisting of High, Mid and Low drivers
is used here as an example. For 2-Way systems, use the same
procedure by replacing LOW for MID and following steps 2
through 5. NOTE: If you are running two separate Channels on
the crossover, tune up only one Channel at a time, using the same
procedure for both.
1. Place the analyzer microphone about 15 feet in front of the
speaker stack and at a height about midway between the high
and mid drivers. Turn all crossover LEVEL controls fully down.
2. Connect the pink noise source to the INPUT of the crossover
(or mixer or wherever is convenient). Turn up the crossover
MASTER LEVEL control and the MID LEVEL control
until noise is heard from only the mid driver at a comfortable
volume.
3. With a healthy but not uncomfortable volume of noise from
the mid driver, set the analyzer Display Level control so the
LED’s corresponding to the high crossover frequency are read-
ing 0 dB (this would be a green LED at the crossover frequen-
cy with any of the Rane analyzers set in the ±1 dB mode.) For
example, if your high crossover frequency is 2 kHz, set the RA
30 in the ±1 dB mode and then adjust the Analyzer Gain con-
trol until the green LED is lit in the 2 kHz band. There…easy.
4. Now press in the MID MUTE switch on the crossover so that
the tone is removed from the mid driver. Without re-adjusting
either the meter or the crossover MASTER or MID LEVEL
controls, turn up the HIGH LEVEL control until the tone
coming from only the high driver reads 0 dB (a green LED at
the crossover frequency).
5. Now release the MID MUTE switch on the crossover so that
pink noise is heard from both the high and mid drivers. Switch
the display sensitivity to ±3 dB on Rane analyzers (not neces-
sary with full scale analyzers) and observe the display reading
at the crossover frequency:
i. If the display shows a +3 dB reading, then the drivers are
properly phase aligned and no delay is necessary; leave the
MID DELAY control at minimum.
ii. If the display shows less than +3 dB reading, slowing turn up
the MID DELAY control on the crossover until the display
shows +3 dB. Now the drivers are electronically phase
aligned and the MID DELAY control should be left in this
position at all times unless the speaker system is physically
altered.
iii. If you have turned the MID DELAY control all the way
up and still do not have a +3 dB reading, you will have to
physically move the high driver farther forward until the
display shows +3 dB. The amount of displacement correc-
tion available from the delay depends on the actual cross-
over frequency: the higher the frequency, the less amount
of correction capability. If the drivers are built into a single
Time Delay Adjustment Using
a Realtime Analyzer and Pink
Noise.
This method outlines the use of a realtime analyzer, pink
noise generator and flat response microphone to set crossover
time Delay. Some references will be made to Rane RA 30 ana-
lyzer for those with the intelligence and good taste to use one of
these regularly. The procedure applies to virtually any analyzer
system. We recommend using a one-third or two-thirds octave
analyzer as either of these is more likely to match your specific
crossover points than a one-octave analyzer. And it is important
to match the analyzer to the crossover point as closely as possible
for proper phase alignment, otherwise the analyzer readings may
be misleading.
Fig. Corrected In-Phase Axis Response With Electronic Time Delay
on Low Frequency Driver
Fig. In-Phase Axis Response Without Time Delay