User manual RANE AC 23B

[. . . ] OPERATORS MANUAL AC 23B ACTIVE CROSSOVER QUICK START Labels above the controls refer to the unit being operated in the 2- or 3-Way Stereo mode. Labels below the controls refer to the unit being operated in the 4- or 5-Way Mono mode. The AC 23B is a fully balanced version of the popular AC 23 and is equipped with 3-pin (XLR-type) connectors instead of the standard ¼" TRS jacks. A STEREO/MONO switch has been added to the AC 23B and should be set appropriately. [. . . ] If the display shows a +3 dB reading (red LED on with Rane analyzers in the +3 dB mode), then the drivers are properly phase aligned and no delay is necessary; leave the MID DELAY control at minimum. If the display shows less than +3 dB reading (still in green or in yellow on Rane analyzers), slowing turn up the MID DELAY control on the crossover until the display shows +3 dB (red LED just on with Rane analyzers). Now the drivers are electronically phase aligned and the Delay control should be left in this position at all times unless the speaker system is physically altered. If the MID DELAY control is all the way up and you still do not have a +3 dB (red) reading, you will have to Fig. 1 In-Phase Axis Response Without Time Delay Fig. 2 Corrected In-Phase Axis Response With Electronic Time Delay on Low Frequency Driver Time Delay Adjustment Using Realtime Analyzer & 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 the Rane RA 27 realtime analyzer 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 1/3 or 2/3 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. Manual-11 physically move the high driver farther forward until the display shows +3 dB (red). The amount of displacement correction available from the Delay depends on the actual crossover frequency: the higher the frequency, the less amount of correction capability. If the drivers are built into a single cabinet and/or it is impossible to change relative positions, then you will have to obtain additional external delay to achieve proper phase alignment. If turning the MID DELAY control up makes the display reading decrease instead of increase, this means that the high driver is actually in front of the mid driver; adding delay to the mid driver only worsens the situation. There are a couple of ways to deal with this: a. Try to move the high driver back as far as possible without losing stability in balancing the speaker stack. You may want to raise it up as well to restore dispersion close to the stack. If you cannot move the high driver, then you will have to use an additional delay source to align the high and mid drivers. The built-in delay system in the AC 23B is designed to accommodate the majority of common speaker configurations; if you encounter confusion or difficulty with your particular system, it is best to consult your dealer or the Rane factory for assistance. If this decrease in the display due to the DELAY control occurs at a low frequency crossover point below about 150 Hz, set the DELAY control to minimum and leave it there. Frequencies below 150 Hz are actually omnidirectional, so that phase misalignment is virtually inaudible below this point. Subwoofers will often possess long folded or straight horns, resulting in the diaphragm being well behind the rest of the stack. Most authorities agree that phase alignment of subwoofers is unnecessary. [. . . ] Install the capacitor, and solder the leads from the underside using fresh solder. Replace the top and bottom covers. Monoing the Low Frequency Outputs It is possible to mono the Low Frequency Outputs of the AC 23B by an internal jumper modification. This requires that the Delay 1 and Delay 3 circuits be removed from the signal path, and that R33 be removed. The following procedure will assist you through the modification. [. . . ]