ac22b - MusicResourcesUSA
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1. Chances are that even careful visual alignment on these will often yield a Frequency error greater than a full detent on the AC 22B 3 If it is absolutely critical to obtain the exact Crossover Fre quency Mil Spec P A etc the selector can be positioned between detents if necessary This of course will require the aid of a precision signal generator and other equipment to verify the exact setting For best overall system results try to choose the speaker components so that each operates well within its recommended limits This will provide valuable leeway so that you may move crossover points in order to fine tune the system and will also yield higher system reliability If at all possible beg borrow or best yet always use some kind of realtime analyzer to tune your crossover and fine tune the system for each different location with an equalizer Keep reading for further alignment details Manual 6 Time Delay Adjustment Before jumping feet first into the realm of time delay and how to adjust it it might help to spend a moment here to re af firm why on earth this Delay is really necessary For a detailed and enjoyable short course on time delay Linkwitz Riley and other mouth watering details we urge you to read the RaneNote Linkwitz Riley Crossovers available in the Library section of the Rane website In the way of summary a few words are in order here to outline the basic effects of time delay in crossovers Prob2. and perhaps a little trickier get a hold of a pink additional equalization of the High Frequency outputs for CD noise generator again try electronics and hi fi stores You may horns This modification should only be attempted by an experi also use a sweep or tone generator in place of a pink noise source enced technician who is adept at soldering If so be sure to look at several different tones within each cross It is important to know the 3 dB down point of the CD over section to get a good average of driver response driver s frequency response The manufacturer of your driver 1 Run pink noise into the crossover Inputs through the mixer should be able to supply you with a chart showing a frequency or directly as is convenient response curve Find the point where the high end starts to roll 2 To start turn all crossover LEVEL s all the way down and all off and look for the point on the chart that is 3 dB down from amplifier level controls at least half way up that point toward the right as the higher frequencies roll off 3 Turn the crossover MASTER LEVEL s half way up Place Find the frequency at the bottom of the chart of this point an the SPL meter at least 15 feet from the speaker stack and approximate is fine you don t have to be exact Find the closest about chest high Once positioned the SPL meter must frequency in the table below to determine the correct value ca remain in the exact same location for the rest of the p
3. INPUT Plug the output of the mixer equalizer or other signal source to this Input for mono opera tion Do not use the Channel 2 INPUT for MONO 3 WAY operation HIGH OUTPUT Connect this Output to the input of the high frequency amp MID OUTPUT Connect this Output to the input of the mid frequency amp LOW OUTPUT Connect this Output to the input of the low frequency amp SUBWOOFER switch Set this switch for 2 gt CHANNEL MONO 3 WAY operation SYSTEM MODE switch Set this switch for MONO 3 WAY operation POWER input connector Use only an RS 1 or other remote AC power supply approved by Rane This unit is supplied with a remote power supply suitable for connection to this input jack Consult the factory for replacement or substitution This unit s power input is designed for an AC supply delivering 18 24 volts from a center tapped transformer capable of supplying at least the current demanded by this product Using any other type of supply may damage the unit and void the warranty Chassis ground point A 6 32 screw is supplied for chassis grounding purposes Units with external power supplies do not ground the chassis through the line cord In case of a grounding problem try connecting crossover chassis ground to amplifier chassis ground or directly to the grounding screw on a grounded AC outlet cover by means of a wire secured on both ends with star washers to guarantee proper contact See the Chassis Grounding Note on page
4. MASTER LEVEL controls the overall Level without altering the relative settings of the HIGH MID and LOW Outputs Unity gain for all Level controls is at 7 LOW LEVEL controls the Level of signal going to the LOW Output LOW MUTE When pressed to the iz position all signal is removed from the LOW Output This eases tune up procedure as described on pages Manual 7 12 LOW DELAY control adds from 0 to 2 ms of time Delay to the LOW Output only This allows a low frequency driver to be electronically phase aligned with a high frequency driver whose diaphragm is situated behind the low frequency diaphragm Refer to Time Delay Adjustment on page Manual 6 for the procedure LOW MID FREQUENCY This 41 detent selector determines the crossover Frequency between LOW and MID Outputs The detents will assure maximum accuracy and consistency between Channels Refer to Selecting Crossover Frequencies on page Manual 6 to determine proper setting for your particular system NOTE The Channel 1 HIGH LEVEL and Channel 2 MASTER LEVEL controls are automatically bypassed when the System Mode switch is set to MONO 3 WAY as shown on the facing page Adjusting these controls have no effect in MONO mode MID LEVEL controls the Level of signal going to the MID Output MID MUTE When pressed to the in position all signal is removed from the MID Output This eases tune up procedures as described in pages Manual 7 12 MID DELAY control adds fro
5. MID 3 Clean the solder pad on the underside of the board so that the LEVEL control until you obtain a 0 dB reading on the SPL appropriate capacitor can be inserted Install the capacitor meter Now the low and mid speakers are set at the same level and solder the leads from the underside using fresh solder 7 Now press the MID MUTE switch on the crossover so the Clip the excess leads pink noise again disappears 8 Repeat this process for each crossover frequency section end ing with the highest frequency NOTE It is possible you may turn one of the frequency section output LEVEL controls all the 0068 pf way up and still not have enough volume for a 0 dB reading as 0056 pf determined by previous section levels This is probably due to dif ferent sensitivities of amps speakers and other level controls in the system When this happens re set the SPL meter so that it reads 0039 pf 0 dB on this frequency section you may have to down range 0036 pf the meter and re adjust the crossover MASTER LEVEL control 0030 pf Now go back and re adjust the previous crossover LEVEL con trols turning these down to get a O dB reading on the meter D024 pi Once the HIGH LEVEL control is set for 0 dB on the meter disengage all of the MUTE switches on the crossover and check that noise is emitting from all the speaker components 0047 pf xO The crossover should now be aligned Make any overall level adjustments with the MAS
6. 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 oth 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 av im i If the display shows ess 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 i 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 ii 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
7. disconnected in MONO SUB mode SUBWOOFER switch disconnects the Output from Channel 2 LOW OUT and sums it with Channel 1 LOW OUT The result is taken from the Channel 1 LOW OUT SYSTEM MODE switch Set this switch for STEREO 2 WAY operation POWER input connector Use only an RS 1 or other remote AC power supply approved by Rane This unit is supplied with a remote power supply for connection to this input jack Consult the factory for replacement or substitution This unit s power input is designed for an AC supply delivering 18 24 volts from a center tapped transformer capable of supplying at least the current demanded by this product Using any other type of supply may damage the unit and void the warranty Chassis ground point A 6 32 screw is supplied for chassis grounding purposes Units with external power supplies do not ground the chassis through the line cord In case of a grounding problem try connecting crossover chassis ground to amplifier chassis ground or directly to the grounding screw on a grounded AC outlet cover by means of a wire secured on both ends with star washers to guarantee proper contact See the Chassis Grounding Note below IMPORTANT NOTE CHASSIS GROUNDING If after hooking up your system it exhibits excessive hum or buzzing there is an incompatibility in the grounding configuration between units somewhere Your mission should you accept it is to discover how your particular system wants to be grounded
8. is then locked behind a security cover posted guard is optional and never again touched It is then the job of the system equalizer s to normalize or flatten the system to each different room The Fix It With The Crossover School Here the crossover knobs get a good workout for the crossover is used at each loca tion 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 to back it up not to mention a licensed set of ears Regardless of which school you profess the absolute impor tance and effectiveness of some kind of realtime analyzer in your system cannot be overstressed No this is not a callous plug for our other products analyzers in general have come a long way They re out of the lab i e closet and into the hands of every smart working musician and sound technician An analyzer will save tremendous amounts of time and provide the absolute con sistency accuracy and plain old good sound that very few ears on this earth can deliver They are affordable easy to use and amazingly effective You owe it to yourself and your audience to at least look into one of these analyzers you ll wonder how you managed at all without one Whether by analyzer or by ear here are a few recommended methods of setting the crossover Output Levels Setting Levels Wi
9. stable object Set the switches on the SPL meter to C weighting slow Be sure to minimize background noise air conditioners fans traffic wild animals etc as these will effect the meter reading 3 Slowly turn up both the crossover MASTER and MID LEV EL controls until the tone is heard through the mid driver Adjust the SPL meter control and or the crossover LEVEL controls until you obtain a 0 dB reading on the meter Verify that no sound is coming from any other speakers except the mid driver 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 con trols turn up the HIGH LEVEL control until the tone com ing from only the high driver reads 0 dB on the SPL meter 5 Now release the MID MUTE switch so that the tone is emit ted from both the high and mid drivers Check the reading on the SPL meter i ii i pae E If the meter reads 3 dB then the drivers are properly phase aligned and no Delay is necessary leave the MID DELAY control at full minimum If the meter reads ess than 3 dB slowly turn up the MID DELAY control until the meter just reads 3 dB 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 i If you have turned the MID DELAY control all the way up and still
10. 25 35 o 250 1 15 2 25 35 amp 300 1 1 5 2 2 5 3 5 A 400 1 15 2 25 4 4 450 1 is 2 25 4 iL 500 1 15 2 25 4 5 800 1 is 2 3 5 gt Ik 1 1 5 22 3 6 2 1 2k 1 15 22 35 MAX 4 1 5k 1 15 23 35 MAX 6 2k 1 15 23 MAX 2 5k i 15 23 MAX 3k 1 17 24 MAX 3 6k 1 17 MAX 4k 1 1 8 MAX 6k 1 2 MAX 7k 1 2 MAX Manual 10 12 15 18 21 24 5 6 7 8 MAX 5 6 7 8 MAX 5 6 7 8 MAX 5 6 7 MAX 5 6 7 MAX 5 7 8 MAX 55 7 MAX 6 8 MAX 6 8 MAX 6 8 MAX T MAX MAX Displacement a Fig 3 Vertical Driver Displacement Setting the Output Level Controls Choosing the crossover frequencies was the easy part Now it gets real fun The idea is to 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 has a habit of always getting into the act so things get messy As a result there seems to be two schools of thought regarding the use of active crossovers The Set It Once And Glue It School The philosophy here is to use the crossover to flatten system response as much as pos sible without room acoustics involved This means setting up the system outside unless you happen to have a very large anechoic chamber handy and with the aid of a realtime analyzer and pink noise source ala RA 30 adjust all of the crossover outputs so that the system is as flat as possible Once the system is tuned the crossover
11. Here are some things to try If your equipment is in a rack verify that all chassis are tied to a good earth ground either through the line cord grounding pin or the rack screws to another grounded chassis N Units with outboard power supplies do not ground the chassis through the line cord Make sure that these units are grounded either to another chassis which is earth grounded such as an amplifer or directly to the grounding screw on an AC outlet cover by means of a wire connected to the grounding screw on the chassis QO Try moving the device away from high magnetic field sources such as large transformers used in power amplifiers A Be sure of properly balanced inputs and outputs Connect balanced devices with balanced connectors and cables Runs longer than 10 feet 3 meters require balanced interconnect Refer to RaneNote Sound System Interconection for more information on system grounding and balanced unbalanced connections Manual 3 FRONT PANEL MONO 3 WAY CONFIGURATION Mono 3 Way labels in this row CH1 Low LOW HIGH HIGH STEREO CH 2 Low MASTER mono SUB pe MASTER INACTIVE MONO SUB O 1ok AC 22B T ACTIVE i 7 CROSSOVER oo MIN MAX oO To Jo MINAK f fe LEVEL MUTE DELAY a ened mie LEVEL LEVEL MUTE DELAY PRbGENET POWER oO LOW MID INACTIVE MID HIGH TET seiis Observe the labels below the controls for Mono operation CHANNEL 1
12. Manual 3 Manual 5 OPERATING INSTRUCTIONS Selecting Crossover Frequencies Most speaker manufacturers supply low and or high frequen cy cut off points for each driver especially if these are supplied in a system These cut off frequencies are based on each driver s per formance at and beyond this point with a certain safety margin to accommodate more gentle filter roll offs and resultant higher output beyond the recommended performance range The AC 22B utilizes 41 detent crossover Frequency selectors which are precision potentiometers The detents assure consis tent accuracy from Channel to Channel and unit to unit This is a distinct advantage over the continuously variable designs using low tolerance parts possible knob misalignment and panel screening variations Even with 41 choices it is possible that the exact recommended Crossover Frequency may not fall on one of the detents on the selector Not to panic for these sound reasons 1 The AC 22B possesses 24 dB octave roll off so the Crossover points may be set to the nearest detent above or below the recommended limit with virtually no hazard to the driver or degradation in sound quality If extremely high power levels are expected it is safer to defer to the high frequency drivers and shift the Frequency up rather than down 2 Detents do not rely on knob alignment silk screen accuracy parallax and other variables which erode the accuracy of continuously variable designs
13. RANE OPERATORS MANUAL AC 22B ACTIVE CROSSOVER O CH1 LOW LOW HIGH HIGH STEREO CH2 LOW LOW HIGH HIGH O MASTER mono suB Pa pn MASTER INACTIVE MONO SUB a isb 250 500 250 500 4s 4A8 4A8 180 700 4 A6 4A8 a AS ER 180 oo 4 A6 RANG CY CY C 120 io lt fizo L gt AC 22B 2 8 2 8 2 a 20 nl a 8 2 8 2 8 2 s 20 15k 2 8 ACTIVE 80 2 0k 80 2 0k 5 lt s88 Karm 1 K i a ie ro CROSSOVER oto oto mN Max 30 Sek 010 oto oto min max 70 Sex 010 o LEVEL LEVEL MUTE DELAY FREQUENCY LEVEL LEVEL LEVEL MUTE DELAY FREQUENCY LEVEL POWER O MASTER LOW LOW MID INACTIVE MONO inactive MID MID HIGH HIGH Q QUICK START The AC 22B can be either a Stereo 2 Way or Mono 3 Way crossover Labels above the controls refer to the unit being oper ated in the 2 Way Stereo mode Labels below the controls refer to the unit being operated in the 3 Way Mono mode The fact that the AC 22B is a multiple function unit means the outputs are switched around depending on the SYSTEM MODE and SUBWOOFER switches on the back of the unit To operate the AC 22B in Stereo 2 Way mode be sure that the Mode switch is set for STEREO 2 WAY Follow the labels above the controls and jacks When operated in the Mono 3 Way mode the switch should be set in the MONO 3 WAY position Follow the labels below the controls and jacks In Mono 3 Way mode the Channel 1 High Output is unusable This outp
14. TER LEVEL level controls and leave the output LEVEL controls unchanged Rane Corporation 10802 47th Ave W Mukilteo WA 98275 5098 USA TEL 425 355 6000 FAX 425 347 7757 WEB www rane com Manual 12 106180
15. an 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 2 Corrected In Phase Axis Response With Electronic Time Delay on Low Frequency Driver 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
16. directivity horns see the Con stant Directivity Horn Modification section on page 12 If for example you are adjusting the HIGH FREQUENCY control and observe a decline in frequency response somewhat above the crossover point then set the HIGH 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 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 qui et 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 Manual 11 Setting Levels Using an SPL Constant Directivity Horn Meter and Pink Noise Generator Equalization Modification The MUTE switches on the AC 22B make using an SPL Constant Directivity or CD horns need additional equal meter an easy and relatively accurate means of tuning a system ization to help cover the same area a long throw horn can cover First obtain a good SPL meter from a local electronics or hi fi Additional circuitry has been added to the AC 22B layout for the store Second
17. do not obtain a 3 dB reading you will have to physically move the high driver farther forward until the SPL meter reads 3 dB The amount of displacement correc tions 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 cabinet and or it is impossible to change relative positions then you will have to obtain additional delay to achieve proper phase alignment such as the Rane AD 22B If turning the MID DELAY control up makes the SPL 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 then 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 obtain an additional external delay source to align the high and mid drivers The built in Delay system in the AC 22B is designed to accommodate the majority of common speaker configurations if you encounter con fusion or difficulty with your particular system it is best to consult your dealer or the Rane factory for assistance b If this decrease in the display due to the LOW DELAY control occurs at a low frequency crossover po
18. eft of the table the cor responding DELAY knob setting will then be the closest for your system For example if you have a two way system crossed over at 800 Hz with the compression driver voice coil located about 9 behind the woofer voice coil the Delay knob setting corre sponding to a 9 displacement at 800 Hz on the table would be 5 as indicated on the front panel In order to phase align two drivers you must observe only the crossover frequency which is common to both drivers Pink noise can be used if all other frequencies are disregarded since room acoustics and imperfect driver response will cause errone ous alignment attempts Using pink noise as a source each driver is individually tuned to an arbitrary 0 dB level on the analyzer display only at the crossover frequency When both are turned on simultaneously the combined response of the two drivers should read 3 dB higher at the crossover frequency on the display If the drivers are not phase aligned some cancellation will occur on axis resulting in a combined response less than 3 dB Turn ing up the DELAY control causes the lower driver to electroni cally move backward until the analyzer reads 3 dB then the two drivers are electronically aligned and the on axis cancella tion is eliminated see Figure 2 on page Manual 6 Voice Coil Displacement Inches Hz 75 15 3 6 9 70 1 is 2 25 35 80 1 15 2 25 35 100 1 is 2 25 35 150 1 ig 2 25 35 200 1 is 2
19. his Channel In the MONO SUB mode the Channel 1 LEVEL control sets the Level of the MONO SUB Output Channel 2 s LEVEL control is inactive LOW MUTE When pressed to the iz position all signal is removed from the LOW Output This eases tune up procedures as described on pages Manual 7 through 12 In the MONO SUB mode the Channel 1 LOW MUTE switch mutes the MONO SUB Output Channel 2 s MUTE is inactive LOW TIME DELAY control adds from 0 to 2 ms of time Delay to the LOW OUT only This allows a low frequency driver to be electronically phase aligned with a high frequency driver whose diaphragm is situated behind the low frequency diaphragm Refer to Time Delay Adjustment on page Manual 6 NOTE Both DELAY controls are inactive in the MONO SUB mode LOW HIGH FREQUENCY This 41 detent selector determines the crossover Frequency between the LOW and HIGH Out puts The detents assure maximum accuracy and consistency between Channels Refer to Selecting Crossover Frequencies on page Manual 6 to determine the proper setting for your particular system HIGH LEVEL controls the Level of signal going to the HIGH Output in this Channel CHANNEL 2 MASTER LEVEL controls the overall Level of Channel 2 without altering relative settings of the HIGH and LOW Outputs POWER switch and indicator Two choices on or off If the power supply is plugged in this yellow LED is lit and the POW ER button is depressed then the unit ready to operate Ma
20. ime by the tone generator First the highest crossover frequency is run through the crossover and each of the two speakers sharing the crossover point is set separately to an arbitrary 0 dB level on the SPL meter When both drivers emit the crossover tone simultaneously the combined response should read 3 dB higher on the meter If the drivers are not phase aligned some cancellation will occur on axis resulting in a combined response ess than 3 dB Turning the DELAY control up causes the lower frequency driver to electronically move back ward until the SPL meter reads 3 dB then the two drivers are electronically aligned and the on axis cancellation is eliminated see Figure 2 on page 6 This procedure is then repeated for the next lower crossover point s STEP BY STEP PROCEDURE A 3 Way mode consisting of high mid and low drivers is used here as an example For other configurations use the same procedure starting with the highest crossover point and repeat steps 2 through 5 for each lower crossover point 1 Set the tone generator to the highest crossover frequency and plug it into the Input of the crossover Turn all crossover LEVEL controls fully down 2 Position the SPL meter microphone about 15 feet in front of the speakers and at a height about midway between the high and mid drivers It is very important that the meter remain in exactly the same position throughout the test so affix it to a mic stand small tree or other
21. int below about 150 Hz set the LOW DELAY control to mini mum and leave it there Frequencies below 150 Hz are actually omnidirectional so that phase misalignment is virtually inaudible below this point Subwoofers will of ten 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 Otherwise you will have to obtain additional delay equipment to align these to the rest of the system 6 Tune the tone generator to the next lower crossover frequency and then repeat steps 2 through 5 using the appropriate Level and Delay controls Once the Delay control is set you may re adjust any of the crossover Level controls at the beginning of each alignment procedure Once all of the crossover Delay controls are set then re adjust the output Level controls as outlined in Setting the Output Level Controls on page Manual 11 Manual 9 Delay vs Frequency Table If you do not have the equipment necessary to electronically align the system as described in the previous sections you may use the table below to obtain a rough and approximate phase alignment of your drivers Measure the horizontal displacement between the voice coils of the two adjacent drivers sharing the same crossover point then find the column in the table nearest your actual displacement Move down this column to the proper Crossover Frequency as indicated on the l
22. lems pop up when two different speakers emit the same frequency as occurs in the crossover regions of two three four and five way systems Because the two drivers are displaced verti cally cancellation occurs somewhere off axis because the sound waves have to travel different distances from the two speakers and hence will arrive shifted in phase This forms a lobe or radiation pattern bounded on either side by cancellation lines or axes which narrow the dispersion pattern or listening area of the speaker Fine So we put up with it But to make matters worse when the two drivers are horizontally displaced that is one is in the front of or behind the other this lobe or dispersion pattern gets tilted usually upward toward the driver that is further behind see Figure 1 This gets hard to put up with because the end result is that your speaker system will have two three four or more tilted radiation patterns and only two or three people in the house will have decent seats And we re not talking trivial pursuits here this rampant lobing error can make a sound system a real headache to listener and operator alike The idea then is to be sure that all drivers are vertically aligned and that all components are always in phase Then all the main lobes are on axis well behaved and the system enjoys the widest possible dispersion pattern so that everyone gets good sound The one catch is that in many cases it is physical
23. ly or otherwise impossible to get all the drivers vertically lined up at the sound source This is where time delay comes in By electronically delaying the signal going to the driver up front enough time is allowed for the sound from the rear driver to literally catch up to the forward driver s voice coil so that signal from both drivers is emitted in phase See Fig 2 And it works Time delay can make an appreciable improvement in overall sound The trick is finding the proper amount of time delay hence the rest of this section Unfortunately the amount of time delay is a function of two factors life ceased to be simple after age 9 right the amount of horizontal displacement between driver voice coils and the actual crossover frequency involved Setting Delay controls by ear is supposedly possible but very tricky and unreliable The following methods are a couple of but by no means all means of setting time Delay 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 th
24. m 0 to 2 ms of time Delay to the MID Output only This allows a mid frequency driver to be elec tronically phase aligned with a high frequency driver whose diaphragm is situated behind the mid frequency diaphragm Refer to Time Delay Alignment on page Manual 6 for procedure MID HIGH FREQUENCY sets the crossover Frequency between the MID and HIGH Outputs Refer to Selecting Cross over Frequencies on page Manual 6 HIGH LEVEL controls the Level of signal going to the HIGH Output only POWER switch and indicator Two choices on or off If the power supply is plugged in this yellow LED is lit and the POW ER button is depressed then the unit ready to operate Manual 4 REAR PANEL MONO 3 WAY CONFIGURATION im Mono 3 Way labels in this row oa ouT Oa ouT STEREO 2 waY 6 ouT AC 22B O ove R MADE IN U S A Si SUBWOOFER SWITCH MUST POWER RANE CORP Y eset To 2 cHANNEL V PIN 2 PosITIVE wx te ae en zeae acn 001 345 482 SYSTEM MODE a SUBWOOFER ig TORGNON STEREO i MONO 2 m moa G suB 2 WAY 3 WAY CHANNEL Oma OMIT FOR me SUB nono s tee G CLASS 2 EQUIPMENT gt HIGH OUT OMIT MONO MONO 3 WAY OMIT MONO MONO 3 WAY 8 2 High Amp 3 Mid Amp ARI DH Low Amp Observe the labels below the Inputs and Outputs for Mono operation MONO CHANNEL 1
25. nual 2 REAR PANEL STEREO 2 WAY CONFIGURATION Right Input 6 Left Input Stereo 2 Way labels in this row AC 22B HIGH OUT LOW OUT STEREO 2 WAY HIGH OUT LOW OUT CHANNED 1 IN EC MOEN USA panal Open X RANE CORP BE SET TO 2 CHANNEL PIN 2 POSITIVE X CE For wono say PIN 3 NEGATIVE Cano 345 402 SYSTEM MODE Qj SUBWOOFER es 2 STEREO M MONO 2 m_ MONO sug S76 2 WAY 3 WAY CHANNEL 160mA OMIT FOR MONO SUB MONO SUB OUT CLASS 2 EQUIPMEN HIGH OUT MID OU OMIT MONO MONO 3 WAY OMIT MONO LOW OUT MONO 3 WAY ad d High Amp ped d High Amp ee Low Amp Low Amp Observe the labels screened above the Inputs and Outputs for stereo operation CHANNEL 1 INPUT connects to the left channel output of the mixer equalizer or other source CHANNEL 2 INPUT connects to the right channel output of the mixer equalizer or other source HIGH OUTPUTS Connect Channel 1 HIGH OUT to the left channel input of the high frequency amp and the Channel 2 HIGH OUT to the right channel input of the high frequency amp LOW OUTPUTS Connect the Channel 1 LOW OUT to the left channel input of the low frequency amp and the Channel 2 LOW OUT to the right channel input of the low frequency amp When using the MONO SUB switch use Channel 1 LOW OUT Channel 2 LOW OUT is
26. over frequency the higher the frequency the less amount of correction capability If the drivers are built into a single Manual 7 cabinet and or it is impossible to change relative positions then you will have to obtain additional external delay to achieve proper phase alignment iv 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 then 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 obtain an additional delay source to align the high and mid drivers such as the Rane AD 22B The built in Delay system in the AC 22B is designed to ac commodate the majority of common speaker configura tions if you encounter confusion or difficulty with your particular system it is best to consult your dealer or the Rane factory for assistance b 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 om nidirectional so that phase misalignment is virtually inaudible below this point S
27. rocedure _ pacitor to install in the AC 22B to correct for this high frequency Minimize all background noise fans air conditioners traffic roll off wild animals etc to get accurate readings Set the SPL meter to C weighting slow if those switches are present STEP BY STEP PROCEDURE 4 Slowly turn the LOW LEVEL up until there is a healthy The following procedure is for Stereo 2 Way For a Mono rumble coming from the bass speakers For this example 3 Way system with a CD horn on the high output only place the 3 Way mode is used the same procedure applies to all C212 in Channel 2 configurations starting with the lowest frequency and ending with the highest Adjust the SPL meter and or LOW LEVEL 1 Remove the top and bottom covers of the AC 22B until you get a OdB reading on the meter After this point do not change the controls on the SPL meter 2 Locate the positions for C112 and C212 on the board layout 5 While leaving the LOW LEVEL control at the 0 dB adjust page of the schematics and on the circuit board C112 for ment just obtained press the LOW MUTE switch on the Channel 1 is located near the middle of the board C212 for crossover so the pink noise disappears from the bass speakers Channel 2 is located near the middle and right edge of the 6 Now slowly turn up the MID LEVEL control so pink noise board is heard from the mid frequency speakers Without chang ing any settings on the SPL meter adjust the crossover
28. th a Realtime Analyzer NOTE If you are running two Channels tune up only one Channel at a time 1 Set all LEVEL controls to minimum leave Delay and cross over 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 traf fic 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 con trols at least half way up 4 We will use the 3 Way mode here as an example the pro cedure applies to all configurations Turn up the MASTER LEVEL control about half way 5 Slowly turn up the LOW LEVEL control until you hear a healthy level of noise through the low frequency drivers it should sound like rumble 6 Adjust the display controls on the analyzer so that it shows the greatest number of 0 dB LED s green on Rane equipment below the crossover frequency 7 Now slowly turn up the MID LEVEL control until the display shows the same output level average as the low frequency sec tion 8 Repeat this procedure for all crossover frequency sections so that the end result is as flat as possible a response on the analyzer display IMPORTANT Compression driver or horn roll off bass roll off and room acoustic usually cannot be corrected by the crossover If you are using constant
29. ubwoofers 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 Otherwise you will have to obtain additional delay equip ment to align these to the rest of the system 6 Lower the microphone until it is vertically midway between the mid and low drivers Repeat steps 2 through 5 using the crossover LEVEL control MUTE switch and next DELAY control You may start each series of steps 2 through 5 at a different volume as necessary but once the Levels are set in step 3 do not alter these until step 5 is completed Once all of the crossover DELAY controls are set adjust the output LEVEL controls as outlined in the Setting Levels Section on page Manual 12 Manual 8 Time Delay Adjustment Using SPL Meter and Tone Generator Now that good quality realtime analyzers are becoming more affordable and easier to use there are few reasons why one of these should not be regularly used in any sound system If an analyzer is simply not available or for some reason inappropriate an accurate Delay setting can be obtained by using a straightfor ward SPL meter obtainable at most local electronics stores the best is the Rane RA 30 and some kind of variable tone genera tor In order to exclude the effect of room acoustics and imper fect driver response only the crossover frequencies are to be emitted one at a t
30. ut is the high pass only por WEAR PARTS This product contains no wear parts tion of the midrange filter The Channel 1 High Level and the Channel 2 Master Level are also defeated on the front panel In agreement with IEC and AES ANSI standards AC 22B wiring convention is pin 2 Positive pin 3 Negative return pin 1 chassis ground See the Sound System Interconnection Rane Note included with this manual for more information on cabling and grounding requirements NEVER CONNECT ANYTHING EXCEPT AN RS 1 OR OTHER APPROVED RANE AC POWER SUPPLY TO THE THING THAT LOOKS LIKE A TELEPHONE JACK ON THE REAR This is an AC supply and requires some special at tention if you do not have an operational power supply EXACT LY like the one that was originally packed with your unit Manual 1 FRONT PANEL STEREO 2 WAY CONFIGURATION Stereo 2 Way labels in this row CH1 Low LOW HIGH HIGHN STEREO H2 MASTER mono SUB 320 MASTER ici pa SUB O Fry AC 228 crossover oio f Q o to LEVEL MUTE MREQUENCY LEVEL LEVEL LEVEL MUTE LAY OPREQUENCY eat O LOW MID INACTIVE MONO INACTIVE MID HIGH TITRI Serr Observe the labels screened above the controls for stereo operation CHANNEL 1 MASTER LEVEL controls the overall Level of Channel 1 without altering the relative settings of the HIGH and LOW Outputs Unity gain for all LEVEL controls is at 7 LOW LEVEL controls the Level of signal going to the LOW Output in t
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