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OPERATORS MANUAL SAC 22
STEREO 2-WAY ACTIVE CROSSOVER
QUICK START
Whoa, hold on there. Even if you don’t read manuals as a matter of principle, at least read this section to avoid hurting
yourself or your equipment.
Connect the SAC 22 with the power off. Balanced XLR cables are recommended, but if you must convert to ¼" connec-
tors, buy or make a cable like the ones on page Manual-11 and keep them as short as possible. This device uses low imped-
ance balanced line drivers. Do not connect the “+” or “–” output pins to ground, as this may cause the power supply to
shut down. For unbalanced use, leave the unused output pin (“+” or “–”) unterminated.
Consult the speaker manufacturer for the correct crossover FREQUENCY setting. As rugged as some drivers are, many
(especially compression drivers) will not accept frequencies outside of their normal range without producing distortion and
possibly self-destruction.
With all equipment turned off and LEVEL controls down, begin making connections to the system as shown on page
Manual-4 or 5. When turning on the system, switch on the power amplifiers last. Now, feed the SAC 22 some program
material. Start by turning up the LOW LEVEL and HIGH LEVEL to the 0 dB marks. Slowly increase the INPUT
LEVEL, even if it goes all the way to 10, so the +4 dBu (green) light blinks occasionally and the OL (red) light stays out.
This delivers the best signal-to-noise performance.
The MONO SUB OUTPUT is a sum of the Left and Right Low Outputs. The MONO SUB LEVEL adjusts only this
Output and is not affected by the LOW LEVEL control.. When using a single subwoofer along with full-range cabinets
that have internal crossovers, set the 100 Hz FILTER to OUT, allowing the front panel FREQUENCY to control the
subwoofer crossover point. When used with biamp cabinets and a subwoofer, set the 100 Hz FILTER switch to IN to allow
only frequencies below 100 Hz at this output jack. This way, the SAC 22 almost does the job of a Stereo 3-Way crossover,
but without removing that awesome bass from the Left and Right Low Outputs.
WEAR PARTS: This product contains no wear parts.
Manual-1
Page 2
RISK OF ELECTRIC SHOCK
DO NOT OPEN
CAUTION
IMPORTANT SAFETY INSTRUCTIONS
1. Read these instructions.
2. Keep these instructions.
3. Heed all warnings.
4. Follow all instructions.
5. Do not use this apparatus near water.
6. Clean only with a dry cloth.
7. Do not block any ventilation openings. Install in accordance with manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, registers, stoves, or other apparatus (including ampliers) that produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized plug has two blades with one wider than the other. A grounding-type plug has two blades and a third grounding prong. e wide blade or third prong is provided for your safety. If the provided plug does not
t into your outlet, consult an electrician for replacement of the obsolete outlet.
10. Protect the power cord and plug from being walked on or pinched particularly at plugs, convenience receptacles, and the point where it exits from
the apparatus.
11. Only use attachments and accessories specied by Rane.
12. Use only with the cart, stand, tripod, bracket, or table specied by the manufacturer, or sold with the apparatus. When a cart is used, use caution
when moving the cart/apparatus combination to avoid injury from tip-over.
13. Unplug this apparatus during lightning storms or when unused for long periods of time.
14. Refer all servicing to qualied service personnel. Servicing is required when the apparatus has been damaged in any way, such as power supply
cord or plug is damaged, liquid has been spilled or objects have fallen into the apparatus, the apparatus has been exposed to rain or moisture, does
not operate normally, or has been dropped.
15. e plug on the power cord is the AC mains disconnect device and must remain readily operable. To completely disconnect this apparatus from
the AC mains, disconnect the power supply cord plug from the AC receptacle.
16. is apparatus shall be connected to a mains socket outlet with a protective earthing connection.
17. When permanently connected, an all-pole mains switch with a contact separation of at least 3 mm in each pole shall be incorporated in the electrical installation of the building.
18. If rackmounting, provide adequate ventilation. Equipment may be located above or below this apparatus, but some equipment (like large power
ampliers) may cause an unacceptable amount of hum or may generate too much heat and degrade the performance of this apparatus.
19. is apparatus may be installed in an industry standard equipment rack. Use screws through all mounting holes to provide the best support.
WARNING: To reduce the risk of re or electric shock, do not expose this apparatus to rain or moisture. Apparatus shall not be exposed to dripping
or splashing and no objects lled with liquids, such as vases, shall be placed on the apparatus.
NOTE: is equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the FCC Rules. ese
limits are designed to provide reasonable protection against harmful interference in a residential installation. is equipment generates, uses and can
radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to
radio or television reception, which can be determined by turning the equipment o and on, the user is encouraged to try to correct the interference
by one or more of the following measures:
• Reorient or relocate the receiving antenna.
• Increase the separation between the equipment and receiver.
• Connect the equipment into an outlet on a circuit dierent from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
CAU TION: Changes or modications not expressly approved by Rane Corporation could void the user's authority to operate the equipment.
is Class B digital apparatus complies with Canadian ICES-003.
Cet appareil numérique de la classe B est conforme à la norme NMB-003 du Canada.
WARNING
To reduce the risk of electrical shock, do not open the unit. No user
serviceable parts inside. Refer servicing to qualied service personnel.
e symbols shown below are internationally accepted symbols that warn
of potential hazards with electrical products.
is symbol indicates that a dangerous voltage
constituting a risk of electric shock is present within
this unit.
is symbol indicates that there are important
operating and maintenance instructions in the
literature accompanying this unit.
Page 3
INPUT LEVEL control and indicators
This controls the overall level
without altering the relative settings of
the Low and High frequency Outputs.
Input gain is +6 dB at “10”. With signal
applied, set this control so the +4 dBu
LED lights occasionally, indicating
sufficient signal. Flashing of the OL
(overload) LED during peaks can be
avoided by turning the INPUT LEVEL
down.
MONO SUB OUTPUT
LEVEL control
This controls the level of the
summed signals of the LEFT and
RIGHT LOW OUTPUTS. It may be
used instead of, or along with the LOW
OUTPUTS. The output may be adjusted
with the LEVEL trim from +0 dB to
OFF. Unity gain is reached at the “0
dB” mark with the INPUT LEVEL set
to “10”.
LOW LEVEL control
This controls the level of signal
going to the LOW OUTPUT jacks.
Unity gain is reached at the “0 dB”
mark with the INPUT LEVEL set to
“10”. This control does not affect the
MONO SUB OUTPUT level. Refer to
Operating Instructions on page Manual-
6.
Manual-2
HIGH OUTPUTS
These are balanced Output jacks.
Connect the LEFT HIGH OUTPUT to
the left channel input of the high
frequency amplifier, and the RIGHT
HIGH OUTPUT to the right channel
input of the high frequency amplifier.
When using different model amplifiers
for the low and high outputs, use the
amplifier with the most power for the
low outputs.
LOW OUTPUTS
Connect the LEFT LOW OUTPUT
to the left channel of the low frequency
amplifier, and the RIGHT LOW
OUTPUT to the right channel of the low
amplifier. When driving a single
subwoofer, use the MONO SUB
OUTPUT jack instead.
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LOW/HIGH FREQUENCY control
This 31-position selector sets the
crossover frequency between the Low
and High frequency Outputs in both
Channels. Consult the manuafacturer of
the drivers or cabinets for the correct
setting.
HIGH LEVEL control
This controls the level of signal
going to the HIGH OUTPUT jacks.
Unity gain is reached at the “0 dB”
mark with the INPUT LEVEL set to
“10”. Refer to Operating Instructions on
page Manual-6.
Power ON switch and LED
Your basic, straightforward power
switch. When the yellow LED is lit, the
SAC 22 is ready to go.
MONO SUB OUTPUT and
100 Hz FILTER switch
This Output contains the summed
signals of the LEFT and RIGHT LOW
OUTPUTS. It may be used instead of,
or along with the LOW OUTPUTS.
Switch the 100 Hz FILTER to IN for
best results when using a subwoofer
along with the LOW OUTPUTS. This
sends only the very lowest frequencies
to the subwoofer. With the switch OUT,
the MONO SUB OUT still produces the
summed LOW OUTPUTS without the
100 Hz FILTER.
INPUTS
These are balanced Inputs. It is best
to use balanced lines, especially when
connecting cables over 10 feet in length.
If you are feeding the SAC 22 from a
device that does not have balanced XLR
connectors, consult SOUND SYSTEM
INTERCONNECTION on page
Manual-10.
Cable Wiring
In agreement with IEC and AES/
ANSI standards, Rane wiring convention is pin 2 Positive (hot), pin 3
Negative (cold or return), and pin 1
signal grounded and chassis grounded
(to allow unbalanced operation). The
XLR case is chassis grounded. This
device uses low impedance balanced
line drivers. Do not connect the “+” or
“–” output pins to ground, as this may
cause the power supply to shut down.
For unbalanced use, leave the unused
output pin (“+” or “–”) unterminated.
Manual-3
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APPLICATION — PASSIVE 2-WAY WITH MONO SUB
Use this configuration if you have full-range cabinets with passive crossovers built-in, i.e., no separate speaker inputs for
the low and high drivers. Connect as shown for a mono subwoofer. Set the 100 Hz FILTER switch to the OUT position. The
front panel LOW/HIGH frequency control determines the frequency division between the main cabinets and the mono
subwoofer.
APPLICATION — ACTIVE 2-WAY WITH (or without) MONO SUB
Use this configuration if you have separate speaker inputs for the low and high drivers, regardless of whether they are in the
same or different cabinets. Connect as shown for a mono subwoofer. Set the 100 Hz FILTER switch to the IN position. If a
mono subwoofer is not used, the FILTER switch setting will not matter. The front panel LOW/HIGH FREQUENCY control
determines the frequency division between the high and low drivers, and the subwoofer also receives the low frequencies
below 100 Hz.
Manual-4
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OPERATING INSTRUCTIONS
Selecting Crossover Frequencies
Most speaker manufacturers supply low and/or high
frequency cut-off points for each driver, especially if these are
supplied in a system. These cut-off frequencies are based on
each driver’s performance, with a certain safety margin to
accommodate more gentle filter roll-offs.
The SAC 22 utilizes a 31-position precision DC control
voltage potentiometer to select the LOW/HIGH FREQUENCY point. This crossover circuit design assures
consistent accuracy from Channel-to-Channel and unit-tounit. This is a distinct advantage over continuously variable
designs using ganged potentiometers which can yield large
variations in channel-to-channel matching. Even with 31
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 drivers have their own gradual rolloffs and
tolerance variations. Just pick the closest one. When in doubt,
choose the higher Frequency setting.
The illustration and table below details the crossover
frequencies available on the detents that are not labeled. For
best overall system results, try to choose the speaker components so that each operates well within its recommended
limits. This provides valuable leeway so that crossover points
may be adjusted in order to fine-tune the system. This also
yields higher system reliability. If at all possible, always use
some kind of realtime analyzer to tune your crossover, and
then fine-tune each system with an equalizer. Keep reading
for further alignment details.
Setting the Output Level Controls
The INPUT LEVEL is an overall system sensitivity
adjustment. Use this control to decrease the overall sensitivity
of the entire sound system, including the mono subwoofer if
you are using one. You will generally want to start with this
control in the full clockwise (or 10) position.
The LOW LEVEL, HIGH LEVEL and MONO SUB
OUTPUT LEVEL controls allow you to compensate for
sensitivity variations in amplifiers and drivers. Do not use
these to adjust overall system sensitivity unless you plan to
re-align the system afterward. With these set to the 0 dB mark
and the INPUT LEVEL set to 10, the crossover yields no
level change from input to output. This is the best gain
structure and provides the best signal-to-noise performance.
Crossover Philosophy
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-lt-Once-And-Glue-lt School
The philosophy here is to use the crossover to flatten
system response as much as possible 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,
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 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 response for each
different room.
The Fix-lt-With-The-Crossover School
Here the crossover knobs get a good workout, for the
crossover is used at each location to help flatten the system
along with the equalizer.
Regardless of which school you profess, the absolute
importance and effectiveness of some kind of realtime
analyzer in your system cannot be overstressed! An analyzer
saves tremendous amounts of time and provides the absolute
consistency, 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 today’s cost-effective
analyzers—you’ll wonder how you managed at all without
Figure 1. See unmarked Frequency detent steps below.
STEP 0 1 2 3 4 5 6 7 8 9 101112131415161718192021222324252627282930
SILK
100 125 200 250 325 500 650 1000 1500 2000 3000 3200
SCREEN
CALC.
100 100 100 107 123 141 162 187 214 246 283 325 373 429 492 566 650 746 857 985 1131 1300 1493 1715 1970 2263 259 9 2986 3200 3200 3200
FREQ.
one.
Figure 2. Frequency detent table with actual frequencies of all detent steps.
Manual-5
Page 7
Setting the Mono Sub Output Level
Begin with the MONO SUB OUTPUT LEVEL control set
at MAX. The LOW LEVEL control has no affect on the
MONO SUB OUTPUT. Make subwoofer level changes with
either the MONO SUB OUTPUT LEVEL or with the amplifier level control. If you are using the MONO SUB OUTPUT
instead of the LOW OUTPUTS, be sure the 100 Hz FILTER
is switched OUT.
Setting Levels With a Realtime Analyzer
Any good 1/3-octave realtime analyzer will do, however,
Rane makes a rather inexpensive yet accurate one—the
RA 27. We had to get our plug in.
1. Set the INPUT LEVEL as described previously on page
Manual-2, and the LOW and HIGH LEVEL controls to
minimum; leave the FREQUENCY control as it was 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, wild animals, etc.) that could affect 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. 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).
4. 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.
6. Now slowly turn up the HIGH LEVEL control until the
display shows the same high frequency output level
average as the low frequency section.
IMPORTANT: Compression driver or horn high frequency
roll-off, bass roll-off, and room acoustics usually cannot be
corrected by the crossover.
If, for example, you are adjusting the HIGH FREQUENCY LEVEL 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. Use an equalizer 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.
Move the microphone and check the analyzer system
response at several other locations. Adjust the crossover to
reach a fixed compromise setting as necessary. 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.
Setting Levels Using an SPL Meter and Pink Noise
Generator
First, obtain a good SPL meter from a local electronics or
hi-fi store. Second, and perhaps a little trickier, get a pink
noise generator—again try electronics stores. You may also
use a sweep or tone generator in place of a pink noise
source—be sure to look at several different tones within each
crossover section to get a good average of driver response.
1. Run pink noise into the crossover Inputs (through the mixer
or directly, as is convenient).
2. Make sure all crossover LEVEL(s) are turned all the way
down and all amplifier level controls are at least half way
up to start with.
3. Turn the crossover INPUT LEVEL all the way up. Place
the SPL meter at least 15 feet from the speaker stack and
about chest high. Once positioned, make sure that the SPL
meter remains in the exact same location for the rest of the
procedure. Minimize all background noise (fans, air
conditioners, traffic, wild animals, etc.) to get accurate
readings. Set the SPL meter to “C-weighting” and “slow” if
those switches are present.
4. Slowly turn the LOW LEVEL up until there is a healthy
rumble coming from the bass speakers. Adjust the SPL
meter and/or LOW LEVEL until you get a 0 dB reading on
the meter. After this point do not change the controls on the
SPL meter.
5. Make a note of the LOW LEVEL control setting at the 0
dB adjustment just obtained, then reduce the LOW LEVEL
to “0” so that the pink noise disappears from the bass
speakers (revel in the silence...).
6. Now slowly turn up the HIGH LEVEL control so that pink
noise is heard from the high frequency speakers. Without
changing any settings on the SPL meter, adjust the crossover HIGH LEVEL control until you obtain a 0 dB reading
on the SPL meter.
7. Return the LOW LEVEL to the previously recorded
setting. Now the low and high speakers are set at the same
level. The crossover should now be aligned. Make any
overall level adjustments with the INPUT LEVEL controls
and leave the output LOW and HIGH LEVEL controls
unchanged.
It is possible that you may turn one of the frequency
section output LEVEL controls all the way up and still not
have enough volume for a 0 dB reading (as determined by
previous section levels). This is probably due to different
sensitivities of amps, speakers and other level controls in the
system. When this happens, re-set the SPL meter so that it
reads 0 dB on this frequency section (you may have to “down
range” the meter and re-adjust the crossover INPUT LEVEL
control). Now go back and re-adjust the previous crossover
LEVEL controls, turning these down to get a 0 dB reading on
the meter.
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com
Manual-6
104967
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