Rane MX 23 Manual

OPERATORS MANUAL
MX 23
STEREO 3-WAY 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 MX 23 with the POWER off. Balanced XLR cables are recommended, but if you must convert to ¼"
connectors, buy or make a cable like the ones on page Manual-11 and keep them as short as possible. 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.
Consult the speaker manufacturers for the correct crossover FREQUENCY settings. 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 MX 23 some program
material. Start by turning up the LOW LEVEL, MID 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 mono bass bin along with stereo mid- and
high-range cabinets, set the 100 Hz FILTER to OUT, allowing the front panel FREQUENCY to control the subwoofer
crossover point. When used with 3-way 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 MX 23 almost does the job of a Stereo 4-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
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 amplifiers) 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. The wide blade or third prong is provided for your safety. If the provided plug does not
fit 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 specified by Rane.
12. Use only with the cart, stand, tripod, bracket, or table specified 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 qualified 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. The 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. This 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
amplifiers) may cause an unacceptable amount of hum or may generate too much heat and degrade the performance of this apparatus.
19. This 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 fire or electric shock, do not expose this apparatus to rain or moisture. Apparatus shall not be exposed to dripping
or splashing and no objects filled with liquids, such as vases, shall be placed on the apparatus.
NOTE: This 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. These
limits are designed to provide reasonable protection against harmful interference in a residential installation. This 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 off 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 different from that to which the receiver is connected.
• Consult the dealer or an experienced radio/TV technician for help.
CAUTION: Changes or modifications not expressly approved by Rane Corporation could void the user's authority to operate the equipment.
This 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
CAUTION
RISK OF ELECTRIC SHOCK
DO NOT OPEN
To reduce the risk of electrical shock, do not open the unit. No user
serviceable parts inside. Refer servicing to qualified service personnel.
The symbols shown below are internationally accepted symbols that warn
of potential hazards with electrical products.
This symbol indicates that a dangerous voltage
constituting a risk of electric shock is present within
this unit.
This symbol indicates that there are important
operating and maintenance instructions in the
literature accompanying this unit.
INPUT LEVEL control and
indicators
LOW LEVEL control
This controls the level of signal going to the
This controls the overall level without
LOW OUTPUT jacks. Unity gain is reached at
altering the relative settings of the Low, Mid the “0 dB” mark with the INPUT LEVEL set
and High frequency Outputs. Input gain is
to “10”. This control does not affect the
+6 dB at “10”. With signal applied, set this MONO SUB OUTPUT level. Refer to Operating
control so the +4 dBu LED lights occasion- Instructions on page Manual-6.
ally, indicating sufficient signal. Flashing of
the OL (overload) LED during peaks can be
avoided by turning the INPUT LEVEL down.
LOW/MID FREQUENCY control
This 31-position selector sets the crossover
frequency between the Low and MId
frequency Outputs in both Channels. Consult
the manufacturer of the drivers or cabinets
for the correct setting.
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
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
balanced line drivers. Do not connect the
amplifier. When using different model
“+” or “–” output pins to ground, as this
may cause the power supply to shut down. amplifiers for the low and high outputs, use
For unbalanced use, leave the unused output the amplifier with the most wattage for the
low outputs.
pin (“+” or “–”) unterminated.
Manual-2
MID OUTPUTS
These are balanced Output jacks. Connect
the LEFT MID OUTPUT to the left channel
input of the mid frequency amplifier, and the
RIGHT MID OUTPUT to the right channel
input of the mid frequency amplifier.
MID & HIGH LEVEL controls
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.
MID/HIGH FREQUENCY
control
This 31-position selector sets the crossover
frequency between the Mid and High
frequency Outputs in both Channels. Consult
the manufacturer of the drivers or cabinets
for the correct setting.
Power ON switch and LED
Your basic, straightforward power switch.
When the yellow LED is lit, the MX 23 is
ready to go.
MONO SUB OUTPUT,
LEVEL trim, 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. The output may be adjusted with
the LEVEL trim from +6 dB to -10 dB. Unity
gain is straight up at 12:00. Switch the 100
Hz FILTER to IN when using a subwoofer
along with the LOW OUTPUTS. This sends
only the lowest frequencies to the subwoofer.
INPUTS
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.
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 MX 23 from a device that does
not have balanced XLR connectors, consult
the SOUND SYSTEM INTERCONNECTION
section on page Manual-10.
Manual-3
APPLICATION — ACTIVE 3-WAY WITH (or without) MONO SUB
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, since all low frequencies will
be sent to the LEFT and RIGHT LOW OUTPUTS.
The front panel LOW/MID FREQUENCY control determines the
frequency division between the low and mid drivers, while only low
frequencies below 100 Hz are sent to the mono subwoofer.
Manual-4
OPERATING INSTRUCTIONS
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, MID, HIGH, 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.
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 MX 23 utilizes 31-position precision DC control
voltage potentiometers to select the FREQUENCY points.
This crossover circuit design assures consistent accuracy from
Channel-to-Channel and unit-to-unit. This is a distinct
advantage over continuously variable designs using ganged
potentiometers which can yield large variations in channel-tochannel 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 illustrations and tables below detail 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.
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
one.
Figure 1. See unmarked Frequency detent steps below.
STEP
0
1
2
LOW/MID
80
SCREEN
LOW/MID
80
FREQ.
MID/HI
350
SCREEN
MID/HI
FREQ.
3
4
85
80
80
85
5
100
93
420
6
7
125
8
9
150
10
11
12
200
13
14
15
250
16
17
300
18
19
400
20
21
22
500
23
24
600
102 114 126 140 154 170 189 209 231 255 283 313 346 383 423 468 518 573 634 702
600
750
1000
1500
2000
2500
3200
25
4000
777
5000
26
27
28
29
30
850
1000
859
950 1000 1000 1000
6500
7000
350 350 350 372 419 472 532 600 676 762 859 969 1092 1231 1388 1565 1765 1990 2242 2527 2850 3212 3621 4082 4602 5188 5848 6593 7000 7000 7000
Figure 2. Frequency detent table with actual frequencies of all detent steps.
Manual-5
Setting the Mono Sub Output Level
Begin with the MONO SUB OUTPUT LEVEL trim 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.
1. Set the INPUT LEVEL as described previously on page
Manual-2, and the LOW, MID, and HIGH LEVEL controls
to minimum; leave the 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, 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 MID LEVEL control until the
display shows the same high frequency output level
average as the low frequency section.
7. Repeat this procedure for all crossover frequency sections,
lowest to highest, so the end result is as flat response as
possible on the analyzer display near each crossover point.
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.
Manual-6
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 MID LEVEL control so that pink
noise is heard from the high frequency speakers. Without
changing any settings on the SPL meter, adjust the crossover MID LEVEL control until you obtain a 0 dB reading
on the SPL meter.
7. Turn down the MID LEVEL and repeat this process for the
HIGH LEVEL. Return the LOW and MID LEVELS to the
previously recorded settings. Now all drivers are set at the
same level. Make any overall level adjustments with the
INPUT LEVEL controls and leave the output LOW, MID
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.
SOUND SYSTEM INTERCONNECTION
Rane’s policy is to accommodate rather than dictate.
However, this document contains suggestions for external
wiring changes that should ideally only be implemented by
trained technical personnel. Safety regulations require that all
original grounding means provided from the factory be left
intact for safe operation. No guarantee of responsibility for
incidental or consequential damages can be provided. (In
other words, don’t modify cables, or try your own version of
grounding unless you really understand exactly what type of
output and input you have to connect.)
THE ABSOLUTE BEST RIGHT WAY TO DO IT
Use balanced lines and tie the cable shield to the metal
chassis (right where it enters the chassis) at both ends of the
cable.
A balanced line requires three separate conductors, two of
which are signal (+ and –) and one shield. The shield serves
to guard the sensitive audio lines from interference. Only by
using balanced line interconnects can you guarantee (yes,
guarantee) hum-free results. Always use twisted pair cable.
Chassis tying the shield at each end also guarantees the best
possible protection from RFI [radio frequency interference]
and other noises [neon signs, lighting dimmers].
THE NEXT BEST RIGHT WAY TO DO IT
The quickest, quietest and most foolproof method to
connect balanced and unbalanced is to transformer isolate
all unbalanced connections. Your audio dealer can recommend such a transformer.
The goal of transformer adaptors is to allow the use of
standard cables. With these transformer isolation boxes,
modification of cable assemblies is unnecessary. Virtually
any two pieces of audio equipment can be successfully
interfaced without risk of unwanted hum and noise.
Another way to create the necessary isolation is to use a
direct box. Originally named for its use to convert the high
impedance, high level output of an electric guitar to the low
impedance, low level input of a recording console, it allowed
the player to plug “directly” into the console. Now this term is
commonly used to describe any box used to convert unbalanced lines to balanced lines.
THE LAST BEST RIGHT WAY TO DO IT
If transformer isolation is not an option, special cable
assemblies are a last resort. The key here is to prevent the
shield currents from flowing into a unit whose grounding
scheme creates ground loops (hum) in the audio path (i.e.,
most audio equipment). Do not be tempted to use 3-prong to
2-prong “cheater” adapters to lift grounds. This is a dangerous and illegal practice.
It is true that connecting both ends of the shield is theoretically the best way to interconnect equipment – though this
assumes the interconnected equipment is internally grounded
properly. Since most equipment is not internally grounded
properly, connecting both ends of the shield is not often
practiced, since doing so can create noisy interconnections.
A common solution to these noisy hum and buzz problems
involves disconnecting one end of the shield, even though one
can not buy off-the-shelf cables with the shield disconnected
at one end. The best end to disconnect is a matter of personal
preference and should be religiously obeyed; choose inputs or
outputs and always lift the side you choose (our drawings
happen to disconnect the outputs). If one end of the shield is
disconnected, the noisy hum current stops flowing and away
goes the hum — but only at low frequencies. A one-end-only
shield connection increases the possibility of high frequency
(radio) interference since the shield may act as an antenna.
Many reduce this potential RF interference by providing an
RF path through a small capacitor (0.1 or 0.01 microfarad
ceramic disc) connected from the lifted end of the shield to
the chassis. The fact that many modern day installers still
follow this one-end-only rule with consistent success indicates this and other acceptable solutions to RF issues exist,
though the increasing use of digital and wireless technology
greatly increases the possibility of future RF problems.
See the following page for suggested cable assemblies for
your particular interconnection needs. Find the appropriate
output configuration from either your mixer output or the MX
22 output (down the left side), and then match this with the
correct balanced or unbalanced input to the MX 22 or the
amplifer (down the right side.) An “off-the-shelf” cable may
be available or modifiable. Soldering should only be attempted by those trained in the art.
SUMMARY
If you are unable to do things correctly (i.e. use fully
balanced wiring with shields tied to the chassis at the point of
entry, or transformer isolate all unbalanced signals from
balanced signals) then there is no guarantee that a hum free
interconnect can be achieved, nor is there a definite scheme
that will assure noise free operation in all configurations.
WINNING THE WIRING WARS
• Use balanced connections whenever possible.
• Transformer isolate all unbalanced connections from
balanced connections.
• Use special cable assemblies when unbalanced lines cannot
be transformer isolated.
• Any unbalanced cable must be kept under ten feet (three
meters) in length. Lengths longer than this will amplify
the nasty side effects of unbalanced circuitry's ground
loops.
This information was condensed from Rane Note 110,
“Sound System Interconnection”. If you would like the
complete note, call or email the factory, download it from
Rane's web site, or ask your dealer for a copy.
Manual-7
VARIOUS XLR CABLE ASSEMBLIES
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com
Manual-8
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