Rane MP 24 Manual
MP 24
Don't! Quick-starting an MP 24 is like trying to quick-start a 747. It's just not something you do. Trust us, you don’t
want to make mistakes with this sucker. So just this once—please—we highly recommend you read this entire manual:
front-to-back, every single page, every single word. It will familiarize you with the many intricacies of the MP 24, not to
mention all the nooks and crannies.
1. POWER “ON” indicator: This yellow LED illuminates anytime the MP 24 is connected to an appropriate power source
(see #28, Rear Panel).
2. SOURCE CONTROL selectors: These four position rotary switches provide Input selection between the various Phono
and Line Inputs for their respective mixing Channels.
3. Input channel faders: These faders control the relative Levels of each of the four Input mixing Channels.
4. Channel CUE selectors: Engaging any single or combination of CUE pushbuttons sends any program present at the
respective Channel’s SOURCE CONTROL selector to the Headphone Cue section. The yellow LEDs adjacent to each CUE
select button illuminate when the switch is engaged.
5. CROSSFADE ENGAGE switch: Engaging this switch activates the CROSSFADER and disables manual mixing capabilities. The adjacent green LED illuminates whenever the Crossfader is active.
6. Left-hand CROSSFADE ASSIGN switch: This four position rotary switch ASSIGNS the left side of the Crossfader to any
of the four Input Channels when the Crossfader is activated by its ENGAGE switch.
7. Right-hand CROSSFADE ASSIGN switch: This four position rotary switch ASSIGNS the right side of the Crossfader to
any of the four Input Channels when the Crossfader is activated by the ENGAGE switch.
8. CROSSFADER: This fader controls the Levels of any two Channels assigned to it by the left and right Crossfade ASSIGN
switches when the ENGAGE switch is activated. The entire Crossfader assembly is replaceable from the front panel
without disassembling the entire unit. See SERVICE INFORMATION on page Schematic-1for instructions.
9. ENGAGE MIC switch: This pushbutton enables the Microphone Inputs to feed the Booth, Zone, and Main Outputs. The
adjacent red LED flashes whenever the ENGAGE MIC switch is down and locked. This switch also activates a “ducker”
circuit in the Booth Output.(See #15 Front Panel and #20 Rear Panel.)
10. MAIN MIC LEVEL control: This rotary control sets the Level of the balanced low impedance MAIN MIC Input.
11. AUX MIC LEVEL control: This rotary control sets the Level of the unbalanced high impedance AUX MIC Input, most
often used for wireless mics.
12. Microphone equalization controls: These three rotary controls adjust the frequency contour of both Microphone Inputs.
They have no effect on any other program material.
13. LOOP ENGAGE switch: This pushbutton controls the Switchable Effects Loop; pressing it to its down and locked
position routes the main signal through the processor attached to the SWITCHABLE LOOP connectors on the rear.
14. MASTER LEVEL fader: This control determines the program and microphone Level at the Main Outputs. Unity gain is
approximately “4.5”
15. BOOTH LEVEL control: Controls the program and microphone Level at the Booth Outputs. Unity gain is approximately
“6.5”. This Output utilizes a “ducking” circuit that reduces the microphone Level when the MIC ENGAGE switch is
activated. See #20, Rear Panel.
16. ZONE LEVEL control: Controls the program and microphone Level of the Zone Outputs. Unity gain is approximately
17. PROGRAM EQUALIZER controls: These four rotary controls are used to contour the frequency response of the
program at the Main, Booth and Zone Outputs. This is not designed to be the only equalizer in the system, this is intended
to provide EQ between varying program materials.
18. PROGRAM EQUALIZER ENGAGE switch: Engaging this switch enables the Program Equalizer to function. In the out
position, the Equalizer is bypassed.
19. HEADPHONE LEVEL CONTROL: Clockwise rotation of this rotary control increases the headphone drive level.
20. HEADPHONE PAN CONTROL: This rotary control serves two purposes; in the STEREO mode it changes the relative
levels of the Cue and Program mixed together in both earcups. In the MONO mode it changes the balance between the
Mono Cue in the left ear cup and the Mono Program in the right.
21. HEADPHONE CUE mode switch: In the up position, this switch feeds STEREO Program and Cue to both earcups, in the
down position the Headphone circuit provides MONO Cue to the left ear and MONO Program to the right.
22. HEADPHONE output jack: A tip-ring-sleeve stereo jack provides for the insertion of stereo headphones.
23. PEAK PROGRAM METER: This stereo LED bargraph provides a visual indication of program output voltage. The
calibration of the indication is user adjustable. (See #6, Rear Panel.)
Fader Care:
With heavy use in harsh environments, the faders may need lubrication. Rane recommends spraying one or two bursts of
CaiLube MCL into the fader. Work the fader back and forth a few times after spraying. This treatment extends longevity and
can make used faders as good as new.
Order CaiLube MCL® from:
CAIG Laboratories, Inc.
16744 W. Bernardo Drive
San Diego CA 92127-1904
Phone 619-451-1799
Fax 619-451-2799
Web www.caig.com
1. BALANCED MAIN OUTPUT connectors: These three-pin connectors provide a fully balanced Main Output signal, pin 2
is (+), pin 3 is (–) and pin 1 is signal ground. Pin 3 must never be grounded for unbalanced operation. Use only pin 2 as hot
and pin 1 as return for any unbalanced operation.
2. UNBALANCED MAIN OUTPUT connectors: These ¼" unbalanced connectors provide MAIN OUTPUT signals.
3. BOOTH OUTPUT connectors: Connecting to the Left Output only supplies a mono BOOTH monitor OUTPUT; connecting to both Left and Right provides a stereo Output.
4. ZONE OUTPUT connectors: Connecting to the Left Output only supplies a mono ZONE OUTPUT, connecting to both
Left and Right provides a stereo Output. The Zone Outputs are located Post-EQ, which includes the Microphone Output.
An internal jumper block programs the Zone to Pre-EQ (and no mic) if required. See SERVICE INFORMATION on page
5. MAXIMUM OUTPUT GAIN REDUCTION control: This rotary control decreases the maximum Level of the balanced
and unbalanced MAIN OUTPUTS of the MP 24 as it is rotated CCW.
6. METER SENSITIVITY ADJUST: Clockwise rotation decreases the full-scale sensitivity of the PEAK PROGRAM
METER, as indicated by the full-scale voltage calibrations around the control.
7. SYSTEM MONO/STEREO switch: Engaging this pushbutton converts all Outputs (except tapes and loops) to MONO,
regardless of the nature of the Input signals.
8. EQ RANGE switch: In the out position, the maximum boost/cut available from the Program Equalizer is ±8dB. In the
switch’s in position, this range is reduced to ±4 dB.
9. LIGHT CONTROL OUTPUT jack: This ¼" TRS connector provides a transformer-coupled mono program signal for use
by a lighting controller’s trigger input. The tip is positive, the ring is negative and the sleeve is floating.
10. LIGHT OUTPUT LEVEL attenuator: Counter-clockwise rotation reduces the Output Level at the LIGHT CONTROL
OUTPUT jack.
11. TAPE OUTPUT jacks: One pair of RCA jacks provides pre-EQ, pre-LOOP Program Outputs. The other pair supplies preEQ, post-LOOP Program Outputs. The microphone signals are not available at these Outputs, however they are selectable
using an internal jumper block. (See SERVICE INFORMATION on page Schematic-1.)
12. SWITCHABLE LOOP SEND jacks: Use these ¼" unbalanced Left and Right Outputs for driving the inputs of a processor activated by the front panel LOOP button.
13. SWITCHABLE LOOP RETURN jacks: Use these ¼" unbalanced Inputs for receiving the outputs of the above device.
14. MAIN EFFECTS LOOP SEND jacks: These ¼" unbalanced connectors provide drive to the inputs of a signal processor
which is not to be switched from the front of the mixer. Connecting only to the LEFT EFFECTS SEND provides a mono
Output; connecting to both Left and Right provides a stereo feed.
15. MAIN EFFECTS LOOP RETURN jacks: A pair of ¼" unbalanced Inputs for receiving the processed signal generated
from the Main Effects Loop Sends above.
16. Balanced MAIN MIC Input jack: Use this 3-pin connector for connecting a balanced microphone of any impedance,
either dynamic or condenser.
17. Unbalanced high-impedance AUX MIC Input jack: This ¼" unbalanced Input is for wireless or other high-impedance
18. MIC LOOP jack: This ¼" TRS (Tip-Ring-Sleeve) connector is for inserting external signal processing in the microphone
circuit only. This is a tip-send, ring-return configuration. This feature does not affect the operation of the Main Program
19. PHANTOM POWER switch: Engaging this pushbutton applies +15 V Phantom Power to the 3-pin balanced MAIN MIC
Input only. It has no effect on the Auxiliary Microphone Input. The adjacent red LED illuminates whenever Phantom
Power is active.
20. BOOTH DUCKER switch: When in the ACTIVE position, the ENGAGE MIC switch on the front panel reduces the
Microphone level at the Booth Outputs. When this switch is in the DEFEAT position, Microphone level is not reduced.
21. PHONO/AUX input jacks: Use these stereo Phono Input pairs for connecting any moving-magnet type cartridges to the
mixer. Internal jumpers are provided to convert these into Line level Inputs (See SERVICE INFORMATION, page Schematic-1). When these jumpers are set to PHONO (as shipped from the factory), these Inputs should never be used for any
other purpose due to the amount of gain and RIAA equalization present. Any unused Phono Input should have the Phono
Shorting Plug installed to prevent interference from an outside source. Do not put any of the Phono Shorting Plugs into the
Tape Out jacks, as this will short all the Outputs.
22. AUX/PHONO 3 input jacks: As #21 above, except shipped with the internal jumpers in the LINE position.
23. LINE 1 & 3 through 6 Input jacks: These stereo pairs of RCA connectors are unbalanced, Line level Inputs only. They
are suitable for all line-level devices such as the audio outputs of VCRs, compact disc players, tape recorders, etc.
24. LINE 2 Input jacks: This is a fully balanced, ¼" Tip-Ring-Sleeve Line Input. The tip of the jack is (+), the ring is (–) and
the sleeve is ground.
25. GROUNDING POST: This terminal is provided to facilitate your hum chasing, buzz eliminating experiments. Its purpose
is to provide a place to connect those otherwise unusable extra wires coming out of the turntables.
26. Chassis ground point: A 6-32 screw and toothed washer is provided for chassis ground. Since the MP 24 does not get
chassis ground through the AC cord, this point is provided in case your system does not have another earth ground such as
the rack rails. See the CHASSIS GROUNDING note on page Manual-8 for details.
27. GROUND LIFT SWITCH. This switch separates chassis ground from signal ground. Normally, this switch should be in
the LIFT position. In some circumstances, moving it to the opposite position eliminates stubborn hum and buzz problems.
If you are tempted to move this switch with your power amplifiers turned on and cranked up, don’t. Always turn your
system levels down before changing your grounds around and then bring them up slowly.
28. POWER input connector: No, this is not where Commissioner Gordon plugs in his Bat-phone, in fact it is not a telephone
jack at all. The MP 24 uses an 18 volt AC center-tapped transformer only. Use only a model RS 1, or other remote AC
power supply approved by Rane.
Even though the system variations are limitless in most
applications where the MP 24 is used, an installer must follow
some basic interconnect guidelines. Unfortunately, even
though the system and the primary components such as
mixers, processors and amplifiers are of commercial grade,
most of the source components, i.e. turntables, disc players,
tape decks and so on are consumer grade, with consumer
interconnect limitations. Therefore, on the input side of the
MP 24, RCA connectors will prevail with unbalanced lines
thereto attached. It is recommended, for no scientific reason,
that the turntable furthest to the left be connected to Phono 1,
and proceed from left to right with Phono 2 and then Phono 3,
if used. See SERVICE INFORMATION on page Schematic-1
to convert any PHONO level Input into a LINE level Input.
When determining which Line Inputs to use for what, the
process becomes a bit more difficult. Obviously, if one of the
line devices feeding the MP 24 is of the commercial variety
sporting balanced outputs, use Line 2 for this due to its
unique ability to accept such foreign substances. The rest of
the assignments are pretty much a matter of what you want to
appear where on the source switches. As you can see, Lines 1
through 3 appear only on Input Channels 1 and 2; Lines 4
through 6 appear only on Input Channels 3 and 4. So the
layout will depend on how heavily you will use the Phono
Inputs and how many line level devices you will be using.
On the Output side, things are a bit less restrictive. On the
MAIN OUTPUTS you have been given a choice between
3-pin balanced and ¼" unbalanced. Which you use should be
derived from some consideration of how far the cable has to
run from the mixer to the next component, how much ambient
noise there is in the local atmosphere (Radio Moscow in the
next building, 36,000 SCR controlled light dimmers in the
next rack), and any other possible encumbrance on the quality
of the audio inside the jacket. Most experienced installers and
users of commercial sound equipment have a good handle on
which to use in a given situation. The general rule is: if the
Output from the MP 24 is running longer than 10 feet, use
balanced cables. If the input to your system equalizer,
crossover, or power amplifier is balanced, go balanced. If
you keep the cable length short and your destination has
unbalanced inputs, you can probably get away with using the
¼" unbalanced connectors.
The TAPE OUTPUTS are unbalanced RCA connectors;
the assumption being that most readily available tape recording equipment such as would be used in a club situation
would be of similar type. Simply determine whether you want
the signal processing in the Effects Loops to have an effect on
the recording being made and connect the record inputs (left
and right) to the appropriate PRE-LOOP or POST-LOOP
TAPE OUTPUTS. These Tape Outputs do not contain any
signal from the Microphone section. If you need to record the
Mic, use the Unbalanced Main Outputs, Zone Output, or the
Booth Output with the Booth Ducker circuit defeated. (If
none of these are available, see SERVICE INFORMATION
on page Schematic-1 for instructions to change internal
jumper blocks.)
The front panel switchable LOOP is for stereo devices
only, so consider which effects are connected where. Some
processors, such as delays and reverbs, have only one mono
input and two outputs. This is accommodated automatically
by using the MONO Output of the MAIN EFFECTS LOOP.
The Zone Outputs and the Booth Outputs are the automatic mono/stereo type. If mono is required, simply connect
only to the LEFT OUTPUT. Inserting a plug into the RIGHT
OUTPUT automatically renders it stereo. All of these Output
connectors are unbalanced. Attempting to run TRS balanced
on any of these results in an open leg on the receiving
component and causes problems.
This is a good place to discuss the problems encountered
in connecting the MP 24 to all of the different types of cables
and connectors that one finds when basing a system on
consumer goods (the pieces of equipment with the RCA
connectors), commercial audio products (¼", 3-pin balanced
etc.), and no telling what else. In consumer audio devices, one
rarely finds ground-lift capabilities, or any of the other hum
prevention devices normally provided on commercial
equipment. Chassis ground and signal ground are normally
the same thing, a situation which may cause problems when
the two species get on the same bus.
The best we can do to try to help you eliminate hum,
oscillations, or other stray characters from your system is to
tell you to experiment. If you think lifting the ground on the
MP 24, crossovers, equalizers or power amplifiers might help,
go ahead and try it. There is science involved in de-humming
a system, however it is sometimes faster to just experiment.
Occasionally, directly grounding the chassis of the mixer to
the power amplifiers with a large gauge wire helps. And by
the same token, isolating the two when they are installed in
the same rack may have a quieting effect. A word of caution:
Don’t do anything with Level controls up, power on, or under
any condition that could cause damage to delicate loudspeakers and ears. Make your changes with the system off, then
power up carefully to make sure you haven’t made matters
worse. Bring up Level controls slowly and with great caution.
Surprises are nice on birthdays and Christmas, and rarely any
other time.
If hum problems only exist on the Phono Inputs, there is
always a possibility for experimental troubleshooting at this
end also. Experience has shown that just because the manufacturers put ground wires on them, they are not always
connected! Some turntables even have two ground wires, one
for the tone arm and one for the chassis. Sometimes only one
of these should be connected for optimum signal-to-noise,
sometimes both, sometimes none. The rule is: “Whatever
works, works.”
Operation of the MP 24 is fairly straightforward, deviating
only slightly from other products of its type. Assuming at
least one turntable is connected and assigned to PHONO 1,
operation consists of the following: Make sure all faders are
set to zero, the MIC, LOOP, EQ, and CROSSFADER are all
disengaged, (switches out) and that all rotary LEVEL controls
are either fully CCW or in their center detents, whichever
applies. Select PHONO l on Input Channel 1. Simultaneously
raise the Channel 1 fader and the MASTER LEVEL fader.
Before much travel is reached on the faders, the results should
be heard. If not, shut everything down and recheck connections, power to the mixer (look for the yellow POWER light)
and ancillary devices (EQs, crossovers, amplfiers, etc.)
Once an output is established from the turntable, go ahead
and try everything else. Assign all Inputs to the Channels they
will be used, and test the system. Once all sources are set as
desired, proceed.
There are some controls on the rear panel which need to
be set. Set the METER SENSITIVITY ADJUST so the
system is at maximum level, (usually just short of amplifier
clipping). Run the system up to this maximum level and turn
the METER SENSITIVITY ADJUST so that the highest
peaks on the PEAK PROGRAM METER occasionally hit the
+8 dB indicator. This warns the operator that further pressure
on the throttle will overdrive the system.
At this point check the MAXIMUM OUTPUT GAIN
REDUCTION control so that with the MASTER LEVEL at
“10”, the meter responds as it did in the previous step. This
would be a good time to make the adjustment. This may be
accomplished by turning the rear panel MAX OUTPUT
GAIN REDUCTION adjustment all the way down, pushing
the MASTER LEVEL fader all the way up, setting a normal
mix level on the Input fader, and then turning up the MAX
OUTPUT GAIN REDUCTION adjustment on the rear until
the required output level is attained. In some cases, make this
adjustment with both the Source Level and the MASTER
LEVEL faders all the way up. This is acceptable only if
sources can be adjusted such that they all have equal output
before they reach the Input of the MP 24. If this is not
possible, full system drive will not come from some components. To accomplish this feat, identical cartridges in all
turntables are required so the phono levels are all the same.
Having done all of this it is possible to use the MAX OUTPUT GAIN REDUCTION on all of your sources.
The other rear panel adjustment that should be made at
this time has to do with the maximum deviation to the
frequency response of the system left to the operator. This is
controlled by the EQ RANGE switch. In the out position, the
range of all of the EQ controls is ±8 dB. In the in position,
this range is reduced to ±4 dB. The latter is considered safer
in situations where taste makes waste—in drivers, that is.
To use the HEADPHONE CUE System, signal must be
present at one of the Inputs. (Well, at least you do to make
sure it works.) Depressing the CUE switch for the respective
Input Channel presents this signal to the Headphone Cue
amplifier. An LED illuminates next to the CUE switch,
attesting to the fact that it was indeed pushed down. Now
select how to listen to it — Mono Cue in one ear, Mono
Program in the other, Stereo Program in both ears, or Stereo
Cue in both ears. The STEREO/MONO CUE switch allows
this flexibility. To vary the level between Cue and Program,
rotate the HEADPHONE PAN control in the desired direction. CCW rotation increases the Cue Level, CW rotation
increases the Program Level. The overall volume of all of this
is then controlled by the rotary HEADPHONE LEVEL
First, press the Crossfade ENGAGE switch. The green
LED next to the switch illuminates. The Crossfade ASSIGN
switches determine the two Input Channels that are mixed by
the Crossfader. As an example, assume the left ASSIGN
switch is set on 1 and the right ASSIGN switch is on 2. This
activates both mix faders on Channels 1 and 2. Their outputs,
however, are under the control of the Crossfader. When in its
left-most position, only Channel 1 appears at the Outputs.
Both Channels are present in equal levels in the when the
Crossfader is brought to the middle, and only Channel 2 is
heard once the far right is reached. Note that the sound
pressure level does not change as this transition is effected.
This is a constant power Crossfader, meaning that if the two
input signals are equal, a steady volume level is maintained
no matter where the Crossfader is positioned. This, of course,
gets a bit sticky to predict when one song may be in fade-out
as the operator crossfades from one to the next which is
building in volume.
Once crossfaded to Channel 2, maybe cue up some video
and put the audio on Channel 4. Hard to do? No way. Simply
pull the Channel 1 fader to zero, set the ASSIGN switch on
the left of the Crossfader to Channel 4, Cue up 4, set the level
on fader 4 and Crossfade into it. We realize that it’s a bit
strange to Crossfade from 2 to 4 by sliding the fader to the
left, however it’s just an unavoidable oddity caused by having
so much flexibility.
To use the mic, connect it to the appropriate connector,
and set the PHANTOM POWER switch to the desired mode
(it’s a good idea to have the Phantom Power in the on position
for condenser mics, off for dynamics). Leave the MASTER
LEVEL fader in roughly the same location as it was for the
music that’s been playing, press the MIC ENGAGE switch
and slowly adjust the MAIN MIC (or AUX MIC) LEVEL.
Once this has been accomplished, the tonal balance may be
adjusted via the MIC EQ controls located above the LEVEL
controls. Modifying the sound of the mic in this way won't
affect the EQ of the music in the system. The two Equalizer
sections (Mic and Program) are totally independent. When the
microphone is not in use, release the MIC ENGAGE switch
again to its upward position. When the switch is down, the red
LED flashes. When off, the LED will be out. If the microphone preamp becomes overloaded, the red LED OverLoad
light illuminates. If this is a problem, lower the appropriate
MIC LEVEL control and increase the level of the MASTER
LEVEL fader to restore desired microphone level.
Set the Input Channel faders near their maximum levels to
preclude required excessive gain from the Output stage.
Optimum noise performance is achieved by running the
majority of the gain on the Input stages. Taking the least
amount of gain on the Output stage ensures that the system
doesn’t have to amplify the unavoidable noise generated by
the input buffers and summing amplifiers.
There may be situations where a mono output signal is
preferable to a stereo output. If this is the case, mono outputs
may be obtained on all of the Outputs (Master, Booth, Zone)
by engaging the SYSTEM MONO switch on the rear panel.
When engaged, the SYSTEM MONO switch sums the Left
and Right buses together. In this situation, if only one of the
stereo Inputs on any of the three Phono or six Line sections is
driven, the applied signal appears in equal quantities at both
Left and Right OUTPUT connectors.
The mono LIGHT CONTROL OUTPUT allows use of
lighting systems designed to be triggered from an audio
source. A LIGHT OUTPUT LEVEL control adjusts the
output level appropriate for the lighting controller. There
appears to be a wide variety of sensitivities in different brands
of controllers, therefore some adjustment is likely required. In
the full CW position of the LIGHT OUTPUT LEVEL control,
the signal delivered is amplified 20 dB relative to the premaster fader level. If this is excessive, CCW rotation of the
LIGHT OUTPUT LEVEL control decreases the drive
amount. None of the Level controls past the Input Channel
faders affect this drive level.
The ZONE OUTPUT is an additional Stereo Output with
it’s own ZONE LEVEL control that can be routed to an
amplifer that feeds the bar, another tape recorder, etc. This
output is Post-EQ, which means also that the mic is heard
from the Zone Outputs along with any Program EQ changes
(This can be changed with an internal jumper block). The
BOOTH OUTPUT operates much the same way, with an
added feature: When the ENGAGE MIC switch is activated,
the gain of the BOOTH OUTPUT “ducks” down 13.5 dB to
prevent feedback from the booth speakers. If this Output is
used for something else and this feature is undesired, a
BOOTH DUCKER DEFEAT switch is provided on the rear
panel. Be sure this switch is in the ACTIVE position if booth
speakers are used.
The MP 24 is supplied with a rear mounted ground-lift
switch. The unit is shipped with this switch in the
“grounded” position, tying circuit ground to chassis
ground. If after hooking up your system it exhibits
excessive hum or buzzing, there is an incompatibility in
the grounding configuration between units somewhere.
Here are some things to try:
1. Try combinations of lifting grounds on units that
are supplied with ground lift switches or links.
2. 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.
3. This units outboard power supply does NOT ground
the chassis through the line cord. Make sure that this unit
is grounded either to another chassis which is earth
grounded, or directly to the grounding screw on an AC
outlet cover by means of a wire connected to a screw on
the chassis with a star washer to guarantee proper contact.
Please refer to RaneNote “Sound System Interconnection” (supplied with this manual and available on request
at no charge separately) for further information on system
©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF