Rane MP 24x Manual



Quick-starting an MP 24x 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—




recommend you read this


manual: front-to-back, every single page, every single word. It will familiarize you with the many intricacies of the MP 24x, not to mention all the nooks and crannies.



1. POWER “ON” indicator

: This yellow LED illuminates anytime the MP 24x 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.


Engaging this switch activates the CROSSFADER and disables manual mixing capabili ties. The adjacent green LED illuminates whenever the Crossfader is active.

6. Left-hand CROSSFADE ASSIGN switch:

This four position rotary switch ASSIGNS the


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


side of the Crossfader to any of the four Input Channels when the Crossfader is activated by the ENGAGE switch.


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.


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


and locked position routes the main signal through the processor attached to the SWITCHABLE LOOP connectors on the rear.(See #12 & #13,

Rear Panel


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 “6.5”.


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.


Engaging this switch enables the Program Equalizer to function. In the


position, the Equalizer is bypassed.


Clockwise rotation of this rotary control increases the headphone drive level.


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


position, this switch feeds STEREO Program and Cue to both earcups, in the


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.


This stereo LED bargraph provides a visual indication of program output voltage. The calibration of the indication is user adjustable. (See #6,

Rear Panel



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.

12200 Thatcher Ct.

Poway, CA 92064 Phone 619-486-8399 Fax 619-486-8396 Web www.caig.com


The Crossfader may be removed from the front of the MP 24x without any disassembly of the unit itself, and may be performed while the unit is operating with no interruption of the audio signal.

1. Remove the two (2) outer screws attaching the crossfader assembly to the front panel.

2. Firmly pull the Crossfader Assembly forward, unplugging it from the connector on the bottom board.

3. Install the replacement assembly by reversing the above instructions.




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



These ¼" unbalanced connectors provide MAIN OUTPUT signals.

3. BOOTH OUTPUT connectors:

Connecting to the Left Output only supplies a


BOOTH monitor OUTPUT; connect ing to both Left and Right provides a stereo Output.

4. ZONE OUTPUT connectors:

Connecting to the Left Output only supplies a


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 Sche matic-1.


This rotary control decreases the maximum Level of the balanced and unbalanced MAIN OUTPUTS of the MP 24x as it is rotated CCW.


Clockwise rotation decreases the full-scale sensitivity of the PEAK PROGRAM METER, as indicated by the full-scale voltage calibrations around the control.


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


position, the maximum boost/cut available from the Program Equalizer is ±8 dB. In the switch’s


position, this range is reduced to ±4 dB.


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,


-LOOP Program Outputs. The other pair supplies pre EQ,


-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.) Manual-4


Use these ¼" unbalanced Left and Right Outputs for driving the inputs of a proces sor activated by the front panel LOOP button.


Use these ¼" unbalanced Inputs for receiving the outputs of the above device.


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


Output; connecting to both Left and Right provides a stereo feed.


A pair of ¼" unbalanced Inputs for receiving the processed signal generated from the MAIN EFFECTS LOOP SENDs.

16. Balanced MAIN MIC Input jack:

Use this XLR 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 mics.

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 Channels.

19. PHANTOM POWER switch:

Engaging this pushbutton applies +15 V Phantom Power to the balanced (XLR) 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. AUX/PHONO 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).

AUX/PH 1 and AUX/PH 2 jumpers are set at the factory for PHONO. The PH/AUX 3 jumper is set at the factory for a LINE level input. When these jumpers are set to PHONO, never use these Inputs 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


the Outputs.

22. PHONO/AUX 3 input jacks:

As #21 above. Note this Input is 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.


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 24x 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

ChassisS Grounding

note on page Manual-8 for details.


This switch separates

chassis ground


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 24x 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 24x 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 24x, 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 24x 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 XLR 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 24x is running longer than 10 feet, use


cables. If the input to your system equalizer, crossover, or power amplifier is balanced, go


. 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 record ing 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 internal jumper changing instructions.) 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 auto matic mono/stereo type. If mono is required, simply connect


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 24x 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", XLR etc.), and no telling what else. In consumer audio devices, one rarely finds ground-lift capabilities, or any of the other hum preven tion 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 24x, crossovers, equalizers or power amplifiers might help, go ahead and try it. There


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 manu facturers 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.” Manual-6



Operation of the MP 24x 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 ACTIVE CROSSFADER are all


, (switches


) 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, amplifiers, 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 24x. If this is not possible, full system drive will not come from some compo nents. 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 OUT PUT 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


position, the range of all of the EQ controls is ±8 dB. In the


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


. Now select


to listen to it — Mono


in one ear, Mono


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 direc tion. 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 control.


Active Crossfader™

technology combines state of the art voltage controlled amplifier design with a professional quality, dual-rail Alps crossfader control. This combination sets new standards for performance, reliability and service ability. Virtually all crossfader noise is eliminated. Channel to channel crosstalk is greatly reduced and the


isolation of the faded channel is greatly increased.

Active Crossfader

technology dramatically increases the service life of the crossfader. In the unlikely event of crossfader failure, there is no loss of signal. If a crossfader becomes rough or noisy, it may be “hot-swapped” during a performance

with no inter ruption of the audio signal

. Simply use the input faders to set the audio levels while the crossfader is out of service.

For normal operation, press the Crossfade ENGAGE switch. The green LED next to the switch illuminates. The Crossfade ASSIGN switches determine the two Input Chan nels 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


position for condenser mics,


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


position. When the switch is


, the red LED flashes. When off, the LED will be


. If the micro phone 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.


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 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


, 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.


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.


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 pre master 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 MP 24x 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


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 Interconnec tion

” (supplied with this manual and available on request at no charge separately) for further information on system grounding.

©Rane Corporation 10802 47th Ave. W., Mukilteo WA 98275-5098 TEL (425)355-6000 FAX (425)347-7757 WEB http://www.rane.com


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