YAMAHA MX12/4 MIXING CONSOLE Owner's Manual

Product Overview

The Yamaha MX12/4 is a 12-input, 4-group output mixing console designed to offer an ideal balance of operability, functionality, and simplicity. This owner's manual provides comprehensive instructions for setup, operation, and maintenance, ensuring long and trouble-free use of the MX12/4.

The console features a user-friendly layout with dedicated controls for each channel and a master section for overall mix management. It includes built-in digital effects and phantom power for condenser microphones, making it suitable for a wide range of audio applications.

Precautions

1. Avoid Excessive Heat, Humidity, Dust and Vibration

   Keep the unit away from locations likely to be exposed to high temperatures or humidity (e.g., near radiators, stoves). Also avoid excessive dust accumulation or vibration, which can cause mechanical damage.

2. Ventilation

   The unit has ventilation slots on the rear and bottom panels. Do not block these vents.

3. Avoid Physical Shocks

   Strong physical shocks can cause damage. Handle the unit with care.

4. Do Not Open the Case or Attempt Repairs or Modifications Yourself

   This product contains no user-serviceable parts. All maintenance should be referred to qualified Yamaha service personnel. Opening the case or tampering with internal circuitry voids the warranty.

5. Always Power Off Before Making Connections

   Always turn the power OFF before connecting or disconnecting cables. This prevents damage to the unit and other connected equipment.

6. Handle Cables Carefully

   Always plug and unplug cables, including the AC power cord, by gripping the connector, not the cord.

7. Clean With a Soft Dry Cloth

   Never use solvents such as benzine or thinner to clean the unit. Wipe clean with a soft, dry cloth.

8. Always Use the Correct Power Supply

   Ensure the power supply voltage specified on the rear panel matches the local AC mains supply. Also, ensure the AC mains supply can deliver enough current for all equipment in your system.

FCC Information (U.S.A.)

IMPORTANT NOTICE: DO NOT MODIFY THIS UNIT! This product, when installed as indicated in the instructions, meets FCC requirements. Modifications not expressly approved by Yamaha may void authority to use the product.

IMPORTANT: When connecting this product to accessories and/or another product, use only high quality shielded cables. Cables supplied with this product MUST be used. Failure to follow instructions could void FCC authorization to use this product in the USA.

NOTE: This product has been tested and found to comply with FCC Regulations, Part 15 for Class "B" digital devices. Compliance provides reasonable assurance that your use in a residential environment will not result in harmful interference with other electronic devices. If interference occurs, try relocating the product or affected device, utilizing different power outlets, installing AC line filters, or reorienting the antenna for radio/TV interference. Contact a local retailer or Yamaha Corporation of America, Electronic Service Division, for assistance if issues persist.

* This applies only to products distributed by YAMAHA CORPORATION OF AMERICA.

Important Notice for the United Kingdom

Connecting the Plug and Cord

WARNING: THIS APPARATUS MUST BE EARTHED

IMPORTANT: The wires in this mains lead are colored in accordance with the following code:

• GREEN-AND-YELLOW: EARTH
• BLUE: NEUTRAL
• BROWN: LIVE

If the colors of the wires in the mains lead do not correspond to the markings on your plug, proceed as follows:

• The wire colored GREEN and YELLOW must be connected to the terminal marked E, the safety earth symbol, or GREEN and YELLOW.
• The wire colored BLUE must be connected to the terminal marked N or BLACK.
• The wire colored BROWN must be connected to the terminal marked L or RED.

* This applies only to products distributed by YAMAHA KEMBLE MUSIC (U.K.) LTD.

Features

• The MX12/4 provides 12 input channels, mixing them to stereo or to four group outputs.
• A C-R OUT jack is provided for convenient connection to a sub amp for monitoring. Users can monitor the main stereo output, TAPE IN input, and effect/monitor signals.
• A digital effect unit is built-in, allowing for polished mixes without additional equipment.
• Two SEND jacks are provided: MONO 1 (pre fader) and EFFECT/MONO 2 (post/pre fader). These can be used for external effects or a monitor system.
• Phantom power is provided for easy connection of condenser microphones requiring an external power supply.
• INS I/O jacks are provided for input channels 1-4, allowing individual effects to be inserted into each channel.
• Input channels 1-8 provide both XLR type mic inputs and TRS phone line inputs. Channels 9-12 provide stereo line inputs. The MX12/4 accommodates a wide range of sources, from microphones to line level devices and stereo output synthesizers.
• TAPE IN jacks and REC OUT jacks simplify connecting tape decks for playback and recording.

Front Panel Controls

Channel Control Section

1. GAIN control

   Adjusts sensitivity according to input signal level for appropriate input. For optimal S/N ratio and dynamic range, adjust so the peak indicator lights occasionally. The range -60 to -16 indicates MIC input adjustment, and -34 to +10 indicates LINE input adjustment.

2. PEAK indicator

   Detects peak level post EQ. Lights red 3dB before clipping, warning that clipping level is near.

3. Equalizer

   Provides ±15dB of control over the high, mid, and low ranges at the following center frequencies.

   • HIGH: 12kHz (shelving)
   • MID: 2.5kHz (peaking)
   • LOW: 80Hz (shelving)

   Frequency response is flat when the knob is in the "▼" position.

   (Textual description of frequency response graph: The graph shows three curves representing the High, Mid, and Low equalizer bands. The High band shows a shelving response, boosting or cutting frequencies above 12kHz. The Mid band shows a peaking response centered around 2.5kHz. The Low band shows a shelving response, boosting or cutting frequencies below 80Hz. The horizontal axis represents frequency from 20Hz to 20kHz, and the vertical axis represents response in dB from -20dB to +20dB.)

4. MONI (monitor) control

   Controls the level of the signal sent from each channel to the MONI bus. This control is placed before the channel fader, allowing independent level control from the fader setting.

5. EFFECT control

   Controls the level of the signal sent from each channel to the EFFECT bus. This control is placed after the channel fader, so signal level is affected by the channel fader setting.

6. Group select switches

   These switches send the signal of each channel to GROUP buses 1-4. When 1/2 is on, signal goes to GROUP buses 1/2. When 3/4 is on, signal goes to GROUP buses 3/4. When both are on, signal goes to GROUP buses 1/2 and 3/4.

7. PAN (panpot) control / BAL (balance) control

   PAN knobs (channels 1-8) set the stereo position of the signal sent to GROUP buses 1/2 or 3/4.

   BAL knobs (channels 9-12) set the balance between left/right channels, assigning signals from inputs 9 L (MONO) and 11 L (MONO) to GROUP buses 1/3, and signals from inputs 10 R and 12 R to GROUP buses 2/4. If signals are input monaurally to 9 L (MONO) or 11 L (MONO), the same signal will be sent to groups 1-4.

8. Channel fader

   Controls the output level of the input channel signal, adjusting volume balance between channels. Faders of unused channels should be lowered.

Master Control Section

1. ST OUT output select switch

   Selects the signal output via the ST fader from the ST OUTPUT jacks.

   • ST position (■): ST OUTPUT jacks output the ST bus signal (post-fader signals of groups 1-4, RTN inputs, internal digital effect return, and TAPE IN inputs).
   • GROUP position (—): ST OUTPUT jacks output the pre-fader signals of groups 3/4. When selected, input channel signals go directly to the ST bus, bypassing group buses 1-4, allowing the MX12/4 to function as a 12 in-2 out mixer.

2. ST master fader

   Adjusts the final combined level of all channels and sends the signal to the ST OUTPUT jacks. Meters display L and R output levels.

3. GROUP 1~4 faders

   Adjusts signal levels of groups 1-4, sending signals to GROUP OUTPUT 1-4 jacks and to the ST bus. Groups 1 and 3 are sent to ST L, and groups 2 and 4 are sent to ST R.

4. Stereo graphic EQ

   A stereo 7-band graphic equalizer adjusting tonal quality of the signal output to ST OUTPUT jacks. Provides ±12dB boost or cut at 125, 250, 500, 1k, 2k, 4k, and 8kHz frequency bands.

5. TAPE IN jacks

   Line level input jacks for external DAT recorders or CD players for monitoring. Signals are sent to the ST bus. Input levels are adjusted by the TAPE IN ST control. Signal can also be monitored directly from the C-R OUT jack depending on C-R•PHONES select switch setting.

6. REC OUT jacks

   Allows connection of external DAT or cassette recorders to record the same signal as ST OUTPUT jacks. Signals are not affected by ST master fader or graphic EQ settings. Recording level adjustments should be made on the recording device.

7. PHANTOM indicator

   Lights when the PHANTOM switch (rear panel) is on.

8. POWER indicator

   Lights when the MX12/4's power is on.

9. ST control

   Adjusts monitor level of external device (tape deck etc.) connected to TAPE IN jacks.

10. DIGITAL EFFECT

    • MONI control: Adjusts level of return signal from internal digital effect to MONI bus.
    • ST control: Adjusts level of return signal from internal digital effect to ST bus.
    • Effect select switches: Selects effect type: VOCAL, L HALL (large hall), or S HALL (small hall). Do not turn off all switches or press multiple simultaneously to avoid malfunctions.
    • ON switch: Turns internal digital effect on/off. When off, no signal is sent from the internal digital effect.

11. RTN

    • MONI control: Adjusts level of signal from RTN jacks to MONI bus.
    • ST control: Adjusts level of signal from RTN jacks to ST bus. If signal is input only to RTN L (MONO) jack, same signal is sent to ST bus L and R.

12. SEND

    • MONI 1 control: Adjusts level of MONI bus signal output to SEND MONI 1 jack.
    • EFFECT/MONI 2 control: Adjusts level of EFFECT bus or MONI bus signal output to SEND EFFECT/MONI 2 jack. The level of signal sent from EFFECT bus to internal digital effect is fixed and not adjustable by this control.
    • Output select switch: Selects signal output to SEND EFFECT/MONI 2 jack.
      • EFFECT position (■): EFFECT bus signal is output.
      • MONI 2 position (—): MONI bus signal is output.

13. C-R PHONES

    Selects and adjusts signal output to C-R OUT jack and PHONES jack.

    • C-R PHONES control: Adjusts output level to C-R OUT jack and PHONES jack.
    • Output select switch: Selects output signal for the C-R OUT jack and PHONES jack.
      • When the upper switch is on (TAPE IN —), signal from TAPE IN jacks is output.
      • When the upper switch is off (■):
        • When the lower switch is off (ST ■), same signal as ST OUTPUT jacks is output.
        • When the lower switch is on (EFFECT/MONI —), signal of SEND MONI 1 jack is sent to L channel, and SEND EFFECT/MONI 2 signal is sent to R channel.
    • Meter: LEDs indicate output level before C-R•PHONES control. 0 indicates nominal level; PEAK lights red when clipping level is approached.

Connector Section

1. INPUT

   • MIC (1-8): Balanced XLR type mic input jacks (1: ground, 2: hot, 3: cold). Compatible with 50-600Ω microphones.
   • LINE (1-8): Balanced TRS phone type line input jacks (T: hot, R: cold, S: ground). Compatible with 600 ohm line level devices. Unbalanced phone plugs can be connected, but long cables or electromagnetic interference may introduce noise.

   Note: It is not possible to connect both the MIC INPUT jack and the LINE INPUT jack for an individual input channel. Only one or the other jack may be used.

   • INS I/O 1-4: Input/output jacks placed between the equalizer and fader of input channels 1-4. Nominal input level/impedance: 0dB/600Ω. Nominal output level/impedance: 0dB/10kΩ. Used for connecting devices like graphic equalizers, compressors, or noise filters. These provide bi-directional connections using TRS phone jacks and require a special insertion cable.

     (Textual description of INS I/O cable diagram: The diagram shows a TRS (Tip-Ring-Sleeve) phone plug splitting into two mono phone plugs. The Tip of the TRS plug connects to the input jack of an external processor, and the Ring of the TRS plug connects to the output jack of an external processor. The Sleeve of the TRS plug is common ground.)

2. RTN L (MONO), R

   Unbalanced phone type line input jacks, nominal input level and impedance of +4dB/600Ω. Signals are sent to ST bus and MONI bus. Typically used for return signals from external effect devices (reverb, delay) or as auxiliary stereo inputs. If only the L (MONO) jack is connected, the same signal is sent to both R and L jacks for monaural input.

3. SEND MONI 1, EFFECT/MONI 2

   Unbalanced phone type output jacks. Nominal input level and impedance: +4dB/600Ω. MONI 1 jack outputs MONI bus signal. EFFECT/MONI 2 jack outputs EFFECT bus or MONI bus signal. Used to send signals to external effect units or monitor systems (e.g., cue box).

4. INPUT 9-12

   Unbalanced phone type stereo line input jacks, compatible with 600Ω line level devices. If only the L (MONO) jack is connected, the same signal is sent to both L and R jacks for monaural input. In this case, the group select switch (channel control section ⑥) sends the same signal to group buses 1/2 or 3/4.

5. ST OUTPUT (L, R)

   Balanced XLR type output jacks with nominal output/impedance of +4dB/600Ω. Provide stereo output of mixed signal, normally connected to a power amp driving main speakers. Can also be used to record the signal at a level adjusted by the ST fader.

6. GROUP OUTPUT 1-4

   Unbalanced phone type output jacks output signals of group buses 1-4, with nominal output/impedance of +4dB/600Ω. Normally connected to input jacks of an MTR or external mixer.

7. C-R OUT

   Stereo phone type output jack for connection to a monitor system. Nominal output/impedance: +4dB/10kΩ. Source monitored by this jack is selected by C-R•PHONES output select switch (master control section ⑬).

   Note: An insertion cable can also be used when connecting this jack to a stereo monitor system.

8. PHONES

   Stereo phone type output jack for connecting headphones. Source monitored by headphones is selected by C-R•PHONES output select switch (master control section ⑬).

Rear Panel

(Textual description of rear panel layout: The rear panel features the POWER ON/OFF switch on the left and the PHANTOM MASTER switch (CH1-8 ON/OFF +48V) on the right.)

1. POWER switch

   Applies power to the unit when on. When turning off power, audio equipment should be turned off in order of closeness to speakers (normally starting with the power amp).

2. PHANTOM switch

   Turns phantom power on/off for all channels 1-8. Use when using condenser microphones. When on, +48V DC is supplied to pins 2 and 3 of all XLR type MIC INPUT connectors. Set to OFF if phantom power is not required.

   Note: Connecting balanced dynamic microphones or line level devices with this switch on will not cause problems. However, connecting unbalanced devices or devices with an ungrounded transformer center may cause hum or malfunction.

Connector polarity

Application Example

(Textual description of application example diagram: The diagram illustrates a typical setup for the Yamaha MX12/4 mixing console.

On the top left, "Monitors speakers" are connected to a "Power amp", which receives its input from the MX12/4's C-R OUT.

On the top right, "Main speakers" are connected to another "Power amp", which receives its input from the MX12/4's ST OUT.

An "Effects processor" is shown connected to the MX12/4's INS I/O jacks. Another "Effects processor" is connected to the SEND and RTN jacks.

A "Headphone" is connected to the PHONES jack.

A "Cassette deck or DAT" is connected to the TAPE IN and REC OUT jacks.

An "MTR" (Multi-track Recorder) is connected to the GROUP OUTPUT jacks.

Below the main console representation, multiple "Mic and line input" sources are shown connecting to the INPUT channels of the MX12/4.)

Specifications

General specifications

Input specifications

¹ Sensitivity is the lowest level that will produce an output of +4 dB (1.23V) or the nominal output level when the unit is set to maximum gain.
² XLR type connectors and phone jacks (TRS) (T=Hot, R=Cold, S=Gnd) are balanced.
³ Phone jacks are unbalanced.
⁴ Phone jacks (I/O) (T=OUT, R=IN, S=GND) are unbalanced.
• 0dB=0.775Vrms, 0dBV=1Vrms

Output specifications

¹ XLR type connectors are balanced.
² Phone jacks are unbalanced.
³ ST phone jacks (T=L, R=R, S=GND) are unbalanced.
⁴ Phone jacks (I/O) (T=OUT, R=IN, S=GND) are unbalanced.
• 0dB=0.775Vrms, 0dBV=1Vrms

Dimensions

The Yamaha MX12/4 mixing console has the following approximate dimensions:

• Width (W): 436.2 mm
• Height (H): 83.1 mm
• Depth (D): 401.2 mm

(Textual description of dimension diagram: The diagram shows front, top, and side views of the mixing console with measurements. The top view shows a width of 436.2mm and a depth of 310mm for the main body. The side view shows a total depth of 401.2mm including connectors, a height of 83.1mm, with specific measurements for the front panel angle and base.)

Specifications are subject to change without prior notice.

Block and Level Diagram

(Textual description of the Block and Level Diagram: The diagram illustrates the internal signal flow and level points within the Yamaha MX12/4 mixing console.

Input Section:

• MIC Inputs (1-8): XLR inputs with Phantom Power (+48V) and PAD. Signals pass through a HA (Head Amp) and then to the EQ section.
• LINE Inputs (1-8): TRS inputs with PAD. Signals also pass through a HA and EQ.
• INS I/O (1-4): Insert points located between the EQ and the channel fader, allowing external processors to be patched in.
• Stereo Inputs (9-12): L(MONO) and R inputs with HA and EQ.

Channel Processing:

• After EQ, signals proceed to the GAIN control, then to the PAN (panpot) for mono channels or BAL (balance) for stereo channels.
• From the PAN/BAL, signals are sent to the GROUP select switches (1/2 and 3/4).
• Each channel also has sends to MONI (Monitor) and EFFECT buses. The MONI send is pre-fader, and the EFFECT send is post-fader.
• A PEAK indicator is present on each channel path.

Group and Master Section:

• GROUP OUTPUTS (1-4): Signals from the group buses are sent to dedicated GROUP OUTPUT jacks.
• ST (Stereo) Bus: Signals from the group buses (Groups 1 & 3 to ST L, Groups 2 & 4 to ST R) and direct channel sends (when GROUP position is selected on ST OUT switch) feed into the ST bus.
• RTN (Return) Inputs: L(MONO) and R inputs for external effect returns or auxiliary inputs. These signals feed into both the ST bus and MONI bus.
• TAPE IN: L and R inputs for tape decks, feeding into the ST bus.
• Internal Digital Effect (DSP): Receives signal from the EFFECT bus. Its output returns to the ST bus and MONI bus.
• 7-Band ST Graphic EQ: Located on the ST bus, allowing equalization of the main stereo mix.
• ST Master Fader: Controls the overall level of the ST bus signal before output.
• REC OUT: Outputs the ST bus signal before the ST master fader and graphic EQ.

Monitor and Send Outputs:

• MONI Bus: Receives signals from channel MONI sends, RTN inputs, and the internal digital effect.
• SEND MONI 1: Outputs the MONI bus signal.
• SEND EFFECT/MONI 2: Can output either the EFFECT bus signal or the MONI bus signal, selectable by a switch.
• C-R OUT (Control Room Out): Outputs the monitor signal, selectable from TAPE IN, ST bus, or EFFECT/MONI sends.
• PHONES: Outputs the same monitor signal as C-R OUT.

Level Diagram:

The accompanying level diagram illustrates typical signal levels at various points in the console, showing how signals are attenuated or boosted through the different stages (e.g., MIC input at -60dB, LINE input at -30dB, ST bus at 0dB, GROUP/EFFECT/MONITOR at 0dB, REC out at -10dBV). It shows the relative levels of LINE, MIC, ST, RTN, EFFECT, MONITOR, TAPE, GROUP, and REC signals.