The Yamaha EM-Mixers, including models EM-100II, EM-150IIB, EM-200B, and EM-300B, are multi-input, stereo output mixers designed for sound reinforcement (PA) and recording applications. These compact and functional units integrate power amplifiers and Accutronics reverb units, offering a range of features suitable for various audio setups.
Function Description:
The EM-Mixers serve as central control boards for audio signals, allowing users to mix multiple input sources, apply equalization, and route signals to various outputs. Each input channel features controls for:
- Fader: Adjusts the mix level of each channel into the stereo program bus.
- High and Low EQ Controls: Continuously adjustable knobs providing ±15 dB of bass and treble equalization. The center position offers a "flat" response. Low-EQ boost adds "fullness" to vocals and instruments, while cut removes "boominess." High-EQ boost adds "edge" or "attack" to instruments and vocals, while cut reduces hiss and sibilance.
- Monitor 1 Send (Rev/Echo): Feeds the input signal to a mix bus that drives the Monitor 1 output and the built-in reverb or external effects units. This send is post-EQ and fader.
- Monitor 2 Send: Feeds a pre-EQ and pre-fader signal to a second monitor mix bus, which then feeds the Monitor 2 output. This allows for a separate monitor mix independent of the main program mix.
- Pan: Assigns the input signal to the Left and Right program mix buses, positioning the channel across the stereo perspective for the Speaker, Line, and Graphic EQ outputs. A 12 o'clock position centers the signal.
- Input Level Selector Switch: Adjusts the input channel's sensitivity for optimal results with different input sources. On EM-100II and EM-150IIB, this is a 3-position slide switch (Line/Instr/Mic). On EM-200B and EM-300B, it's a 5-position rotary knob with nominal input sensitivities ranging from -50 dB (low output dynamic microphones) to +4 dB (high level line sources).
Master controls include:
- Master Program Faders (Left and Right): Adjust the level of the corresponding Left and Right program mixing buses, feeding the Speaker, Graphic EQ, Line, and Headphone outputs. These do not affect Monitor or Echo outputs.
- Master Monitor Faders (1 & 2): Adjust the overall level of the Monitor Outputs.
- Master Reverb/Echo: Sets the level of the returning Reverb/Echo signal (from the built-in spring or external unit) mixed into the stereo program bus. If the Echo Return jack is used as an auxiliary monaural line input, this control adjusts its level.
- Auxiliary Volume: Controls the level of any program fed to the mixer via the Left and Right Aux Input jacks. These are also affected by the Master Program faders.
- Aux Pan (EM-200B and EM-300B only): Positions Aux 1 and Aux 2 Input signals Left-to-Right on the stereo program bus.
Output monitoring is provided by:
- VU Meters: Two meters indicate the average speaker power output level. On the EM-300B, an additional set of meters indicates the average output level of the two Monitor mix buses. Meters are illuminated when AC POWER is ON.
Important Technical Specifications:
- Channel Inputs (HI-Z & LO-Z): XLR (low-impedance, unbalanced) and TS phone jacks (high/medium impedance). XLR inputs can be converted to balanced (floating) with optional Transformer Balancing Modules (not available for EM-100II).
- Input Level Switch settings:
- EM-100II/EM-150IIB: -50 dB (Mic), -35 dB (Inst), -20 dB (Line).
- EM-200B/EM-300B: -50 dB, -40 dB, -30 dB, -20 dB, +4 dB.
- Nominal Input Level: -50 dB (2.5 mV) to +4 dB (1.23 V).
- Max. Before Clip: -22 dB (6.2 mV) to +32 dB (31 V).
- Aux In (L & R): Phone jacks, -20 dB (78 mV) nominal input level.
- Echo Return: Phone jack, -30 dB (25 mV) nominal input level.
- Graphic EQ In (L & R): Phone jacks, +4 dB (1.23 V) nominal input level (not on EM-100II).
- Monitor Sub In (1 & 2): Phone jacks, +4 dB (1.23 V) nominal input level.
- Power Amp In (L & R): Phone jacks, +4 dB (1.23 V) nominal input level.
Outputs:
- Speaker Output Jacks (L & R): Standard phone jacks, two paralleled per channel.
- Power Output (8 ohms/channel at 0.5% THD, 1 kHz):
- EM-100II: 50 watts
- EM-150IIB: 75 watts
- EM-200B: 85 watts
- EM-300B: 140 watts
- Line Output Jacks (L & R): Phone jacks, 0 dB (775 mV) nominal output level.
- Monitor Output Jacks (L & R): Phone jacks, 0 dB (775 mV) nominal output level.
- Graphic EQ Output Jacks (L & R): Phone jacks, 0 dB (775 mV) nominal output level (not on EM-100II).
- Echo Send Jack: Phone jack, -20 dB (78 mV) nominal output level.
- Headphones Jack: TRS stereo phone jack, 0 dB (0.775 V) nominal output level.
General Specifications:
- Number of Inputs:
- EM-100II/EM-150IIB: 6 channels (HI-Z & LO-Z), Aux In (L & R), Monitor Sub In (1 & 2), Echo Return, Power Amp In (L & R). EM-150IIB also includes Graphic EQ In (L & R).
- EM-200B: 8 channels (HI-Z & LO-Z), Aux In (1 & 2), Monitor Sub In (1 & 2), Echo Return, Graphic EQ In (L & R), Power Amp In (L & R).
- EM-300B: 12 channels (same as EM-200B).
- Mixing Buses: Program (L & R), Monitor (1 & 2).
- Echo and Reverb: Built-in Accutronics spring-type reverberation unit; provisions for external effects devices.
- Channel Equalization: Low-EQ, ±15 dB max. at 100 Hz; High-EQ, ±15 dB max. at 10 kHz; shelving characteristic.
- Graphic Equalization (Speaker Outputs):
- EM-150IIB: 7 controls (63 Hz, 150 Hz, 400 Hz, 1 kHz, 2.5 kHz, 5 kHz, 10 kHz), ±12 dB max.
- EM-200B/EM-300B: 9 controls (63 Hz, 125 Hz, 250 Hz, 500 Hz, 1 kHz, 2 kHz, 4 kHz, 8 kHz, 16 kHz), ±12 dB max.
- Power Requirements: 110-120 V AC, 50 or 60 Hz, 3-wire grounded outlet.
- EM-100II: 140 watts
- EM-150IIB: 170 watts
- EM-200B: 290 watts
- EM-300B: 400 watts
- AC Mains Fuse(s): AGC type fuse (3A for EM-100II, 7A for EM-150IIB/EM-200B, 7A for EM-300B).
- Output Protection: Output power decreases as load impedance falls below 2.5 ohms; relay mutes input to power amplifier to protect speakers from Turn-ON or Turn-OFF transients.
- Physical Dimensions (W×H×D) / Weight:
- EM-100II: 56×17.1×47 cm (22×6¾×18½") / 16 kg (35.3 lbs).
- EM-150IIB: 56×21.4×50.8 cm (22×8½×20") / 24.5 kg (54 lbs).
- EM-200B: 62.1×22.9×63.1 cm (24½×9×24¾") / 28 kg (61.7 lbs).
- EM-300B: 78.7×22.9×63.1 cm (31×9×24¾") / 35 kg (77.2 lbs).
Usage Features:
- Flexibility: The EM-Mixers offer extensive patchable inputs and outputs, allowing for integration with external effects, additional power amplifiers, tape recorders, and other mixers. This provides the flexibility of separate components within a compact unit.
- Input Level Setting Procedure: A recommended procedure involves connecting inputs, wearing headphones, setting all channel faders to minimum, panning left, raising the Left Master Program fader, and then adjusting each channel's Input Level switch from least sensitive (Line or +4 dB) until the VU meter peaks around 0 dB without distortion.
- Speaker Output Considerations: Designed for 8-ohm or higher impedance speaker loads. Users must ensure speaker power capacity is compatible with the mixer's output. Speaker cables should be heavy gauge (18-gauge or larger for short runs, 16-gauge or larger for long runs) and use high-quality phone plugs.
- Graphic Equalizers: These are powerful tools for reducing acoustic feedback and shaping the tonal characteristics of the Speaker outputs. Separate equalizers for Left and Right program channels allow for precise frequency response adjustments. They can also be used for special effects, though extreme settings should be avoided to minimize distortion.
- Linking Mixers: Two or more EM-Mixers can be linked to increase total input capacity. Line Out jacks of one mixer can connect to Aux In jacks of another.
- Recording: Line Outputs can feed a tape recorder or professional recording console. Monitor 2 Output can be used for a pre-EQ/fader mono mix to a recorder, allowing a different mix for recording than for the house PA.
- Balanced Input Transformer Modules (Optional): Available for EM-150IIB, EM-200B, and EM-300B, these modules convert XLR inputs to balanced (floating) for improved signal quality. Installation involves removing jumper connectors and securing the transformer module. When installed, the +4 position of the Input Level switch should not be used for LO-Z XLR inputs to prevent transformer saturation and distortion.
Maintenance Features:
- Fuse Holders: Fuses should always be replaced with the same size and type (AGC or equivalent). Repeated fuse failures indicate a problem that needs to be addressed (e.g., shorted speaker cables, too low impedance load, or power line issues). Using a fuse of higher rating will damage the mixer and void the warranty.
- Power Switch Polarity Reversal: The AC POWER switch has two "ON" positions that reverse AC power line polarity, which can help minimize hum in certain instances.
- Air Vents: Never cover the air vents on the top or bottom panels to prevent overheating and damage.
- Cleaning: Use a soft cloth to dust panels and control knobs. A damp sponge with a mild dish detergent can be used for cleaning. Avoid solvents as they may cause discoloration.
- Troubleshooting Chart: The manual provides a chart to help diagnose common issues such as no power, no signal output, very low signal level, fuse blown, sound distortion, feedback, and loud buzzing, along with possible causes and solutions.
- Warranty and Service: The EM-Mixers come with a one-year limited warranty on parts and labor. Users are advised to register their product and contact an authorized Yamaha dealer for service. The warranty does not cover abnormal strain, neglect, abuse, modification, accidental damage, normal wear, or products with altered identification numbers.
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