ELECTRO-VOICE MA-1206 (01) PDF Document

The ELECTRO-VOICE MA-1206 features the following:

• Level controls for each input and a master volume control.

• Individual bass and treble tone controls.

• Automatic muting circuit with threshold adjustment.

• 600 ohm transformer-isolated line input for paging, with automatic muting of all other inputs.

• Low distortion.

• Output protection circuit.

• Auxiliary line level inputs with internal mixing for stereo source.

• Balanced line level output.

• Insertion point between preamp and amplifier.

• Phantom power on all microphone inputs enables microphones to be used without separate power supplies.

To avoid hum in the output, be certain that all input cables are physically separated from power wiring and transformers. Speaker cables should also be kept away from input cables and power cables. For the best grounding, connect the amplifier to an earth ground such as a cold water pipe or ground rod using the ground terminal on the back panel. If additional equipment is installed along with the amplifier, make sure their chassis are connected together to reduce noise and hum.

To remove the heat generated by the power amplifier, provide ample ventilation around the unit. Avoid blocking or impeding the vent slots in the cabinet. Locate the unit where it is free from direct sunlight, humidity, dust, and vibration.

The Mic inputs on the ELECTRO-VOICE MA-1206 are for use with balanced Low Impedance (approximately 200 ohms) or unbalanced high impedance (approximately 20k ohms) microphones. For high impedance microphones, cables should be as short as possible, with a recommended limit of 30 feet, to avoid loss of high-frequency response. You can connect microphones using either XLR connectors or 1/4″ phone plugs.

Phantom power on the ELECTRO-VOICE MA-1206 allows you to use condenser microphones without separate power supplies. When phantom power is on, 24 V dc is produced at pins 2 and 3 on the Mic inputs. To enable phantom power, move the selector switch to the 24V position above the desired input connector on the rear panel.

When a microphone or other source is connected to input 1 on your ELECTRO-VOICE MA-1206, you can use the auto-muting feature. Follow these steps:

1. Place the front panel mute switch in the ON position.

2. Advance the threshold control to the point where a typical voice, and not room noise, will operate the mute circuit.

The microphone’s on/off switch can be left on, and the actual voice announcement will trigger the mute for other channels. To disable this function, place the mute switch in the OFF (defeat) position.

You can connect high-level unbalanced sources to the Aux 1 and 2 jacks on the back panel of the ELECTRO-VOICE MA-1206. Appropriate sources include a tape player, compact-disc player, AM/FM tuner, mixer-preamplifier, wireless microphone, or a turntable equipped with a ceramic or crystal cartridge. Use a single-conductor shielded cable for these connections. If connecting a turntable with a separate ground wire, connect it to the ground terminal on the back panel to minimize hum.

When connecting speakers to your ELECTRO-VOICE MA-1206, consider the following:

1. Matching Speaker Impedance: The amplifier can accommodate both Low Impedance and high impedance constant-voltage speaker loads (25, 70.7, and 100 volt lines). Power amplifiers deliver rated power into a rated load impedance. Significantly lower impedances may cause the amplifier’s protection fuses to open, especially at high volume levels, and should be avoided.

2. Power Loss in Speaker Wire: Ideally, speaker wire impedance would be zero. However, long wire runs, especially with smaller gauge wires, can cause power loss. High load impedances allow for the use of longer, smaller gauge wiring with less power loss.

3. Low Impedance Speakers: The low impedance ohm output terminal is for direct connection of standard low impedance speakers. For example, connect a single speaker system to the common and 4 ohm terminals. Connecting multiple low impedance speakers requires following the rules of series and parallel impedance summation.

High impedance systems allow for smaller diameter wire over longer runs and easier adjustment of individual speaker levels. To set up a constant-voltage system with your ELECTRO-VOICE MA-1206:

1. Use speakers equipped with transformers that have the same voltage rating (e.g., 25, 70.7, or 100 volts).

2. Connect the transformer primaries (inputs) in a simple parallel connection to the corresponding output terminals on the amplifier.

3. The total of all the power taps (labeled in watts on the transformers) should be equal to or less than the amplifier’s rated output power (60 watts for the MA-1206). Avoid power totals greater than the rated amplifier power, as this will drop the total load impedance below the amplifier’s rated load.

The front panel of the ELECTRO-VOICE MA-1206 has the following controls:

1. “Mute” function switch: Turns the “Voice Priority” or page “ducking” function on or off for input 1.

2. Auxiliary 1&2 / Input 1-10 Controls: These knobs adjust the level of the two stereo summing auxiliary inputs and the 10 multi-use inputs.

3. Music signal monitor output level control: A screwdriver adjustment that individually sets the volume of a headphone connected to the “MONITOR OUTPUT” jack or a small speaker connected to the 1W 8 ohm terminals on the rear panel.

4. MONITOR OUTPUT Jack: Headphone output jack.

5. Overload indicator light: Illuminates and interrupts the output signal when the amplifier’s output overloads. The output resumes when the volume is lowered or the offending load is removed.

6. Power Switch and Power Indicator: This switch supplies power to the unit. The indicator lights when power is applied.

7. Master: Adjusts the level of the combined input signals to the power amplifier.

8. Treble: Adjusts the high frequency response, providing up to 7 dB of boost or 12 dB of cut at 10 kHz.

9. Bass: Adjusts the low frequency response, providing up to 7 dB of boost or 12 dB of cut at 100 Hz.

The rear panel of the ELECTRO-VOICE MA-1206 features the following controls and connections:

• Main cord connector (10): For connecting the supplied AC line cord.

• AC fuse (11): Replaceable fuse. This service should only be done by an EV service center.

• “GND” screw (12): For grounding the amplifier’s metal parts if the main outlet does not provide a ground conductor.

• Terminals for DC battery supply (13): Allows connection of an external 24V DC power supply (e.g., a battery) for operation during a power outage.

• Output terminals (14): For all speaker connections, supporting 25V/70V/100V and low impedance loads.

• “PRE OUT” terminal (15): Provides the mixed audio signals of all sources to feed an external power amplifier or signal processor. You must remove the bridging-strip between this and the “MAIN IN” terminal to use it.

• “MAIN IN” terminal (16): After removing the bridging-strip, you can connect the output of an external signal processor here to insert it into the audio chain before the power amplifier stage.

• “AUX 1” and “AUX 2” inputs (17): RCA-type connectors for external high-level unbalanced signal sources like a CD player or tuner.

• INPUT 1-10 jacks (18): Combination type jacks (XLR and 6.3mm) for connecting condenser microphones (with 24V phantom power), dynamic microphones, or high-level sound sources.

• INPUT 1-10 sensitivity switches (19): Set the input to “LINE” for high-level sources, “MIC” for dynamic microphones, or “24V” to enable phantom power for condenser microphones.

• AUX1-2 input sensitivity switch (20): Optimizes the input sensitivity for various sources like CD players, tuners, or cassette players.

• TEL. Paging input level control (21): Sets the volume of the sound source connected to the “Tel. Paging” terminals.

• LINE OUTPUT CONNECTOR (22): An XLR balanced output that mixes audio signals from all sources, suitable for feeding an external tape deck or other appliance.

• Input “TEL.Paging” (23): Connects to an auxiliary signal (600 ohms) and features a “Voice Priority” function that overrides all other input signals.

• “Priority” terminal (24): Short-circuiting these terminals attenuates the “AUX1”, “AUX2”, “CASSETTE”, and “TUNER” signals, while inputs 1-10 remain unchanged.

• Output terminal for auxiliary loudspeaker (25): For connecting a small external 8 ohm loudspeaker (1 watt output) which plays the mixed audio from “AUX1”, “AUX2”, “CASSETTE”, and “TUNER”.

• DC switch (26): Turns the battery supply on or off.

Please observe the following safety precautions when operating your ELECTRO-VOICE MA-1206:

1. The power supply voltage is high enough to risk electrical shock. Never install, connect, or disconnect the equipment with the power supply switched on.

2. The metal parts are earthed via the power cable. If your power socket is not earthed, have a qualified electrician earth the equipment using the provided terminal.

3. Ensure the power supply cable cannot be trodden on or crushed.

4. There are no user-serviceable parts inside. Do not open the unit.

5. Prevent objects or liquids from getting inside the amplifier to avoid short circuits.

6. Do not attempt any repairs not described in the manual. Contact authorized service personnel if the equipment malfunctions, the power cord is damaged, objects/liquids have entered the unit, or it has suffered a heavy impact.

7. For long periods of non-use, switch off the unit and disconnect the power supply cable.

8. If the equipment emits a strange odor or smoke, switch it off immediately and disconnect the power supply.