Clear-com MS-704 4-Channel Main Station

Clear-com MS-704

Clear-com MS-704 4-Channel Main Station

Product Code: MS-704
Clear-Com MS-704

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• Supports up to 55 beltpacks or 10 speaker stations on 4 channels
• Automatic short-circuit protection and reset with LED indicators
• Visual and audible call signaling
• 3 interruptible IFB channels
• Individual volume controls for each channel

Clear-com MS-704 Four Channel 2RU Main Station

Clear-com MS-704 is a 2RU four-channel main station with programmable front panel buttons,
individual channel short-circuit protection, individual channel volume control, and a regulated
fail-safe power supply. The MS-704 supports up to 55 beltpacks or 10 speaker stations, or 12
headset stations.

Monitoring System

The MS-704 accepts five separate program audio sources: four line-level balances inputs and
one assignable line-level input. The assignable program input accepts a balanced signal and is designed for monitoring external audio. The four balanced program inputs can be used to create individual program feeds on the intercom channels. The MS-704 can monitor intercom activity on one or all four channels with individual volume level controls. Monitoring intercom activity is possible through a headset or the internal high-sensitivity loudspeaker.

Talk Selection

The MS-704 has mic pre-amps with limiters and speech-shaping circuits. An individual
electronic momentary/latching Talk button is available for each channel. Illuminated
dual-action Talk buttons light an LED dimly when latched: blue-color while in standby, ambercolor when latched. The latching feature can be disabled. The channels can be accessed separately or simultaneously without tying them together. A selector switch toggles between the headset or microphone. The Talk buttons can also be controlled with a footswitch.

Announce Output

For paging, the MS-704 provides a balanced, line-level output signal to a ¼-inch TRS connector on the rear panel. The front panel Announce button activates the output and the Announce relay. The relay circuit, on a separate ¼-inch TRS connector, is typically used to mute monitors.

Call Signaling

The MS-704 has individual Call buttons with visual call signaling for each channel on the
partyline. The visual signal will flash brightly and will emit an audible signal if the remote station operator holds the Call button for more than 2 seconds. The call signaling feature can be programmed to the Talk buttons.

Remote Mic Kill (RMK)

The MS-704 has a global Remote Mic Kill button that will turn on the microphone talk circuits of all beltpacks on the system, eliminating extraneous noise from the open headset microphones.

Program Input and Interrupt (IFB)

The MS-704 accepts a line-level external program input for monitoring in the headset and speaker, and/or mixing with intercom audio on up to three of the four channels. When Interrupt is selected, the program signal is interrupted when the Talk button is pressed.

Configuration Panel

The MS-704 has a removable front panel for easy access to the station’s configuration switches and trim pots. Clearly labeled and easy to adjust, these controls allow the MS-704 to be configured quickly. When configuration is complete, the front panel can be reattached so it
shows only the needed controls.


The MS-702 has a visual indication of power supply conditions. In the event of a short circuit or current overload on a channel, that channel will shut down while the other one continues to operate. As soon as the fault condition is removed, the auto-reset circuitry will restore power to that channel, even under full-load conditions.


• Supports up to 55 beltpacks or 10 speaker stations on four channels
• Separate short-circuit protection for each channel
• Dual-action electronic momentary/latching Talk buttons
• Three interruptable IFB channels
• Call signal buttons for each channel
• Global Remote Mic Kill
• Announce output with relay
• Microphone limiting
• Volume controls for each channel
• Visual and audible Tone Alert signaling
• Channel Linking
• Built-in speaker
• External switchable line termination on each channel
• Universal voltage power supply

• Panel Microphone Input

Input Type: Electret

Input Impedance: >=2K

Mic Limiter Threshold: 0dBu ± 3dB

Mic Limiter Range: >= 20dB

• Headset Microphone Input

Input Type: Dynamic

Input Impedance: >= 1K

Mic Limiter Threshold: 0dBu ± 3dB

Mic Limiter Range: >= 15 dB

• Program Line Input

Maximum Level before Clipping: >= 20dBu

Input Impedance: >= 5K

• Headset Output

Load Impedance: >= 8

Output Impedance: <= 25

Output Limiter Threshold: +5dBu ± 3dB

Maximum Output Level before Distortion: >= 17dBu

• Speaker Output

Load Impedance: >= 4

Max Output Level before 1% Distortion: 20dBu ± 2dBu

• Partyline Output

O Noise: < -74dBu

Output Impedance: >10K

• Partyline Input

Crosstalk: < -60dB

Max level before Clipping: >= 12dBu

Sidetone Null Capability: > 25dB

• Stage Announce/Balanced Line Out

Type: Balanced

Output Impedance: >= 200

Load Impedance: >= 600

• IFB/Hot Mic

Type: Unbalanced

Output Impedance: 180

Load Impedance: >= 600

• Frequency Response

Panel Mic - Partyline: 600 - 10kHz ± 3dB

Headset Mic - Partyline: 200 - 12kHz ± 3dB

Headset Mic - Line Out: 200 - 12kHz ± 3dB

Program Input - Partyline: 100 17kHz ± 3dB

Program Input - Headset Out: 200 - 10kHz ± 3dB

Program Input - Speaker Out: 300 - 10kHz ± 3dB

Partyline - Headset Out: 200 - 10kHz ± 3dB

Partyline - Speaker Out: 300 - 10kHz ± 3dB

• Max Distortion

Panel Mic - Partyline: <= 0.5%
Headset Mic - Partyline: <= 0.5%
Headset Mic - Line Out: <= 0.5%
Program Input - Partyline: <= 0.2%
Program Input - Headset Out: <= 0.2%
Program Input - Speaker Out: <= 0.5%
Partyline - Headset Out: <= 0.2%
Partyline - Speaker Out: <= 0.5%

• Noise

Panel Mic - Partyline: < -65dBu

Headset Mic - Partyline: < -70dBu

Headset Mic - Line Out: < -55dBu

Program Input - Partyline: < -85dBu

Program Input - Headset Out: < -60dBu

Program Input - Speaker Out: < -60dBu

Partyline - Headset Out: < -50dBu

Partyline - Speaker Out: < -50dBu

• Max Gain

Panel Mic - Partyline: >= 37dB

Headset Mic - Partyline: 41dB ± 2dB

Headset Mic - Hot Mic Out: 55dB ± 3dB

Headset Mic - Announce Out: 55dB ± 3dB

Program Input - Partyline: >= -16dB

Program Input - Headset Out: >= 18dB

Program Input - Speaker Out: >= 24dB

Partyline - Headset Out: >= 34dB

Partyline - Speaker Out: >= 40dB

• Min Gain

Panel Mic - Partyline: <= 25 dB

• Mains Power

Input Voltage Range: 100 - 240V AC

Input Frequency Range: 50 - 60Hz

Input Power: <= 60V AC

Output Voltage: 30V DC ± 0.5V

Output Current per Channel (Continuous): 1.2A

Output Current per Channel (Peak): 2A (Do not exceed the 1.2A rating for more than 2 seconds per 1 minute period)

Short Circuit Recovery Time (1st short):<= 0.5 sec

Short Circuit Recovery Time >= 20 shorts in 20sec: <= 20 sec

• Environmental

32 - 122°F (0 - 50°C)

• Dimensions

19 x 3.5 x 10.5in (WxHxD)

(483 x 88 x 267mm)

• Weight

6.1lbs (2.8kg)

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