S CR664
Weight: kg



The Crown 135MA is a high value mixer-amplifier for commercial audio. It provides 8-ohm and constant-voltage outputs (70V and 100V). Typical uses are paging, background music, and music-on-hold. The 135MA provides 3 inputs (each with a volume control) and a 35W amplifier output. Other features include priority muting, voice activated muting, phantom power, and Bass and Treble controls.


  • 3 inputs (each with a volume control), and one 35W amplifier output channel
  • Ideal for paging, background music, and music-on-hold
  • Balanced Phoenix-type mic/line input, telephone output, dual RCA stereo music inputs, screw-terminal speaker outputs
  • Priority muting by VOX or external switch
  • Bass and Treble controls on master output
  • Three-Year, No-Fault, Fully Transferable Warranty completely protects your investment and guarantees its specifications


  • Minimum Guaranteed Power into 8 ohms or 70V/100V Output: 35W
  • Frequency Response (at 1 watt from line out): 50Hz to 20kHz +/-1dB; 19Hz to 34kHz +0, -3dB
  • Signal to Noise Ratio (ref. to rated power, master volume at minimum):
    Mic: > 58 dB.
    Line: > 60 dB.
    Telephone: > 60 dB.
    Inputs 2 or 3 (and 4 in 160MA): > 78 dB
  • THD+N: <0.5% at rated power at 1kHz; <0.1% at 5W at 1kHz
  • Input Sensitivity (for full output at maximum gain):
    Input 1: Mic 3mV, Line 800mV.
    Input 2: 400mV.
    Input 3: 400mV.
  • Input Impedance (nominal):
    Mic: 2.2 kilohms.
    Line: 10 kilohms.
    RCA: 10 kilohms.
  • Crosstalk: -82dB at 1kHz (Ch. 1 line input 0.8V, Ch. 1 volume at minimum, other channel volumes at maximum)
  • Line Output Level (nominal): 1V into 10 kilohms
  • Phantom Power: 15 VDC
  • AC Line Voltages Available: Universal Power Supply. Line voltage tolerance +15%, -20%
  • Operating Temperature/Humidity: 0° C to 40° C at 95% relative humidity (non-condensing).
  • Storage Temperature: Storage Temperature: –20° C to 85° C.
  • Cooling: Convection cooled.
  • Protection: Included protection mechanisms are current limiting, over-temperature thermal cutout, and DC-fault load protection. The unit is protected against turn-on/turn-off thumps.
  • Included Accessories:
    Power cord
    Non-touch cover for output connectors
    Phoenix-type connectors
  • Optional Accessories
    Part no. IST 600-ohm Isolation Transformer for Telephone Output or Input 1.
    Part no. RM1 single rack mount kit for mounting a single MA unit in a rack.
    Part no. RM2 double rack mount kit for mounting two MA units side-by-side in a rack.
    Part no. S-Cover 10-pack of security knobs.
  • Dimensions:
    Width: Half rack width (9.5 in. or 24.1 cm).
    Height (front panel): 3.5 in. (8.9 cm).
    Height (including feet): 4.1 in. (10.5 cm).
    Depth (front panel to back panel): 12.2 in. (31.0 cm).
    Depth (front of knobs to back panel): 13.9 in. (35.2 cm).
  • Weight: 8 lb 2 oz net; 10 lb 16 oz shipping

Front Panel Controls and Indicators

  • Power Switch: Pushbutton on-off switch.
  • Input Volume Controls: Four controls, one per input. Detented potentiometers with knobs.
  • Tone Controls: Bass and Treble non-detented recessed potentiometers under master output volume control. Bass ±10 dB at 100 Hz, Treble ±10 dB at 10 kHz.
  • Power Indicator: Blue LED indicates power on.
  • Input Signal Presence Indicators: Green LED, one above each channel's input attenuator, illuminates when input signal exceeds –40 dBu.
  • Input Signal Clip Indicators: Green LED, one above each channel's input attenuator, fl ashes brightly at threshold of audible distortion.
  • Output Signal Presence Indicator: Green LED above master output volume control illuminates when any input signal exceeds –40 dBu.
  • Output Signal Clip Indicators: Red LED above master output volume control fl ashes brightly at threshold of audible distortion.
  • Master Output Volume Control: Detented potentiometer with knob.

Back Panel Controls, Connectors and Indicators

  • AC Power Inlet: Detachable IEC accepts US or Euro style power cords.
  • Amplifier Output Connector: 4-position terminal barrier block with COM (Common), 8 ohms, 70V and 100V terminals. Accepts up to 10 AWG terminal forks. Non-touch cover included.
  • Preamp Line Out Connector: 3-pin balanced Phoenix-type for connection to external amplifiers. Level independent of master volume control.
  • Input Connector 1: 5-terminal Phoenix connector. 3 terminals for balanced signal, 2 terminals for priority contact closure, which mutes other channels when DIP switch 3 is on.
  • Input Connector 2: Unbalanced line-level RCA-type connectors.
  • Input Connector 3: Unbalanced line-level RCA-type connectors.
  • Telephone (MOH) Output Connector: 4-terminal Phoenix connector (2 terminals for 1W output to 8-ohm speaker, 2 terminals for 600-ohm output to PBX music-on-hold port).
  • MOH Level Control: Trim pot adjusts level for Music-On-Hold output from Telephone (MOH) Output Connector.
  • Amp Configuration DIP Switch: DIP switch selection for multiple functions.
    1. On: Sets CH1 to Mic Input. Off: Sets CH1 to Line Input.
    2. On: Sets CH1 to Normal mode (no priority).
    3. On: CH1 priority contact closure mutes other channels.
    4. On: CH1 VOX mutes other channels by sensing signal through Input 1.
    5. On: Routes CH1 to MOH output.
    6. On: Routes CH2 to MOH output.
    7. On: Routes CH3 to MOH output.
    8. On: 15V phantom power.
  • VOX Threshold: Trim pot controls how loud the voice on CH1 must be before muting other channels. Can be set for no muting.