API MC531 Monitor Controller

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API Audio's new studio monitor volume controller brings the features you need and the build you expect!

Featuring the same level of craftsmanship found throughout API’s entire product line, the MC531 offers a stand-alone version of the monitoring functionality built into the center section of API’s legendary analog consoles. Specifically designed to include fully-featured monitor control for DAW workflows, the MC531 can integrate seamlessly into any audio production environment where functionality, ease of use and an accurate reference of each audio source is required.

“In our ongoing mission to provide audio professionals with products suited to their evolving workflow, the company decided that a monitor controller would be a natural next step in product design,” commented API’s Director of Engineering Todd Humora. “We’ve certainly had many requests for a unit like this over the years. The MC531 provides users with the exact same circuitry they would find in an API console, plus a few extra features that many people will find useful.”

Drawing inspiration from the monitor control modules of all API consoles, the MC531 features a Main and two Alternate stereo outputs, the latter having individual trims for speaker level matching. Programmable subwoofer integration allows the user to link the Sub with the Main and/or either of the Alternate outputs. With a total of seven selectable stereo input sources (three analog line-level inputs, AES, USB, plus 3.5mm and Bluetooth), the MC531 can meet the monitoring needs of almost any studio setup. Two independent Headphone outputs and a built-in Talkback mic complement the feature set. Of course, the classic API 41-detent Control Room Knob is right at your fingertips.


  • 3 stereo balanced line level analog audio inputs
  • Digital audio input, selectable between AES3 or USB
  • 3.5 mm input on front and rear panel
  • Bluetooth connectivity
  • All 5 inputs are buffered with the API 2510 Op Amp.
  • 3 stereo balanced line level outputs with individually adjustable trim levels
  • Mono balanced line level output for feeding a subwoofer with adjustable trim level
  • Independently assignable SUB output
  • Stereo outputs include full mute, mono, and DIM controls
  • 2 stereo headphone outputs
  • Headphone source selection toggle switch for C/R or CUE SOURCE
  • CUE SOURCE selectible from any of the 5 inputs
  • Built-in Talkback Mic with gain control and activation button
  • 18 segment stereo LED meter
  • Balanced unity level meter output for connecting to an external meter system
  • External power supply


  • Input Connections:
    • ST-1, ST-2, ST-3: ¼” Balanced Analog, 30K Ohm Input Impedance
    • ST-4: Digital Input, USB Type-B, XLR female AES3
    • ST-5: Bluetooth, Mini Jack front and rear in parallel
  • Output Connections:
    • Control Room Outputs: XLR, selectable electronic or transformer balanced, 75 Ohms
    • Meter Output: ¼” Balanced
    • Headphone: ¼” Stereo
  • Maximum Input Level: +28dBu
  • Maximum Output Level: +28dBu
  • Frequency Response: +/- 0.5dB 20Hz to 50KHz
  • Signal to Noise Ration: 115db
  • Power Consumption: 16 Watts
  • Unit Size: 11.0” x 12.75” x 4.0”
  • Shipping Size: 14.5" x 13.5" x 8.5"
  • Unit Weight: 8.5 lbs
  • Shipping Weight: 12 lbs

Block Diagram


Our ONE WITH EVERYTHING ZEN WARRANTY extends the standard manufacturer warranty by one year, see our ZEN WARRANTY page for details.