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Comprehensive sound level measuring and logging for Q-SYS™

SPL Logger is an audio loudness monitoring and logging plugin for QSC® Q-SYS™ DSP systems. Simplify your adherence to occupational safety and health rules as well as organizational policy. Providing real-time and historical loudness data, SPL Logger will make it easier than ever to keep your shows to a safe volume.

SPL Logger is indispensable for theaters, amusement parks, live shows, bars, and restaurants.

Try SPL Logger for yourself! Download the demo here.

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  • SPL, Leq 1, and Leq 10 - all the measurements you need to provide a safe environment.

    • Leq is the equivalent continuous sound level over a period. You can think of it like an average. SPL Logger provides the equivalent continuous sound level for the last 1 and 10 minutes.

  • Linear, A, and C weighting filter options (ANSI S1.42 A and S1.42 C).
  • Calibration procedure built in to the plugin (requires microphone and calibrator, not included).
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  • Graph the current SPL, Leq 1, and Leq 10 measurements to keep your show right in the sweet spot.

  • Each measurement can be turned on independently, and the view scale can be customized.

  • Place the graph on your UCI for easy viewing, and customize the colors for use in a dark theater or outdoor festival.

  • Set a timer to disable the graph display, or turn off the timeout for constant display.

Log Files

  • SPL Logger logs your loudness data to a CSV file so you can review the data at any point in time. Data points are written once per second.

  • 3 different logging modes are offered.

    • Manual mode: Manually enable logging at the start of your event or use the scheduler built in to Q-SYS™ to determine when to log.

    • Threshold mode:  Set a minimum threshold, and when the sound reaches that level, the plugin begins logging. No need to log loudness overnight when the venue is inactive.

    • Continuous mode: 24/7 SPL logging.

  • Automatic log maintenance: Configure logs to be automatically deleted  after a set period of time, from 1 to 365 days.

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Limit Thresholds

  • Set maximum limits for SPL, Leq 1, and Leq 10 and get visual feedback when the limit is exceeded. Depending on your needs, these control pins can be tied to a warning light, email notification, or even additional Q-SYS programming.

*One SPL Logger license can be used for up to 3 instances of the plugin on a single Q-SYS™ core. There is no limit to the number of instances that can be run on a single core.

Who might need SPL Logger?

SPL Logger is a tool to assist in maintaining compliance with safety and health rules concerning sound levels. Themed entertainment, houses of worship, lecture halls, and other large venues come to mind.

System Requirements
  • Q-SYS Core running Q-SYS v7.0.0 or later. Cores running Q-SYS v9.0 or later require SPL Logger to be updated to v1.1.0.

  • Q-SYS v8.1.1 or later is required to display the graph. SPL Logger will run on v7.0.0-8.0.0 but will not display the graph.

  • ​Use of User Control Interfaces requires a Q-SYS™ Core UCI Deployment Software License.

  • Measurement microphone

    • Microphone calibrator (recommended)

How is SPL Logger licensed?
  • One SPL Logger license can be used for up to 3 instances of the plugin on a single Q-SYS™ Core.

  • There is no limit to the number of instances that can be run on a single core.

  • All future updates are included.

Does SPL Logger need internet access?


Is there a trial version of SPL Logger?

Yes. SPL Logger can be used in demo mode for 10 minutes to evaluate the plugin. The 10 minute period can be restarted by restarting the Q-SYS™ design. Use of the plugin in demo mode for commercial purposes is prohibited.

Use of the plugin is contingent on your acceptance of our Plugin Software License Agreement. The plugin will function in a limited demo mode until activated with a license key purchased from Forward Thinking Designs.

For volume licensing or specific questions, please message us on our Store page contact form.

License Keys are manually generated and usually sent out within two hours of your purchase for orders received from 9 AM - 5 PM EST.





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