MlsTool Free

Free application to measure impulse responses

MlsTool screeshot

MlsTool is an application used to measure impulse responses. You can use MlsTool to measure the room reverberation of acoustical spaces, or to measure digital effects units, speaker cabinets, spring or plate reverbs, etc. The impulse responses from MlsTool can be loaded into our ConvologyXT plug-in to reproduce the measured system.

There is no purchase or registration required.

On MacOS, MlsTool is distributed as a package installer in a DMG file. Open the DMG and then double-click on the PKG file to run the installer. On Windows, MlsTool is distributed as a zip archive containing the application and a PDF manual.

After installing, run the application and select Audio Settings to select the playback and recording devices. It’s recommended to use an external USB audio interface, and you should use the same audio device for both playback and recording, so that the sampling clocks for D/A and A/D conversion are perfectly synchronized. See the manual for more information.

After selecting the audio devices, choose an MLS length and click Start to begin the measurement. The app will play a few seconds of white noise, and will then write the measured impulse response to the file “impulse.wav”. At this point one generally repeats the measurement a few times while tweaking the output and input levels to get a good record level. When the levels are correct you can examine your impulse response in a sound editor, or load directly into Convology XT.


  • Maximum-length sequence (MLS) measurement application
  • MacOS or Windows
  • Measure up to 16 channels out x 16 channels in
  • 24-bit WAV, 16-bit WAV or ACSII text output files
  • Auto normalization option
  • Auto crop option
  • IR lengths from 255 samples to 1M samples
  • Supports ASIO devices
  • Supports any sampling rate provided by audio interface


MacOS or Windows. It’s also recommended to use an external USB audio device for both playback and recording.

  • MacOS

    MacOS 10.8 and up, 64-bit only

    Universal binary supports Intel x86 and Apple Silicon

  • Windows

    Windows 7/8/10/11

    MlsTool is a 32-bit Windows application