“This is a reverb device that works with impulse-responses. Impulse-responses are generated by recording short broadband signals and their corresponding room-reflections. What you get contains the information needed to reproduce the same room with other signals.

Due to technical reasons SIR1 works with a fixed latency of 8960 samples that is compensated for by the VST-host. SIR2 has a zero latency mode .

Sir is a stereo plugin. To take full advantage of stereo impulses for mono signals, you must first convert the track to stereo. You can download impulse-responses here at There is a great and extensive collection there. It’s important though to cut out the initial signal at the beginning of the file (which normally has already been done for you).


  • freeware
  • Windows VST-Plugin
  • works with a fixed latency of 8960 samples (possibly compensated by VST-Host).
  • you can adjust predelay, attack-time, length and stereo width of the impulse response
  • Stretch (up & down sampling of impulse response)
  • FFT EQ (to adjust the frequency spectrum of the impulse-response)
  • Auto Gain (automatic volume compensation)
  • Dynamic CPU Consumption (use only the CPU power that is needed to get the result)”

Source : SIR