SIR Audio Tools
SIR2 is an easy to use native audio-plugin to use for high quality reverberation. It's available for the plugin formats VST and AudioUnit. It offers zero-latency processing with low CPU-consumption and non-destructive audio processing of impulse responses. SIR2 includes high definition impulse responses (HDIR) of *real* places produced by Pinguin, Hamburg. You can also use various impulse responses from free or commercial sources.

Learn more about SIR2!

"SIR2 is a truly elegant piece of software, providing a great range of general-purpose convolution facilities within a no-nonsense interface. It's relatively CPU light, requires no dongle, and I can't fault the sound quality.
However, what really sets it apart for me is that it makes working with convolution at mixdown so straightforward. As a result, it's usually first call whenever I need reverb, and if you forced me to choose just one reverb plug-in for everything in my mix, it would certainly be SIR2.

-- Mike Senior, author of Mixing Secrets For The Small Studio and Sound On Sound's 'Mix Rescue' & 'Mix Review' columns.
SIR2 Screenshot
Zero Latency processing CPU efficient
Usable even at pre-production stage Low CPU-spiking even with small sound-device buffers
Multi Platform True Stereo Impulses included
for Macintosh 32-bit/64-bit (VST/AU) & Windows 32-bit/64-bit (VST) High definition impulse responses of real places included
Fair Copy Protection Flexibility
NO challenge/response - NO Dongle required - license key based imports various file formats including WAV, AIF, FLAC, BWS, OGG

Audio Samples    (flash required)

Click here for more Audio Samples! (SIR2 in the mix!)


  • Zero latency processing.
  • Low CPU-spiking even with small sound-device buffers.
  • Includes Pinguin's High Definition Impulse Responses.
  • "True Stereo" processing (a stereo convolution takes place for every source channel (left + right)).
  • Routing capabilities ( mono->mono, mono->stereo, stereo->stereo...).
  • High-quality internal sample rate converting.
  • Imports WAV, AIF, FLAC, BWS, OGG file formats.
  • Linear phase FFT-EQ.
  • Fair Copy-Protection - NO challenge/response NO Dongle required - license key based.
  • Free non-destructive amplitude envelope.
  • Free non-destructive filter envelope.
  • Pre-delay (0ms - 2000ms).
  • Stretch control (high quality re-sampling).
  • Forward / reverse switch.
  • Stereo In / Stereo IR Control.
  • Preset-managing.
  • Separate dry/wet control (-60db .. +20dB).
  • Auto-gain (automatic volume compensation).
  • Signal routing options.
  • HDIR-Direct On/Off switch.
  • "Beat-Scale"-mode.
  • If you have two stereo files, one with "L" and one with "R" at the end of the file name, you can click with right mouse button on one of the files to create a true stereo file. This is useful for third-party impulse response libraries.
  • Built in impulse-file browser (with folders).
  • Picture association.
  • Waveform Zoom.
Computer Music Logo
...For anyone looking for a more capable and professional version of SIR or simply a great convolution processor, SIR2 fits the bill nicely...
Computer Music 11/2007

Sound und Recording Logo
...SIR2 läuft stabil, ist performant und bietet ausgezeichnete Klangqualität...
Sound&Recording 10/2007

Beat Logo
...Das Plug-in überzeugt in punkto Klang und Flexibilität auf ganzer Linie...
Beat 12/2007

Differences between SIR1 and SIR2

Platforms Windows Mac(VST/AU) Windows (VST)
64-bit support - X
Latency 8960 samples 0 samples
Sample-rate Conversion low quality (linear interpolation) high quality (sinc interpolation)
Import Formats WAV SIR, WAV, AIF, FLAC, BWS, OGG
Start Locater - X
HDIR-Impulses - Church, Recording Studio, Jazz Chamber, Theatre
HDIR-Direct Option - X
"True Stereo" processing - X
Preset managing - X
Pre-delay 0-300 ms 0-2000 ms
Stereo In Control 0% - 100% 0% - 150%
Stereo IR Control 0% - 100% 0% - 150%
Forward/Reverse Switch X X
Autogain X X
FFT Equalizer low quality high quality (linear phase)
Free Volume Envelope - X
Free Filter Envelope - X
Stretch low quality (linear interpolation) high quality (sinc interpolation)
Beat Scale - X
Waveform View linear logarithmic
Waveform Zoom - X
Impulse Picture - X
Price freeware see purchase info


No Dongle required
  • Windows XP or Windows Vista
  • 100 MB hard disk space
  • Intel Pentium 4 or better
  • VST-Host application (like Cubase, Tracktion...)
  • Mac OS 10.5 or newer
  • 100 MB hard disk space
  • Intel Processor required
  • universal binary Audio-Unit or VST compatible Host software


Download Windows Demo VST Plug-in 32/64-bit Download Mac Demo Audio-Unit/VST Plug-in 32/64-bit Other Downloads
View 64bit install instructions

Please run the including installer application and follow the instructions.
After installing SIR2 will run in demo mode. The demo limitation is a periodic bell sound which will start every 10 seconds. The Impulse Response "Theatre" is disabled in demo mode.

Download Manual (PDF)

Download free impulse responses

Copyright 2010 Christian Knufinke. VST is a trademark Copyright of Steinberg Media Technologies GmbH. All other trademarks and copyrights are the property of their respective owners.