Stereo Tool 2.10

(April 4th 2008): Stereo Tool 3.0 is out! Please go to our new site,, to download it.
If you have any problems with Stereo Tool 3.0, please send me an email at Thanks!

Stereo Tool is a free Winamp plugin that can be used to manipulate sounds.
It was originally created to repair phase shift problems in stereo recordings, but it can do a lot more,
like keeping the playback of each song at the same volume.

Stereo Tool, free Winamp plugin
Currently, Stereo Tool offers the following sound processing options:
  • A singleband compressor/limiter
    This can be used to make soft sounds louder or loud sounds softer, and to reduce loud peaks in the sound.

  • An 8-band multiband compressor/limiter
    If one song contains a lot of bass, and the next contains a lot of treble, this filter can make them sound equal. Can also be used to keep the volume at the same level. At aggressive settings, the result sounds "fuller".

  • A stereo channel separation widener/narrower
    With this you can move the instruments to the center, or further away from each other. This can be used among others to let both speakers play all the sounds at the same level (so if you only hear one speaker, you don't miss any sounds), and still keep a part of the stereo effect.

  • A stereo phase shift widener/narrower
    Phase shift widening makes the stereo stand out more, which can make music sound more powerful. The instruments do not change position though. Phase shift narrowing can be useful for example if you have a mono output channel: Sounds converted to mono using this filter sound just as full and powerful as the original stereo recording. This enables transforming any recording to mono without audiable artifacts, and achieving better quality encoding for low bitrate MP3 files.

  • A phasing error (AZIMUTH) correction filter.
    Old tape recordings and many cheap CDs often suffer from severe phasing errors. These phasing errors can make listening very unpleasant, and when the phasing error changes over time the sound can seem to "float" around you. It can also cause severe artifacts when converting the sound to mono or when playing it on a surround system. This filter automatically detects and repairs such errors.

  • A center bass speaker filter
    In some very rare circumstances, playing sounds using a single (center) bass speaker can result in less powerful and deformed bass sounds. This filter optimizes the bass for playback on a single bass speaker.

  • A channel delay filter
    Play back one channel with a small delay to create a fake stereo effect.

  • A lowpass filter
    Useful if you want to feed the Winamp output into an FM transmitter. This filter can completely remove any FM pilot tone interference. Also useful to hear how a recording would sound on an AM station etc.

This was a real life-saver for me. I have two, four-disc collections of rock n roll from the 50s and 60s. It apparently was taken from vinyl, transfered to tape with significant phase issues, THEN burned to CD. I got them cheap... and I got what I paid for.

The mono cuts, I'm analizing the channels to find the better quality and using only that channel. The stereo cuts, though, are only fixable by putting them through Radio Tool. Sometimes a recording sounds OK... then I run it through Radio Tool and suddenly the lead singer is ROCK SOLID dead center of the image.

I never had a full appreciation for the program until I ran into this situation... seeing what I used it for might help others see its value.

Gene Savage
Tulsa, Oklahoma USA

Stereo Tool 2.x     (C) Copyright 2006 by Hans van Zutphen     Email: