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Help: What is Stereo Tool? - Stereo Tool 3.0
Stereo Tool is a plugin that can be used to influence the sound of audio recordings. It can make recordings sound equal and consistent in volume and sound color, bring out the details, and increase existing stereo effects. Because the processed audio makes better use of the available equipment, it often sounds better and richer and richer than the original - more details can be heard. Stereo widening is provided to further improve the listening experience.

Special support is provided for (FM) radio stations: Extra loudness (+5.5 dB), FM pre-emphasis, and software stereo and RDS encoding. Using Stereo Tool, even a very cheap (€15 / $20) mono transmitter can sound like the big commercial stations, broadcasting in full stereo with RDS.

Stereo Tool contains a dualband pre-limiter, 10-band multiband compressor/limiter with clipping, 10-band equalizer, 3-level overshoot protection, extra loudness filter, AZIMUTH corrector, stereo image manipulator, lowpass filter, FM pre-emphasis, stereo and RDS encoder.

The dualband pre-limiter and multiband compressor can be used to get equal sound levels in different files, or to limit the maximum sound level. The overshoot protection filters make sure that peaks in the sound stay below a configurable level.

The stereo image manipulator can be used to convert stereo to mono without getting any of the artifacts that are normally caused by this, to repair recordings with phasing problems, to increase the stereo image, and even to create a stereo sound such that both speakers still play all the instruments.

The lowpass filter can be used to filter out certain high frequencies, such as the 19 kHz pilot tone if you want to send the Winamp output into an FM transmitter.


Back in 2001, I started my own internet radio station (Weird Titan Radio). At the time the highest stream quality that my provider offered was 56 kbit/s MP3. After some tests I quickly decided that the only way to get a decent quality was in mono.

Unfortunately, converting music to mono often causes the sound to get distorted, and even if that doesn't happen, the end result often sounds very "thin". To solve this, I created some software to convert stereo to mono, without this quality effect. I also wrote some separate tools for volume compression etc.

In 2004, I decided to convert all my processing software to C++ and create a WinAmp plugin: Stereo Tool.

In 2006, I created a new version with more features, a better interface and much lower CPU usage: Stereo Tool 2.0

In 2008, I added a lot of extra features that can be found on professional (FM) radio stations, which often cost thousands of Euros (or dollars). Because of that, some of those features are no longer free in this new Stereo Tool 3.0 version - but that's only the features that are interesting to (some) webcasters and FM radio stations, normal users should be able to use Stereo Tool 3.0 without ever noticing that some parts are not free.
This website is © Copyright 1999-2014 by Hans van Zutphen
Stereo Tool is shareware. You are free to give Stereo Tool to others, publish it on shareware CDs/DVDs, websites etc.