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Stereo Tool

Stereo Tool is a software-based audio processor which offers outstanding audio quality and comes with many unique features. It is used by over 3000 FM stations ranging from small local stations to 50-100 kW stations and nation-wide networks with dozens of transmitters, thousands of streaming stations and many DAB+, HD, AM and TV stations. It can be used for both live and file based processing.

Beside performing traditional audio processing, Stereo Tool can also repair many common audio problems on the fly, and optimize outgoing audio for better FM reception. A full list of features can be found below on this page.

How do I use it?

Stereo Tool can be used like any hardware audio processor, where the input comes from a sound card input and the output is sent to a sound card output and/or stream. For this, you will typically need the stand alone version of Stereo Tool.

Alternatively, Stereo Tool can run inside most playout or streaming software. Depending on what your software support, you will need to download one of the VST or DSP plugins for that. If your playout or streaming software doesn't support audio processing plugins, you can instead route audio through the stand alone version via programs such as VB Cable or Virtual Audio Cable.

Scroll down for more information about these usage types.

What license do I need?

There are several licenses for Stereo Tool, ranging from very cheap licenses for hobby users to more expensive licenses for large broadcast networks with dozens or hundreds of stations. A description of what the different features do can be found here. Some features are free for home use.

Stereo Tool
Loud and clean

Loud and clean

Generates the loudest and cleanest sound on the dial, optimizing reception at the same time.

Automatic audio restoration

Automatic audio restoration

Repairs problems like clipping distortion, low bitrate encoding artifacts and background noises.

Used by more than 14000 radio stations

Used by more than 14000 radio stations

Used by thousands of stations in at least 94 countries, among which more than 4000 FM stations.


Repairs clipped audio
Removes distortion, restores dynamics
Also used by police forensics labs


Improves sound of MPEG2/MP3 files
Reduces pre-ringing
Fills up gaps in the spectrum


Removes unwanted constant sounds,
such as a 50/60 Hz hum from bad cables

Spectrum Control

Non-compressing spectrum equalization


- Wideband AGC
- Two multiband compressors, 2-9 bands
- Wideband compressor
- Low level boost for classical music

Stereo Widening

Choice of multiple stereo wideners

Using Stereo Tool as a stand alone processor

 This is similar to using a hardware audio processor. Stereo Tool will process the audio coming from one or more input sound cards (or AES67), and send the result to one or more output sound cards and (IceCast/ShoutCast/MicroMPX) streams.

To use Stereo Tool like this, download one of the stand alone binaries, and select the proprer input and output sound cards.

If you are using Stereo Tool as an FM processor, check this old video that describes how to install and configure it. 


Using Stereo Tool as a plugin in your playout software

 If your playout software supports VST 2 plugins, VST 3 plugins, DSP plugins or our own plugin format, then download the matching plugin or installer and install it in the proper location. The DSP plugins come with an installer that already recognizes a number of playout programs, if yours isn't supported, browse to the Plugins directory of it. The VST plugins need to be placed in the correct location manually, in most programs you need to specify where you want it to search for VST plugins. If our own plugin format is supported, the binary is usually delivered with the software.

Feeding Stereo Tool from other software on your computer

 If you want to feed Stereo Tool from a program that doesn't support audio processing plugins, or for example when you just want to send all the audio (eg. YouTube video's) through Stereo Tool, you need a 3rd party program to route the audio to Stereo Tool, which installs a "virtual" sound card. You can then send the audio from other software to that virtual sound card (or make it the default sound card in Windows, so all audio is automatically sent to it), and in Stereo Tool, read the input from the virtual sound card, and send the output to the real sound card.

Two programs that can be used for this are VB Cable and Virtual Audio Cable. Make sure to get a recent version of these programs, older versions often have issues with newer Windows versions, which can cause buffer underruns or overruns in Stereo Tool.


All features


- Repairs clipped audio
- Removes distortion, restores dynamics
- Also used by police forensics labs


Improves the sound of MPEG2/MP3 style lossy compressed files


Removes unwanted constant sounds, such as a 50/60 Hz hum from bad cables

Natural Dynamics

- Boosts percussion instruments
- Great to restore dynamics in compressed music

Automatic Gain Control

- Slowly adjusts the input level
- Can speed up on large changes
- Program-dependent dynamic timing

Low Level Boost

- Intended for classical music
- Raises the level of very low level sounds without compressing louder sounds

Multiband compressors

- Two multiband compressors
- Selectable number of bands, 2-9
- Program-dependent dynamic timing

Auto EQ / Bass EQ

- Corrects spectrum without compression
- Consistent sound without affecting dynamics

Stereo effects

- Choice of multiple stereo wideners
- AZIMUTH phase problems repair
- Mono compatible mode, no phase cancellation
- Automatic phase flip for anti-phase input

Immersive Bass

- Generates upper bass harmonics
- Much warmer, more consistent sound
- Makes bass audible on small speakers

True Bass

- Subharmonics generator
- Adds deep bass that's missing, mainly in older recordings

Streaming final clipper

- Clean and very loud
- Hybrid clipping/limiting mode avaialble
- Safe to use for low bitrate streaming

IceCast / ShoutCast stream

- Built-in IceCast / ShoutCast streaming
- MP3 and ogg/Vorbis, for now

AM processing

- Upto 200% asymmetry
- C-QUAM stereo and NRSC curve supported
- Extremely steep bandpass filters

FM Stereo / RDS / RDBS

- FM pre-emphasis
- Built-in stereo and RDS encoder
- Remote control via UECP or Telnet
- Supports RT+, EON, TMC, EWS, IH etc

FM ITU-R BS.412 limiter

- Inaudible(*) BS.412 leveling
  (required in some EU markets)

(*) If setup correctly

FM Composite Clipper

- Clean and very loud
- Upto 140% audio level at 100% FM modulation
- Gives 2-3 dB extra headroom for highs
- Improves reception
- Strict ITU-R SM.1268 ('Stokkemask') compliance
- Be the loudest and cleanest station on the dial!

FM multipath protection

- Reduce RF bandwidth to improve reception
- Compatible with all receivers
- Upto 30 km bigger stereo reception area (*)

(*) Reported by several stations, after switching
     to Stereo Tool from other processors.

FM MicroMPX streaming

- Streams the full composite signal,
  with pilot / RDS, to transmitter sites over IP.
- Minimum required bitrate 320 kbit/s
- Redundancy possible
- GPS syncronization possible
- Software and hardware decoders available

Built-in microphone processor

- Software mixing console (control via tablet!)
- 2 channels
- Runs alongside normal compression
- No extra latency added