Stereo Tool performs FM pre-emphasis, FM Stereo and RDS encoding without needing special hardware.
Just connect your sound card output directly to your FM transmitter, and you are ready to go!
On top of this, Stereo Tool also offers professional quality sound processing to make your station stand out both in quality and loudness.
Advantages of Stereo Tool over hardware Stereo and RDS encoders:
Easy to use - just run Stereo Tool and plug your transmitter in the sound card output.
Easy to configure - all the relevant RDS settings are available on a single screen.
Dynamic texts possible - making it easy to include for example the current song title.
Cheaper - no special hardware needed. You only need a 192 kHz capable sound card. Creative (SoundBlaster, X-Fi) sound cards distort the sound and don't work properly.
Quality - when using a high quality sound card, the RDS and stereo signals are nearly perfect, with noise levels below -90 dB.
Built-in composite limiter which does not alter the pilot or RDS signal.
Stereo Tool is available as a (Winamp-style) plugin for broadcasting programs such as SAM Broadcaster and RadioBOSS.
A stand-alone version for live broadcasts of external sources is also available.
Stereo Tool is available in a free and a registered version. The registered
version is intended for commercial users of Stereo Tool, especially aimed at
FM radio stations.
¹ If these features are enabled on the free (non-registered)
version, a message ('This sound is processed by Stereo Tool') is played once
every 24 hours. This should not interfere with most non-commercial usage.
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 is a Winamp plugin that delivers professional quality audio processing - for free¹.
Have you ever wondered why on the radio all songs have the same volume, while
if you play CDs or MP3s, the volume and the type of sound changes all the time? That's because
the big commercial radio stations use expensive equipment that ensures that all songs sound
the same, and that they sound good on a wide range of cheap up to expensive audio systems.
Now Stereo Tool offers you similar processing, which you can use while
listening to your own music.
Many people have reported that the processed audio sounds better
on their equipment than the original unprocessed audio.
Besides this, Stereo Tool offers a stereo widener which makes music sound
'fuller' and more 'spacial' (less is also possible), and it can repair phase
shift problems in recordings (cheap CDs, vinyl, tapes).
¹ Although most options of Stereo Tool are free, some options that
enable FM radio stations to sound louder than their competitors, as well as
some options that enable broadcasting in stereo and adding RDS texts to the
broadcast without using extra hardware are limited in the free version of
Stereo Tool.
Currently, Stereo Tool offers the following sound processing options:
10-band multiband compressor / limiter / clipper
If one song contains a lot of bass, and the next contains a lot of treble,
this filter can make them sound equal. The volume is also kept at the same
level. Many people have reported that music sounds better on their equipment
when using the multiband compressor.
The clippers reduce sudden bursts of loud sounds, without causing pumping
or other artifacts.
Stereo channel separation widening / narrowing
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.
Stereo phase shift widening / narrowing
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
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.
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.
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.
3-level overshoot protection
If your goal is to make the sound loud, the 3-level overshoot protection
filter can remove the remaining peaks after all the other processing
has ended. By using 3 levels, any pumping artifacts that would normally
be caused by such a filter are reduced as much as possible.
Loudness filter
This filter can make sounds up to 5 dB louder, without causing higher
amplitude peaks in the signal, with very little effect on the sound.
Especially useful for radio stations that want to sound loud.
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.
FM transmitter support
The following options can be used to prepare sounds for broadcasting on
an FM transmitter.
FM pre-emphasis filter
Prepares the sound to be sent through an FM transmitter, such that
the pre-emphasis step in the transmitter does not cause clipping.
The multiband compressor and overshoot filters take into account that
the FM transmitter will pre-emphasize the sound.
For FM transmitters that do not contain a pre-emphasis filter, Stereo
Tool can also output the pre-emphasized sounds.
FM stereo encoder
The software FM stereo encoder enables broadcasting in stereo using a
simple mono FM transmitter.
FM RDS encoder
The software RDS encoder enables broadcasting RDS texts without using
a hardware RDS encoder.
The last two steps don't work on every sound card
(details).
FM transmitter support have been tested
with a very cheap (€ 15,= / $ 20,=) mono FM transmitter. When enabling
Stereo Tool, the orignal mono, dull, soft and sometimes clipped sound
becomes stereo and as clear and loud as that of the big commercial
stations.
More sophisticated FM transmitters may contain filters that disrupt the
signal generated by Stereo Tool
(details).
Channel delay filter
Play back one channel with a small delay to create a fake stereo effect.
