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Stereo Tool FAQ

General questions

Just download the software from our website. The stand-alone version contains all features, but plays a beep or spoken message in the processed sound every once in a while (depending on which features are in use). There is no time limit on the trial version.

Yes! There are many settings in Stereo Tool that can be used to tune its behaviour to match your desired sound, whether your stations plays pop, rock, jazz, classical or any other genre.

This question comes up a lot, but it's really impossible to answer.

Often people ask for a preset for their specific format. But, and this is especially the case for FM stations, the "sound of the market" is usually far more important than the format of a station, except for some very specific formats such as classical or talk. If you drive to a different country or state, stations will often sound completely different - and usually all of them will sound quite similar, at least if you compare them against the sound of stations in a different state or country.

Most of the presets in Stereo Tool are suitable and will give consistent results for a wide range of music, and the best advise that we can give you is to try out a number of presets until you find one that you like, and slightly tweak it if needed (Quick Adjust is intended for high level tweaking without a lot of knowledge of what goes on under the hood).

Since people usually keep asking us which preset they should try out: The best ones are in the top section of the presets list. Our favorite preset is "Dutch Chocolate Moose", but we are in the Netherlands and this preset was tailored for the Dutch market so that makes sense.

Stereo Tool started as a hobby project, many years ago, and at the time it was free. We don't want people to keep using old versions of our software, so all the features that once were free are still free today.

There is no catch! We love what we do, and we want to have as many users as possible. So we prefer selling a lot of licenses for a low price over selling a few licenses for a high price.

FM-related questions

You need a sound card that supports sample rates up to 192kHz. If this is the case, you can output a full MPX signal with stereo and RDS, which can be fed directly to your transmitter.

Basically, yes. However, the flatter the frequency response of the sound card, the better. If the sound card contains a high pass filter, the lowest frequencies are removed which may cause overshoots in the output signal. If the sound card contains a lowpass filter, high frequencies are attenuated, which may result in less stereo separation. Stereo Tool can compensate for these issues, upto a point - it does require some extra steps when setting it up though.

Of course, we cannot test every sound card out there. We have a list of cards that we know work well, but this list is certainly incomplete.

Note that if you're outputting digital MPX (newer transmitters often support that), it really doesn't matter which sound card you use, because there's no quality difference between digital signals.

The most important 'feature' that a sound card must have to be able to use it for MPX output is that the frequency response must be as flat as possible between 0 Hz and 60 kHz. Flatness at the low end is the most important part, because if it's not flat on the low end that can cause overshoots. Stereo Tool can compensate deviations on either end of the spectrum, and once calibrated, there isn't really much difference between a calibrated sound card and one that's really flat, but setting it up requires a bit more work.

PCIe sound cards

PCIe sound cards can give you the lowest latency. The following are known to work well:

  • Any Marian card (see
  • The AudioScience ASI5810, 5811, 5812 
  • ESI Juli@, which is no longer produced, requires a bit of low frequency tilt correction

USB sound cards

  • Behringer UMC202HD

Raspberry Pi sound cards

  • All HifiBerry sound cards (DAC+, DAC+ Pro, DAC+ADC, DAC+ADC Pro)

Other cards

There are many cards that we have not tested but will probably work well. Also, many Realtek on-board sound cards work pretty well (although they tend to have a higher noise level), but for those it really depends on how the motherboard manufacturer has integrated it. You almost always need to use tilt calibration for the low frequencies, but that depends completely on the motherboard manufacturer.

If you have a sound card that requires calibration, follow this video:

Working with 3rd party software

Yes, as long as your automation system supports VST or DSP plugins, or our own plugin format that gives the automation software full control over anthing that happens in Stereo Tool. Systems that support these plugins are e.g. SAM Broadcaster, Station Playlist, ProppFrexx, mAirlist, GML and many others. Check with your automation system vendor whether you need the 32-bit or the 64-bit plugin version.

If your playout software does not use plugins, there is an alternative: Use a program like Virtual Audio Cable (VAC) or VB Cable to send the audio to. See the next question for that.

The simplest solution in that case would be to use a virtual cable, either via Virtual Audio Cable (VAC) (paid) or via VB Cable (free). After installing one of these programs, select (typically) Virtual Cable 1 as output in your playout software, and as input in Stereo Tool. Select the target output device(s) in Stereo Tool as well. That's all.

Yes! There are multiple ways of doing this, depending on what you want or need exactly. If you want to support many different plugins, it might be easiest to support the VST or DSP plugin versions of Stereo Tool. If you want full control and maximum flexibility, we have our own plugin format and SDK which is already supported by several software vendors and other larger media groups who have built their own streaming platform. Integrating it in your software should typically take only a few hours, we have example code available - for minimal integration you only need to call 3 functions (initialize, process audio, terminate). But our SDK makes it possible to access all the settings and meters from Stereo Tool from your own software if needed, load and save presets, you can even let the plugin handle all the sound card I/O so your software is just a wrapper around it. Contact us for details and pricing.


None! Well, that depends. If you only stream a playlist and don't need any external audio, you don't need a sound card at all. A sound card can still be useful for monitoring purposes, but that doesn't affect what your listeners hear. If you do need external audio, for example microphone audio, basically any sound card will work. Better quality cards may give a cleaner signal with less noise and other artefacts.