The Mid Side Simulator is used to route stereo audio through an orthonormal matrix which isolates edges of sound field from its center. Controlled by keyboard keys or mouse for quicker access, it illustrates how Left and Right channels is converted into Mid and Side signals. It further illustrates how these signal re-build the stereo image.
Beginning at top is the feed stock section. Here you select your three audio scenario that go into the matrix. Unison sends same oscillator signal to each of two buses. The result is a single mono source. Harmony split sends root and third to left channel. It sends fifth and seventh to right channel. The result is plenty of side information. Answer antiphonal alternates phrases from one channel to the other. It produces dynamic movement in stereo field.
How to Use the Mid Side Simulator
To change scenes press button or appropriate key on 1, 2, 3. Choose your signal and tap F (or the screen) on Feed a four-bar phrase. Use monitor matrix buttons to check out the signal in different areas. Rebuild L + R displays familiar left-right stereo image. Check M in both ears sends equal amounts of Mid signal to both channels. You can see now what is mono-compatible: the content at the center of everything. Check S in both ears to isolate just Side information. That way you can listen for what’s out in the stereo width.
Tap buttons or hit the M, S, B keys to cycle through them. You can change matrix parameters on the fly using main controls. Edge span controls the width coefficient, which scales how much Side channel is contributing when it’s being decoded. It can be set at zero percent which will collapse image down into mono. Anything over 100 percent will start pushing things out more different than normal speaker placement for a hyper-wide effect.
The center trim controls gain of the Mid channel. You can use this to either cut or boost mono core of sound. The bench level controls overall output volume. Pressing I key (or clicking Invert the S lane) flips polarity of Side signal. This swaps left and right edge information.
You can perform advanced experimentation with snapshot features. Save what is currently set by clicking Capture A coefficients and Capture B coefficients. This includes polarity, Mid gain, and Side width. Morph one setting to another by clicking Traverse the A→B matrix corridor. You can morph from state A to state B while audio plays. You can hear how each setting affect your spatial configuration. Press X or click Fold Side through the looking glass to demonstrate running that side coefficient from zero to double width and then back again. It’s like a visualizaton of stereo field expanding and contracting.
As you’re exploring, here are a few practical tips to keep in mind. With a mix, set Edge span to 0%, how does it hold up in mono? Next, listen to Center trim. Invert the Side lane and see if there is a phase issue. Do that while listening to Rebuild output.
Keyboard shortcuts allow your hands to stay on keys. Change scenes with numbers and monitor mode with M, S, and B. Use them to switch monitoring modes without looking at screen. Stop audio anytime by pressing Escape. It’ll also reset the visual indicators.
To reset whole interface, press 0 or click Restore the orthonormal matrix. The default values of all sliders is restored. Left prime = Left and Right prime = Right. This is a blank slate from which to make fresh experiments.
To get quick reference on what’s going on mathematically, click How to play in the lower part of widget. This will open help panel. To have distraction-free view, click Fullscreen button. This will put the widget into fullscreen mode.
Select your feed stock, hit feed, then listen. You’ve now got your baseline. Move to Side isolation to hear how it affect the width. Slowly adjust Edge span while feeling for change in the image. If you go too far, you’ll lose focus in center. With simulator, you can ‘feel’ your way into understanding Mid-Side processing. It’s more than ‘turning knobs on a plugin’. Play with it. You’ll notice how different materials responds to the matrix manipulation.