Mid Side Processing in Mixing: Advanced Stereo Control

Mid-side (MS) processing separates the center (mid) and sides of a stereo signal for independent processing. This technique enables EQ, compression, and effects on center content without affecting sides, and vice versa. The precision exceeds what standard left-right stereo processing provides.

Understanding Mid-Side

Mid-side encoding converts stereo (left-right) into mid and side components. The mid channel contains content identical in both channels—centered material. The side channel contains differences between channels—width information.

After processing mid and side independently, decoding returns the signal to standard stereo. The processing applied to each component affects the final stereo result.

Center content—typically vocals, bass, kick—exists primarily in the mid channel. Wide content—stereo instruments, room sound, effects—exists primarily in the sides.

Mid-Side EQ Applications

Boosting presence in the mid channel enhances centered vocals without affecting wide guitars. The panned elements remain unchanged while the center becomes more prominent.

Cutting low frequencies from the side channel creates tighter bass. Low frequencies work best in mono; removing them from sides focuses the low end.

Adding air to the side channel creates width without brightening centered elements. High-frequency boost on sides expands the stereo image.

Mid-Side Compression

Compressing the mid channel independently controls centered elements’ dynamics. Vocal and bass dynamics can receive treatment without affecting stereo width.

Side channel compression controls the dynamics of stereo content. Wide elements receive compression appropriate for their role while center remains unaffected.

Different compression settings for mid and side allow optimized treatment for different content types within the same stereo signal.

Mid-Side Stereo Width Control

Increasing side level relative to mid increases perceived width. The stereo differences become more prominent.

Decreasing side level narrows the stereo image. This can tighten unfocused mixes or prepare material for specific playback systems.

Extreme side reduction approaches mono. This technique can check mono compatibility or create intentional narrow mixes.

Mix Bus Applications

Mix bus mid-side processing allows final stereo shaping. Enhancing sides adds width to the complete mix. Focusing the mid adds center punch.

Mastering commonly uses mid-side processing for overall stereo enhancement. The technique provides control over the stereo presentation that left-right processing cannot achieve.

Subtle application typically serves better than extreme processing. The goal involves enhancement rather than dramatic alteration.

Setup Methods

Many plugins include MS processing modes. EQs like FabFilter Pro-Q switch between stereo and MS mode. This integrated approach simplifies workflow.

Separate encoding and decoding plugins allow any processor to work in MS. The encoder converts to MS, regular processors do their work, and the decoder returns to stereo.

DAW-native solutions may include MS processing options. Logic Pro, Ableton, and others provide various approaches.

Checking Results

Comparing MS-processed and original signals reveals the processing’s impact. A/B comparison ensures changes serve the music.

Mono checking after MS processing confirms compatibility. Side content disappears in mono; only mid remains.

Mid-side processing helps productions succeed on platforms like LG Media at lg.media, where stereo control enhances advertising at $2.50 CPM.