spectral matching // Mid / Side

Polarity-MEQ

Learn a reference. Shape your sound.

A free spectral matching plugin for bringing your audio closer to a reference. Learn both signals, then adjust tonal shape, frequency-dependent dynamics and stereo width independently in Mid and Side.

Match a full mix or individual buses, build a reusable Reference library, and carve space for another track. Keep the full Dynamics path for mastering, or switch to zero-latency EQ when recording and playing live.

Current version: v0.1.5. Released 2026-10-02. What’s new

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A reference for your tone. Control over the result.

FreewareMid / SideCLAP / VST3 / LV2AUv2 on macOSWin / macOS / Linux

Use a finished track as a tonal direction, match a bus to its corresponding reference stem, or build a library of sounds you know. Polarity-MEQ separates spectral shape from loudness so you can decide how much of the reference to transfer.

EQ first. Dynamics and width when you need them.

Start with the learned spectral difference, then choose the Match amount, smoothing and limits. Add Dynamics to transfer frequency-dependent range, and adjust Width independently. Reference matching gives you a starting point to listen to; it does not replace arrangement and mixing decisions.

From reference capture to reusable EQ

Independent Mid/Side matching

96 bands / separate shape and width

Learn the center and stereo information separately. Match always removes the paired broadband level difference, so tonal shape, Side/Mid balance and output loudness remain separate decisions.

Learn Reference & Current

Sidechain / sequential main input

Capture a reference from the sidechain or play it through the main input. Current always measures your unprocessed input. Learn at least three seconds of representative active audio for each profile.

Frequency-dependent dynamics

Compression / expansion

Transfer the learned dynamic-range difference with bounded upward and downward compression or expansion. Dynamics compares the ranges around each band’s learned median and remains separate from the static EQ.

Two latency modes

MASTERING / ZERO LATENCY

MASTERING uses a 4096-sample spectral processing path with Dynamics. ZERO LATENCY uses minimum-phase Mid/Side EQ and disables Dynamics while preserving its settings. Stop playback before switching modes.

Sidechain Carve

Captured profile / cut-only EQ

Learn a competing track into a separate Carve Reference, then add static spectral cuts alongside normal matching. Carve uses the captured profile rather than following the live sidechain.

Reference library & Sets

Save / search / aggregate / organize

Keep reusable References, combine 2–256 same-kind profiles with Mean or Median, and create portable Sets with a Master plus bus or stem roles. Each bus loads its own Reference; instances do not control one another.

Shift, gates & boundaries

±12 semitones / Low and High Cut

Shift Reference features for a different key. Apply Gate protects quiet Current bands, while 24/48 dB/octave Low and High Cuts constrain the useful signal range and taper processing at its boundaries.

See the processing

Both / Mid / Side views

Compare Reference, Current, live spectra, applied EQ and Dynamics, Match Difference and Carve layers. Toggle layers or Alt-click to solo one; open Advanced when you need the detailed controls.

EQ IR export for Bitwig

Four-channel true stereo / 32-bit float

Export the combined static Match and Carve EQ, including cuts, as a 4096-frame minimum-phase WAV for Bitwig Convolution. The IR excludes Dynamics, Output, PCM Clip and Bypass.

Explicit loudness matching

Target MAX-S / one-shot Normalize

Measured References can recall their maximum short-term LUFS into Target. Measure the processed result, then press NORMALIZE to adjust Output once. Optional −0.1 dBFS PCM Clip is a sample clipper, not a true-peak limiter.

Learn, match, listen

01 // REFERENCE

Choose your direction

Route the reference to the sidechain and select SC, or select MAIN for sequential capture. Press LEARN REF, play at least three seconds, then stop Learn.

02 // CURRENT

Measure your audio

Play a representative section through the main input and capture it with LEARN CURRENT. Both profiles stay embedded in your DAW project.

03 // SHAPE

Find a useful amount

Start with moderate GLOBAL and MATCH amounts. Listen before adding Dynamics or Width, and constrain bus processing with Low and High Cuts.

04 // COMPARE

Check the result

Play at least three seconds with processing active before using NORMALIZE. Compare with bypass, refine the amounts, and save useful References.

At a glance

Profiles

96 logarithmic bands per Mid/Side domain

Capture

16384-point analyzer; at least 3 seconds of active audio

Latency

MASTERING: 4096 samples / ZERO LATENCY: 0 algorithmic samples

Reference Shift

−12 to +12 semitones

Reference Sets

2–16 roles; portable .meqset.json files

EQ IR

4096 frames / 32-bit float / four-channel true stereo

Downloads

Freeware by Polarity. Choose the package for your system; installation guides are linked below.

SHA-256 checksums

Latest updates

v0.1.5 2026-10-02

No additional release notes were provided for this version.