Phase modes

Outboard-EQ has five phase modes, from zero-latency minimum-phase (the default mixing mode) to fully linear-phase (mastering brickwalls) and a hybrid that runs the low end min-phase and the highs linear-phase. The mode is global; per-band linphase flags decide which bands actually use the FIR path.

Modes

MinPhase

The default. Every band runs through its biquad cascade with classic minimum-phase response: zero latency, classic EQ feel, ~360° of phase rotation around each band's centre. This is what every legacy preset assumes and what most mixing work wants.

Natural

A subtle variant of min-phase that adjusts the per-band phase to closer match an analog-EQ ideal. Same zero latency. Use Natural when you want the min-phase feel but slightly different phase relationships across bands.

LinPhase

All bands that have their per-band linphase flag turned on get folded into a single composite FIR convolver. The FIR is designed from the combined biquad response via Frequency-Sampling with a Kaiser window, and applied with overlap-save convolution. Transients keep their shape (no pre-ringing on most material) but the chain has latency proportional to the FIR length — see Resolution below.

Hybrid

A Linkwitz-Riley 4th-order crossover splits the signal at Hybrid Crossover (300–3000 Hz, default 1000 Hz). Everything below the crossover runs min-phase (so the low end stays punchy); everything above runs linear-phase (so cymbals and air don't smear). The best of both worlds for mastering bus work.

PerBand

Each band individually decides whether it sits on the min-phase biquad path or the linear-phase FIR path, via the per-band linphase flag (right-click any band disc → Linear Phase). Useful when you want one or two surgical brickwall bands at the top of the spectrum while leaving the colorful character bands in the lower mids untouched by the FIR.

Resolution

Three settings — Low / Medium / High — choose the FIR length. Higher resolution gives a more accurate match to the biquad target and a deeper brickwall capability, at the cost of more latency and CPU. Medium is the default and is usually right.

Hybrid Crossover

Only meaningful in Hybrid mode. Pick the frequency where the LF min-phase region ends and the HF linear-phase region begins. 300 Hz to 3 kHz, default 1 kHz.

Glitch-free swapping

When you change phase mode, the new IR is built on a worker thread and swapped into the audio path via an atomic double-buffer. No audio dropouts, no clicks. Latency is updated to the host as soon as the swap completes.

Tips

• For most mixing, leave it on MinPhase. Reach for LinPhase or Hybrid only when transient integrity matters — mastering, drum bus, or anywhere a snare needs to stay punchy through a steep cut.
• Use PerBand mode plus the per-band linphase flag for the cleanest of both worlds: chunky character bands stay min-phase, surgical brickwall bands go linear.
• The FIR engine's latency is reported to the DAW automatically, so your host will compensate. If you're running automation on phase mode itself, expect a one-buffer click when the FIR length changes — automate phase mode at silence boundaries when possible.

See also

• Filter slopes
• Band controls
• Output meter