Spectrum analyzer

> Outboard-EQ has three spectrum taps in one engine — pre, post, and external — plus a cross-instance broker so you can overlay the spectrum of another Outboard-EQ instance on this one. All settings l

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Outboard-EQ has three spectrum taps in one engine — pre, post, and external — plus a cross-instance broker so you can overlay the spectrum of another Outboard-EQ instance on this one. All settings live in the Analyzer popover in the header.

Taps

Pre

The signal as it enters the plugin, before any EQ or character processing.

Post

The signal as it leaves the EQ, before the output meter and monitor iso. This is the default tap shown on the EQ display.

External

Either the plugin's sidechain input (when Sidechain is selected) or another Outboard-EQ instance's post-tap, served via the Spectrum Broker (when Broker is selected). Useful for comparing tracks, or for sidechain-style spectrum hunts.

Engine settings

All three taps share the same FFT engine; the settings below apply to all of them at once.

FFT Size

Fast — 2048 points. Quick reaction, lower frequency resolution.
Medium (default) — 4096 points.
Slow — 8192 points.
Ultra — 16384 points. Slow reaction, very high frequency resolution. Useful for low-frequency analysis.

Window

Hann — general purpose. Good frequency selectivity, modest leakage.
BlackmanHarris4 (default) — very low side-lobe leakage, slightly wider main lobe. Best for general spectrum work.
Nuttall — extremely low side-lobe leakage.
FlatTop — wide main lobe, very accurate amplitude readings. Use when you care about the peak level of a tone more than its exact frequency.

Smoothing

Fractional-octave smoothing, from 1/3 octave (very smooth, almost a tonal curve) to 1/48 octave (almost raw FFT bins). Default 1/12 — a good readability/detail compromise. The smoothing is Gaussian and applied in the log domain so the visual perception of "smoothness" is uniform across the spectrum.

Tilt

0 to 6 dB/oct. Default 4.5 dB/oct. Pink noise on the input shows as a flat line at this tilt — handy when you're comparing material against a pink-noise reference.

Peak Hold

Off — no peak indicators.
Instant — peaks decay immediately. Useful when you want to read the current spectrum without history.
Decaying (default) — peaks decay over time at the Peak Decay rate.
AllTime — peaks accumulate forever (until reset). Useful for "what's the loudest the kick got across the whole song?"
Freeze — peaks freeze in place. Useful for A/B comparisons.

Peak Decay

0.1 to 30 dB/sec. Skewed for resolution around 6 dB/sec, default 12 dB/sec. Only meaningful in Decaying mode.

External-source mode

Off — no external tap.
Sidechain — use the plugin's stereo sidechain input.
Broker (default if at least one external slot is published) — pick another Outboard-EQ instance's post-tap.

When Broker is selected, the Broker Slot picker (32 slots) chooses which instance's spectrum to overlay. The UI looks up friendlier names via /broker_slots.json.

Display

The three taps are toggled from the Overlays popover in the header:

Spectrum toggle — turns the post tap on/off.
Overlays → Pre spectrum — adds the pre tap (drawn behind in a lighter shade).
Overlays → External spectrum — adds the external tap (drawn in a third colour).

Tips

For mastering, set Tilt to 4.5 dB/oct and Smoothing to 1/6 oct — close to a typical mastering reference view.
For surgical work, drop Smoothing to 1/24 oct so individual resonances jump out of the curve.
Broker mode is especially useful in mastering chains: have an A/B reference instance with the post tap visible on every other Outboard-EQ in the project.