Aetherial De-Esser¶

The Aetherial De-Esser tames harsh 'S' and 'T' sibilance by ducking a narrow band when it exceeds a sidechain threshold. It uses split-band processing: only the sibilant bandpass output is attenuated, leaving lows and mids untouched. This fixes the broadband-attenuation bug that previously caused approximately 30 W of TX power loss. The panel shows the sidechain bandpass response, a 24 dB gain-reduction meter, six tuning knobs (Freq, Q, Thresh, Amount, Attack, Release), and a user-selectable cascade slope (12/24/36/48 dB/oct).

Applet instances: - TX instance: "Aetherial De-Esser" (shown in the docked Applet Panel) - RX instance: "Aetherial De-Esser — RX" (reachable through the Aetherial Audio Channel Strip)

Before you start¶

AetherSDR must be open and the Aetherial Audio (TXDSP or RXDSP) processing chain must be visible.
The DESS stage must already exist in the CHAIN widget. If the de-esser has never been enabled, the DESS stage may not be present.
The de-esser is available on both TX and RX audio paths. Each path has its own independent instance of the Aetherial De-Esser.

Bypass the de-esser from the chain¶

Remove the Aetherial De-Esser from your TX or RX audio path without changing any of its settings. Bypassing is useful when you want to compare treated and untreated audio, or temporarily disable de-essing for a particular session.

Steps for TX de-esser bypass¶

Locate the CHAIN widget in the Aetherial Audio (TXDSP) container.
Find the DESS stage in the chain.
Single-click the DESS stage to toggle bypass on or off.

Steps for RX de-esser bypass¶

Locate the CHAIN widget in the Aetherial Audio (RXDSP) container.
Find the DESS stage in the chain.
Single-click the DESS stage to toggle bypass on or off.

When bypassed, the entire de-esser tile renders at reduced opacity (55 % of normal). Single-clicking again re-enables it and restores the tile to full opacity. The ClientDeEssTxEnabled and ClientDeEssRxEnabled settings are updated immediately.

Opening the de-esser settings panel¶

The de-esser settings panel has two instances: - TX instance: "Aetherial De-Esser — TX" (accessible from the Aetherial Audio Channel Strip's TX path) - RX instance: "Aetherial De-Esser — RX" (accessible from the Aetherial Audio Channel Strip's RX path)

To open the appropriate instance: 1. Open the Aetherial Audio Channel Strip. 2. Click the DESS stage to open the de-esser settings panel for that path (TX or RX). 3. The panel title bar shows either "Aetherial De-Esser — TX" or "Aetherial De-Esser — RX" depending on which path you accessed.

De-esser controls¶

The Aetherial De-Esser panel contains the following controls:

Label	Kind	Default
Sidechain response curve	indicator	—
Gain-reduction bar	meter	—
Freq	knob	6000 Hz
Q	knob	2.00
Thresh	knob	-30.0 dB
Amount	knob	-6.0 dB
Attack	knob	1.0 ms
Release	knob	100 ms
Slope	push_button	24 dB/oct (2 stages)

Control details¶

Freq (logarithmic mapping, 1000 to 12000 Hz): Sets the centre frequency of the sibilance band. Labels show "6.0 kHz" above 1 kHz, "N Hz" below.
Q (linear mapping, 0.5 to 5.0): Sets the bandwidth of the sibilance band — higher Q equals narrower bandwidth. Labels show "X.XX".
Thresh (linear mapping, -60.0 to 0.0 dB): Level above which the de-esser starts attenuating the band.
Amount (linear mapping, -24.0 to 0.0 dB): Maximum attenuation applied at peak sibilance. Values are negative (or zero) because they represent reduction.
Attack (exponential mapping, 0.1 to 30.0 ms): Sets how quickly the de-esser responds once sibilance crosses the threshold. Present in the Channel Strip StripDeEssPanel (RX and TX). The docked ClientDeEssApplet omits this knob.
Release (exponential mapping, 10.0 to 500.0 ms): Sets how quickly gain returns after sibilance drops below the threshold. Present in the Channel Strip StripDeEssPanel (RX and TX). The docked ClientDeEssApplet omits this knob.
Slope (cycles through 12/24/36/48 dB/oct): Sets the sidechain bandpass cascade count. Each stage adds 12 dB/oct of rolloff outside the sibilant band. Higher slope equals narrower effective notch, less mid-band collateral on Ess-heavy phrases. Present in the floating StripDeEssPanel (left column, bottom). Label shows "N dB/oct". Present for both TX and RX paths. Persisted as ClientDeEssTxSlopeStages / ClientDeEssRxSlopeStages.

Indicators¶

Label	States	Meaning
Centre-frequency ball	resting on curve peak	Marks the currently-tuned sibilance centre frequency on the response curve.
Gain-reduction strip	empty, soft-red fill	Current attenuation applied to the sibilance band. The meter is a horizontal soft-red strip, right-filled. Scale maxes at 24 dB; a tick marks the -6 dB typical amount. Refreshed at approximately 30 Hz.

Inline value editing on knobs¶

The de-esser knobs (Freq, Q, Thresh, Amount, Attack, Release) support inline value editing. Instead of dragging the knob, you can type a value directly.

To edit a knob value using inline editing¶

Click the value text below any de-esser knob. A small text field appears, outlined in cyan when focused.
Type the new value. You can include units (e.g., "6 kHz", "-24.0 dB", "100 ms") or just the number (e.g., "6000", "2.0", "0.1").
Press Enter or click anywhere else on the panel to commit the value.
To cancel editing, press Escape — the previous value is restored.

The value is automatically clamped to the knob's valid range. Locale-aware parsing is supported (e.g., "12,5" works in comma-decimal locales).

Theming and knob colors¶

In v26.6.1, the knob component colors are now sourced from the theme manager's color.knob.* namespace: - color.knob.background — the knob ring background - color.knob.foreground — the knob value arc - color.knob.handle — the knob pointer indicator

The de-esser applet container is registered as applet/deess, which allows per-applet container overrides (e.g., the de-esser can have an amber knob foreground while other applets use a different color). Label and value text below the knob continue to use color.text.secondary and color.text.primary respectively.

The sidechain response curve widget also sources its colors from theme keys: - color.background.0 — curve background - color.background.1 — grid lines - color.text.label — axis labels - color.accent.danger — the sibilant band curve (soft red) - color.accent.dim — threshold indicator line

Tips¶

Bypassing does not reset any knob values. Freq, Q, Thresh, Amount, Attack, Release, and Slope all retain their current settings when you re-enable the stage.
The TX and RX de-esser instances are independent. Changing settings on one does not affect the other.
The sidechain response curve and gain-reduction meter reflect the currently active instance (TX or RX) in the panel title bar.
You can use inline value editing to enter exact values without dragging knobs. This is especially useful for fine-tuning or when you know the precise setting you need.
The Slope button cycles through 12 → 24 → 36 → 48 dB/oct when clicked. Use a steeper slope for narrower filtering around the sibilant frequency to reduce collateral attenuation on mid-range speech.
The de-esser container (applet/deess) allows theme authors to customize knob colors specifically for the de-esser panel without affecting other comp knobs.
The gain-reduction meter uses a smoothing algorithm that only triggers repaints when the displayed value changes significantly. This reduces CPU usage during steady-state operation while maintaining responsiveness during transient sibilance events.