Ancora — Manual

Stereo gave music its space. Ever since Blumlein demonstrated stereophonic recording in the 1930s, we have been able to place sounds across a field - to give a mix width, depth and a sense of room. But everything that lives in two channels eventually has to survive being collapsed back into one: radio, phone speakers, club PAs and smart speakers all sum stereo to mono, and even a vinyl groove is cut from the mono sum and the stereo difference of the two channels.

To see what survives that fold-down and what does not, picture a single sine tone playing from both speakers. If the left and right copies are identical - same level, same phase - the tone sits dead centre and is effectively mono. From here the two channels can differ in only two fundamentally different ways, and the whole of stereo is built from them.

Panning is a level difference. Turn the right channel up and the left down and the tone moves to the right, but both channels still carry the very same waveform, perfectly in phase. The position changes; the relationship stays coherent. Summed to mono nothing cancels - a panned tone is mono-safe, it simply sits louder or quieter in the balance.

Width is a phase difference. Keep both channels at the same level but shift one slightly in time against the other, and the tone stops being a single point - it spreads wide. Width, in essence, is a phase (or timing) difference between left and right, and a small amount is exactly what gives music its sense of space. The trouble begins only when that difference grows too large: as left and right drift toward opposite phase, their mono sum shrinks, and at full antiphase they cancel completely and the tone vanishes. This is why excessive width is the real problem - the widest frequencies are precisely the ones that hollow out when a mix is folded down toward mono.

Panning is the safer of the two, but not always free: on vinyl a hard-panned element feeds the same vertical groove modulation that excessive width does, so a cutting lathe struggles with both - too much low-frequency difference pushes the stylus beyond what the groove can hold, causing tracking problems and skipping. This is why mastering engineers have long kept correlation in check for clean, reliable pressings. And none of this is one number for the whole mix - it varies by frequency. A vocal may sit perfectly centred while cymbals spread wide; bass usually wants to stay tight and mono-solid while the highs can afford more air. Managing the stereo field therefore means working frequency by frequency, not with a single global width control.

Ancora (from the Latin for 'anchor') manages the stereo field exactly that way: frequency by frequency, without fixed crossovers, analysing the image in real time. Its measurement is based on spectral Mid/Side balance rather than a traditional correlation meter, so it reads both phase relationships and panning asymmetries across the whole spectrum. Ancora shapes the result through three curves - Depth, Timing and Target - and addresses the two phenomena above with two complementary modes.

L/R mode is the panning compressor. It compresses excessive left/right level imbalance for a frequency, moving an off-centre element back toward its place without collapsing its width - the mix keeps its sense of space, only the balance is corrected.

M/S mode is the width compressor. It compresses Side content that exceeds the Mid level, raising correlation and narrowing the image only where the phase difference has grown too large. Target sets the threshold and Depth the amount - in compressor terms a percentage equivalent of ratio (50% behaves like 2:1, 100% like a limiter). An optional RePhase function restores the energy that narrowing would otherwise lose, keeping punch and presence intact.

The order matters. A panning imbalance also shows up as Side content, so if you reach for M/S narrowing first you pull the off-centre element toward the centre and take its width with it - you sacrifice spread that was only ever off-balance. So correct panning first in L/R mode, leaving the width untouched; whatever Side energy remains is then genuine width, which M/S mode can rein in precisely where it is excessive.

Because all of this is dynamic and level-independent, Ancora works as a true "set & forget" processor - in effect two frequency-dependent compressors in one, a width compressor in M/S and a panning compressor in L/R, taming excess where it occurs while preserving the natural spatial character of your mix. Mixes processed with Ancora often feel more stable and focused without sounding narrower.

The spectrum display serves as both a real-time analyzer and an interactive curve editor:

• Click and drag any handle to adjust its frequency and value.
• Double-click to add new points at specific frequencies.
• Double-click on a handle to remove it.
• Left-click and drag to create a selection rectangle around multiple handles for grouped adjustments.
• Hold Shift and drag horizontally to lock the value.
• Hold Alt and drag vertically to lock the frequency.
• Hold Ctrl and click to select or deselect multiple handles.
• With Auto Curve Selection on, hover to highlight the nearest curve and click to select it, or grab a handle to select and drag its curve in one motion. Toggle it in the context menu.
• Hold the right mouse button over the display to Listen — audition a sweepable band of the input, its width set by the mouse wheel. Listen can also be bound to a key in the shortcuts dialog.
• While auditioning, left-click to drop a matching notch on the Depth curve — four points spanning the band with its edges anchored open and the inner pair pre-selected, so a single drag sets the notch depth.

Each curve maintains between 1 and 12 active points, automatically interpolating smooth transitions between them.

The bidirectional connection between sliders and curves employs an intelligent priority system to prevent feedback loops and ensure smooth operation:

When you adjust the main slider (Depth, Timing, or Target), the corresponding curve handles update proportionally while maintaining their relative positions. Conversely, when you modify individual curve handles, the main slider automatically reflects the average of all active points.

This system uses a priority mechanism that gives precedence to the most recent user action. Whether adjusting via the plugin GUI or through DAW automation, Ancora ensures that intended changes are applied without conflicts or unwanted feedback. For automation purposes, it is recommended to use the main sliders (Depth, Timing, Target) rather than individual curve points. Hold Shift while dragging the master slider to activate multiplicative scaling mode, preserving the relative proportions of curve points. (When dragging individual curve handles, Shift instead locks the frequency — see Curve Editing.)

Ancora processes any channel layout from simple stereo up to 9.1.6. The stereo-image correction is applied per symmetric channel pair — the front L and R, the side and rear surrounds, the height (ceiling) channels — each inheriting the L/R or M/S mode you have selected. Centre and LFE have no stereo pair and always pass through untouched. Surround and immersive layouts are supported in the VST3, AU and AAX versions.

By default only the front L/R pair is corrected. Additional channel sets are switched on individually, so a surround mix stays predictable and CPU is spent only where you actually want correction. All per-pair controls and meters live in the Channels panel, opened from the toolbar.

Additional options can be accessed using the standard context menu. This is opened by Right-clicking on a blank area anywhere in the UI. A click outside of the menu closes it.

• Auto Curve Selection — when enabled, hovering the display highlights the curve nearest the cursor and a single click selects it for editing. Off by default; your choice is remembered.
• Shortcuts… — opens the keyboard shortcuts configuration dialog.
• UI scale — switches to one of the quick scale presets from the settings dialog (100%, 125% and 150% by default). A preset your screen cannot fit is left out, and the greyed line Larger scales do not fit this screen says so.
• Copy state (Ctrl+C) — copies the current control states to the clipboard.
• Paste state (Ctrl+V) — pastes the control states from the clipboard.
• Save screenshot to desktop — captures the current plugin window and saves it as a PNG to your desktop.

Default shortcuts:

• Active (toggle): E
• Delta (toggle): D
• Depth (− / +): Q / W
• Timing (− / +): A / S
• Target (− / +): Y / X
• RePhase (− / +): R / T
• Bands (− / +): F / G
• Width (− / +): B / V

Step keys increment or decrement the parameter using snap values for stepped control.

Ancora continuously monitors the incoming signal and its internal state — filter memory and the like — and releases processing resources whenever they are not needed.

On a track that only plays during part of an arrangement, Ancora detects the silence and bypasses its filters and processing entirely, dropping to almost 0% CPU within a few milliseconds. Processing resumes the moment audio returns, with no change to the sound or to your settings.

In practice: more instances per project, and shorter export times.

Ancora was conceived and developed by Jan Ohlhorst.
Original documentation by Shane Johnson.

Software evaluation by:

Ady Connor, Aleksi Vuolevi, Andrew Boult, Bob Olhsson, Castle Mastering, Clément Bastiat | Storm Mastering, Cyril Meysson, Dan Suter | echochamber, Dan Worrall, Dax Liniere | Puzzle Factory, Dean, Dennis J Wilkins | Studio 12 Below, Diogo C. Borges, Eden Puder | Why Giacomo, Eric Recourt, EvilDragon, Ezequiel Morfi | Titanio Studios, Greg Reierson, Gregg Janman | Hermetech Mastering, Helmut Erler | mastering.heyrec.org, Ilya Orlov, Janne Hatula, Jean Dante, Jeffrey Rippe, Jerry Anthony Mateo, Joe Caithness Mastering, Joseph Lyons, Juan Carlos Sotelo | Campo Estéreo, Justin Perkins, Karl Mohr | Multibeat, Kosher Butcher Studios, Laurent Sevestre, Marco Vincis | Tera Mastering, Mark den Hartog | Zownd, Michael Wynne, Miro Pajic, Murray Campbell | Beatworld, Niklas Silen, Nil Hartman Mastering, Pete Grandison, Resoundsound Mastering, Rich Prewett, Richard Pentrose, Robi Bulesic, Roger Baltensperger | flameworks, Roland Löhlbach, Ronny Pries, Ruairi O'Flaherty, Sean Diggins, Sergey Makeev, Thaddeus Moore | Liquid Mastering, Uri Grzenda | Titanio Studios, Valentin Viktorovich | Zvukofor Sound Labs, Vitaly Zolotarev.