KERO • Spatial Mastering

Spatial meter

Stereo field

Spatial confidence · awaiting audio READY FOR AUDIO

Selected field pair—

Width0Height0Depth0Force0

Frequency range10 Hz – 30 kHz

Width meter

Polar field

Spatial confidence · awaiting audio

Stereo energy map · L / centre / R · play audio to measure

Mastering chain

Every module listens to the same spatial model.

TONE

Musical tilt+0.2 dB

Low shelf−0.6 dB

Sub bass+0.0 dB

Upper bass+0.0 dB

Mid range0.0 dB

Low mid+0.0 dB

Centre mid+0.0 dB

High mid+0.0 dB

High shelf+1.0 dB

Upper high+0.0 dB

Air+0.0 dB

NEURAL SPACE

Safe width78%

anchorednaturalwide

Mono bass120 Hz

20 Hz120 Hz220 Hz

Mid / side balance0%

mid0side

Centre shift0%

leftcentreright

Depth field62%

Centre focus65%

PEAK

True peak ceiling−1.0 dBTP

−3.0−2.0−1.00.0

Intersample protectionSTANDARD

Intersample status—

Awaiting source analysis

Delivery profileCUSTOM

Sets a complete, safe starting point. Always verify the delivery requirements of your distributor or cutting engineer.

LIMIT

Target loudness

−9.0LUFS

INPUT

0.0

MASTERED

0−6−12−18−24

Target loudness−9.0 LUFS

−16−12−9−6

Limiter amount32%

gentlecontrolleddense

Limiter contourDYNAMIC

OriginalPreview

Peak——

Loudness——

Intersample——

Final check

Mastering Guard

AWAITING ANALYSIS

Mono—

True peak—

Intersample—

Gain reduction—

Stereo field—

Bass stability—

Analyse a source to start the preflight check.

Backstage Pro required

00:0000:00

Delta / auditionFULL MIX

Current source

Upload a track to begin

Format—Sample rate—Bit depth—Channels—

KERO • Spatial Mastering render

Processing

Preparing your master…

KERO • Spatial Mastering

Export settings

Bit depthSample rateEdit WAV metadata before export

WAV METADATA

Tag editor

These fields are written into the exported WAV as RIFF/INFO metadata.

ArtistTitleYearGenreISRCAlbumLabelCopyrightComment

KERO • Spatial Mastering ACCESS

Sign in

Use your Audion Backstage email or username and password. You will stay in KERO • Spatial Mastering.

Email or usernamePassword

KERO • Spatial Mastering GUIDE

From measured stereo to a controlled master.

Upload a stereo file, wait for its full-file analysis, then listen to the processed output while adjusting. Every control changes audio; every meter reads the current processed output during playback.

01 · ANALYSEKERO • Spatial Mastering reads the full source: peak, estimated loudness, intersample risk and stereo balance.

02 · LISTENUse play/pause or Space. The energy maps read only while audio plays.

03 · SHAPEMake a small move, listen, then use module bypass or Reset to compare.

04 · EXPORTChoose WAV bit depth and sample rate in Settings, then render the master.

LIVE STEREO METERS

Polar field: Each point comes from the current processed L/R audio samples. Left/right placement shows measured channel-energy balance; height is sample energy and side content. It is a live meter, not a 3D object map.
Width: Shows measured Mid/Side width from the same live output. Example: increasing Safe Width should spread the field when the source contains side information.
Correlation: Shows a smoothed L/R similarity from −1 to +1. Example: a sustained negative value calls for a mono compatibility check; brief movement is normal.
Stereo field: Uses the same measured energy trace inside the editable 4D control field. The grid is a control surface; the mist is live audio.

STEREO FIELD & 4D POINTS

Safe Width L / R: The outer paired nodes set the safe stereo boundary. Drag them symmetrically to change the maximum field width.
Centre field: The middle node moves the processed centre left/right and raises or lowers its emphasis. Example: use tiny centre shifts only to correct a persistent imbalance.
Side field: The inner paired nodes shape the area between centre and edges. Example: bring them in to make diffuse ambience more focused.
+ Add point: Adds a mirrored L/R pair. Width, Height, Depth and Force are then available below the grid. Example: start with Force 15–30% and listen before making a larger move.

TONE

Musical Tilt: Broad overall tilt. Example: a small positive move opens a dark mix; a negative move calms excess brightness.
Low Shelf + bass detail: Low Shelf is the broad bass control; Sub Bass and Upper Bass make narrower corrections around the lowest octave and upper-bass weight.
Mid Range + detail: Mid Range is broad presence; Low Mid, Centre Mid and High Mid target mud, focus and bite separately.
High Shelf + air: High Shelf is broad brightness; Upper High and Air refine brilliance and extreme top end. Example: use small moves first—often 0.5 dB is enough.

NEURAL SPACE, PEAK & LIMIT

Mono Bass: Sets where low frequencies are centred before spatial processing. Example: 90–120 Hz usually keeps kick and sub dependable.
Depth / Centre Focus: Depth controls the restrained spatial blend; Centre Focus protects the lead anchor. Increase Centre Focus if widening weakens vocals, kick or bass.
True Peak / Intersample: True Peak is the final ceiling. Standard is the normal intersample mode; Max is the most cautious option.
Target / Amount / Contour: Target sets loudness, Limiter Amount sets compression density, and Contour chooses Dynamic, Transparent or Loud. Example: start Dynamic with a lower Amount to avoid pumping.

A meter confirms behaviour; listening decides the master. Keep changes small, compare with bypass, and preserve mono compatibility and low-end stability.

KERO • Spatial Mastering GUIDE

Measured mastering, from source to delivery.

KERO • Spatial Mastering analyses the uploaded source before controls unlock. Every processing control changes the listening preview and the export uses the same chain. Read meters as evidence, then decide with your ears.

01 · ANALYSEFull-file source analysis measures loudness, true peak, intersample risk, stereo and bass stability.

02 · LISTENUse Play/Pause or Space. Live fields update only while audio plays.

03 · SHAPEMake small moves, use module bypass and compare with Delta.

04 · GUARDCheck mono, peaks, density, stereo and bass before export.

METERS & SPATIAL CONFIDENCE

Polar field: Live L/R energy map of the processed preview. It is a meter, not a 3D object map.
Stereo field: The mist is measured output; the 4D grid is the control surface that shapes the spatial processing.
Spatial confidence: Summarises the measured correlation, width and balance as Centre stable, Wide but safe or a mono warning.
Correlation: A sustained low or negative value needs a mono check. Short movement is normal.

DELTA / AUDITION

Mono: Auditions the L+R mono sum of the current master preview.
Sides: Auditions only side information: ambience, width and phase-sensitive content.
Low Band: Auditions the processed low band below 180 Hz to check kick, bass and low-end stability.
Delta: Plays KERO • Spatial Mastering processing minus a neutral, time-aligned reference. With every module off it is silent; click the active mode again to return to Full Mix.

STEREO FIELD & 4D POINTS

Safe Width L / R: Outer paired nodes define the safe stereo boundary. Drag them symmetrically.
Centre / Side fields: Centre adjusts the anchor; Side field shapes space between centre and edges.
+ Add point: Adds a mirrored L/R pair. Width, Height, Depth and Force then affect both sides together.
Force: Sets how strongly that field point influences its spatial area. Start low, listen, then increase only if needed.

TONE & NEURAL SPACE

Tone: Musical Tilt, broad shelves and the smaller bass, mid and high-band controls all use gentle ±3 dB ranges. Small changes matter.
Mono Bass: Centres low frequencies before spatial processing. Around 90–120 Hz usually keeps kick and sub dependable.
Safe Width / Focus: Width adds side energy; Centre Focus protects lead vocal, kick and bass. Use width and focus together.
Depth: Applies a restrained spatial blend. It should add depth without thinning the centre or low end.

PEAK, LIMIT & DELIVERY

True Peak / Intersample: Ceiling sets the final limit. Standard is normal protection; Max is most cautious. Off leaves risk visible rather than protected.
Target / Amount / Contour: Target sets loudness, Amount controls limiting density and Contour chooses Dynamic, Transparent or Loud. Keep gain reduction modest to avoid pumping.
Delivery Profiles: Streaming safe, Apple Digital Masters, Club, Dynamic and Vinyl pre-master set ceiling, protection, target, amount and contour together. They are starting points, not certifications.
Mastering Guard: Preflight uses full-file source analysis; playback adds live gain-reduction and output checks; export completes the rendered full-file verification.

EXPORT, TAGS & LIBRARY

Export settings: Choose 24- or 16-bit WAV and 48, 44.1 or 96 kHz before export.
WAV Tag editor: Enable Edit WAV metadata before export in Settings to enter Artist, Title, Year, Genre, ISRC, Album, Label, Copyright and Comment. KERO • Spatial Mastering writes them as RIFF/INFO metadata.
Library: Every saved source or master belongs to the current user. Choosing a master restores its audio and saved KERO • Spatial Mastering settings.
Final step: Export renders a new WAV, saves audio plus settings to the Library, then starts the browser download.

A clear meter is useful, but it does not replace listening. Compare Full Mix, Mono and Delta, preserve mono compatibility and low-end stability, and keep the master coherent rather than merely louder or wider.

KERO • Spatial Mastering

Library

No saved KERO • Spatial Mastering sources or masters yet.

KERO • Spatial Mastering LIBRARY

Delete file?

—

This permanently deletes the audio from KERO • Spatial Mastering storage. If it is a master, its KERO • Spatial Mastering settings JSON is removed too. This cannot be undone.