01 / Vocal automation

Open source · Free · GPL-3.0
Windows 10/11 (x64) · VST3 format
Offline · No account · No data collection

SCVB — Synchain Vocal Balancer

Give your time back to the music.

Every song has a dozen or more vocal tracks waiting for you to draw their pan and volume automation — slow, tedious, repetitive, and an easy way to end up with tendinitis. SCVB analyses all your vocal tracks together, works out pan and volume curves for each one, and writes them straight into your DAW as automation.

Meet SCVB Skip to download

Drawing time18:26

Drawn by hand: 1,106 of 1,106 values

Keep the voices from crowding into one spot,

make every singer's part sound equally loud,

track by track, section by section, even line by line.

One point a second — still 18 minutes for this song.

This is a job for an algorithm.

Using the plugin's built-in demo project: 15 tracks · 5 minutes · 553 phrase segments × pan/volume = 1,106 values to decide by hand.

Or — play it once, click once, play it again.

01 · CaptureTurn capture on and play the song through once. SCVB records only each track's loudness features — never the audio.
02 · AnalyzeOne click: it segments automatically, balances the loudness of every segment, then spreads the voices apart with equal-power panning. Before you click, it tells you which segments will change and which manual edits it keeps.
03 · WriteSwitch the output to “Write automation”, put your DAW in Latch (recommended) or Write, and play it again: 15 tracks × pan/volume, 30 automation lanes written into your project.

Affects 553 intervals / 15 tracks; 48 manual edits will be kept

89% of the range is covered; uncovered parts stay as they are

02 / The real thingThis is SCVB Output.

02 / The real thing

This is SCVB Output.

Workflow

Four steps. Done.

Play to capture
Analyze
Arm host automation(Latch / Write)
Done

Play to captureAnalyzeWrite host automationYou're done

The whole vocal stack on one screen.

Hover any card or any item below.

01 Capture: One pass; loudness only, never audio.
02 Analyze: One click segments and balances loudness and pan.
03 Output: Write automation, then play it again.
GROUP: Eight groups, A–H, 15 tracks each.
WIDTH: Set the width you want.
MS BALANCE: Bus Mid/Side balance.
LEAD SELECT: Detected by the algorithm, or pick a track as lead.
Pan and volume per track: Position is pan, bar height is volume.
Transition time between segments: 20–300 ms ramps, never a jump.
RANGE: A capture range you can switch freely.
Angle volume: An EQ over pan angle.

15 tracks, and any one can take over.

Each track explains one control: hover any track.

01Lead Vocal 1Status light: Connection status at a glance
02Lead Vocal 2CH: Channel number
03Harmony LTrack name: Taken from the host track name, editable
04Harmony RPAN: Pan knob, driven by the engine
05Harmony CW: Stereo spread
06Ad-lib 1Volume: Live level and peak; driven by the engine
07Ad-lib 2PRIO: Track priority in the pan algorithm
08Octave DownLEAD: Lead lock, kept centered
09Octave UpPair: Linked pair, mirrored
10Chorus LJoin volume: Whether it joins volume balancing
11Chorus RJoin pan: Whether it joins pan balancing
12FXFreeze P: Pan adjusted by hand
13SpokenFreeze V: Volume adjusted by hand
14Chorus CON: Whether this track joins the algorithm
15OutroRestore auto: Clear manual tweaks, follow the engine again

Cut by phrase, with cuts landing on breaths.

Hover the areas of the waveform page.

Features only: Retune thresholds with live preview, no new capture.
Redo a selection: Tick track headers to pick the tracks to recapture or analyze.
Snap: Dragged boundaries snap to pauses and breaths.
E / C: Edited segments show E, new ones C; reanalysis leaves them alone.
Per segment: Every segment has its own pan and volume, editable and lockable.
Zoom: Zoom the lanes freely, horizontally and vertically.

Demo project · 15 tracks · 553 segments · 48 manual edits

03 / Capabilities

Put your energy
where it matters more

15
tracks / group
8
vocal buses (A–H)
2
version slots
30
automation lanes
20–300
ms adjustable segment transitions
中ENFR
UI languages

Auto-segmentation + loudnessBS.1770 K-weighted / RMS / peak dBFS
Equal-power panningLead stays centred; paired parts mirror left and right
Dual-pan + width for stereoNo M/S widening, so mono compatibility is guaranteed
Level curve by pan angleLike an EQ, except the x-axis is pan angle
Stores features, not audioAdjust thresholds with live preview — no recapture
Partial recapture / reanalysisRedo only the segment and tracks that went wrong
Compare two version slotsA/B the two versions at any time
Undo / redoAnalysis, manual tweaks and restoring auto can all be undone
Suggestion table + CSV exportData you can export and check
UI scaling 50–200%Fits small laptops and 4K monitors alike
One-minute interactive tourLearn the plugin's features with demo data, anytime
Warning bannersRouting, sample-rate and version mismatches — clearly explained

04 / Setup

Input, Output and a standalone monitor window

SCVB Input goes in the last slot of every vocal track's plugin chain; pick a channel (01–15) and a group (A–H). SCVB Output goes in the first slot of the vocal bus: it analyses, balances, sums and writes the automation. SCVB Monitor is optional: it only watches, takes no channel and writes no data.

While the connection is healthy, Input mutes its own track and the sound comes out of the Output bus instead. Volume and pan are recorded and controlled by 30 automation lanes, and you can fine-tune them by hand.

Connection healthy: 15 Inputs have taken over; the sound comes out of the Output bus.

15 tracks per group
8 groups, A–H
2 version slots
30 automation lanes
plugins talk only via local shared memory

05 / Open source

0Cost
0Accounts
0Data collection
0Network requests

Free. Open source. Quiet.

SCVB never goes online: no update checks, no data collection, no account. The source code and documentation are fully public — use, modify and redistribute them under the terms of the GPL-3.0-or-later.

GPL-3.0

Source and docs, all public

The plugin, UI, tests and design docs live in one public repository, updated with every plugin release.

View source Third-party notices

Offline

None of your information ever leaks out

No update checks
No data collection
No online license check

Verifiable

Unsigned, but checkable to the letter

The package is not code-signed; every release ships a SHA-256 that matches the GitHub Release notes character for character.

If it saved you a few hours, tell a colleague about it.

06 / Download

Starting now,
give your wrists a break

Pre-release · Release Candidate

This is SCVB's first public release, published as a pre-release, so it may still have known issues. Before you download, take a look at the known-issues list (in Chinese).

SCVB-v0.9.0-rc.1-win64.zip8.2 MBWindows 10/11 (x64) · VST3 format

v0.9.0-rc.1Pre-releaseReleased Sep 30, 2026

Download v0.9.0-rc.1 Source

Mirror: GitHub asset · Release page

SHA-256

12d4fd4bdbb99ba8d5a04ced2f0652a342d4334f92442997f88d0ea96c36ba69Get-FileHash .\SCVB-v0.9.0-rc.1-win64.zip -Algorithm SHA256

In the package

SCVB Input.vst3required
SCVB Output.vst3required
SCVB Monitor.vst3optional
INSTALL.txt
LICENSE.txt
THIRD-PARTY-NOTICES.md

Install in 5 steps

Download and verify the SHA-256Run Get-FileHash in PowerShell and compare it with the Release notes, character for character.
Extract the zipRight-click the zip → Extract All. If Properties shows an “Unblock” checkbox before you extract, tick it first; if not, there's nothing to do (the plugins are not code-signed).
Copy the three .vst3 bundlesThe whole folder of each, into C:\Program Files\Common Files\VST3\ (Monitor is optional)
Rescan in your DAWInput, Output and Monitor appear in the plugin list.
Read the “nine rules of use” firstOpen the docs (updated with every plugin release)

System requirements

OS: Windows 10 1809+ / 11
Arch: x64
Host: A DAW with VST3 support
Runtime: WebView2 Evergreen

All three plugins come from one zip: install and update them together, and never mix versions.

Waiting for your feedback

Cubase 14 / 15	Tier 1	Tested
REAPER 7	Tier 2	Partly verified
Ableton Live 12	Tier 3	Awaiting feedback
Studio One 6	Tier 3	Awaiting feedback
FL Studio	—	Not in v1 scope

Mac visitors: currently available for Windows 10/11 (x64) · Watch on GitHub

On your phone? Open this page on a computer to download

07 / FAQ

Questions you might have
before installing.

Didn't find your answer? Open an issue on GitHub, or see the Synchain FAQ page.

Will SCVB make decisions for me?

No. It writes first, then you fine-tune: what it prints is ordinary DAW automation — a starting point, not the final word. You always have the last say: host automation takes priority over frozen manual values, and manual values take priority over the engine's curves.

My vocal tracks went silent after installing — why?

While the connection is healthy, Input mutes its own track and the sound comes out of the Output bus instead — that's by design, not a fault. If Input can't detect Output, each Input automatically switches back to passthrough and the track plays as usual. We recommend reading the “nine rules of use” before you install.

Why does rendering a vocal track on its own give me silence?

Once connected, the track's sound comes out of the SCVB Output on the bus, so rendering that track on its own — a single-track export, Freeze or Render in Place — gives you a silent file; if you choose to replace the original audio, the original is replaced with that silence. Export the vocal bus as a whole; if you really need a file of that track alone, bypass or remove its SCVB Input before rendering. See Exporting and rendering in the user guide.

Which DAWs are supported?

Listed honestly by tier: Cubase 14 / 15 tested (Tier 1); REAPER 7 partly verified (Tier 2); Ableton Live 12 and Studio One 6 waiting for your feedback (Tier 3); FL Studio is not in v1 scope. That doesn't mean hosts that are off this list or outside Tier 1 aren't supported — we just haven't tested their stability and behavior yet.

Is there a Mac version?

SCVB is currently available for Windows 10/11 (x64). To get notified as soon as a new version is out, Watch the repository on GitHub.

Does it need an internet connection or an account?

No. SCVB has no update checks, collects no information and needs no account; Input, Output and Monitor talk to each other only through local shared memory.

Will it touch my existing automation?

It only writes when you turn on “Write automation” and confirm, with your DAW in Latch or Write mode — please don't use Touch. When you reopen a project, SCVB shows a guard banner first and only continues after you confirm.