Kerf Audio Analyse 1 for REAPER · coming soon
Analyse 1
Free LUFS meter and master-bus analyser for REAPER
See everything leaving your master bus. Loudness, VU, peak, phase, the waveform and the spectrum, all live in one strip docked across the top of REAPER. No plugin to insert and nothing to arm: it reads what REAPER is actually sending to your speakers.
Try it here, in your browser
This is the Analyse 1 strip, rebuilt for the web. Press play and a drum break runs through it. The meters are measuring it live, and the tools work: fold to mono, solo the low end, dim, freeze, and click the peak label to change scale.
Momentary and short-term LUFS
Momentary (the last 400 ms) and short-term (the last 3 seconds), measured to ITU-R BS.1770-4 and EBU R128. The one to watch when you work to a target.
The weight of the mix
A classic needle with proper 300 ms ballistics, 0 VU at -18 dBFS. Slow on purpose, so it shows body rather than every transient.
Fast peaks, with RMS
Left and right peak meters with an RMS marker, orange then red near full scale. Click the label for dBFS, K-12, K-14 or K-20.
Width and phase at a glance
A stereo vector scope with a correlation bar from -1 to +1. If it keeps lighting up red on the left, part of the mix will vanish in mono.
A waveform that stands still
Triggers on rising zero crossings, so a steady tone holds its place. Scroll to zoom the time axis. Louder is brighter.
A scale that never moves
20 Hz to 20 kHz on a fixed log scale, so sessions compare by eye. Hover to read the frequency, the nearest note and the level.
The spectrum over time
A scrolling waterfall that catches resonances, ringing tails and noise too quick for the spectrum. Hover to see how long ago.
Check the mix without touching it
Mono, LF solo and a 20 dB dim act on what you hear only, never on a render. An orange bar tells you when one is on, so you cannot forget it.
Hold one moment still
Every module has its own freeze button, and Freeze all holds them at the same instant, so the spectrum and the waveform really match.
Nothing to insert, nothing to arm
Most meters are plugins: you put them on the master, remember where they are, and hope nothing after them changes the sound. Analyse 1 is a REAPER extension instead. It listens at the very end of the chain, after the master bus and its effects, so whatever you hear is what you see.
Open it from Extensions › Kerf Audio Analyse 1: Show/hide panel and it starts working. It docks across the top of REAPER, at the right height, the first time it opens.
On REAPER’s audio thread it does one thing: it copies the output into a buffer. It never waits, never locks and never asks for memory, so it cannot cause a dropout by being busy. The measuring and drawing happen about fifty times a second on the interface thread, and stop entirely when the panel is hidden.
Make the strip yours
Show, hide, reorder
Pick the modules you want, drag them into any order and drag the gap between two to resize them. Save layouts by name.
Pop one out
Put any module in its own window, such as the spectrum on a second screen. Close it to send it back.
Four accents, light or dark
Coral, teal, blue, or one that follows your REAPER theme. The screens look the same in both modes, so a meter reads the same at 2am and at noon.
What it runs on
- Format
- REAPER extension
- Host
- REAPER 7.8 or later (64-bit)
- Platforms
- Linux, macOS coming soon
- Requirements
- REAPER 7.8 or later, 64-bit Linux x86_64 with glibc 2.35 or later: Ubuntu 22.04, Debian 12, Fedora 36 or newer macOS 26 Tahoe or later: coming soon
- Version
- 0.5.0, 11 October 2026
- Licence
- Free when it launches, on as many computers as you like. No licence key.
Questions
Will it be free?
Yes. When Analyse 1 launches there is no trial, no licence key and no card. Install it on as many computers as you like.
Why do I need an account?
So the download, and every update after it, lives in one place you can come back to. You can also choose to hear about new releases, but that is up to you.
Do I need to put a plugin on the master?
No. Analyse 1 reads REAPER’s output directly, after the master bus and its effects. There is nothing to insert or arm.
Does it measure integrated loudness and true peak?
No. Analyse 1 shows momentary (400 ms) and short-term (3 s) LUFS and sample peak, which is what you watch while you mix. For the integrated figure and the true peak of a finished master, use REAPER’s own JS loudness meter, or the loudness statistics from a dry-run render.
REAPER already has a loudness meter. What does this add?
REAPER’s JS loudness meter is a plugin you insert, and it measures loudness. Analyse 1 needs nothing inserted: it reads the real output after the master bus and shows loudness, VU, peak, phase, the waveform and the spectrum together, in one strip docked across the top of REAPER.
What LUFS should I master to?
There is no single right number. Spotify, YouTube, Tidal and Amazon Music play back at about −14 LUFS integrated, and Apple Music at about −16; louder tracks are turned down to match. Many genres are mastered louder than that on purpose. Watch the short-term reading in the loudest section, and keep true peaks below about −1 dBTP so the streaming encoders do not clip.
Which is the best free LUFS meter?
It depends on what you need. If you work in REAPER and want metering with nothing on the master, Analyse 1. If you need an integrated reading or true peak, in any DAW, a plugin meter does that: Youlean Loudness Meter has a free version, and REAPER has its own JS loudness meter.
Can Mono, LF solo or Dim end up in a render?
No. They change only what you hear, on the monitoring path after everything else. They never touch your project or a render, and an orange bar shows while one is on.
Will it slow REAPER down?
On the audio thread it only copies samples into a buffer, without waiting or locking. Measuring and drawing happen on the interface thread, and stop when the panel is hidden.
Is there a Mac version?
Not yet. Analyse 1 launches on Linux first, and the macOS build, for macOS 26 Tahoe and later, follows. Sign up below and we will email you when each one is ready.
Which Linux distributions does it run on?
Any 64-bit x86 Linux with glibc 2.35 or later: Ubuntu 22.04, Debian 12, Fedora 36 or newer, or any current rolling distribution. Install it with ReaPack, or copy the .so into REAPER’s UserPlugins folder. Neither needs sudo.
Is there a Windows version?
No. Kerf is Linux first: we do not make Windows versions of our REAPER extensions or plugins, and we have no plans to. The Windows build of the 0.5.0 beta has been withdrawn and will not be updated or supported.
Recent changes
Analyse 1, free when it launches
Analyse 1 is coming soon, on Linux first. It will be free, with no licence key and no card, on as many computers as you like.
Keep informed about access
One email when Analyse 1 is out. Nothing else unless you ask for it.
Kerf Modulators for REAPER
Envelopes, LFOs, drawn waves and followers for any plugin parameter, from one docked panel. Coming soon, at a £19 beta price.