LoRo downmix matrix
LoRo Downmix – Fold a 5.1 Mix to Stereo With Control Over the Matrix
- 1st conversion free
- No installation
- No plugin
- Files stay local
Drop your surround mix
5.1, 7.1, quad or LCR. WAV, AIFF, MP3, M4A, FLAC, OGG. Folded to stereo LoRo in your browser
✓ 1st conversion free. ✓ Your audio stays on your device.
What this tool does for you
- Convert a 6-channel 5.1 file to a two-channel stereo master
- Control how much centre, surround and LFE reaches the fold
- Preview the result before export
- Everything runs in your browser. Files are never uploaded to a server.
How it works
01. Drop the 5.1 file
Channel roles are detected from the layout and metadata.
02. Balance the matrix
Nudge the centre and surrounds until the dialogue sits right.
03. Export the stereo
WAV, AIFF or MP3, at the rate you choose.
The 5.1 fold in practice
Channel order comes first
Before folding anything, confirm the file's channel order. SMPTE order is L, R, C, LFE, Ls, Rs; film order often places LFE last. Fold a film-ordered file with SMPTE assumptions and dialogue ends up in a surround leg.
One deliverable, two masters
A stereo fold is a deliverable in its own right, not a preview. Most audiences will hear it rather than the 5.1, so it deserves its own level check and its own listen on small speakers.
Professional use cases
Post-production
Produce the stereo companion to a 5.1 master for online and broadcast platforms.
Filmmaking
Make a festival screener that plays correctly on a stereo playback system.
The coefficients, channel by channel
| Channel | Goes to | Default coefficient |
|---|---|---|
| L — left | Lo | 1.0 (0 dB) |
| R — right | Ro | 1.0 (0 dB) |
| C — centre, dialogue | Lo and Ro | 0.707 (−3 dB) |
| LFE — low frequency effects | dropped | 0 (fader available) |
| Ls — left surround | Lo | 0.707 (−3 dB) |
| Rs — right surround | Ro | 0.707 (−3 dB) |
Every coefficient above is a starting point, not a lock. Each channel has its own fader, so a mix where the surrounds carry a lot of hard effects can be folded with the surrounds a few dB lower without touching the dialogue, and a dialogue-heavy scene can have its centre pushed back up. Judge it on the live preview rather than on the numbers.
Your audio stays on your device
Decoding, processing and export all run in your browser: compressed formats are decoded with the Web Audio API, and WAV, AIFF and MP3 files are written by JavaScript in the page. Your audio is never uploaded to our servers. Only anonymous page analytics and, if you sign in, your account and payment details go online.
Frequently asked questions
- What is the LoRo downmix matrix?
- Lo = L + 0.707 × C + 0.707 × Ls and Ro = R + 0.707 × C + 0.707 × Rs. The centre and the surrounds are folded in at −3 dB so the summed stereo pair keeps roughly the same energy as the surround mix.
- Why is the dialogue quieter after a LoRo fold down?
- Because the centre channel, where the dialogue lives, is attenuated by 3 dB in the matrix. Raise the centre fader a couple of dB before exporting and the dialogue sits back where it should.
- What happens to the LFE in a LoRo downmix?
- It is dropped by default, which is the usual practice: the LFE is a separate effects channel, not a bass extension of the mix. You can fold it back in with its fader if the material relies on it.
- Is this the same as an LtRt or a broadcast downmix?
- No. LtRt encodes the surrounds with a phase shift for matrix decoders, and broadcast chains add their own dialnorm and loudness handling. This tool applies the LoRo matrix only, with manual per-channel gain.
- Which layouts can I fold down?
- 5.1, 7.1, 5.0, quad and LCR. Channel roles are read from the file layout and can be reassigned by hand if the delivery used a different channel order.
- How do I avoid clipping when summing channels?
- Summing three sources into one leg can exceed 0 dBFS. The peak level of the folded pair is shown before export, so pull the offending fader down rather than letting the export clip.
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