MS RAW Decoder

I confess straight away that I am a novice with audio. I have a Zoom H6 which I enjoy and have been reading about MS RAW files. I have been watching some videos but they baffle me but it seems as though it is something that I might make use of.

Does anyone know of any tutorials or articles that might help without drowning me in jargon?
Is anyone ever likely to produces a plug-in or does one exist?
Is it as technically difficult as I seem to think?


This audacity plug-in has a MS decoder option …
https ://
( but I’ve not used it myself: I use MSED plug-in in Audacity on Windows, but it is available for MACs ).

MS RAW files

I’m not sure about the “RAW” part… Usually RAW means a PCM audio file with no WAV file container/header.

Does anyone know of any tutorials or articles that might help without drowning me in jargon?

I don’t know… It’s an special recording technique and it’s not commonly used. There’s a lot of “mythology” in audio so you could end-up reading a lot of nonsense.

There could be an advantage in some situations simply because you have a microphone pointed directly at the main-source (such as the singer in the middle). And since the center mic is a different type/model of microphone and the mics are pointed differently, it will have a “different sound” than regular stereo. That different sound could be better or worse.

Is it as technically difficult as I seem to think?

Normally it’s a little tricky to set-up M/S recording and you normally need a figure-8 microphone which isn’t rare in a recording studio but most people don’t own one. But, I guess it’s easy with the H6.

“Mathematically”, it’s simple for the computer. You convert stereo to M/S by adding left-right to get the center (M) and subtracting to get the sides. The process is simply reversed to get-back the stereo original stereo. It’s 2-channels either way so you can save M/S in a normal 2-channel stereo file. And, it’s a lossless* & reversible.**

Some mixing/mastering engineers convert stereo to M/S so they can process the center & sides as separate “mono” files (EQ or reverb, etc.). But, you have to be careful because you can get some strange side-effects when you restore the stereo.

You convert stereo to mono with addition (that’s the “M” without the “S”). That can be done in analog or digitally.

Subtraction is an “old trick” for center-channel vocal removal (that’s the “S” without the “M”). The Audacity vocal removal works that way (with some optional frequency filtering so you can keep the centered-bass, etc.)

Subtraction can also be done with analog or digital. A million years ago I made a crude surround-sound setup with an (analog) op-amp sending the difference signal to the rear speakers (leaving the front stereo untouched).

The Zoom website says:

Together with the onboard MS decoder provided by the H5 and H6, they capture a fully mono-compatible stereo image that can actually be adjusted after recording –

So, maybe you’re getting a regular stereo recording from the M/S microphone setup, and/or maybe “RAW” means you’re getting the original M/S recording.

***** Of course you have to remember it’s M/S or it’s going to sound screwy when played-back in stereo. :wink:

****** To be perfectly lossless it has to be done in floating point because you can get clipping when you sum in an integer format. (Audacity uses floating-point internally)

That plug-in is very easy to use.
It’s a “Nyquist plug-in” and installation instructions are here:

Once installed and enabled, all you need to do is to select the track (Selecting Audio - Audacity Manual), then launch the “Channel Mixer” effect from the Effect menu. Select the “Mid-Side Decode” option, and apply.

Thanks everyone.

There’s a lot to take in there but I found the responses generous and helpful.

In my meanderings I found this YouTube tut which made sense to me.

Thanks again


The “Mid-Side Decode” option in “Channel Mixer” does all of those steps automatically.

Thank you

I will definitely check that out.