Mid/Side processing in modular

I've been playing around with Mid/Side processing in Eurorack, lately. As it's not easy to find helpful information on that topic, I thought it might be a good idea, to start a thread here, for discussing and collecting information.

Mid/Side processing is a commonly used mastering technique (more info here and here), but can also be used in modular synthesizers, to enrich/enhance/manipulate your stereo image. The basic principle is based on splitting a stereo signal into one sum (Mid) and one diff (Side) signal. These are mono signals of their own, which can be processed independently and differently, before being combined, to form a stereo signal again.

In Eurorack this can be done with modules such as the Worng LRMSMSLR or Shakmat SumDif.

I usually use this method inside my system to gain a wider stereo image, by splitting my master stereo out and processing the Side signal as follows: cutting its low end, boosting its mid frequencies and raising its volume. Works pretty well (apart from that irritating but logical behaviour described and clarified here).

I think it's a great technique to play around and get creative with. I would be interest in how others judge and use this in modular synthesis. What are your experiences, tips or best practices regarding Mid/Side processing in Modular?

EDITED Dec 19th 2020, 12:02

I don't use this on my modular gear, Instead, what I find useful about M/S "abuse" is its ability to spread the mix and, thanks to some phasing trickery in the typical M/S network, the ability to cause the stereo image to exceed the left-right boundaries. So I tend to use these on submixes when I need a 'wider' result, and on some more ambient stuff, I'll put a M/S network plugin on the mixbus to make that stereo field sound massive and deep.

Mind you, there are some risks to this. One thing it'll do is to make your mixes VERY mono-incompatible. Also, you have to keep an ear out for phase cancellations that the M/S network settings might be causing in more extreme settings. Plus, if you want to put something processed like this on vinyl, you'll have to use some serious low-end summing to mono to make the track's low end under control. If that's not done, your lathe engineer will be cussing you up and down, because out of phase BASS results in a situation where the cutting head cannot physically cut that to a lacquer...and REALLY extreme out of phase bass can, in fact, wreck the cutting head!

Hi Klngvrhltnss and Lugia,

Interesting tread! How to place something in stereo right or left field is kind of half-way understood however getting something beautifully placed in the middle, so it sounds perfectly well in the stereo sweet spot is getting less clear to me. Then, even more unclear to me is, how to put for example one instrument in the front-middle of stereo and another instrument in the back-middle of the stereo field; I have no idea. With that I mean that you really can hear that one instrument is "closer" to you while the other instruments seems to be more far away from you (i.e. away from the listener). Any information on that would be very welcome. Preferable within Eurorack but if that's getting too difficult then out of the Eurorack is fine too.

Thank you very much in advance and kind regards, Garfield.

My suggestion for listening to get a real sense of how stereo field depth (or field depth in general) to work would be to pick up a copy of the Beach Boys' "Pet Sounds", especially the recent (2001) reissue that contains both the original mono mix by Chuck Britz and Brian Wilson, but which ALSO has a new stereo mix made by Brian and Mark Linett. This is a great opportunity to really deep-dive and study HOW these mixes work, because the stereo version went back to the source reels for the new mix, so in BOTH cases, they're working from the same recorded material.

What's really amazing is how the stereo field behaves...and then contrasting that with the 1966 mono version. In both cases, there are a lot of "depth cues", but this just makes the 1966 mix even more jaw-dropping, because Britz and Wilson were able to give an apparent front-back depth of field WITHOUT the use of stereophonic mixing. It's hard enough to get that feel out of a stereo mix (M/Sed or not!), which frankly makes the 1966 mono mix a work of pure genius. Seriously, this one album deserves to be carefully studied by ANYONE working with audio engineering, whether they do electronic music or not!

Hi Lugia,

Thank you very much for the recommendation of Beach Boys - Pet Sounds (2001 reissue), I couldn't find it that quickly (the right reissue version that is), so I have put that on my CD/LP wish list, hopefully I can find it one day (here in Europe).

That's indeed very interesting to get that front-back depth without the use of stereophonic mixing, however in "our case" of a Eurorack, any idea how to do that? Or is this some kind of "secret-recipe" (like top chef-cooks also wouldn't tell us their recipes) for audio engineers not telling us how to do it? :-)

Thank you very much and kind regards, Garfield.

It's voodoo, really...while I can understand stereo field depth, how Brian Wilson and Chuck Britz got that depth in a MONO mix still mystifies me...along with a lot of other people. "Pet Sounds" is so full of audio mysteries, one could (and many HAVE) spend one's entire doctoral dissertation in audio engineering studying it and breaking down what can be gleaned from it. Some of what I hear, though, seems to involve the amount of reverb added to different layers along with some very hi-tweak level settings. But there's a problem there, in that what they used for reverb weren't clear. Mark Linett thinks they used plates, but from my experiences with my own Ecoplate II, I'm more inclined to think that we're hearing a combination of those on some isolated parts, and the rest is piped thru United Western's chamber. Nevertheless, the album only uses tape slap and reverb for processing, and there's some indication that they actually printed the reverb on the original takes in many cases, not opting to add all of it in mixing.

The biggest problem, though, lies with Brian himself...this album marked the beginning of his acid-fueled mental decline, something which would go full-blown when work on "Smile" was under way. And since Chuck Britz died in 2000, the actual details of HOW this was mixed are rather lost now. It's known, though, that this was mainly done on 4-track machines, not unlike what The Beatles would also use on "Sgt. Pepper", and "Pet Sounds" may well have pushed that decision by them and George Martin. So, yeah...this album remains an amazing audio engineering mystery in a number of aspects; reading how Mark Linett had to re-piece together all of the master reels for the stereo mix in the reissue's liner notes just sounds like utter madness! Nevertheless, the album is a frickin' monument...it's arguable that ALL prog started from it, given its popularity in the UK and its similarities to the first prog albums that would start to appear in subsequent years. But in the USA, it was largely dismissed when it came out...it's only been in the past 20 years or so that the importance of "Pet Sounds" has become lots clearer. Frankly, I'd put it right up there with Stockhausen's "Kontakte" as a body of work that requires careful (and rewarding!) study.

You are making me want to listen to the Beach Boys!

You ought to! After all, this is the first album where they used the "tannerin", a ribbon-controlled theremin, on "I Just Wasn't Made for These Times". "Good Vibrations" usually gets the nod for that, but the truth is that this other track came out first, despite both of them being cut on the same set of sessions.

Hello Lugia,

Thank you very much for the insight information, very interesting. I wrote down the Karlheinz Stockhausen - Kontakte album on my "to buy list" :-) For the Pet Sounds I can't find an available copy though.

Kind regards, Garfield.

It should be out there somewhere. Have you tried looking for a used copy via Amazon? I often find that 'difficult to find stuff' turns up there routinely...you just have to be careful to avoid the collector-dealer types so that you don't wind up paying twice the price.

As for "Kontakte", there's actually TWO versions of it...and you can get both via the Stockhausen-Verlag website. Their editions are more expensive than others, but the MASSIVE liner notes (by Da Man Hisself!) on every work in the series is well worth the cost. Anyway, there's a version that's ONLY the electronics, and the other with piano and percussion. Both are 100% worth having. http://www.stockhausen-verlag.com/

Hi Lugia,

Thanks a lot for that stockhausen link, will check with them, seems they are located here in Germany, so should be easy for me then :-)

Thank you and kind regards, Garfield.