Mid Side Processing

Hey All! Recent Drambo convert here. I’m in love with the workflow and it’s slowly becoming the center piece of my music creation. I wanted to share what I’ve learned in trying to do Mid Side processing and also get some advice on improving it!

I currently have a mid side rack which has a Stereo to L/R followed by the add and subtract math modules to get the mid and side out of it. I then have racks within the rack to process each path independently and then recombine on the other side with more math modules and an L/R to stereo. This is working ok, but immediately out of the gate colors the sound more then I would like. When you then add a few peaking eqs into the mix even before tweaking the settings it’s colored even more.

This isn’t a huge deal for creative sound design, but I was hoping to use the technique in an all Drambo mastering chain I’m cooking up. is this inherent to the Drambo audio engine? It sounds like subtle phase issues. I’d love to hear your thoughts and experiences. I can upload some audio and patch examples later as well!

Comments

  • edited October 25

    This would require a closer look at your project.

    Phase delays can indeed be introduced by some modules, mainly the ones that do more than just simple arithmetic calculations.

    M/S depends on the correct phase so it may be necessary to add a delay module here and there to keep everything in-phase.

  • Oh and by the way, welcome to our forum! 😊

  • edited October 25

    Thanks @rs2000! I’ve attached a project file with a synth that has a lot of stereo information followed by my mid side rack. When toggling the rack on and off you can easily hear the phase issues being introduced. I tried adding a delay to the mid signal and adding around 1ms helped a lot but it was still a different signal coming out of the other side.

    i wonder if this is just too precise for how the Drambo sound engine works. Thinking about it more, I may need to add delays for the input and output processing modules as well if they are also being processed at slightly different sub 1MS speeds. I think it’s more trouble then it’s worth from a mastering stand point, but I will still play with it from a sound design perspective. I’d love to be proven wrong though!

    Thanks for the warm welcome!

  • Ok I did some more investigating and realized my rack has a mistake. The left and right output are flipped. After fixing that, the rack with no additional processing is completely transparent when toggled on and off. However, adding processing to the rack still has some weirdness in it I don’t understand. I’m going to investigate some more!

  • edited October 25

    I have solved it! It’s all about headroom. The add and subtract modules both double the amplitude of the wave form and when the amplitude maxes out hard clips them. I fixed this by dropping the signal down -36db upon entering the chain and boosting back up by +30 upon leaving (the math modules inherently add 6 db to the signal). You then have another round of attenuation for the processing section, but now any compression or EQ applied works and doesn’t introduce any artifacts, phase issues or loss of dynamics. So happy!

    if anyone wants to play with it, I added it to patch storage here:

    https://patchstorage.com/mid-side-channel-strip/

  • Wow, perfect @parkerfrost, you solved it faster than I could even respond 😃

    Thanks also for sharing it on Patchstorage, way to go!

    Have a great weekend...

  • @rs2000 Haha! Sometimes all it takes is trying to explain the problem to someone else. Thanks for your help!

  • Nice work @parkerfrost and welcome aboard!

  • This thread inspired me to do some experiments myself (great work @parkerfrost )

    have been having plenty of fun just processing stock loops beyond recognition.

    But clear me out, separating mid/sides is just this easy, or am I missing something?


  • @pedro

    I tried your example and it isn't as simple as that though I was hoping that

    it was because it would've saved me some time and effort ages ago.

    Here's my MS-Decoder which works as expected.

    https://patchstorage.com/ms-decoder-v-1/

    There's a Knob labelled S-M Mix, (stereo to mono mix)

    When it's fully at S then you will hear the stereo image only without mono and conversely when it's fully at M then you will only hear mono.

    Obviously if you want to process the stereo image and/or the mono image all you have to is open it up and have a play.

  • Just starting to study your preset, why is there a need for stereo to L/R? You can subtract center from a stereo signal, with no need to separate channels. Can’t we?

  • Basically that's how I put it together at the time (shrugs shoulders and grins).

    Admittedly it's been awhile since I've looked at it however I know it works as expected which is why I pulled it back up,

    however I've just tried subtracting the mono image from the stereo image

    the way you have done it in place of what I had done for the Side and it works as expected.

    It does need the mid signal as well for it to work properly which is

    why it didn't make sense when doing it just with the example you provided so thank you.

    Learning everyday. :)

    Oh and for the record more often than not I just get things working instinctively which is useless

    when trying to explain things hence why I haven't volunteered for the module descriptions. :)

  • @gravitas oh I totally understand you, it’s just that over the years some of @rs2000 ’s wisdom (less is more) has rubbed off on me and I find myself asking if things couldn’t be simpler. They usually can. I don’t think we give nearly enough credit to how @giku has worked hard to make this “just connect anything to anything” mentality dummy-proof

  • Agreed for sure.


    My MS-decoder was put together when I first started learning dRambo so it was a set and forget.

    @rs2000 assistance and teaching over the years has also rubbed off on me so when I get things working

    I walk away for awhile and then open up a project and see if I can firstly figure out why I did something

    and then the next step is to figure out how to simplfy it if possible.

    If you were to look at some of my earlier projects they are big and clunky and now they much smoother

    and that is definitely because of @rs2000 and @giku.

  • @pedro @gravitas Love the additional insight here! @gravitas It’s amazing how there are so many ways to do the same thing! Love your approach.

    I've been refining my technique since I last posted. My MS rack now features independent encoders and decoders. The encoder bonds the mid signal on the left and side channel on the right of the stereo stream. The decoder undoes that. In the middle you can do whatever processing you want!

    I plan to update my patch as well as upload a compressive m/s utility pack, but that won’t be for a little while. Here’s the current iteration of my MS rack if anyone needs it!


  • @parkerfrost

    Thanks, I've always learnt by rite of fire. :)

    The one thing about dRambo is that there are no hard and fast rules except the signal path goes from left to right, up to down.

    There are some workarounds but that's it.


    Thank you for sharing.

  • The real patch is the friends we make along the way 😂

  • edited October 29

    @parkerfrost @gravitas now that I had a proper listen, your module sounds much cleaner than my simplified attempt. I actually started from a stereo to L/R approach, guess it pays here not to simplify too much 😅

  • Nothing much, just having fun

  • @pedro thanks for sharing! Nothing like the time honored tradition of mangling the Amen break. Dig the vibes

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