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Creating A Z-Plane Filter In Ableton Live Tutorial

Ableton Live Tutorials

About the author: The Creature is an up and coming Bass Music Artist residing in Vancouver, BC. Taking compositional cues from his previous 8 years of drumming in Progressive Rock and Fusion Jazz ensembles, he dishes out musicality not often heard in today’s electronic music. Combined with his voracious appetite for fresh sound design techniques and machine-like work ethic, he is rapidly becoming a force to be reckoned with.

In my first 2 years of making bass music, I remember spending countless hours scouring forums like dogsonacid for tidbits of information that would hopefully take my production to the next level. One topic which I came across that intrigued me was from a Billain Q&A approximately three years ago. He discussed (a few times during the Q&A) a “z-plane filter”. He only hinted at how he achieved it, though, and to this day as far as I know it remains a trade secret of his. Looking at other posts around that time, plenty of other people were also interested in how this would be done but nobody posted a solution that I found to be simple and concise enough to be usable.

Z-Plane Filter In Ableton Live

Before I show you the method at which I have arrived for creating this elusive beast, let’s get a little bit of background on the z-plane filter. It was first conceived by a company called EMU in 1993 on their hardware synth called the Morpheus. It allowed smooth audio interpolation between up to 8 filters by a large array of different modulation sources. Each of the 8 filters could be one of the basic filter shapes (lowpass, highpass, bandpass, & bell EQ). There were 3 interpolation controls for most of the z-plane presets: X, Y, and Z (approximately 100 of the 197 presets had this). It would become a staple of EMU synths for years to come.

If the last paragraph is a little much to wrap your head around, I’m going to break it down for you here: the way I think of the z-plane filter (in terms of creating one inside Ableton) is a parallel rack within a parallel rack. This would only require 2 axes of modulation. I use the third axis of modulation to control filter frequency.

Z-Plane Filter Ableton

The red lines (x-axis) represent the automation of a single filter’s frequency~ a basic filter movement. The green lines (y-axis) represent a cross-fade between between two of these simple filters placed in a parallel rack. The grey lines (z-axis) represent the cross-fade between two groups of the previous x-y axis parallel racks.

Now let’s dig in and make one. First create an empty audio effect rack with two chains in it. Place one filter (it really doesn’t matter what type~ there is lots of room for experimentation with this) in each chain. Now map the frequency of each filter to ‘Macro 1’ of the rack and name that macro “X”. When you are done everything up to this step, your rack should look like this:

ableton rack filters
(I only show the notch chain, but the frequency of BP is also mapped to “X”)

Next, you are going to open up the chain selector window (click the “Chain” button above the list of chains) and set up a smooth cross-fade between your two filter chains you just set up. Select both chains, and drag the blue bars all the way to the right.

crossfader ableton rack

Now you will notice that there is a small white bar on top of each chain’s blue bar. Drag the top one all the way from right to left, and the bottom one from left to right. This creates the cross-fade between the two chains. To control this cross-fade, map the chain selector (above the cross fades) to “Macro 2” in the rack, and name it “Y”. This creates a more true fade between the two filters than macro’ing each chain volume, as other people might do. [This is due to the logarithmic nature of the decibel scale~ the macro control is linear and will create a dip in output volume when it is at 50%]

ableton crossfade parallel fillter

To realize the Z-plane control in this parallel rack is easy at this point. Select the whole Audio Effect Rack and group it again, to put it inside another rack (ctrl-G for Windows or command-G for mac users). Map the “X” and “Y” Macros to Macro 1 and 2 in your outermost rack. Select the chain containing your first Rack, and duplicate it. Name one ‘TOP’ and one ‘BOTTOM’. Repeat the previously explained process of setting up a cross-fade, this time between your ‘TOP’ and ‘BOTTOM’ racks. Now it will look something like this:

ableton advanced rack

All that is left to do at this point is go into the ‘BOTTOM’ rack, replace the filter in each chain with a new choice, and re map their frequency as desired.

This style of filtering (from the experimentation I have done so far) can create wildly varying results. What sound you get is not only dependent on what filters you place in each chain, but also how the “X” control is mapped to them, and then furthermore how you automate each control axis (cross-fade). It is one of these situations where it is best not to try and predict exactly how your macros will affect the sound, but instead try different automations as you go along and see what sounds best. Automating all the axes as you go along will likely yield a completely different output that doing them one at a time~ both methods are completely acceptable and I would recommend trying both.

Another thing to note is that this is a different take on the Z-Plane filter than the original from EMU. Before making the X-axis control a filter frequency automation, I originally tried creating their version of it, where each corner of the theoretical filter cube was a non-automated filter or EQ (8 filters in total). The X-axis control was a third level of chain cross-fade which moved between two different filters. I did not achieve the results I was looking for and found it too hard to wrap my head around, though it is an area that likely warrants further testing.

There is still much to be explored with this rack set-up. If you think about it, many more parameters can be mapped to each of the control axes than I have just described. I, myself, have only utilised it successfully a handful of times. I hope, though, that throwing it out to the public will revive this 3-year-old piece of sound design lore and perhaps the community at large will be able to push its application further than I could on my own.

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5 replies
  1. Elliot Wardle says:

    This is quite interesting but the Z-Plane filter is specifically MORPHING between various filters, not to be confused with CROSSFADING. Great read though 🙂

      • Elliot Wardle says:

        Hey Luke 🙂 I have absolutely no idea unfortunately. I’ve been researching Z-Plane filters over the past few weeks, its some seriously complicated shizznickle 😛 Howvere, I did find out that there is actually a Z-Plane filter built into Ableton’s Sampler, if you have a look in the filter tab there’s M12dB & M24dB (Im pretty sure the M stands for Morph), If you select either one of them and then start to play with the Morph slider directly below the M12/M24dB bit it allows actual morphing, let me know if that helps! 🙂 (I’ve just realised you can post pictures on here, I’ve attached on to help understand a bit better 🙂

  2. Face Invada says:

    Billain actually showed me how to do this briefly the other day in fruityloops — from memory i think he was using the lfo tool and assigning automation to that and linking them all together so that he could ‘control’ it — wishing i paid more attention but was at a festival! ahahah.

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