Saturday, 8 June 2019

Spectral Hex Ping Pong Delay in MaxForLive for Ableton Live

After playing around with various Ping Pong Delay-like devices for a while, I realised that my 'Hex' template was a good place for experimenting with multiple delays, so I took the internals of the AUDpiPOde device and put it inside the 'hex' device template (six times). The result is AUDhexPPD, where I'm abbreviating ping pong delay to PPD to save characters.

AUDhexPPD


Because AUDhexPPD is another 'wide' device, then here's just the left hand side:


Going across the left to right, the input indicator shows the incoming audio signal (and yes, this does duplicate the tiny meters in-between devices), then the Ping Pong Delay block, with the 'Note value time delay' button grid, followed by the 'Unsync' time tweaker, the 'LR swap' output channel allocator, the 'f' delay freeze button, and the Feedback rotary control (which is individual to each PPD block).

The next block across to the right is the middle block: the three-band 'spectral' filtering, which just gives three outputs via low-pass, high-pass and band-pass filters. Unlike the usual 'crossover' filters that you get in some 'spectral' devices (or loudspeakers, now that I think about it), these filters have a Resonance rotary control, which gives the device the ability to colour the sound, so maybe it is more than just six delays.

Finally, on the right hand side, there is the 'Auto-pan' block, which has an individual meter per audio processing block, the 'X' Active/Muted switch (as per all of the 'hex' devices, and a few others of mine), the new 'Pan Position and LFO Modulation' UI widget that I introduced recently (move the white 'thumb' down and horizontal for pan position, and up for LFO modulation), and finally the LFO Rate rotary control, which goes from very slow to not very quick, but then it is a modulation control and audio rate modulation of pan position is not something I'm a great fan of...

On the far right-hand side, there are the usual memory buttons (Click to recall, Shift-click to save (red when empty, grey when filled)) and the Dry/Wet rotary control, followed by three 'common' controls which affect all of the six audio processing blocks: Feedback, Resonance, and Freeze. These just make it easier to alter all of the six audio processing blocks at once!


As usual in the 'hex' devices, the right hand half of the front panel is mirrored, which looks interesting, and makes it very clear that this is a stereo device. Just repeating things twice can make it look like they are arranged in series... There isn't a perfect solution for this, but this way works for me, and it isn't too hard to flip one half if you need an unmirrored custom device...

MaxForLive

So, what's interesting in the M4L code for this device? As I have mentioned previously, I prefer stereo in and out for my devices, and this is normally done with pairs of mono in and mono out devices where the output can be panned across the stereo image... However, each of the 6 audio processing blocks in AUDhexPPD is a tapped delay with a mono input and stereo outputs, and so instead of having one output that needed to be panned, then I had two - and for a ping pong delay then these two outputs should be in the Left and Right channels (or vice-versa - which is what the 'LR Swap' button does). But with two outputs then I needed two auto-pans, and so the obvious answer was to have two auto-pans in anti-phase, so that when one output was on the Left, then the other would be on the Right. 'Dual anti-phase auto-panning' isn't a very catchy description, so I'm going to call it 'Helicopter' mode, because the two pans circle around each other rather like the blades on a helicopter...


Yes, I could have changed the balance between control values and audio signals in this - so the 'snapshot~' and 'sig~'could have been removed from the panning part, but then I would have had to add them back in to the LFO Depth and LFO Out to get control values. This way works for me...

Alternatively, I could have had two SEPARATE auto-pans for each of the two outputs: one LFO for Left, and another LFO for Right. This would have required a doubling of all of the controls in the centre 'panning' block, and would have made the device even wider! (and more complex to use) I decided to go for the simpler solution and leave the 12 pan LFO version for another time (Maybe in an 'mc' version as a way to explore this new feature of Max 8!)

The Max code just inverts the (0 to 1) control value for the multipliers so that the two inputs are affected in opposite ways. Remember that the audio inputs are called 'L' and 'R' because this is the convention for ping pong delays - the first echo comes from the Left channel, then the next from the Right channel. These are not the main incoming audio channels to the whole device - each audio processing block has a mono input and two 'stereo' outputs. So, for each audio processing block, the two inputs are coming from a tapped delay, and so these input signal will be 'bouncing' back and forth between those inputs, and this auto-panning then adds additional pan control on top of that. If you stop the LFO and fix the pan position to Left or Right, then the result is ordinary ping pong echo - where the repeats 'bounce' between Left and Right.

Note that this is the auto-pan arrangement for just one of the six parts in the Pan block. So if you have just one 'X' highlighted and the rest muted, then that ping pong delay will bounce between the Left and Right output channels, panned according to the pan position and LFO modulation as set in that block. If you have two 'X's highlighted (one in the Left half, and one in the Right half), then you have two ping pong delay in parallel - and so the outputs can bounce between the Left and Right outputs independently. If you have all six blocks active, and use the 'triangle' tweak controls to 'unsync' the time delays, then you start to move away from 'echo' and towards 'reverb'-type sounds. The more asynchronous echoes you have, then the more 'reverb'-like the result will be - which, of course, is exactly how real reverb is produced: lots of echoes with different delay times. You 'could' put several 'AUDhexPPD' devices in series, but it is probably going to take a lot of adjusting to get something even approximately like a conventional reverb sound...

Getting AUDhexPPD

You can get AUDhexPPD on http://www.maxforlive.com/library/device/5522/audhexppd

Here are the instructions for what to do with the .amxd file that you download from MaxforLive.com:

     https://synthesizerwriter.blogspot.co.uk/2017/12/where-do-i-put-downloaded-amxd.html

(In Live 10, you can also just double-click on the .amxd file, but this puts the device in the same folder as all of the factory devices...)

Oh, yes, and sometimes last-minute fixes do get added, which is why sometimes the blog post is behind the version number of MaxForLive.com...

RAM and CPU in Live

This MaxForLive device has six tapped delays, so it will use lots of RAM storage and CPU power - but it is worth it, IMHO!

Effects Rack Equivalent in Live

I haven't tried it, but it ought to be possible to get quite a lot of the functionality of AUDhexPPD with an Effects Rack in Ableton Live, although the UI is not going to be as compact, and it might even be possible to implement the spectral crossovers using the band-pass filters inside Delay (or Ping Pong Delay if you aren't using Live 10.1).


What is interesting is that the limitations of building AUDhexPPD inside Live result in something which is a nice, usable effect, but it isn't the same as the MaxForLive version. Anyway, it was a good exercise in translation, and I'm making it available for free. You can download it from here...

Modular Equivalents

In terms of basic modular equivalents, then AUDhexPPD would require two high-pass filters, two low-pass filters, two band-pass filters, six tapped time delays, six LFOs, six panner, some utility switches, and two mixers, giving a total of about 24 ME. It is interesting that this is also a 'wide' device in MaxForLive!







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