Partikl 3 User Guide

Partikl Sound Synthesis Tutorial 2

Working with the Partikl Modular Synthesizer

Try launching partikl. This is the place where you activate and program Partikl ... and where MIDI sound creation for the Intermorphic Sound System (ISS) gets very interesting!

Note that Partikl is an application that shows how the range of its own default modules can be controlled. The audio plugin framework that underpins Partikl is an open framework, and has been designed to allow 3rd party developers to create application UIs into which they can plug in their own or other 3rd party sound processing modules, including support for the Intermorphic modules if so required.

When you start using Partikl for a MIDI line, what you have is an independent, non-midi, polyphonic synthesizer The sound generation limitations of MIDI pretty much go out of the window.

Partikl is no lightweight. It has a degree of flexibility that is comparable to the old, monster modular synths. It includes some features that are seldom seen, even on very expensive, "famous name" hardware synths. Inevitably, something so well featured and flexible isn't able to hide its complexity too well so there will be a bit of a learning curve to negotiate if you are going to be able to harness this power in a creative way. This tutorial aims to help you up along that curve.

We won't be creating full pieces of music in this tutorial; instead, we'll concentrate on programming sounds using Partikl.

The Path

To get the best from any synthesizer you really need to have some understanding of the path the various signals take inside it. If you have had some experience of hardware synths you will probably be used to imagining a left to right signal path, with the sound generating oscillators at left hand side and the sound output stage at the far right. Partikl signal path pretty much follows this convention...

If you click on the Synth Module button, you will see that the Synth Module Dialog appears. This dialog lets you review the modular synth settings for each of the MIDI lines in the piece.

Select an active MIDI line number, and then set the "Poly" list item to be 1, and press the edit button. This displays the Synth Module Editor Dialog. It is here, in this dialog, that we design the sound for the selected MIDI line. As you add synth units to your sound design, they appear as boxes in the bottom part of the dialog. We sometimes refer to these units as "slots"; you can have as many "slots" as you want, where you insert the various modules and units that, together, will make your synthesizer module. The sound you eventually hear will come only from the signal rate unit in the rightmost slot. So, if you were to construct the simplest of synthesizers, using one tone generator and a LFO, you would have to put the tone generator in a slot somewhere to the right of the LFO. Put them the other way round and, if it was fast enough, all you would hear would be the LFO!

With the proviso that the sound comes out of the right most unit, the signal-flow is pretty strict in terms of left-right ordering. Signals from one module can only ever be passed to modules that are to the right of it in the design. In practice you must put control-rate units (your controllers and shapers, such as envelopes and LFOs) sound BEFORE the sound generating modules (i.e. before your tone generators). So, if you want to use an envelope to control the output from a LFO, you'll have to put the envelope to the left of the LFO. This does of course help you keep a handle on what your signal path is doing. With practice, you won't be confused!

Control signals are different!

Says it all really!

Partikl makes an important distinction between audio signals and control signals. Here's how it works.

Most signals in the system are "audio-rate" signals; they are rendered at whatever sample rate the platform is running at, for example 22Khz.

The only signals that can be used to modulate parameters of a synth unit (e.g. to amplitude or wave shape) are control-rate signals, that must come from a control-rate unit. To save CPU resources for the things that matter, control signals are rendered at a very low sample rate; typically 100Hz. So, if you try to modulate a parameters between units at audio frequencies the best you are going to get is 100Hz. This is not going to be good enough for specialised applications such as FM synthesis! :)

The reason that we do this, is that it saves a lot of CPU horsepower; to render subsonic waveforms at near CD quality would be pretty pointless. You don't want or need to hear the direct output of an envelope unit or a slow LFO.

On tuning

A fixed architecture synthesizer with limited flexibility can hide a lot of things from the end user. Because Partikl has been designed for flexibility it is up to you to take care of some of the details to make sure that the results you get are the results you expect. This is particularly the case when making sure your MIDI line is in tune with the others in a piece.

The thing that is most likely to catch you out is when you use a LFO to modulate the frequency of a tone generator. If you use the LFO with most of its settings at the default there will not be a problem. However, if you adjust the min or max value sliders you will have a tuning problem that will need correction. Why?

If you recall in the synthesis tutorial, we said that changing these values was the same as applying a DC offset to the LFO wave, i.e. the zero crossing line has a non-zero value! So, if you route a LFO that has been shifted in this way to the frequency of another oscillator you are, in effect sending two values. One is the LFO amplitude, which will change over time and the other is the DC offset which is a constant. This DC offset will have to be allowed for by adjusting the pitch of the sound generating oscillator to get it back into tune.

So, if you have an out of tune MIDI line, check what is modulating the frequency!

A word about resources

All soft synths are serious processor hogs. A lot of effort has gone into minimising the hit that Partikl will make on your processor but you can't cheat physics. Making complex sounds in realtime means doing hard sums very fast and there will be a limit to the strain your CPU can take.

Tips

If your piece can use built-in wavetable (e.g. for basic drum sounds), or custom audio samples, then consider using them where possible rather than the modular synth. Remember that sample-based drum sounds can be very effective.
Very importantly, use a polyphony value that is as small as your piece can get away with!
Wherever possible, put your effects in the effects line (see the Effects Button) rather than directly in your synth module design!
Be economical with units! Think about ways in which you can maybe use one unit more than once in a voice.

Finally, a word about polyphony. With Partikl, each MIDI line can become an independent, polyphonic synthesizer.

But rather than always thinking of Partikl as a polyphonic synthesizer, you can think also think about it as a synthesizer that has lots of multiple instances a monophonic synthesizer If you set the "Poly" parameter to 2 or more, what Partikl does is create the corresponding number of identical monophonic synthesizers that can operate simultaneously, one for each possible note. So, setting your "Poly" parameter high is an excellent way to use up your processor resources - which you will want to try to conserve! Use it with care.

OK, enough of the preliminaries. Lets get on with making some sounds. The terminology and concepts we will be using will assume you are up to speed!

Voice 1 Simple subtractive synthesis

This is how to set up Partikl as a simple two oscillator synth in the classic style. We'll go through this in some detail because, once you have got the principles of Partikl established, working in more adventurous ways gets much, much easier.

Use your favourite sequencer to setup a simple MIDI piece that plays long notes with a start pitch of 30 or thereabouts to give us something to test the sound with. Alternatively, use the simple noatikl piece we've already constructed for you using Noatikl (documents/Intermorphic/partikl/tutorial/tutorial1.noatikl). Either way, take your piece, Open it with Partikl and you should hear it start playing!

First up, you need to activate the Modular Synth for the voice in question. Launch the Synth Module dialog to do this; set the poly for the actively playing MIDI line (which is line 1 if you took our example noatikl file) to be 1 or more. Once you set a tone generator in your synth module design, this will then (and only then!) override any midi instrument settings that your piece is using.

So: we need to design the module that our MIDI line will use. As we are going to make a classic kind of synth we will need two tone generators, a filter and an envelope to control it.

Click on the Edit button for your line, and up pops the effects editor dialog. The exact content of this window will vary depending on the module you are using but they all follow the same basic conventions as noted earlier.

Click on "Type?" to change the effect type of the unit that was automatically created for you (unit 1); make this "c/envelope", which is a control-rate envelope. Then, click on the "Add After" button and change the Type of the new Unit (unit 2) to be "tg/osc" (a very flexible Tone Generator!). Select "Add After" to add another unit (unit 3) and also make this a "tg/osc" tone generator. Finally select "Add After" to add another unit (unit 4) and set this to "filter".

Using a Signal-rate Junction

Hold on - the filter is only fed from the output from the unit immediately before it; and what we really want is to feed the filter with the combined outputs from units 2 and 3! To do this, we need to route the two tone generators into the filter unit. How we do that is fundamental to getting Partikl to work for you!

Select unit 4 (the filter) and press the "Add Before" button; your Filter is now moved to become unit 5! Set the type of the new unit (unit 4 - which is the *new* unit) to be "j". This is a signal-rate junction unit, which lets you add signal rates unit together. In the "Junction Inputs" area, press the Input "Add" button twice. Make sure that the first input item of the two inputs you've just added comes from Unit 2 (the first tone generator), and make sure that the second of the two inputs comes from Unit 3 (the second tone generator). You can set relative scaling factors for the two input units by playing with the scaling factors.

Here is the text that we get if we now press the "Export" button on the synth module editor window (we could subsequently reimport this if we need to by highlighting the text, copying it and pressing the "Import" button):

The signal-rate junction you've just added takes the the signals from the two tone generators, and adds them together. The output from your signal-rate junction automatically feeds the filter unit to its right.

OK, that's the network built. Now lets fine-tune our settings.

Select Unit 2, and click on the Edit button. This displays the Oscillator editor dialog. There is a list down box here where you can select the wave shape for this tone generator. We want a saw wave. The direction of the slope isn't relevant. Close the dialog, select unit 3, press the Edit button and get ready to edit the second tone generator!

Select a sawtooth wave for the second tone generator. Please make sure its direction is the same as its twin in unit 2 or else they will cancel each other out and you won't hear much! :)

To make a big sound, set one of the tone generators to work an octave lower than the other. You can do this with the one in Unit 2 by setting the Octave offset to 1.

Once you've done all that, select Unit 5 (the filter) and press the Edit button to display the Filter editor. Set the filter type to "low pass" and adjust the cutoff frequency and Q (resonance) to taste. The filter will automatically sweep unless you tell it otherwise! :)

Here's what the exported module now looks like:

Next, lets use the control-rate envelope (unit 1) to modulate the frequency of our first tone generator (unit 2). Select unit 2, and and in the "Parameter Controllers" area add a controller by pressing the "Add" button. Set the source Unit to be unit 1 (our envelope), and set the Param(eter) to be Frequency. Your envelope will now be modulating the frequency of your LFO! Use the Scale slider to adjust the amount of modulation. Select unit 1 and press the Edit button to modify the shape of your envelope.

Note that the envelope editor display might look a bit complex to start with, but it it's not really! It can be used to send out negative as well as positive values (it is bipolar!).

For example, you might want an envelope shape that rises slowly to a maximum, falls down to a low level rather slowly and tails off to nothing once the note has ended. So you could set the attack time to around 5 seconds, the decay time to just less than 4, a very low sustain level and a release time of half a second.

Once you have an envelope shape you like it is then just a matter of playing around with things until you get the exact sound you want. Note that you can also use control-rate LFOs ("c/lfo") to modulate parameters; and many units have a large range of parameters that you can experiment with modulating!

Anyways, back to our example: you should hear a more familiar, if rather overused, sound. If you go back to one of the tone generators and tweak the "Micro Offset" value a bit you will find that fattens up the sound nicely.

For a final touch you might want to add some reverb. This is best done by using it as a global effect for the entire piece because you might have several voices that you want to treat similarly.

If you close the Synth Module Editor dialog, and then close the Synth Module dialog, you'll be back to the main application window. Press the "Effects" button, and once the Effects dialog opens, and press the topmost Edit button. Up pops a dialog just like the Synth Module editor you saw before, but this is now being used to edit global effects for the entire piece. Make sure that the effect type is "reverb", and edit the unit to get the sound you want. Then, close the dialog.

And there we have it. One classic, filter swept pad in the traditional subtractive style. Easy!

Now we have a sound that works it is a good idea to save it for use in other pieces. As noted above, you can export & import data directly via the clipboard and a text editor at various levels of the tool; this makes copying sounds around from piece-to-piece very easy.

If we export the settings from your Synth Module dialog; the text should look something like this (depending on exactly what you did!). We need this by the way for our next tutorial step.

Voice 2 Waveshaping

This sounds similar in some ways to Voice 1. But this time, instead of using a filter module to remove harmonics and animate the sound we will use an envelope to change the waveform shape over the duration of each note.

If you recall some of the things we covered in the previous tutorial you will realise that changing the waveshape will change the harmonic content of the sound. And, if we get it right, we'll end up with something that sounds like a traditional filter sweep without the CPU hit that the filter involves. So, really, we are almost using additive methods to make this sound. And it is more economical. Great!

Go back to your MIDI sequencer and copy the MIDI line you prepared earlier to a new line. Alternatively, start from our example piece "tutorial/tutorial2.noatikl". Most of what we need is already set up for us and there is no point in working too hard! Now, Open this piece into Partikl.

Open the Modular Synth dialog, and import the settings from the last voice:

Open the module editor for line 1, export the settings; close module editor, select line 2, set poly to 2, and open the module editor for line 2. Press the "Import" button and both lines are now playing the same way! Now, Select the filter unit and press the Delete button to remove it. The last unit is now the signal rate unit, which just adds the two tone generators together and is a lot easier than implementing a filter in software!

Open up the Editors for the two tone generators. Change the wave type for each of them to STS. You'll notice that you get some interesting control sliders for this wave type.

Here is the synth module definition at this stage:

The STS wave is one of the quietly outstanding features of Partikl. The three parameters, controlling the up/down ratio, squareness and slope give you the capacity to morph a waveshape.

It might be a good idea to set up a simple voice just using this waveshape in a single tone generator and play around with the sliders to get the feel for what you can do with this. Basically, if you set the up/down to 100%, squareness to zero and right/left% to either 100% or zero you will hear a sawtooth wave. If you now move the right/left slider towards the centre you will hear the sound mellow until, at 50%, you get a triangle wave. Now move the squareness slider and you hear the sound harden again as the wave become more pulse like. We already know that changing the up/down ratio of a square wave (the duty cycle) will change the harmonic character in other ways. Check it out!

So, by varying these three parameters in different ways in real time you can generate some excellent harmonic changes without resorting to a filter. Lets do it!

We don't need to change the current Envelope settings, but you can play with this if you like. But we do want to route the envelope controller (unit 1) to the appropriate destination!

In the Parameter Controllers area, for both units 2 and 3, add a controller from unit 1. Ensure that this new controller is used to modulate the Up/Down Ratio parameter. Now do this again, adding new controllers, but this time to use unit 1 to also modulate the squareness ratio. Then do this again for the slope ratio!!

As this is the "suck it and see" school of synthesis, the next bit is down to you and your ears. Hit play and adjust the settings levels on these parameters until you get a sound you like. You'll find that, if you overdo the levels you can flatten the waveshape out and loose the sound altogether!

Here is the synth module definition at this stage:

It shouldn't take you too long to find settings that sound like the filter sweep we created in the first example. If you check the two sounds side by side in the example piece you'll find that this approach actually gives you a greater range of harmonics than using a simple filter. The sound will tend to be richer and brighter, sitting up in the mix more perhaps.

Voice 3 Gentle Ring Modulation

We can use the ring modulator mode of the "osc" unit to give some quite pleasant quality tones that are very similar to those you get from basic amplitude modulation. The key is to make sure that both the tone generators track the pitch of the composed notes.

A ring modulator has to have two inputs for you to hear anything. If you just load up the ring modulator on its own you'll hear nothing. The Partikl oscillator use the internal oscillator as one permanent input. All you need to do is route another source into the ring modulator and off you go.

Change one of your modules such that it is one "osc" unit followed by another "osc" unit. Be sure to check the "ring-modulate?" checkbox on the second unit; verify that the "Use MIDI Notes?" checkbox is also checked.

If you play with the various oscillator parameters you'll discover that the harmonic content of the sound generated depends mostly on how far apart the two tones being modulated are.

Voice 4 Ring Modulated weirdness

Go back to your Ring Modulating unit. Uncheck the "Use MIDI notes".

What you get is a weird, metallic noise! The quality of the noise will depend upon the relationship between the frequency coming in from the tone generator and that of the oscillator in the ring modulator. Adjust this frequency until you get a cleaner, bell like tone. It should be somewhere around 700 Hz.

If you want things to get dafter, add a control-rate LFO "(c/lfo") to modulate the ring modulator's oscillator frequency. Try this. Add a control-rate lfo ("c/lfo") as the first unit. Set the wave type of this LFO to Random and the type to Step. Set the frequency to 2 Hz. Now add this unit as a modulator controller of the ring modulator frequency. Hit play! :)

What you should be getting now is weird, randomized electronic chime noises that change every half second. Strange, isn't it?

Don't forget that you can use custom user samples (e.g. in Ogg format) as the source as well as another Partikl module so you can do ring mod sound warping to your own samples in realtime. And who wouldn't want to do that?

Voice 5 Particles. Making ring modulation look ordinary

Now if you thought ring modulated noises were strange, check out this option. As an alternative to a comprehensive tone generator module, the Partikl packs the utterly unique Particle generator (if you'll pardon the pun!).

The concept is based on granular synthesis. This module generates little wavelets of sound punctuated by little sections of silence. With careful control of the comprehensive set of parameters on offer you can generate the most unworldly sounds.

A little alert before we start. This module does a lot of maths! Don't overuse it in a piece or there won't be much processor time left for anything else.

We'll use it to create an Sci-fi movie background music sort of thing.

Open piece tutorial3.noatikl, which is like tutorial1.noatikl but with a higher frequency (around 55). Assign a "tg/particle" unit as your only unit for MIDI line 1. And that's it! :)

Well, not really. The difficulty now is that this all gets very subjective and rather hard to write about. You just need to hit play and then adjust the many parameters on offer in the Particle module until you get a sound you like. So instead lets just check out the key variables.

The harmonic parameter is one of the most influential factors on the end sound. Low values will keep the base frequency of wavelets close to each other. Larger values will mean much greater differences between individual wavelets and a much wider harmonic range to the sound.

Frequency velocity is like a mini pitch envelope applied to each wavelet. Small values give nice detunes and sweeps. Larger values can cause queasiness!

The attack, sustain and decay parameters are like a mini amplitude envelope for each wavelet. Small values make each wavelet distinct and audible. Larger values will cause a smearing and blending of the sounds which is not unpleasant.

Pause governs the time between each wavelet.

The "Number of Elements" value sets the number of wavelets to be generated. Set this lower and reduce the processor hit for this module.

You will hopefully have noticed that every parameter can be modulated by another unit, so there is plenty of scope to sculpt some quite unique and complex pieces with this little baby!

Voice 6 The Drum Synthesizer

This one is a little bit different because, with this beast, you can achieve so much. So some explanation is in order first.

To make decent percussive sounds using a modular synthesizer takes quite a few modules, most of which would be rather over specified for the task to hand. Such an approach would waste a lot of computational resources. So we took a different path.

The drum synth module incorporates just the tools you need to create a huge range of tuned and untuned percussive sounds with no waste. It looks a bit complex at first sight because it packs a lot into a small area of screen but once you get the hang of it you'll love it!

The module incorporates three tone generators – two generate sine waves, one generates coloured noise. The noise generator has a multi-type resonant filter. Each tone generator has its own simple attack/decay envelope that controls the amplitude. This envelope can also be routed to control pitch in the case of the sine wave generators and the filter cutoff frequency for the noise generator.

The output of the three generators is added together so you control the mix between them using the envelope level parameter. A word of warning – this module has been designed to kick - it goes loud!

One sine wave generator is designated the master and can be set to any frequency from the low 40’s to about 900 Hz. The other sine wave generator slaves to this frequency, i.e. its setting is a ratio of the frequency of the first one. We do this mostly to save CPU resources (the slave oscillator’s maths are slightly less taxing)

One thing worth noting is that the two sine wave generators can cross-modulate the other’s frequency. What’s the point of this?

Well, using the output of one sine wave generator to modulate the frequency of the other will give some metallic-like tones. It is called frequency modulation synthesis. Exactly how metallic will depend upon the difference between the frequencies of the two generators and on the depth of the modulation.

If you then take that modulated output and make a loop so it modulates the frequency of the first tone generator (modulate the modulator as it were!) then the results can get even more harsh and chaotic. At high modulation depths this is just what you need to start to create struck metal percussive effects. Lower depth values will dirty up drum sounds for you rather nicely!

You can force this module to track composed note values. There are loads of possible uses of this feature. The obvious one is to get several percussion instruments for the price of one. If you want to set up an alternating high/low cowbell figure simply load up the relevant preset, enable note tracking on this module and set up a pitched fixed voice type or something similar to take care of the tuning. You can also create a whole battery of tuned percussive instruments; marimbas, bells by using this option.

Enjoy!

And that just about concludes this quick jaunt through the practical application of Partikl. We've really just scratched the surface but hopefully you have collected enough pointers from this and the previous tutorial to make your own way from here.

External Links

Visual Synthesis Tutorial