Picotron instrument design rudiments

introduced by the Packbats

(revision 2.0)

We hope to go over each major element of patching an instrument with Picotron's instrument editor circa v0.1.0e for any musician who finds it incomprehensible. We are not experts; if you want to find some of those on whose shoulders we stand, we especially recommend:

Also, YouTube musicians like the aforementioned RMR, Andrew Huang, Moritz Klein, etc. etc. etc.

Let's go from top to bottom.



0. Controls

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When you are in the INSTrument editor, there are three columns to interact with: the instrument/SFX/ pattern selector on the left; the oscillators, filters, and other nodes in the center column; and the envelopes in the right column. There are 24 available instruments, each of which has 4 available envelopes and up to 7 nodes.

The piano key layout is, assuming no bugs, based on the physical layout of the keyboard reported to Picotron instead of the character values of these keys. The octaves are measured relative to the octave setting; C4=middle C.

Finally, a general note: Picotron's tracker uses a SPD system for timing, where the value of SPD is the duration of each step in a time unit we'll just call music ticks. (Our friend Many, while testing version 1.2 of this guide, suggested thinking of SPD as SteP Duration.) Many time-related values in the instrument editor - like delay on echo filters, FREQ on LFOs, and SPD on data envelopes - use the same music-tick timing function. This means you can set the speed of these relative to the tempo of your piece. For LFO and DATA envelopes, the 0 value will automatically match the SFX SPD, but if you want some other ratio to it (half, 1.5x, 2x, whatever) or to sync some other parameter, you'll have to set that manually.

A. The Output Mixer

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All sounds ultimately go through here to be heard. This panel has three knobs - VOLume, TUNE, and BEND - plus an output waveform display.

Each of these knobs has a radial marker, a colored arc ending on the marker, and an info box showing the knob's mode (e.g. * or +) and the value that the marker is set to. The marker is moved by a left-click and drag; the arc by a right-click and drag.

There is also a line of buttons on the toolbar:

To explain the arc, we have to examine the right column.

B. The ENVelopes

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The arc on each knob corresponds to a range from the far end to the marker end. When there is no envelope, the value at the marker end is used and remains constant. When an envelope is applied - indicated by a little white ear on the info box of the knob with a number in it - the value varies over time through that range.

There are three types of envelopes, plus two special tricks via right-clicking.

ADSR

The four knobs correspond to the four stages of an ADSR envelope.

A: Attack. When a note begins, the value starts at the far end and moves to the marker end. How long it takes is based on the number. 0 means this is skipped and it starts at the marker end.

D: Decay. After the attack phase ends, over a length of time again based on the number, the value drops from its maximum value to...

S: Sustain. A fraction, from 0 to 255, along the arc. 0 is the far end, 255 is the marker end.

R: Release. When the note ends, the value returns to the far end from wherever it is at the moment, with the time to do so again based on the number.

By default, the output volume has envelope 0 attached with the far end at 0 volume (silence) and the marker end at 32 volume. This is so that the note is not blaring constantly in your ear the whole time. You can remove this and put your volume envelopes elsewhere. Or nowhere! We don't know your life.

LFO

An LFO - Low Frequency Oscillator - makes the value sway from one end of the arc to the other at a tempo set by the FREQuency number. PHASE changes where it starts in that arc and which way it goes first.

DATA

The DATA envelope gives you sixteen steps that you can set to different values. Bottom corresponds to the far end, top to the marker end. The envelope will go through these steps at a speed based on SPD starting when the note is played. If LERP (Linear Interpolation) is checked, the value will ramp from each step to the next; otherwise it will jump to the new value. RND stands for Random but it might not work right now.

Besides SPD, there are also LP0 (Loop Point 0), LP1 (Loop Point 1), and T0 (Time 0, i.e. starting value) options. This lets you have a looping envelope - e.g. for a combined ADSR-LFO effect - and change where in the envelope you start for some reason. When the note ends, the looping stops and it continues through to the end of the data.

Envelope Looping

If you right-click the ear with the envelope, three dots - ... - will appear below the number. On ADSR and LFO envelopes, there is a similar three-dots control which opens a subpanel with the same SPD, LP0, LP1, and T0 controls seen in the DATA envelope. Regardless of envelope type, these set up a cycle which starts with the start of the pattern and loops independently of when notes actually play. So, for example, if LP0 is 0 and SPD times LP1 is 40, then every 40 ticks from when the pattern starts, the envelope will reset. This can let you have effects that cycle across multiple notes or the illusion of the note being repeated at a fast rhythm, to name two possible uses.

R

If you right-click where the envelope ear would be on a knob with no envelope set, a pink R ear appears. This causes a random value in the range of the arc to be selected each time the note is played. This is a great way to add textural variation to your notes.


Exercise 1: Volume Vibes

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(For each exercise, it's probably best to start with a new instrument. Also, if you stumble over something you like, save it so you can play with it more later.)

A good first thing to play with is just the volume ADSR envelope you started with, envelope 0. Change the values, play notes, see how it changes the vibes of the instrument.

We generally think of small values for attack, decay, and release as being around or under 10, medium as around 50, and large as around or above 100. That is to say: so fast it feels immediate vs. in the same ballpark as normal rhythms vs. taking an extended length of time. Using these three categories, here are some classic ADSR options to try out:

Mess around, though. Try some other possibilities.

Exercise 2: Vibrato

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Set the Sustain value of envelope 0 to a medium or large value. Then click the ADSR box on envelope 1 to switch it to LFO mode, and attach it to the BEND knob. To start with:

If everything is working, the pitch should be audibly swaying around the note. Play a few long notes, get a sense of the vibe. Then start twiddling knobs and see how it changes. What happens if you go really fast? Or slow? What if you make the range really small or really big?

Exercise 3: Arpeggio

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Grab a new envelope and click the type box twice to get it into DATA mode. Set the SPD to, like, 20 or so and attach it to the TUNE knob.

To make the arpeggio work, you'll need to set the max range of the arp with the marker end of the tune knob (we went with +12, an octave, when testing) and use the loop points to make the notes repeat. What worked for us was to:

...and repeat until we had as many notes in the arpeggio as we wanted.

Once you have that set, play with the SPD value and listen to the effect. At very small numbers, you will get something interesting!


C. Carrier Oscillators

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Oscillators in carrier mode are the starting point of every patch - they're the parts that make sound. Most of the controls are the same as in the output mixer, but there are a few new ones and a couple new ideas we want to cover.

What is a wavetable? For Picotron purposes, this is a spectrum of waveshapes which can be shifted between. You can test this by holding a note while you change the WAVE knob value.

In v0.1.0e, two of the four wavetables have data:

Using the others requires loading data into them. We haven't made any attempts to do so, but others have and begun documenting the process, such as Eiyeron in this post about injecting bytes into WT-2.

Knob Modes

We mentioned these earlier, but it might be a good time to go into detail.

Much of the time, you will want the defaults, but the option is there if you, for example, want to have an oscillator make the initial knock sound for a piano patch and not have the knock turn into a chirp if you play a different note.


Exercise 4: Timbre Modulation

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Set an envelope to LFO mode and attach it to the WAVE knob. Play with:

Try out different options with held notes, short notes, and melodies.

Exercise 5: Sharp Attack

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Attach ADSR envelope 0 - or whatever envelope you are using to control volume - to the WAVE knob. Play with your envelope parameters, and with the WAVE knob's marker and arc values. A bright sound fading to a more mellow one is a classic synth patch trick to imitate plucks and such, but there are many options here.

If you do want that sound: the default WT-0 wavetable gets brighter from sine through triangle to sawtooth (0-137), then gets warmer and less bright from there to square (137-192), and then gets brighter again as the pulse width of the square narrows (192-255). That said, you can get interesting effects by crossing over one of these transitions with your envelope.

(Oh, and you don't actually have to use the same envelope for volume and tone. It's useful - it leaves more of your envelopes free for other purposes, and it's musically effective in this case - but there are good results to be found with separate envelopes.)

Exercise 6: Simple Kick Drum

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Attach a new ADSR envelope to the TUNE knob of an oscillator. Set the decay to something 10-20ish and move the far end of the arc down/left to make the note pitch drop quickly. (Question for you to ponder: why move the far end of the arc and not the marker?) Play notes in the C3-C4 kind of range and dial in the values where you like them. You may also want the sustain of the volume envelope to be low or zero, or to try out different waveforms for different timbres.

Exercise 7: Additive Organ

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If you click +OSC, you can add more oscillators to a patch and the sounds combine. If you use TUNE on these but stick to octaves and fifths above your main frequency - or, if you use the ratio mode, powers of 2 or powers of 2 times 3 - you can quickly get a very organ-like sound. This works with most waveforms!

(Remember to turn down the volume slightly, though.)

Exercise 8: Simple Piano

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A warning up front: piano sounds are complicated. This attempt at a simple one is going to involve combining many of the skills we've discussed so far.

For this patch, you're going to combine two carrier oscillators: a body sound and a knock sound.

For the body sound, you will be using one or two VOL envelopes. A real piano's sound begins loud, drops in volume quickly, and then either fades slowly as you hold the key or cuts off quickly when you release it. If you will only ever be playing short notes, you can ignore the slow fade and have only one envelope with a fast decay and moderate sustain, either on the output mixer or the body oscillator, but to get the fuller effect, you can have an envelope with a very long decay and zero sustain on the other. With VOL in * mode, both envelopes will cause the sound to die out at their own rates.

Additionally, you can reuse one of these envelopes on the WAVE knob to make the sharp-attack effect on the body sound. A subtle mellowing of the tone serves the effect well - on a real piano, the upper harmonics fade more quickly.

For the knock sound, we would put the VOL and TUNE knobs in no-symbol mode, turn down the volume, and then use the kick drum method - ADSR on the TUNE knob - with an even faster decay than usual. You will likely need to turn up the marker a bit to get any audible sound - keep hitting the key to test it. Try this at different levels for the VOL slider at the very top, the tracker volume slider, to see how it sounds with quiet and loud notes.


D. Modulating Oscillators

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When you hit the +MOD button on an oscillator, you get a new oscillator with the same controls that you can set to FM MOD or RING MOD mode (click the word to toggle).

FM synthesis and ring modulation are both rabbitholes. We will repeat: we are not experts on these things. If you do go down these rabbitholes, there's a lot you'll learn that you can apply to Picotron - we're just giving you some rudiments so you can experiment.

For both

Generally speaking, you want to use TUNE * mode to get an integer ratio between modulating oscillator and carrier oscillator. However, you can adjust BEND a little and get some warbly effects that are still musical.

Regardless, every ratio, above or below the original note, will create a different effect. Sometimes this causes an effective repitching; we often add a new oscillator temporarily so we can repitch our modulated one to match it and bring it back in tune.

Changing waveforms on carrier or modulator will also affect the sound, obviously.

For FM

VOL sets how much the sound is affected - more VOL equals more effect. This is a really good knob to modulate, as is WAVE.

For ring

VOL only affects the overall volume - this type of mod is just on or off. However, changing WAVE still works, and if one or both of the oscillators have a hard edge (saw or square) and you're not already detuning with BEND, turning the PHASE knob can make some subtle but interesting effects.


Exercise 9: FM & Ring Futzing

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Load up an instrument, give it an FM modulator, and try several ratios on the mod oscillator's TUNE knob. Compare their sounds - are they rich, thin, piercing?

Repeat with ring modulation. What kinds of sounds can you find? Any strike you as especially pretty?

Now try stacking pairs of them, and see if you can find any combinations that work for you. (You may have to crank up the VOL on ring modulators to keep a combination of them from becoming too quiet.)

Exercise 10: Sharp Edge, FM

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Set up an oscillator with an FM mod. Attach your volume envelope to the VOL knob on the FM mod. Play with envelope parameters and knob settings. The zero- attack, short-decay, moderate-sustain ADSR envelope is a classic FM synth envelope - you've probably heard it loads of times.


E. Effects: Filters

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Picotron offers three effects options: a filter with low pass, high pass, and resonance; an echo with delay and volume/feedback settings; and a volume shape effect which can work as a gain and an overdrive.

Mathematically, you can describe all sounds as the sum of a bunch of sine waves. In white noise, these sine waves come in all frequencies; in a sawtooth wave or triangle wave, they come in multiples of a single frequency (the pitch of the note); in a square wave, they come in odd multiples of the frequency; in a sine wave ... well, it's just that sine wave. More low frequencies means a bassier, fuller sound; more high frequencies means a brighter, sharper sound. And FM and ring modulation can take waveforms and give them loads of new frequencies.

Usually all that's just a bit of math trivia, but when you use a filter on a sound, different frequency sine waves get affected differently. A high-pass filter will discard low frequencies and let the high ones pass; a low-pass filter will discard high frequencies and let the low ones pass; and resonance will amplify any frequencies near the cutoff - the point where a high- or low-pass filter switches from passing to blocking.

That means:

So let's filter some sounds!


Exercise 11: Cutoff Sweep

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Start with one oscillator and one filter. Picotron's filter has three knobs: LOW, which sets the low-pass cutoff; HIGH, which sets the high-pass cutoff; and RES, which sets the resonance. Set the RES knob to something on the left half - any two-digit number seems fine - and set the far end of the low pass cutoff knob somewhere in the top part with the marker closer to zero. And pick an oscillator waveform in the saw-square-pulse region.

If you use an ADSR envelope with zero attack and a short release on the cutoff, you get a cool wah-like effect. Classic subtractive synthesis sound. Play with the variables how you like.

Exercise 12: Simple Noise Percussion

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Start with the noise wavetable. Set the sustain of the volume ADSR envelope to zero, then attach a filter.

For the simplest version: adjust the LOW and HIGH cutoff frequency knobs to make the percussion you want. For mid percussion like a snare, use more low pass than high pass; for high percussion like cymbals and hihats, use more high pass.

For an enhanced effect, attach an envelope - usually your volume envelope will do - to the cutoff frequency knobs and set it so the cutoffs start weaker and intensify (arc going clockwise from marker on knobs). You can also try using a tiny bit of resonance, but you definitely don't need it.


F. Effects: Echo

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An echo effect, at its most basic, takes its input sound and plays it again a little while later. The volume of each repeat (Picotron's echo feeds back into itself) compared to the original sound is set by the VOL knob, and the time from note to repeat by the DELAY knob.

As long as you aren't changing the delay while it is playing, echo is very intuitive - a short delay adds a subtle space, a longer one adds a more obvious repetition. Of particular note is setting the delay based on the SPD of your music - the 0 value is a special option which equals that speed, but using 1.5x your SPD has a fun effect you might try.

No special exercises for this chapter - we don't know any important tricks. Just try it out.

G. Effects: Shape

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Shape gain in Picotron has two clear uses. Some tools, like filters and ring modulation, can drop the output volume significantly, so gain can make up for that. But also, you can use gain to create distortion, drive, or clipping, which can really enhance a lot of your instrument sounds.

Basic procedure for gain-effect distortion:

What you'll see in the window is a bent line, rising sharply then slowly. What this does is squish the waveforms, making them a little more like square waves, and making them more intense in the process. This is really good for your kick and snare drums and for gentle waveforms like sine waves and triangle waves, but play with it.

Also...

The Hidden Setting

If you click just below the bottom right corner of the info box for any knob, far end from the knob, it will cycle through two special modes: "x 4" and "/ 4". We can't tell you what will happen in most cases - it might change as Picotron continues development - but right now, for the ELBOW knob of the shape effect, the x 4 mode unlocks a wave folder, which can make some seriously gnarly sounds if you feed it the right stuff. It's also massively loud, so turn the MIX way down - we're talking, like, 2 out of 255 - before you crank the GAIN way up.

Stay safe and have fun, y'all.