In addition to the sampling engine, strudel comes with a synthesizer to create sounds on the fly.

Basic Waveforms

The basic waveforms are sine, sawtooth, square and triangle, which can be selected via sound (or s):

note("c2 <eb2 <g2 g1>>".fast(2))
.sound("<sawtooth square triangle sine>")

If you don’t set a sound but a note the default value for sound is triangle!


You can also use noise as a source by setting the waveform to: whitepink or brown. These are different flavours of noise, here written from hard to soft.

sound("<white pink brown>")._scope()

Here’s a more musical example of how to use noise for hihats:

sound("bd*2,<white pink brown>*8")

Some amount of pink noise can also be added to any oscillator by using the noise paremeter:

note("c3").noise("<0.1 0.25 0.5>")._scope()

You can also use the crackle type to play some subtle noise crackles. You can control noise amount by using the density parameter:

s("crackle*4").density("<0.01 0.04 0.2 0.5>".slow(2))._scope()

Additive Synthesis

To tame the harsh sound of the basic waveforms, we can set the n control to limit the overtones of the waveform:

note("c2 <eb2 <g2 g1>>".fast(2))
.n("<32 16 8 4>")

When the n control is used on a basic waveform, it defines the number of harmonic partials the sound is getting. You can also set n directly in mini notation with sound:

note("c2 <eb2 <g2 g1>>".fast(2))
.sound("sawtooth:<32 16 8 4>")

Note for tidal users: n in tidal is synonymous to note for synths only. In strudel, this is not the case, where n will always change timbre, be it though different samples or different waveforms.



Synonyms: vibrato, v

Applies a vibrato to the frequency of the oscillator.

  • frequency (number|Pattern): of the vibrato in hertz
note("a e")
.vib("<.5 1 2 4 8 16>")
// change the modulation depth with ":"
note("a e")
.vib("<.5 1 2 4 8 16>:12")


Synonyms: vmod

Sets the vibrato depth in semitones. Only has an effect if vibrato | vib | v is is also set

  • depth (number|Pattern): of vibrato (in semitones)
note("a e").vib(4)
.vibmod("<.25 .5 1 2 12>")
// change the vibrato frequency with ":"
note("a e")
.vibmod("<.25 .5 1 2 12>:8")

FM Synthesis

FM Synthesis is a technique that changes the frequency of a basic waveform rapidly to alter the timbre.

You can use fm with any of the above waveforms, although the below examples all use the default triangle wave.


Synonyms: fmi

Sets the Frequency Modulation of the synth. Controls the modulation index, which defines the brightness of the sound.

  • brightness (number|Pattern): modulation index
note("c e g b g e")
.fm("<0 1 2 8 32>")


Sets the Frequency Modulation Harmonicity Ratio. Controls the timbre of the sound. Whole numbers and simple ratios sound more natural, while decimal numbers and complex ratios sound metallic.

  • harmonicity (number|Pattern):
note("c e g b g e")
.fmh("<1 2 1.5 1.61>")


Attack time for the FM envelope: time it takes to reach maximum modulation

  • time (number|Pattern): attack time
note("c e g b g e")
.fmattack("<0 .05 .1 .2>")


Decay time for the FM envelope: seconds until the sustain level is reached after the attack phase.

  • time (number|Pattern): decay time
note("c e g b g e")
.fmdecay("<.01 .05 .1 .2>")


Sustain level for the FM envelope: how much modulation is applied after the decay phase

  • level (number|Pattern): sustain level
note("c e g b g e")
.fmsustain("<1 .75 .5 0>")


Ramp type of fm envelope. Exp might be a bit broken..

  • type (number|Pattern): lin | exp
note("c e g b g e")
.fmenv("<exp lin>")

Wavetable Synthesis

Strudel can also use the sampler to load custom waveforms as a replacement of the default waveforms used by WebAudio for the base synth. A default set of more than 1000 wavetables is accessible by default (coming from the AKWF set). You can also import/use your own. A wavetable is a one-cycle waveform, which is then repeated to create a sound at the desired frequency. It is a classic but very effective synthesis technique.

Any sample preceded by the wt_ prefix will be loaded as a wavetable. This means that the loop argument will be set to 1 by default. You can scan over the wavetable by using loopBegin and loopEnd as well.

note("<[g3,b3,e4]!2 [a3,c3,e4] [b3,d3,f#4]>")
.n("<1 2 3 4 5 6 7 8 9 10>/2").room(0.5).size(0.9)
.s('wt_flute').velocity(0.25).often(n => n.ply(2))
.release(0.125).decay("<0.1 0.25 0.3 0.4>").sustain(0)
.cutoff(2000).cutoff("<1000 2000 4000>").fast(4)


The “Zuper Zmall Zound Zynth” ZZFX is also integrated in strudel. Developed by Frank Force, it is a synth and FX engine originally intended to be used for size coding games.

It has 20 parameters in total, here is a snippet that uses all:

note("c2 eb2 f2 g2") // also supports freq
  .s("{z_sawtooth z_tan z_noise z_sine z_square}%4")
  .zrand(0) // randomization
  // zzfx envelope
  // special zzfx params
  .curve(1) // waveshape 1-3
  .slide(0) // +/- pitch slide
  .deltaSlide(0) // +/- pitch slide (?)
  .noise(0) // make it dirty
  .zmod(0) // fm speed
  .zcrush(0) // bit crush 0 - 1
  .zdelay(0) // simple delay
  .pitchJump(0) // +/- pitch change after pitchJumpTime
  .pitchJumpTime(0) // >0 time after pitchJump is applied
  .lfo(0) // >0 resets slide + pitchJump + sets tremolo speed
  .tremolo(0) // 0-1 lfo volume modulation amount
  //.duration(.2) // overwrite strudel event duration
  //.gain(1) // change volume
  ._scope() // vizualise waveform (not zzfx related)

Note that you can also combine zzfx with all the other audio fx (next chapter).

Next up: Audio Effects