add doc

website/src/pages/learn/synths.mdx

@@ -38,4 +38,41 @@ Now we not only pattern the notes, but the sound as well!
 
 <JsDoc client:idle name="fmh" h={0} />
 
+## ZZFX
+
+The "Zuper Zmall Zound Zynth" [ZZFX](https://github.com/KilledByAPixel/ZzFX) is also integrated in strudel.
+Developed by [Frank Force](https://frankforce.com/), 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:
+
+<MiniRepl
+  client:idle
+  tune={`note("<c2 eb2 f2 g2>") // also supports freq
+  .s("<z_sawtooth z_tan z_noise z_sine z_square>")
+  .zrand(0) // randomization
+  // zzfx envelope
+  .attack(0.001)
+  .decay(0.1)
+  .sustain(.8)
+  .release(.1)
+  // 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](/learn/effects)...