Greetings and a question


Hello there. I’m a professional software tester and hobby musician (guitarist) of 20 years and have recently started tinkering in the world of electronic music production (synthwavey sort of stuff). I’ve been exploring the possibilities of Sonic Pi and am very excited by the concept of having a highly customized environment in which to write and perform, without the need to learn and experiment with many different user interfaces, VST features etc etc

I’m just trying to understand the tonal possibilities of the synths. I’ve noticed that the TB303 is the only synth with a filter cutoff envelope. Is it possible to simulate an envelope somehow by "control"ing the cutoff for other synths? I’ve seen the feature request and discussion around using a wave to control a parameter. This would be cool for a modulation type effect but I’m referring more to movement of the parameter triggered by each note and eventually ending in silence.


Hello matey,

Welcome to the forums.

Envelope control is possible, I’m just not the right person to explain it. :slight_smile:
I’ll let Robin or one of the others do the honours.



Althugh :tb303 is the most obvious synth to be affected by cutoff settings, if you look at the details on the synths in the help file synth tab you will see that quite a large number of them can be affected by cutoff values. This can be particularly noticeable if you control the cutoff while a note is playing. You can also do this be means of applying fx :lpf which can again be controlled, or perhaps by sweeping a band pass filter as the note plays.

Here is an example which alters cutoff and sweeps a band pass filter as the notes play, using a selection of different synths including a noise source.

In general many parameters for a synth (or sample) can be altered while it is playing using the control mechanism. See section 7 of the tutorial in the help file.

live_loop :test do
  tick_set :slow,look/8 #tick(:slow) at 1/8th rate
  s= (ring :cnoise, :dsaw,:tb303,:prophet,:zawa,:tri).look(:slow) #change every 8 notes
  puts s #current synth
  use_synth s
  with_fx :bpf,centre: 80 do |c| #start controllable band pass filter
    #start note with controllable cutoff
    b=play scale(:e2,:harmonic_minor, num_octaves: 2).choose,cutoff: 100,attack: 0.1, sustain: 1.2,release: 0.2
    control b, cutoff: 50,cutoff_slide: (ring 0.1,0.2,0.4).look # slide cutoff at different rates
    4.times do #sweep bpf 4 times
      control c,centre: rrand(10,100),centre_slide: 0.2
      sleep 0.2
    sleep 0.6


Thanks @robin.newman I’ll have a play with this idea :slightly_smiling_face:


You may also wish to create risers with “line” to affect a parameter you want to rise.

riser0 = (line 10, 0, inclusive: true, steps: 16)

live_loop :attackBeat do
  puts tick
    #Load in your own sample to hear it in action or use a synth
    sample hat, 33, attack: riser0.look
  sleep 2

Alternatively use “.mirror” to create an oscillator sort of like an LFO. This is probably one of the most useful techniques I’ve found for synthwave because you can have multiple LFO’s running different parameters simultaneously. You can use this to drive any parameter even if it’s not an FX parameter. You can also do complex things like have one LFO affect another with math to create a resultant LFO of a weird shape (or slowly morphing shape.

lfo0 = (line 80, 100, inclusive: true, steps: 120).mirror

live_loop :oscSynth do
  puts tick
     #Load in your own sample to hear it in action or use a synth
      with_fx :hpf, cutoff: lfo0.look  do
          sample outrun, 38
  sleep 0.125


Thanks so much @bagofdragonite. So if I’m understanding correctly, in the first example the parameter moves from the first value to the second value in a straight line then remains at the second value. And in the second example it does the same thing but repeatedly moves between the first and second value. Is this correct?

Are “line” and “mirror” sp things or ruby things? I haven’t come across any doco on these as yet.



Line is documented in the Lang section, bottom left of screen… or you can type it in, put the cursor
in it and press F1…

Mirror is somewhere between the two… people use it, but maybe it isn’t formally acknowleged.

The help for line states:

line start (number), finish (number)
Create a ring buffer representing a straight line between start and finish of num_slices elements. Num slices defaults to 8. Indexes wrap around positively and negatively. Similar to range.
Introduced in v2.5

Consider it a ring from A to B, with X number of steps, triggered by Tick?



I think @Eli answered most of your questions.

Regarding line, it will move through the values in a straight line (rising or falling) then repeat in a cycle. If you want the value to remain at the high point use “.ramp” to achieve this. I’m sure once you read through LANG you will understand how to use these better than I’m explaining here.


Hi @aen1gma,


for a documentation of commands to manipulate ring (chapter 8.5 in the inbuild tutorial also).


Glad to see this. I didn’t realize reflect was different from mirror until now.


For a nicely formatted version of section 8.5 see:


Thanks so much everyone. I managed to get the result I was hoping for…

use_bpm 180

melody = (ring :C2, :E2, :G2, :B2, :C3, :B2, :G2, :E2)

live_loop :strange do
  use_synth :saw
  use_synth_defaults sustain: 0.5, release: 0.5
  m = play melody.tick cutoff: 30
  control m, cutoff: 80, cutoff_slide: 0.25
  sleep 0.5


I think there’s a comma missing after melody.tick With that added it works well.


Son of a… I feel like an idiot! That explains why this was the only approach that worked for me lol. So here’s what it should look like (thanks for pointing that out @robin.newman)

 use_bpm 180

melody = (ring :C2, :E2, :G2, :B2, :C3, :B2, :G2, :E2)

live_loop :strange do
  use_synth :saw
  use_synth_defaults sustain: 0.5, release: 0.5
  m = play melody.tick, cutoff: 100
  control m, cutoff: 80, cutoff_slide: 0.25
  sleep 0.5