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6. Recreating a TB-303 acid line with Dune CM

1 Load Acid Riff.mid from Tutorial Files on a new MIDI track in your DAW. Notice how some notes are at a velocity value of 90, while others are at 117? These two velocity values emulate the respective ‘regular’ and ‘accented’ notes that the TB-303’s internal sequencer will spit out. Also observe how each ‘regular’ note is a uniform 32nd-note in length; while longer, overlapping notes represent sequenced notes with ‘slide’ applied.

2 Next, load up Dune CM on the channel, and select Bank B to initialise the synth. Toggle the Mono button in the Output section to recreate the TB-303’s monophonic voicing, then set Glide to 60% to cause overlapping notes to slide into each other. Set Osc 1 as either a saw or square – no fancy waveforms allowed here!

3 Now, the filter: emulate the original unit’s filter design by choosing the LP Ladder 24dB filter. The TB-303’s Decay parameter is used to control filter envelope decay, so let’s set that up in Dune CM: set Filter Envelope’s Attack, Sustain and Release to 0, then Decay to around 60%. Now use the Filter Env knob to set the amount of filter modulation, as with the original’s Env Mod parameter.

4 Twisting the original synth’s Accent knob increases the filter envelope’s effect over accented notes, creating a distinctive ‘wow’ – and level increase – over those notes. We can replicate this in our patch by applying more of the filter envelope’s effect over riff notes with higher velocity values (ie, our ‘accented’ notes): head into the Mod Matrix and set things up as in the screenshot above.

5 To recreate the ‘wow’ shape of the filter’s effect over accented notes, set the Mod Envelope’s Attack, Decay, Sustain and Release to 27%, 44%, 0% and 0%. Now the Velocity » MM Amount 1 mod amount effectively becomes the original unit’s Accent knob, as it defines the amount by which the mod envelope affects the cutoff over our ‘accented’ (ie, higher velocity) notes.

6 The pulse width of the 303’s square wave oscillator subtly changes with pitch, so let’s replicate that in our patch. Set Osc 1 to a square wave, set P/Width to 55%, then head into the Mod Matrix and assign Note # as the source and Pulse Width as the destination, with an amount of +16. Our raw ‘303’ tone is complete: now apply distortion and modulation effects for aggression and movement.