The Roland TB-303 lay at the heart of the mid-80s Acid House scene, filling dance floors with its characteristic squelchy sound. The sound is perhaps a bit clichéd these days, but it remains important because variations of it power basslines in many contemporary dance music styles. Original TB-303 hardware units are now rare and staggeringly expensive, but the instrument’s uncomplicated synth engine is easy to emulate with a monophonic synth such as BLEASS Monolit.
For this we need only a single oscillator, set to produce a square wave. The AMPLITUDE envelope needs a punchy and percussive sound, which means a near instantaneous attack and a fast decay to a relatively low sustain level.
The TB-303 features a low pass filter with a steep 24dB/octave slope, which we can mimic in Monolit by engaging the filter’s “2x” mode. The filter should have a relatively low cutoff frequency with a middling resonance. You will need to come back and tweak the cutoff and resonance as you add modulators to the filter, so don’t worry about setting this perfectly at this stage.
To achieve the characteristic squelchy sound, the TB-303’s single envelope is also used to control the filter cutoff frequency. To mimic this in Monolit, use the ASSIGNABLE EG to create a second envelope that has a similar shape to the AMPLITUDE envelope, and assign this to FILTER CUTOFF. The assignment’s AMOUNT dial can then be used to set the desired intensity of the squelching effect.
The sound can be made more responsive and expressive by increasing the VELOCITY slider of the ASSIGNABLE EG. This causes harder-played notes to have more initial brightness and squelch than softer-played notes.
As things stand, if playing in a legato style, the envelopes will not retrigger when a new note is played. This can give a very pleasing effect, but if you want to ensure the envelopes retrigger every time you play a note, set Monolit’s RETRIG setting to “On”.
The TB-303 also has a Slide setting that can be triggered on a per-step basis by the instrument’s sequencer. We can do similar in Monolit using the GLIDE setting, although this needs to be automated in your DAW or assigned to a controller if you want to apply the effect only to certain notes.
Further expressive control can be achieved by mapping your keyboard’s modulation wheel (or other continuous controller) to the filter cutoff, allowing you to open and close the filter as needed. If your keyboard features realtime control knobs or faders you can also consider assigning these to control the filter resonance and the strength of the ASSIGNABLE EG mapping.
Experiment with changing from a square wave to a sawtooth wave, or using a blend of both. Don’t forget to save your sound when done.
