Blocks bring the world of modular synthesisers into Reaktor. Each Block is a self-contained module - an oscillator, a filter, an envelope, a sequencer - that you patch together with virtual cables, just like the Eurorack-style hardware systems that have become hugely popular. Blocks sit between playing finished ensembles and building from raw modules: you design the system, but each component is already built.
Modular thinking
On a fixed-architecture synth, the signal path is decided for you. On a modular system, nothing is connected until you patch it. That freedom is the point: you can route anything to anything, create feedback loops, modulate modulators, and build instruments no manufacturer would design.
Two kinds of signal travel through the cables:
- Audio - the sound itself.
- Control (CV) - signals that change parameters: pitch, cutoff, amplitude, timing. In hardware these are control voltages; in Blocks they work the same way.
Because both are just signals, you can modulate one with the other - including running audio-rate signals into control inputs for FM-like effects.
Types of Block
- Oscillators - sound sources, from simple waveforms to complex digital and modelled designs.
- Filters - low-pass, high-pass, band-pass and character filters modelled on classic designs.
- Amplifiers (VCAs) - control loudness.
- Envelopes - ADSR and other shapes.
- LFOs and modulators - cyclic and random modulation.
- Sequencers - step sequencers and clocks to drive patterns.
- Utilities - mixers, attenuators, logic, maths, quantisers.
- Effects - delays, reverbs and more.
- MIDI input and output - bring notes from your keyboard or DAW into the patch.
The Blocks community has also built many more in the User Library.
A first patch
- MIDI in - a MIDI Block providing pitch and gate.
- Oscillator - patch MIDI pitch to its pitch input.
- Filter - patch the oscillator output into it.
- VCA - patch the filter output into it.
- Envelope - patch the MIDI gate into its gate input, and its output into the VCA's level input.
- Output - patch the VCA to the ensemble outputs.
That is a complete monophonic synth. Now extend it:
- Patch a second envelope to the filter cutoff.
- Add an LFO to the oscillator's pulse width or the filter.
- Replace the MIDI input with a step sequencer and a clock, so the patch plays itself.
Generative patches
A strength of modular systems is generative music - patches that play themselves and evolve:
- Clock a sequencer at one rate and an LFO at another, so patterns shift against each other.
- Use random modulation to vary pitch, timing or filter settings.
- Quantise random pitches to a scale so the result stays musical.
- Let a slow LFO change the sequencer's length or direction.
Think in systems
- Start simple. One voice, working, before adding complexity.
- Use attenuators on modulation so it does not overwhelm.
- Label and organise your patch as it grows.
- Save versions. Modular patches can change dramatically with a single cable.
Do this now
- Build the six-step first patch above and play it from your keyboard.
- Add a filter envelope and an LFO.
- Replace the keyboard with a sequencer and clock, and create an eight-step pattern.
- Build a simple generative patch with random, quantised pitches and save it.