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In the realm of modular synthesis, logic gates play an interesting role. Derived from digital electronics, these gates process binary signals (high/low, on/off) to produce new outputs based on specific rules. By integrating Boolean logic into a Eurorack system, musicians and sound designers can create complex, dynamic, and responsive patches. This article explores the various types of Boolean logic gates and shares three specific Takaab modules by Siam Modular that exemplify these principles.
Boolean Logic in Eurorack
Logic gates are fundamental building blocks in digital circuits, performing basic logical functions on one or more binary inputs to produce a single binary output. In Eurorack, these gates manipulate gate, trigger, control voltage (CV), and audio-rate signals to achieve various musical and sound design outcomes.
OR Gates
An OR gate outputs a high signal if any of its inputs are high. If all inputs are low, the output is low.
AND Gates
An AND gate outputs a high signal only if all of its inputs are high. If any input is low, the output is low. AND gates are useful for creating conditional triggers and complex rhythmic structures.
XOR Gates
An XOR gate outputs a high signal only when the inputs are different. XOR gates are also practical for adding conditions to your patterns.
NOT Gates
A NOT gate, or inverter, outputs the opposite of its input. If the input is high, the output is low, and vice versa. NOT gates are often used to invert gate or trigger signals, providing an opposite response in a patch.
NAND Gates
A NAND gate outputs low only when all inputs are high; if any input is low, the output is high.
NOR Gates
A NOR (NOT OR) gate outputs a high signal only if all of its inputs are low. If any input is high, the output is low.
XNOR Gates
An XNOR gate outputs a high signal when both inputs are equal, either both high or both low.
Experiment with AND Logic
You might be on a budget and want to test such a module without expanding your rack yet. What if I told you that you probably have all the ingredients to simulate an AND logic module?
Here's a patch note explaining how to achieve it:
Other Use Cases
DivKid showcased several unique and unconventional techniques in one of his videos. Here are some summaries of fresh ideas for using logic modules.
Unique Audio Processing
Logic can be used for unusual audio effects. For instance, XOR logic was demonstrated as a form of square wave ring modulation, which creates distinctive square wave sounds that can be musical and destructive. This technique involves turning any input into a square wave, useful for both rhythmic and melodic textures.
If you want to experiment further with audio-rate processing, here's a patch note that uses a logic module to process audio-rate signals and create a deep, rich tone:
Melody Creation
Logic gates can transform clock signals into melodic patterns. By mixing different clock outputs and routing them through a logic module, you can create evolving sequences and melodies. This approach allows for generating a variety of sequences by adjusting simple clock inputs.
Pulse Synchronization
AND logic can act as a pulse synchronizer or timing quantizer, filtering out signals to only pass through when they align with a clock. This is helpful for quantizing input signals and synchronizing unsynced sources.
Merging Gates and Triggers
OR logic can merge or mix gates and triggers, which is useful for integrating gate and trigger sources to create complex envelope shapes and rhythmic patterns.
Three Takaab Modules by Siam Modular
I recently received several Takaab modules from Siam Modular to push the rhythmic boundaries of my performance system. At the core of my setup is the Flame Instruments Takt, which serves as the brain of the system. I’m sending its gate signals to the Squarp Rample via MIDI and have 8 free gate outputs available. To enhance rhythmic pattern diversity and escape redundancy, I’m creatively merging these 8 gate outputs under various conditions using the following modules.
SOR-1U: Dual Passive Logic OR Gate
The SOR-1U is a dual passive logic OR gate with normalized/switched inputs. As mentioned above, OR logic combines inputs to output a high signal if any input is high. The module can act as a single 6-input gate or two separate 3-input gates. SOR-1U does not require power but has a small voltage drop.
2AND: Dual AND Gate
The 2AND module provides AND logic processing. It includes two 3-input gates, with the 3rd input defaulting to high, allowing for 2-input use. Gate 1’s output is normalized to Gate 2’s first input, making it function as a 5-input AND gate. The module produce a metallic sound similar to an inverted MS-20 ring modulator with square waves.
2XOR: Dual XOR Gate
The 2XOR module offers exclusive-OR logic for Eurorack setups, with two 3-input gates where Gate 1's output is also normalized to Gate 2's first input. This setup allows it to function as a 5-input XOR gate. It outputs a high signal only when the inputs are different.
In Sum
The introduction of Boolean logic gates into a modular setup significantly expands the creative possibilities, allowing for more dynamic and responsive patches. Logic gates are great components in modular synthesis, providing powerful tools for signal processing, rhythmic generation, and complex modulation.
Each type of gate offers unique functions that can be creatively applied within a patch. Whether you are merging audio-rate signals, creating intricate rhythms, or exploring complex modulation patterns, logic gates provide the foundation for endless experimentation and innovation.
Takaab modules are both affordable and compact, making logic easy to integrate into any system. If you, like me, want to multiply your gates and triggers to create innovative variations, logic modules are essential. They can transform your original patterns into new ones, eliminating the need for an additional expensive and large sequencer in your rack. This also means you'll spend less time programming sequences to integrate patterns well with each other.
By the way, Siam Modular offers a wide range of affordable and compact Takaab modules, including the 3HWR, Triple Passive Half Wave Rectifier, the VLH (VCO's Little Helper), Ring Modulator, Sub Oscillator and Noise, the 2NON-1U Passive Dual ON-OFF-ON Switch, and the 2LPG-1U Dual Passive Low Pass Gate. These are all modules I've used and recommend, along with many other options from their lineup.
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