A smattering of Eurorack modules patched together.
These days, it’s not uncommon to find hardware modular synthesizers in personal studios, because they can be used in so many different ways—from synth duties to processing a mix. Many musicians feel that the analog circuitry in these instruments offers a level of sound quality that is unattainable in the digital realm.
Although they look complicated and exotic with their endless tangle of patch cables, a modular synth is fairly easy to use. And modern modules are far less expensive than vintage ones, which also require TLC and maintenance.
A collection of analog modules gives you maximum flexibility in sound design; you can assemble a system that meets your specific needs. Best of all, a modular synth can be fully integrated into your DAW workstation via MIDI using a standard MIDI-to-CV converter or by utilizing software controller plug-ins such as MOTU Volta and Expert Sleepers Silent Way.
If you’re new to hardware modular synths and are interested in assembling one, here are some things to consider.
Form and Function Like a guitar-effect pedalboard, a modular synth holds a collection of devices that you connect using patch cables. However, synth modules are capable of much more than the average stompbox offers. In addition to patching audio through them, modules accept and/or generate control voltages (CVs), which are used to modify parameters in real time with greater resolution than MIDI offers.
Some modules include digital circuitry, though the patch connection between them remains analog. If you’re interested in an analog-only system, you’ll have fewer module options and you may miss out on products that benefit from digital control.
Modular systems come in a variety of form factors based around panel dimensions, cable and jack size, and power requirements. By sticking with a standard format, you’ll create an instrument that is easier to manage than a system that mixes modules of varying sizes and power needs. The format you choose is important because it determines the variety of modules you’ll have access to, which ultimately plays a role in your sound palette.
Typically, musicians choose a format based on the connector size—1/4", 3.5mm, or banana. (The latter two offer stackable plugs.) Modules with 3.5mm connections tend to be smaller than other formats and take up less space, though it also means that the knobs and jacks are closer together. The main formats in this size are Frac Rack (supported by Blacet and Metalbox) and Eurorack. Eurorack has become the most popular modular format, showing explosive growth in terms of manufacturer interest (more than 60 companies support the format) and module diversity. Eurorack and Frac Rack modules are just over 5" tall, and their cases fit into standard 3U racks. However, they have different power requirements, the Eurorack power connectors being the easier of the two to work with.
Some people prefer using 1/4" jacks because the modules tend to be larger and there is more room for your fingers. The main supporters of this format include synthesizers.com and the original Synthesis Technology/MOTM modules.
Other form factors are proprietary, such as those used by Buchla and Modcan. Both companies use banana jacks for control signals, though Modcan also has a line of modules that uses 1/4" jacks.
Regardless of format, the price of a module is usually based on its feature set. Generally, you can put modules into one of two categories—single-function and multi-function. As you would expect, single-function modules are often less expensive than multi-function units. A simple utility module can cost less than $100, while a multifunction module can run nearly two grand. However, you’ll often need more rack space and spend more money using single-function modules to create a sound than you would a multi-purpose module that does the same job within one panel.
Typical Uses With so many modules to choose from, it helps to determine how you’ll use them before you invest in a system. Here are a few of the most common ways modular synths are utilized.
• Subtractive Synthesis If you’re interested in building a classic analog bass or lead instrument, you’ve come to the right place. Your typical monosynth includes a VCO or two, a VCF, a VCA, an envelope generator, and perhaps an LFO. The manufacturer and module you choose for each of these will determine the overall timbral palette your instrument is capable of. By combining modules from several manufacturers, you can create a highly personalized synth that sounds like no other.
• Filter Box Analog filters make everything sound good. Engineers often have a collection of filters for processing audio tracks while recording or mixing, which can include envelope filtering and auto-wah effects. Although you can find plenty of 4-pole Moog-style lowpass filters, you’ll also find other classic sounds (such as recreations of the Oberheim 2-pole or EDP Wasp filters) as well as designs that are more modern. If it can be driven into resonance, a filter module can also be used as an additional sound source.
• Signal Processor While there are hundreds of fuzz and distortion boxes on the market, how many of them have multiple CV inputs? Waveshaping modules, for example, provide a wider array of distorted tones than any pedal, while giving you realtime control over numerous parameters. Imagine slowly modulating the quality of distortion as you play a solo!
Other types of voltage-controllable processing include ring modulation, delay, reverb, and a host of DSP-based effects. In fact, having a voltage controllable DSP-based module allows you to integrate digital processing into a complex patch without having to interface with a traditional rackmount processor or your DAW.
• Control Surface The earliest analog modulars from Buchla and Moog had ribbons and touch-sensitive pads that allowed greater control over sound shaping than traditional piano-style keyboards. A new wave of non-keyboard controllers are available for modern modular systems, ranging from updated ribbons to capacitance pad arrays and force sensing resistors.
• Video Processing A recent development in the Eurorack format are modules designed for use with video. Davey Jones Design offers a single processor, while LZX Industries has a collection of modules that provides a wider range of utility, from video mixing to pattern generation. In addition, Brownshoesonly makes a triple VCA that is compatible with the LZX system.
Gino Robair is a musician, composer, teacher, and author.