November 27, 2022

The Eurorack format used to be mono, but a new generation of modules can bring out the stereo field. How can you integrate them into your system?


Watch our video on how to get into stereo modular.


In 1931, inventor Alan Blumlien was sitting in a local movie theater when he was struck by the idea of ​​applying stereophonic sound to movies. In 1933 he was granted a patent for a unique record cutting process and the first stereo phonograph records were produced that same year. However, the technology—and a skeptical public—would take another two and a half decades for stereo sound to achieve widespread acceptance and the format to become standard in most homes and venues.

This was understandable: the cost of the transition to stereo was considerable, and media was still being produced widely in mono. For stereo sound to become mainstream, it would take a serious effort from both industry leaders and the consumer. Stereo technologies had to become cheaper, more accessible, and the public had to understand the benefits they would bring.

It seems as though a similar situation is now occurring in the modular synth community.

A little more recently, in 1995, Dieter Döpfer introduced the Eurorack synth format to the world, and more than 25 years later, we’re seeing an explosion of stereo tools within the modular realm, almost now expected of new releases Manufacturers and synthesizers alike are delighted with the widespread implementation of stereo modules, and they are becoming more accessible and user-friendly than ever.

Just like the phonograph record, it has taken some time for technology to change and for us as a whole to embrace the power of stereo sound in our systems. Before we had this modern multitude of modular options, you had to have pairs of everything if you wanted to get true stereo. Now, from our oscillators to our effects chains, everything seems ready for stereo processing.

When I started my own modular journey ten years ago, I remember stereo options being limited to a handful of processors – the scene I knew was predominantly mono, and I liked it. Working with mono signals never hindered the joy of implementing a modular system, however, the addition of a rich stereo field has added a new layer of complexity and sonic experimentation that really makes me enjoy the instrument even more.

With a growing number of customization and self-expression options within the Eurorack universe, isolating the right tools to bring stereo into your system can be daunting. So let’s take a minute to highlight some notable manufacturers producing stereo products and some of their modules that are redefining the way we think about our systems.

This Eurorack behemoth is at the forefront of the modular stereo movement. With the announcement of their highly anticipated oscillator, the XPO, they now offer fully stereo modular voice. Here are some featured pieces from our friends in Asheville, North Carolina.

morphage. This beloved module remains one of the most popular Eurorack modules of all time and offers users the power of a digital tape machine in 20 HP. With stereo sample capture and playback, a unique array of audio parameters and tons of CV I/O, the Morphagene has established itself as a modern classic.

XPO. Make Noise’s latest release is an analog oscillator that features three unique stereo outputs. The module’s internal pulsewidth, wavefolder, and varitimbre parameters can be independently modulated on the left or right side. Five additional analog mono outputs, two 1v/o inputs, FM and sync input complete this powerful voice.

QPAS. With a purely analog signal path, multiple resonance peaks, four sets of stereo outputs, internal VCA, and plenty of CV capabilities, this filter offers a ton of control and tonal flexibility. Combine this with XPO, Mimeophon and any of their classic dual utility modules for a complete stereo experience.

Qu-Bit produces some dazzling stereo sound sources and effects modules. Their new release, Aurora, will make you question your concept of what stereo reverb can be.

Data Bender. This has to be one of the most unique offerings to hit the world of modular effects in a long time. Embodying all that stutters, crashes and degrades, the Data Bender scratches an itch you weren’t even sure you had. Its latest firmware update lets you control the depth of its stereo field, and the module’s wide CV inputs allow for intricate modulation possibilities.

surface. Surface stands out among the saturated supply of physical modeling fonts. With crisp, clean tones, multiple sound models and configurable stereo outputs, the Surface makes a great pair with any stereo effects unit.

aurora. Qu-Bit’s latest release redefines the world of modular effects once again. From ambient shimmers to otherworldly textures, the Aurora lives up to its moniker. The front-mounted USB port also allows for instant updates and program changes.

The creative folks at Noise Engineering craft a variety of unique and thought-provoking instruments. Its Versio and Legio series modules are stereo capable and cover many applications.

Virtue Iter Legio. An impressive new digital stereo oscillator, the Virt Iter Legio features independent stereo phase inputs and lush chorus in just 6HP. With such a small footprint, this oscillator is ideal for starting your stereo journey.

Polydactyl version. Unfortunately, equalization and dynamic processing are often overlooked when building a modular system. The Polydactyl Versio offers an elegant stereo solution in just 10 HP. Throw it on the end of the chain to hook your mix, or throw it on an individual instrument and use the saturation to shape new timbres.

If you want to mix stereo signals within your system, you’ll want to familiarize yourself with some mixing options first. You may immediately notice that there are many different modules to choose from, and that size, feature set, and cost can vary significantly. Basic stereo mixers like the Doepfer A-138s start around $90, while more professional tools like the WMD Performance Mixer will set you back more than $1,000.

At the most basic level, a stereo mixer should contain multiple inputs, amplitude controls, and a set of outputs. You can find other features on some mixers, such as internal VCAs, channel panning, aux sends, mutes, or CV inputs for any of the above, and while these extra utilities are great to have built in, they’re not necessary to get started to mix stereo signals Two individual mono mixers can act as left or right channels. Consider combining the power of several modules to achieve a stereo effect.

The word “trend” seemed to come up often when discussing this topic with other modular users. So is stereo just a trend? I do not think so. I see this as a welcome new direction for the format. I have a hard time seeing this as anything other than an improvement on something that’s already impressive. The nature of the instrument has always been innovation for the sake of creativity.

With leading companies focusing more on stereo versions and younger users adopting modular all the time, it seems to me that stereo is here to stay, and personally, I’m excited! Once again, the Eurorack community has been saved from redundancy and continues to offer users new and fresh ways to create and play with sound.

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