For most keyboardists, the word “modular” conjures up images of Keith Emerson, Hans Zimmer, and Wendy Carlos, all surrounded by miles of patch cables. Modular synths have traditionally consisted of analog exotica in racks that fill entire walls—in which just one boutique oscillator or filter can cost as much as a capable modern keyboard synth. Nowadays, with a bit of cash and ingenuity, you can build a modular synth out of stuff that fits more easily into your home studio, or to put it another way, you can use your studio as a modular synth. Even on a sub-$1,000 budget, you can quickly turn the whole enchilada into a warm, fat, dirty mess of oscillating voltages that will deliver results far beyond even the most detailed analog emulations—because it is analog.

Core Synths

The first thing you’ll need is an analog synth with external audio inputs and at least one or two control voltage (CV) ins and outs. Have less than $1,000 to spend? Here are our top picks for that role.

Doepfer Dark Energy
For a list price of $625, the Dark Energy (reviewed Feb. ’10) is a greatest hits package of entry-level modular goodness. Its lowpass filter is among the warmest we’ve heard on a modern analog synth, and its LFOs are capable of audio-rate modulation for gritty FM effects. It’s even got MIDI over USB, so driving it from your computer or controller keyboard is as painless as it gets. What makes the Dark Energy the perfect starter modular, though, is the external audio input, which feeds any signal into its morass of processing options. This lets you enrich the signal of ROMplers, workstations, software synths, ’90s-era digital synths you may have lying around—you name it.

Tom Oberheim SEM
Tom Oberheim’s comeback synth (reviewed Mar. ’10) comes in three flavors: MIDIcontrolled, voltage-controlled, and a hybrid of the two. All are on-point reproductions of the legendary Synthesizer Expander Module, with its multimode, state-variable filters and super-fat oscillators. Here, we recommend the voltage-controlled model, especially if you’re picking up a Dark Energy as well. We’ve had no problems driving the SEM from the Dark Energy’s CV and gate outputs—and the combination of the two is about as close to modular heaven as you’ll get for a total of under $1,500 street price. As with the Dark Energy, you can route external audio into the SEM’s engine.

Moog Slim Phatty
Profiled in this month’s New Gear section on page 16, Moog Music’s latest gives you that famously juicy sound at a fraction of the price of a Voyager. At well under a grand, we’re kind of blown away, as it includes USB MIDI, filter and pitch CV inputs, keyboard gate inputs, and most importantly, an external audio input.

Expanding the Rig

Once you’ve got one or more of the above synths, you’re ready to roll. If you’ve still got some cash left over, consider the following expansion possibilities:

Moogerfooger Pedals
With models that cover everything from ring modulation to 12-stage phasers to analog delays, the Moogerfoogers are the hottest thing in analog effects. Our faves? The MF-104Z Analog Delay (shown) and CP-251 Control Voltage Processor. Adding those two to one of the synths on the previous page will propel you further down the modular rabbit hole. A great option for those on a budget is the MF-101 Lowpass Filter, an authentic Moog filter with CV inputs for cutoff, resonance, mix, and envelope follow amount. If you can’t quite afford any of the Phatties, this pedal imparts a good chunk of Moog sound to your other synths. Run your crusty ROMpler through the MF-101 with the input drive all the way up, and you’ll be treated to a sound that’s light years thicker than you may have thought was possible from the aging beast.

Korg Monotron
While the Monotron (reviewed Nov. ’10) doesn’t have CV ins or outs, it does feature a fully analog recreation of the filter from Korg’s MS-20 synth, a filter LFO that extends well into the audio range for grimy analog FM, and that all-important input for external audio. For a measly 60 bucks, it’s the cheapest way to squeeze some real analog filtering into your rig.

MOTU Volta
For analog buffs, Volta (reviewed Aug. ’09) is the coolest software imaginable, as it converts MIDI note and controller data from your DAW—as well as host automation data—into the control voltages that drive analog synths. A couple of caveats: It’s Mac-only, and you’ll need an audio interface with DC-coupled outputs (such as almost anything MOTU makes) to send the control voltages to your synth(s). Pair Volta with the CV version of a Tom Oberheim SEM, and you have a 21st century version of a classic modular, with a fraction of the fuss. If you have a couple of vintage classics, Volta is happy to command them. I had no problems using it with a 27-year-old Roland SH-101, which I then fed into the Dark Energy for further processing.

Wiring It Up

Basic. The most cost-effective way to get your feet wet is to grab a Dark Energy, plug it into your USB hub, and treat it like an effects processor—albeit one that doubles as a warm and punchy bass and lead synth. If you’ve also sprung for the Korg Monotron, then you’ll also have the option of patching the output of the Dark Energy into the external input of the Monotron for a longer effects chain. Then, when you feed another synth into the Dark Energy, you’ll have two filters to choose from as you process it. By blending both filters, you’ll get results impossible from either alone.

Intermediate. You can use the Dark Energy’s gate and CV outputs to “play” the SEM, and simultaneously feed the Dark Energy’s output into the SEM’s audio input. To hear the Dark Energy alone, open the SEM’s lowpass filter all the way and switch its VCA on so that the signal bypasses the SEM’s envelopes. Since the SEM has two audio inputs, you can dedicate its second input to any other keyboard or module you might have and process that as well.

Things get really interesting when you start patching the Dark Energy’s various CV modulation outputs into the SEM. For example, you can get crunchy, Daft Punk-style vocaloid effects by patching the Dark Energy’s audio-rate LFO 1 CV out into the SEM’s filter CV input, then raising the SEM’s resonance and sweeping its cutoff frequency manually. This type of setup was the cornerstone of my rig for the better part of 2010 and the results have been astonishing.

Advanced. Moog’s brand cachet aside, savvy producers have known for years that Moogerfooger pedals are magic for tracks that ooze character. Once you get bitten by the modular bug, these pedals become more valuable thanks to their CV inputs, which allow tricks like LFOmodulated delay or envelope-modulated phasers.

Adding the CP-251 to our “intermediate” rig gives it a boatload more flexibility by letting you modify the control voltages passing between the SEM and Dark Energy. In addition, you get to a fourth LFO, lag processor (often used for portamento and waveshaping), mixer, noise source, and sample-and-hold effects. Then, adding an MF-104Z delay between the Dark Energy and the SEM (or vice versa) lets you create integrated chorus/flanger effects that truly are impossible to do otherwise.

On the topic of Moog, their CV Output Modification for the Little Phatty adds voltage outputs for gate, pitch CV, volume envelope, filter envelope, and modulation bus. With this, you could easily use a Phatty (instead of a Dark Energy) as the SEM’s control synth in the previous two configurations, telling an envious world, “My modular is a Moog/Oberheim hybrid!”

Master Class. Adding MOTU’s Volta plug-in transforms the audio outs of any DC-coupled audio interface into computer-controlled voltage outputs that deliver ultra-precise LFOs, sequencers, envelopes, and automation for total modular “pwnage.” What’s more, you can calibrate the oscillator CV inputs for your analog synths to be perfectly in tune— a nifty trick. With Volta, you can even forego the USB connectors on the Dark Energy or Moog Phatty and control those synths directly from the plug-in via your audio interface’s outputs, with connections to spare for control of any parameter with a CV input—all of it synced to the tempo of your host project.