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Korg Volca Nubass reviewed by Markkus Rovito

Markkus Rovito

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With vacuum-tube oscillators, motion sequencing, and more, the Volca Nubass is an analog minisynth with a fresh take on the classic TB-303 acid-bass machine.

Photo Above: Weighing less than a pound, the Korg Volca Nubass follows the usual Volca blueprint of packing an impressive amount of sonic manipulation and sequencing into a small, battery-powered box.

Just in time for the reemergence of ’90s-style acid house and techno, Korg has bestowed upon musicians and producers a lovely new synth bass machine that nods to the unmistakable legacy of the Roland TB-303 Bass Line from 1982, while supplying additional sonic richness, modulation options, and sequencing capability. 

If you’re one of the few people who cannot instantly win a round of Name that Synth when you hear the genre-defining sound of the TB-303 or one of its emulators, you may not understand the immediate joy that ensues when turning on the Volca Nubass and hearing its output. For most us who may have dreamed of owning a vintage TB-303 but balked at its price or felt unsatisfied with another 303 emulation, though, a modern analog option with all of the sound for such a low price comes as a true delight. 

There’s a lot more to the Volca Nubass than just recreating the 303. It also has vacuum tubes, a suboscillator, an analog overdrive circuit, an LFO, parameter automation, battery power, and a built-in speaker. It really can sound just like the ’80s classic, but the heft of the Nubass’s suboscillator and analog drive circuit add extra layers of fat. The possibilities realized by the LFO and motion sequencing lend its sound more complex modulation and dynamic variance. 

Like the TB-303, the Nubass has that characteristic smooth analog glide, the biting yet “wet” squelchiness, and that fierce shriek when the filter resonance meets the filter cutoff’s sweet spot. Its sequencer also features the crucial Transpose, Accent, and Slides functions for making authentic acid-bass patterns.

It Squelches and Belches through Vacuum Tubes

To distinguish the Volca Nubass’s sound from the average acid-bass synthesizer, Korg has its Nutube vacuum-tube technology for first (but likely not the last) time. One Nutube drives the main Vacuum Tube Oscillator (VTO), and another works on the drive circuit of the suboscillator, which is one octave below the VTO. The VTO generates sawtooth or square waveforms (selectable via one of the 16 step buttons) and has a Pitch control. The suboscillator has a Level control to pump it up or essentially eliminate it, as well as a Saturation knob for a little extra warmth.

Korg Volca Nubass schematic
The Volca Nubass’s two Nutubes offer the same audio qualities of other vacuum tubes but also utilize vacuum fluorescent display technology for visual flare.

On a bass synth such as this, the filter always steals the show.

True to form, the monophonic Nubass features a voltage-controlled, transistor-ladder lowpass filter. The filter has the largest control section on the instrument, with an oversized Cutoff knob and a large Peak (resonance) pot. The filter envelope has Attack and Decay controls, as well as envelope intensity (EG Int), which provide a wide range of how much the envelope actually changes the filter cutoff. 

Nubass also has an analog overdrive circuit on the Drive control. This both compresses the audio output and applies light distortion. It results by degrees in a heavier, more aggressive and harmonic sound. Positioned below that, the Tone knob applies specifically to the response of the high frequencies, giving them a sharper sound when turned up. When the filter resonance is wailing, the Tone can really ratchet that up to piercing levels. Go ahead and get crazy, but be careful with your ears using headphones. 

Another great addition, the LFO lets you alter the sound in many ways the TB-303 does not. All of its options require using the Function button, though, meaning that it’s difficult or not feasible to tweak the LFO and another parameter at the same time. Like the VTO, the LFO can take the sawtooth or square wave shape, and it can affect one or more of three target parameters: filter cutoff, pitch, and amplifier. Function + Attack adjusts the LFO Rate, while Function + EG Int adjusts the LFO Intensity (modulation depth). 

The LFO is very versatile. When used lightly on just the amp or the pitch, it can introduce a subtle sense of motion or bounce to a pattern, but when used on one or more of its targets at high rate and intensity settings, it can turn a pattern into gurgling, burbling chaos. My favorite use is to modulate the filter cutoff with the LFO and then find the most interesting areas of interplay between the LFO modulation and the other filter settings. That would be even more fun if the LFO had dedicated pots rather than Function-level controls, but you can work around that limitation in a way by using the onboard sequencer’s parameter automation. 

Nubass tubes
The Nutubes’ fluorescent glow shines through the back of the Nubass.

Step by Step

The Korg Volca Nubass’s 16-step sequencer holds 16 pattern memories, called up using the Memory button and the numbered step buttons. Memories 1–10 have preset patterns you can overwrite or alter using real-time or step recording. Memories 11–16 are blank.

I suppose it wouldn’t be a proper acid-bass synthesizer if pattern recording weren’t a bit of a slog. For either real-time or step recording, the button keyboard looks a little off, because the normally black keys are white and vice versa. Also, the downbeat steps 1, 5, 9, and 13 are not easily denoted as they often are on step sequencers. 

I wish that real-time recording had an audible metronome. Instead, a red blinking LED on the Tempo knob indicates the metronome. That works better than nothing, and after recording, the Shift note function works well enough to correct timing errors. 

Step recording—entering notes one by one for each step in the sequence—isn’t the most musical of processes. Nonetheless, it starts to feel more comfortable with practice, and you can check your progress along the way with the Play button. 

The recording modes may not be the smoothest, but then again, part of the fun of an analog step sequencer can be just going for it and making the best of happy accidents that occur. Some of that magic definitely comes into play with the Transpose, Slides, and Accent buttons—key features for achieving the sound of a classic acid-bass synth. You can enter these values per step or randomize them for the whole pattern. The three Transpose values are off, +1 octave, and +2 octaves. Slides sets the amount of smooth glide between notes to none, short, or long. Choose from three Accent levels and specify the overall accent strength with the Accent knob, which can be motion sequenced. 

Motion sequencing is another highlight of the Nubass that you won’t find on vintage machines. It lets you record the movements of the oscillator and filter controls into a pattern. When you turn on motion sequencing and start recording, the Nubass records one pass of control movements and then stops recording while continuing to play, which helps for continuous jams or live performances. 

Synth functions
When recorded motion plays back, the LED-backlit knobs that have motion sequences applied to them light up.

Layering up combinations of motion sequences, such as an oscillator pitch, filter resonance, and envelope intensity, the dynamics of a pattern can become very animated and complex. Because the motions don’t always work well, of course, you can quickly clear all the motion data, or you can save the motions into a pattern. 

Synth patches are not saved with patterns. The sound is always what it is at the moment regardless of whether you change patterns.

Performance

Naturally you’d want a synth groove machine like this to be a good fit for live performance or improvisational recording, and the Nubass has a lot going for it in that arena. Other than the slight inconvenience of needing the Function button to adjust the LFO controls and the miniature format of the Volca’s interface, it’s very easy to quickly explore and morph between the full range of the Nubass’s sounds using the hands-on controls. 

With sequences playing, you can use the Step Jump function to jump the sequencing to a certain step you press at any time to create variation, or just modify the pattern on the fly by playing on the keyboard during normal playback. 

Of all the modern bells and whistles the Nubass provides beyond vintage gear, massive pattern memory is not one of them. Lengthy live performances could benefit from a large store of patterns. Unfortunately, with only 16 patterns of 16 steps each, the Nubass does not have an abundance of patterns. They are relatively short, and you have no way to load patterns or back them up (other than recording them as audio). At least the Chain function lets you string together a range of patterns to play back consecutively and looped, which lets you form long progressions of sequences. Chaining is limited to a range of consecutive patterns on the step buttons, for a pattern range of 1–9, 3–16, 9–12, etc.

Volca Nubass IO

Like other Volcas, the Nubass has Sync I/O cable jacks for connecting and syncing to other Korg gear such as Prologue/Minilogue/Monologue keyboards, certain Electribes, and other Volca units. Nubass also has a 5-pin MIDI In for connecting with other MIDI gear or a computer through an interface. 

For potential stage use or traveling, the Nubass takes six AA alkaline or NiMH batteries to run for an advertised eight hours (on alkaline batteries). In my tests with the included alkaline batteries, I used the Nubass for more than 7.5 hours using a combination of headphones and the internal speaker for the output, and the batteries were still going strong. 

Besides purchasing a separate AC power adapter, you can also power the Nubass with the Korg Volca Mix, which acts as a mixer and power supply for as many as three Volca units. Using a Volca Mix for live or studio use affords you extra capabilities like an independent volume fader, mute, and low/high-cut EQ for each Volca; global analog compression; stereo widening for the mixed output; and an effects send with send amount per channel. 

Korg Volca Nubass display
The Volca Nubass’s small display shows key info such as the active recording or playback mode and other function names.

Everybody Needs a…

When it comes to audio gear, the term “no-brainer” gets thrown around too much, often by those doing the selling rather than the buying. (Full disclosure: I paid full price for the Nubass rather than borrowing a review unit.) The Volca Nubass was an actual no-brainer for me. Even better, it lived up to or exceeded my hopes for how it would sound and what the sequencer would do. I do wish, however, that it had more pattern memory locations, as well as a way to back up patterns.

The Nubass won’t be a no-brainer for everyone, of course. Not everyone likes the Volca format, in which most of the controls are small and spaced closely together. An occasionally cumbersome workflow requires stepping through a lot of button presses and the Function button, too. If you have only a passing interest in the 303-style sound, are satisfied with the 303-like solution you already have, or want something that’s a bit more plug-and-play with a DAW, you can save your two bills for another impulse buy. 

Although I’ve described how the Korg Volca Nubass does more than just ape the TB-303, there seems to be no end to faithful TB-303 clones appearing. Very recently, in fact, Behringer began taking pre-orders for its TD-3 analog bass-line synth for a similar retail price. 

Having experienced the Nubass’s stellar sound coming from its Nutube vacuum tubes and its extra synthesis and sequencer options that go well beyond the original 303, I personally think the Volca Nubass exceeds the value of its street price. I recommend it as a new twist on one of the most recognizable instruments in electronic music.

Website: korg.com

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Price: $200

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