By Gino Robair
Radikal first hit the synth scene several years ago with the Spectralis, a 32-voice module that sported, among other things, analog and digital filters, sequencers, multi-sample playback, step sequencing, and drum programming. Its designer, Jörg Schaaf, is one serious synth player (his credits include work with Klaus Schulze) who set out to create the instrument he’d want to play. As a result, the Spectralis was a constant work in progress, not unlike a modular synth, where new ideas are added and perfected over time.
Schaaf’s new creation, the Accelerator, has had a similarly long development cycle, but it was ready for prime time when it started shipping. The Accelerator is a high-end virtual analog synth featuring multi-part sequencing and arpeggiators, impressive programming flexibility, and modulation by tilting the keyboard along two axes, much like you might with an iPad synth. It’s also scalable: Adding one expansion card ups the base spec of eight voices and two multi-timbral parts to 20 voices and eight parts; a second card bumps polyphony up to 32 voices.
Hardware
The keybed feels solid and has a smooth, responsive synth action. The interface, however, straddles both modern and vintage (as in ’80s-style) synth design. Although recent performance synths have added dedicated controls for the most important parameters, the Accelerator takes a hybrid approach by using endless knobs (a.k.a. rotary encoders) that double as buttons when you push them in. As a result, the interface isn’t overcrowded with knobs (though some synth players might prefer one knob per function), yet you can still access what you need quickly. Still, you should plan to spend a little time getting acquainted with the Accelerator’s interface.
Once you do, you’ll find that the layout is straightforward: Turn a knob to change parameters, or push it in quickly to make a selection or step through menu pages. If you get lost, hold a knob down for two seconds to access the built-in help system, where a text description of what the encoder controls pops up on the LCD. In fact, no matter where you are in the menus, when you turn a knob, a small window pops up in the left corner of the screen to display the values you’re dialing in.
In some cases, there are two ways to get something done—either in the menus or by using the “Direct Edit” controller matrix. Five buttons—VCO, VCF, VCA, LFO, and User—select what the row of eight knobs controls does. For example, to edit VCO 3, press the VCO button three times. Now you have hands-on control over eight parameters (one for each knob): waveform, coarse tuning, and so forth. Need to edit VCF 2? Hit the VCF button twice. The LCD follows your moves, and parameters are printed on the panel so you won’t forget.
To go deeper into editing, turn or push the Page knob and cursor around the LCD with the up and down buttons. The three knobs below the screen change values.
Considering the multi-function controls, the Accelerator is easy to use in live performance. It has dedicated controls for octave shifting, bypassing the effects, setting the effect wet/dry mix, and dialing in arpeggiator and sequencer tempo. An Arp-Edit button calls up parameters that let you “play” sequenced parts using the knobs.
By default, the left button of the pair above the pitch and mod wheels controls rotary speaker speed in the organ presets. However, I programmed these buttons to create sudden interval leaps in several lead patches.
While it became easier to edit Accelerator patches the more I worked with the instrument, I’d prefer to use a software editor. Unfortunately, the editor/librarian is still in development.
What’s in a Voice
While the multitude of features makes programming seem daunting at first glance, the Accelerator’s overall structure is fairly logical. Each synth voice has three oscillators, noise, and the output of a ring modulator that uses oscillators 2 and 3. The oscillator’s waveforms are continuously variable from sine to square, making them perfect modulation targets.
In addition, you can add “time linearity modulation” (TLM) to each oscillator. TLM is similar to pulse width modulation, except that it works with any waveform, not just pulse waves. In essence, it divides the waveform into its positive and negative phases and lets you lengthen one phase while shortening the other, as the LCD shows a graphic of the waveform’s changing shape. You can independently modulate the waveform and the amount of TLM using any of the controllers. As if that isn’t enough, you can sync oscillator 1 to 2, or use oscillators 2 and 3 to phase-modulate all three oscillators. The potential result is some serious harmonic complexity.
The Accelerator’s four LFOs also have continuously variable waveforms, including a random setting. Three of the LFOs are polyphonic and used for modulating voice parameters, while the fourth is global. This lets you create patches where the modulation starts at a different time for each note in a chord. The first thing I did was assign a slow, random LFO shape to the output pan position, so that as I added notes to a chord they panned independently, but in tempo, within the stereo space.
There are two main multimode filters (two- and four-pole varieties of lowpass, highpass, notch, and bandpass) per voice, and a separate filter dedicated to the noise source. In addition, a cool “String Filter” employs something like the Karplus-Strong method that’s typically used for modeling plucked strings. This version has been enhanced with high- and low-frequency damping and the ability to change the phase of the output. Together with its dedicated pitch envelope, the String Filter is well suited for emulating bowed strings, especially when combined with a little filtered noise.
The Accelerator’s envelopes are faster than those in the Spectralis, and it’s very much evident in the factory presets. They’re great for creating snappy percussion and punchy basses.
Savvy synth users will be happy to learn that the modulation capabilities in the Accelerator are extensive, with 50 modulators and 32 potential destinations. In addition to the LFOs and envelopes, modulation sources include pedal inputs, channel aftertouch, key-off velocity, a randomizer, and even a sequencer line.
One modulator that’s unique to the Accelerator is the position sensor, which can read the degree to which you tilt the instrument both left-to-right and front-to-back. Each axis can be assigned to any of the modulation targets. Although the keyboard is relatively lightweight, it’s not light enough for you to use position modulation as freely as you might with an iPad synth. If you dial in too much of it, you’ll hear the results as the keyboard shakes on its stand while you play—it’s that sensitive. (That actually worked surprisingly well for realistic pitch-bends on a Koto.)
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Effects and Sequencing
One of the first things you’ll notice when playing is the high-quality effects processor, which offers distortion, modulated delay, chorus, phase shifting, reverb, and a Leslie speaker emulation. Schaaf’s presets take full advantage of them, and the dedicated FX Dry/Wet knob is handy for dialing in a tasteful amount of signal processing in real time.
The Accelerator’s four stereo effects busses are dynamically allocated, and in the base version of the synth, one effect is assigned to each sound. This lets you change patches on the fly without hearing a bump in the sound due to the effect algorithm being interrupted. Add one expansion card, and you can use all four effects busses at once.
The phaser and chorus sound particularly good, and lend a very ’70s sound to the brass and pads. I had the most fun with the rotary effect because the Accelerator offers independent control over the upper and lower rotors. Just varying their rates creates a stunning effect, especially on external sound sources. The synth’s audio inputs can handle instrument- as well as line-level inputs, so I plugged my 12-string electric guitar right in and wallowed in the psychedelic sounds of the phaser and rotating speaker. It’s not clonewheel-grade Leslie emulation, but it’s very musical.
Speaking of trippy sound, the Accelerator has feature-rich sequencing and arpeggiating. There are two arpeggiators and two sequencers in the basic model, upgradable to eight of each by adding an expansion card. The 32-step sequencer has one row for pitches and chords, and three additional rows for parameter values. Although plenty powerful for songwriting in the studio, the sequencer is optimized for performance, allowing you to “play” parameters while it’s running.
The arpeggiator is equally gig-ready. It can play notes in several directions (including random), while dialing in the number of note repeats and octave leaps, as well as rhythmic values and gating amounts in real time. I spent hours playing Splits where I had an arpeggiated voice in one hand and a pad or brass sound in the other.
Sounds
Single sounds can easily be split into key ranges or stacked as a Dual. It’s easy to set up Splits and Duals on the fly, and to store Performances, which contain all the parts’ settings, including those for the effects and arpeggiator.
Calling up a sound is old school—you select bank and program numbers. Thankfully, you can save a series of ten patches (as well as assorted keyboard functions) in a chain, making it easier to step through them while playing. You can store up to 100 chains.
While there are many bread-and-butter patches in all categories, the current series of presets veer more towards the creative aspects of sound design than instrument emulation. Keyboardists looking for electric piano timbres will find just over a dozen, for example. You have about 200 user slots to save single sounds.
There are 300 factory presets to start with, and the majority of them are musically useful while showing off the programming capabilities of the synth. So while the ten sound categories are conveniently banked by type—Bass, Organ, Sequencer, Lead, Percussion (meaning percussive keyboards), Brass, Arpeggio, Pad, SFX, and Drums—expect to do some archeology in finding sounds for a project. Once you do, put them in a chain for easy recall.
Standouts include “Brassy Pad,” which hints at “Crazy Diamond”-era Pink Floyd; the “2 Filters” bass patch that offers Aftertouch expressiveness; and “Comb Flute 2” with its String Filter breathiness. Overall, the Bass, Brass, Lead, and Pad categories provided the most satisfying starting points for creative tweaking. With the exception of a few kick drums, the big disappointment was the Drum category. Having only two multi-timbral parts in an unexpanded Accelerator doesn’t allow kit building, as the most you can do is split the keyboard into two sounds such as kick and snare.
The Randomize feature is a cool patch starter. It automatically assembles (and names) a new sound by recombining parameters from existing presets.
Conclusions
The Accelerator is a powerhouse of programmability for musicians looking to create signature sounds, but geared towards immediacy and fun in live performance. Its overall audio quality is outstanding. Despite being DSP-based, it conjures realistic and powerful analog timbres when you want them, but easily moves on to the broader palette of sounds you’d expect from a digital keyboard. It’s a musically satisfying synth that has a sound all its own.
Snap Judgment
PROS Excellent sound quality. Deep programmability. Continuously variable oscillator and LFO waveforms. Exceptional modulation capabilities. Built-in help menus.
CONS No editor/librarian software yet. Menu-oriented interface takes some getting used to.
Bottom Line
Sounds so fat you’d think it’s a real analog synth, but has a depth of modulation options only a virtual analog machine can offer at anywhere near this price.
Base: $2,195 direct
Expansion cards: $395 each
radikaltechnologies.com
Key Info
POLYPHONY 8 voices, expandable to 32.
MULTI-TIMBRAL PARTS 2, expandable to 8.
Oscillators per voice 3.
Filters per voice 3.
WEIGHT 19.8 lbs.
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