Radikal Technologies Spectralis: Powerful synthesis, sampling, sequencing, and filtering.
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FIG. 1: The Spectralis is more than a synth module with sample-playback and virtual analog sound engines. It''s also a sophisticated drum machine, step and pattern sequencer, and 10-band filter bank.

I first became aware of the Spectralis more than three years ago, just as the German manufacturer Radikal Technologies was pinning down the final details of its design. It sounded fantastic on paper: a digital synthesizer with analog filters, a fixed filter bank, user multisampling, and independent step and pattern sequencers, all in a performance-oriented tabletop module with loads of hands-on control. It promised to be the mother of all groove boxes, but was it too ambitious to be true? During subsequent NAMM shows I was able to see it, touch it, and hear it in action. I liked what I heard, and it appeared to deliver on its promises. At the very least, I knew that Radikal was on the right track.

The Spectralis is the brainchild of Jörg Schaaf, who was instrumental in developing synths for Quasimidi and has recorded and performed with electronic-music superstar Klaus Schulze. The Spectralis is a self-contained production workstation with features that make it attractive for live performance as well as studio use. Like most workstations, it can be used by itself, connected to other MIDI instruments, or installed as part of a computer-based system.

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Click here for product specifications on the RADIKAL TECHNOLGIES Spectralis: synthesis, sampling, sequencing and filtering..

Although the Spectralis has now been shipping since February 2005, its operating system is a work in progress, with new features arriving in dribs and drabs. I downloaded two minor updates while I was writing this review. Since August 2006, the only official operating system has been update 097. Currently I'm working with update 097L. Radikal says that 098 is right around the corner, but you shouldn't expect every announced function to work until version 1.0.

Uncharted Territory

One look at the Spectralis Analog Synthesizer/Beat Matrix/Filter Bank should tell you it's a serious piece of audio hardware (see Fig. 1). It's as solid as a brick, and it performs virtually all the functions you might expect from a groove box, and more. A 2 × 40-character yellow-green LCD and wood side panels give the Spectralis a distinctively retro appeal. A total of 37 knobs and 52 illuminated buttons are strewn across the front panel. You can press on all the knobs as if they were buttons. Every knob is an encoder that rotates infinitely — even the dedicated Master Volume knob. Because that knob's value isn't displayed in the LCD and it doesn't stop turning when it reaches maximum, you have to guess.

At first glance, the control panel layout may be overwhelming. The panel is divided into 15 discrete sections. At the bottom, a row of 16 numbered buttons lets you perform functions such as programming sequences and selecting parts, patterns, grooves, and motifs. You can also use the buttons to enter note data and to transpose patterns. Just above the buttons are 16 encoder knobs for controlling parameters such as part levels and step-sequencer values.

Above the 16 knobs is another row of 16 buttons, divided into 5 sections. The leftmost section is Num Button Assignment; pressing any of its 5 buttons determines the function of the 16 numbered buttons. To its right is Sequence Edit, which contains 3 buttons that open sequence-editing menus in the main display; pressing the buttons also assigns the 16 knobs and 16 numbered buttons to sequencer functions.

Next is the Groove Edit section, which contains just two buttons. Pressing Step/Accent lets you program drum sequences using the 16 numbered buttons to select steps, the first 12 knobs to select drums, and a menu in the display to specify parameters such as pitch and Velocity. Pressing Function opens another menu, but its functions haven't been implemented in the current OS (more about that later). The Filterbank section also has just two buttons, Level and Pan. To its right is the Mixing Desk section, which supplies buttons that determine whether the 16 numbered knobs will control volume, panning, or one of two effects sends for each of the 16 parts.

In the front panel's upper left, the Part section's 4 buttons — Select, Mute, Solo, and Play — also determine what the 16 numbered buttons do. When you press Select, you can use them to select parts for editing. If a pattern is playing, pressing Mute and selecting a part removes it from the sequence, and pressing Solo removes all the other instruments. Pressing Play allows you to play notes or beats on the currently selected instrument using the first 13 numbered buttons. In Play mode, you an use the final three buttons to shift octaves and to hold a note or chord.

Sections to access the synthesis parameters take up most of the front panel's top half. Three knobs control the LFOs, and three control the VCAs (the amplifiers, despite the name, are not voltage controlled). The VCO section (again, not voltage controlled) has four knobs, as well as two buttons for transposing a maximum three octaves up or down. The VCF section has cutoff and resonance knobs for each of the two filters, four buttons to select the filter slope, and one nonfunctioning button labeled Set Routing. Pressing on the knobs opens filter menus in the display.

The Spectralis's LCD is in the upper right, and below that are four knobs for controlling whatever parameters it displays. Below the knobs, the Advanced Editing section has buttons for scrolling displayed pages up and down, a Shift button for accessing alternate front-panel functions, and Enter, Exit, and Save buttons. Just below Advanced Editing is the Transport section, which includes a Tempo knob.

Making Connections

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FIG. 2: In addition to MIDI and USB ports, the Spectralis has nine analog audio -outputs and a pair of audio inputs for processing external sounds through its filter bank.

Other than USB, an IEC power receptacle, and MIDI In, Out, and Thru ports, all rear-panel connections are on unbalanced ¼-inch audio jacks (see Fig. 2). Two inputs allow you to process external sounds through the Spectralis's filter bank and synth engines. Sum R and Sum L are the main outputs, and Direct 1 through 4 are assignable outputs for individual parts. The synthesizer section has its own pair of outputs, and a headphone jack is also on the rear.

The Spectralis's USB port is exclusively for transferring software updates, samples, and other data files to and from your computer. It does not serve as an audio or MIDI conduit, and there's neither an editor-librarian nor a plug-in for controlling the Spectralis. When USB is connected, the Spectralis's internal 64 MB of flash memory appears on your computer's desktop as if it were a removable hard disk. If you view its contents, you'll see song folders and dozens of files that only the Spectralis recognizes. You can expand the onboard memory by plugging SmartMedia cards into two slots on the front panel, or you can store files on your computer's hard disk and drag them to the Spectralis's flash memory as needed.


At the heart of the Spectralis's Hybrid Synth are four analog-modeling digital oscillators that generate continuously variable waveforms. That means you can morph from one waveshape to another by applying a modulation source. You can also modulate the spectrum of any waveform in a fashion similar to pulse-width modulation using a technique that Radikal calls Time Linearity Modulation. If you want extra grit, you can reduce the bit depth of individual oscillators — a capability that's unusual on hardware instruments. Each oscillator has its own amplitude and pitch envelopes, and you can individually adjust their glide times — very nice. Because the audio oscillators can function as modulation sources, you can combine them in various ways for frequency-, ring-, and phase-modulation synthesis.

The Hybrid Synth (which the manual also calls the analog synth) has two real analog filters that give the Spectralis lots of character. One is a lowpass filter with a 24 dB-per-octave slope, and the other is a 12 dB-per-octave filter with lowpass, highpass, bandpass, and notch outputs. Both can resonate up to self-oscillation.

Remarkably, the Hybrid Synth supplies 10 LFOs and 14 envelope generators. The three LFO knobs let you control rate, depth, and waveform, which is continuously variable from sine to sawtooth to random. Four of the LFOs offer additional parameters such as individual envelopes and definable start points. The Spectralis's envelope generators are of the ADSR variety, but with an additional hold stage. They are hardwired to 14 logical destinations; 8 control volume, 4 control pitch, and 2 control the lowpass and multimode filters. Despite the Spectralis's abundance of front-panel controls, it has no dedicated envelope knobs, but assigning the four knobs beneath the display is only a knob press away.

You might expect an instrument with so many knobs and buttons to make most parameters available on the surface, but the Spectralis goes much deeper than most synths. When you press on a knob in the VCO section, you can scroll through 26 oscillator pages, each containing 4 hidden parameters ranging from routing individual oscillators to the filter bank to specifying Time Linearity Modulation settings.

Surprisingly, the manual provides only limited detail about VCO parameters. Fortunately, you can find information hidden in the Spectralis's onboard help system. Just hold the Shift button, press one of the four encoders beneath the display, and a description will appear in the LCD. Pressing the Page Up and Page Down buttons allows you to read any additional text.

Alternate Engine

Along with the Hybrid Synth, the Spectralis has 3 DSP Synth parts with a combined polyphony of 32 voices. The DSP Synth engine is most useful for playing user samples and drum and percussion sounds. It has its own stereo digital filter with resonance and a 12 dB-per-octave slope; it operates as a lowpass, highpass, or bandpass filter. Two ADSR envelopes modulate the filter and amplifier, and Velocity can modulate them as well.

The Spectralis comes with a collection of multisamples that loads automatically. You can import your own samples by converting 16-bit, 44.1 kHz WAV or multisampled SoundFont 2.0 files into the Spectralis format using the included Smpllmp.exe application, but only in Windows (a Mac version is planned). A simple drag-and-drop procedure quickly converts files.

On the Fly

The Pattern Sequencer lets you create songs by arranging as many as 32 patterns. Each pattern plays 16 individual parts and may be as long as 16 measures. Parts 1 through 11 and part 16 are dedicated to drum and percussion sounds, and parts 12 through 15 are dedicated to synth sounds. Within each pattern are motifs that play each part; a motif is a melody, drumbeat, or chord pattern. The Spectralis comes with a large library of motifs, and you can create your own by either real-time or step-time recording. Every motif can have a different length and time signature.

The Spectralis gives you complete, real-time control over the arrangement and mix of each pattern and song (see Web Clip 1). You can mute and solo parts, adjust their levels and panning, and replace any sound with any other available to that part. You can even exchange motifs and grooves while the sequencer is playing, and jump back and forth from pattern to song mode.

The Step Sequencer has 32 tracks, each with a maximum of 192 steps. You can route tracks to control various parameters that include note value, amplitude, filter cutoff, and so on. You can determine duration, Velocity, and even probability — the likelihood that an event will be triggered when a sequence line repeats. Steps can be played, muted, or skipped, and they can be any length from a 192nd note to 12 measures. In addition, the Step Sequencer can transmit MIDI data to control external hardware and even software instruments.

With the 097L update, the Spectralis has gained not one but six arpeggiators. A complete set of user parameters includes direction, resolution (from 192nd to whole notes), octave range, gate time, and more. A nice twist is that the arpeggiators can respond to notes played by the Step Sequencer. (For information about the Spectralis filter bank, see Web Clip 2.)

To Be Continued …

The Spectralis has something for everyone. For keyboardists who want variety, it's a versatile instrument offering some very good factory sounds and the ability to import your own samples. For sound designers who want to tweak parameters they've never seen before, the Spectralis goes as deep as you want to dig. And for musicians who just want to reach out and make some music, its preprogrammed motifs and patterns serve up speedy gratification. The Spectralis's virtual analog synthesis sounds warm and fat, and its versatile sequencing encompasses the instrument's strongest features.

The Spectralis's routing flexibility is very impressive. You can direct sounds from almost any point in the signal path to virtually anywhere. You can process drum grooves or samples from the DSP Synth with the Hybrid Synth's analog filter, and you can process sounds from any source with the filter bank.

Although you can do an awful lot with the Spectralis, its development is ongoing, and several rather basic functions have not yet been implemented. Most notable is that only one of the two effects processors works at all; its only effect is delay, and it has no user parameters. It's not unusual to maneuver your way to a parameter in the LCD, only to discover that the associated knob is nonfunctional, as indicated in the display by brackets around the parameter name. On the other hand, the Spectralis's designers have left plenty of room for future expansion. You can always add more features through software updates, but adding more knobs and buttons would be impossible.

Radikal describes the Spectralis as being open ended, and I can see some sense in that approach. Instead of having to replace your synth when new and desirable features become available, you could just update the one you have, much as you can with the Korg OASYS or Access Virus. However, the Spectralis's degree of noncompletion is somewhat unusual for a hardware instrument, and more akin to what you might expect from beta software. Somewhere over the horizon are new features such as dynamic effects, Control Change automation, event editing, and support for REX files.

In the meantime, the Spectralis is a very versatile synthesis workstation that suffers somewhat from a rather complex and confusing user interface. It makes some operations (such as copying motifs from one pattern to another) easier than most groove boxes do, but many are more difficult. Even after spending many hours learning my way around, I frequently had trouble finding exactly the parameter I wanted to adjust. If you were to devote yourself entirely to mastering the Spectralis, though, it would offer you a satisfying platform for creating all kinds of electronic music.

EM associate editor Geary Yelton has been playing, programming, and writing about synthesizers for more than 30 years.

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Click here for product specifications on the RADIKAL TECHNOLGIES Spectralis: synthesis, sampling, sequencing and filtering..



synthesizer workstation module



PROS: Warm, fat, and punchy. Impressive versatility. Solid construction. Loads of oscillators, LFOs, and EGs. Analog filters. Imports user samples.

CONS: Unfinished features. No user-programmable effects. Limited USB functionality. No digital I/O. Poor documentation. Difficult to learn. No sample-file translator for the Mac.


Radikal Technologies