Axel Hartmann announces the 20 Synthesizer

What if the design of a synthesizer was not dominated by economic considerations or with regards to certain brand criteria? What, if I could run free, use any material and manufacturing process, that I think feels right, fits and looks the best to design a synthesizer? If I could just choose the right ergonomic concept, no matter what it finally costs?

20 is this instrument. We dedicate this design to 20 years of designing synthesizers at Design Box. The outside is a 3-dimensionally shaped, full aluminium casing with an ultra-thin collapsable panel that opens up with the push of a button. All user interface elements are made of milled aluminium. Everything the user touches is real material, with pleasing haptics.

Me and the team at Design Box invested almost 2000 hours in the aesthetical and mechanical design of the casing and all parts. We spent an infinitely long time to find a company, who can make the aluminium works, or who can laser edge the product graphics on such a wide panel. The body shell is milled out of a massive aluminum block, which alone weighs over 80 kilograms in its raw state.

Like the collapsable panel, it is being produced in a rapid prototyping process on a CAD/CAM-controlled 5-axis milling machine. The milling itself is not trivial at all. We had to redesign the mechanical setup several times to avoid vibration during the process, as this would cause significant inaccuracy, which we absolutely not want. But the aesthetically results of this technology are simply stunning. The inside perfectly includes all PCBs and cabling. The entire surface and the sides of the casing are pillow shaped. The entire outside of the instrument is wearing a slightly structured anodized surface – which looks and feels fantastic.

The synthesizer is handcrafted right in the heart of Europe. It is not a series product – only 20 silver and 20 black units will be built and sold.

To make this project possible, we adapted already existing technology. The sound engine is designed by Waldorf, making this synthesizer an easy to use, yet enormously deep, powerful instrument. Oscillator 1 includes the classic PPG Wavetables for the creation of digital textures and soundscapes, as well as all kinds of bellish / metallic sounds, known from so many number 1 hits of the 80’s up to today. The included sample memory is filled with samples from the prestigious Neuron synthesizer, optimized by Kurt Ader and his team to fit perfectly into the structures of the soundengine.

German high-end audio manufacturer SPL added a specially designed version of their SUPRA op-amps, that integrates right behind the synthesizer DSP. With 120V operating voltage, this technology provides exceptional performance throughout the whole signal processing path for the 20, adding balanced stereo and high-end headphones outputs.

We re-use the basic Frontpanel-PCB layout and setup of the Studiologic Sledge synthesizer. For a better feel, we use pots with a full metal stem, instead of the standard pots with plastic stems. Also, we redesigned the pushbuttons and invested into a taylor made plastic injection-mold. We also replace the standard TP 9 keybed with a high end TP 8 keybed, specially molded for this synthesizer in all black.

The simplicity of the extensive user interface allows for an incomparable experience when working on sound, and makes this synthesizer much more a musical instrument than a technical device. The layout of the user interface mirrors the signal flow of the synthesizer. The interface reads from left to right, starting with the LFOs. The 3 Oscillators follow to the right, feeding the Mixer section, where each of the Oscillators, plus the Noise generator are equipped with an on/off switch.

The Multimode Filter with its dedicated ADSR Envelope Generator to the very right is located on top of the Amplifier Envelope, and the two Effects. All parameters are accessed directly – there are no shift or secondary functions, that distract from sound design. The distance between each of the knobs and switches matches perfectly the golden rules of German Industrial Design (minimum clearance of 40mm’s).


• all black high-end Fatar TP8 61 keys keybed with aftertouch

• 35 pots with aluminium caps

• 3 x 7 positions rotary switches with aluminium caps

• 1 rotary encoder + push function with aluminium cap

• 2 x 16 digits backlit liquid crystal display (black typo on white background)

• aluminium Pitch and Mod Wheels

• Up to 999 programmable sounds

• Fast and efficient sound selection via numeric keypad

• 2 fast LFOs per voice with adjustable Speed and Depth

• 1 extra modulation routing for Mod Wheel, with adjustable Speed and Depth

– LFO Shape: Sawtooth, Rectangular, Triangle, Sine, Sample & Hold, Ramp

– Modulation Destinations: OSC 1, (+) OSC 2, (+) OSC 3, PWM / Wave / FM, Volume, Filter Cutoff

• 24 voices polyphony – Monophonic mode with single or multiple trigger

• 3 Oscillators per voice

– Range from 64′ to 1′ with Semitone ant Detune controls

– Shapes: Sawtooth, Square, Triangle, Sine, Pulse (with Pulse Width Modulation)

– OSC 1 with 66 Original PPG Wavetables + Sample Player (60MB internal memory)

• FM – Frequency Modulation of Sine and Triangle – Oscillator Hard sync (OSC 2 to OSC 3)

• Noise Generator – White and Pink noise

• Mixer with Volume and On/Off switch for each Oscillator and Noise

• Split or Layer mode / programmable split point for each program

• 1 Multi Mode Filter per voice

– 24 / 12dB

– Lowpass

– Highpass

– Bandpass

– Resonance up to Self-Oscillation and beyond – adjustable Key Track and Drive

• 2 fast Envelopes per voice (Filter-Amplifier) with Amount and Velocity control (Filter+Ampli)

• Powerful Arpeggiator – Latch mode – syncable to MIDI Clock

– Direction Up, Down, Alternate – Range up to 10 octaves

• 2 simultaneous Effects

– Effect 1: Chorus / Phaser / Flanger

– Effect 2: Reverb / Delay / Reverb+Delay


• Master Volume Control

• Power Switch

• Expression pedal input

• Sustain Pedal input

SPL analogue audio outputs & headphone amplifier

– Discrete high voltage SUPRA op-amps

– Operating voltage: 120V Rail (+/-60V)

Line Outputs

– XLR & Stereo Jack connectors, electronically balanced

– Frequency Range: 4Hz to 480kHz (-3dB)

– CMR: -82dBu (at 1kHz, 0dBu input level and unity gain)

– Noise: Unweighted -101.87 dB; A-weighted -104.76dB; CCIR: -96.1dB

– Dynamic Range: 134.37dB

Headphone Output

– 6,3-mm TRS connector

– Alps RK27 „Big Blue“ Volume Control

– Pin wiring: Tip = Left, Ring = Right, Sleeve = GND

– Impedance: 5 ohm

– Attenuation Factor: 180@40 Ohm

– Frequency Range: 10Hz to ›480kHz ( -3dB)

– Crosstalk at 1kHz: -106dB

– Noise: Unweighted -101.12dBu; A-weighted -103.98dBu, CCIR -95.02dBu


• USB connector for MIDI IN/ OUT, Firmware Update, Samples Loading (with Spectre)

– uses standard USB MIDI driver provided by host computer OS

– Windows ME minimum, Windows XP or newer recommended

– Mac OS X 10.2 minimum, Mac OS X 10.3 or newer recommended

• Built in power supply


• Solid Case with generous padding

• Power Cord

• Printed User Manual in English and German

• 20 Spectre Software (on USB stick)

38,19″ x 15,94″ x 4,33″         (97 cm x 40,5 cm x 11 cm)


26 Kg / 57,4 Pounds lb



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