Eternal Engine MARS Is the 4-Voice Polyphonic Tube Synth of Your Dreams
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What do you get when you combine a poly synth with tubes? The Eternal Engine MARS, the world’s first polyphonic synthesizer based on vacuum tubes.
Eternal Engine MARS
There are all kinds of synthesizers out there, from analog to digital and all hybrid points between. What you don’t see so often though are tube-based synths. There’s the gorgeous but fabulously expensive Knif Audio Knifonium, the Korg Volca Nubass, and Erica Synths Fusion System II. None of these are polyphonic though. For that, you need Eternal Engine MARS.
A four-voice poly, MARS comes in a 5U rackmount housing with four gorgeous vacuum tubes jutting from the top. It looks a bit like a Studio Electronics SE-1 mashed up with mid-20th century military equipment. Yes, it’s very very cool.
Vacuum Tube-Powered Synthesis
Eternal Engine MARS sports a “fully tube audio path” according to the company, and is based on its APPARATUS duophonic synth. Read more about that here.
The sound starts with the four oscillators, which are based on the R-2R DAC TDA1387, a DAC that can be repurposed into outputting waveforms. This actually makes it a hybrid synth, since this is a digital oscillator. Interesting.
The oscillators have four modes: Basic, with sine, triangle, sawtooth, and fixed pulse width at 1/2, 1/4, and 1/8 cycles; Pulse; Ensemble; and Noise with highpass and lowpass filters. You can operate it in three voice modes: mono, duo, and four-voice polyphonic with auto and continuous portamento and legato.
Next, there’s a voltage-controlled tube filter of the second order with cutoff, resonance that goes into self-oscillation, plus an additional overload circuit for extra grit. Need more harmonic distortion? There’s a separate triode asymmetric overdrive too.
Lastly, the VCA is also tube-based and is modeled on the traditional architecture of tube opto compressors. Super cool.
Pump up the Modulation
On the modulation front, Eternal Engine MARS offers two HADSR envelope generators with pre-delay and multiple retriggers. There’s also an LFO with restart and sync modes, plus smooth waveform transitions between sawtooth-triangle-sawtooth and pulse-square-pulse. You also get sample and hold plus noise with reconfigurable highpass and lowpass filters.
For routing all of this modulation, there’s a four-channel modulation matrix.
Connectivity
Eternal Engine MARS is interesting in that it’s both very traditional (check out the Nixie-lamp display!) and very modern. Along with the 20th century tubes, you get DAW control via a dedicated plugin plus USB PC integration. Additional control connectivity includes five-pin MIDI ins and outs plus four channels of CV plus a gate for working with Eurorack.
There’s even an audio-in jack for processing external audio through the tubes.
Price and Availability
Eternal Engine MARS is admittedly a niche product but if you like synths and you like tubes, or are looking for an instrument with a unique sonic character, check this one out.
The synth is now available from Eternal Engine for $2199 excluding shipping and local taxes. The tubes are removed for shipping. You also get an additional set of tubes, you more can be ordered should you need to.
If you want to experiment with tube-based synthesizers but don’t have the money for this, check out Brainworx’s emulation of the Knif Audio Knifonium.
More Information
- Eternal Engine MARS product page
- All about synthesizers
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2 responses to “Eternal Engine MARS Is the 4-Voice Polyphonic Tube Synth of Your Dreams”
Awesome. I was hoping for PVC pipes but vacuum tubes are a pleasing runner up.
Sounds awesome
There are certainly other poly synths using vacuum tubes. I think Metasonix made one and there is certainly a DIY design that has been around for over a decade. Fosstodon produce one that contains over 300 tubes!!
Looks kool though anyway 🤠