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Martinic AX73

Software Synthesizer By Gordon Reid
Published March 2022

Martinic AX73

Martinic take Akai’s long‑neglected AX73 ball and run with it.

You may not have come across the chaps at Martinic as yet, but they’ve been writing plug‑ins for a while, both for their own brand and for other manufacturers. Avoiding the mainstream, they have so far concentrated on unusual instruments and effects such as the Elka Panther, the Kee Bass and the LEM tape echo, and their latest offering shares this philosophy, being a soft synth based loosely upon the Akai AX73 synthesizer.

The original keyboard was one of a small series of instruments that Akai designed using the CEM3394 ‘synth on a chip’. It offered six voices that could be played as a single six‑voice patch, as a three‑note, dual‑voice but monotimbral layer, or as a six‑oscillator unison monosynth, the last two of these with detune to thicken things up a bit. Each voice was based upon a single VCO and noise, followed by a velocity‑sensitive, resonant 24dB/oct low‑pass filter and a simple 6dB/oct high‑pass filter. Following this, the signal then passed to a velocity‑sensitive VCA and a dual‑mode chorus. There was portamento, an LFO provided modulation, and dual ADSR contour generators could be directed in two modes to the VCO, VCF and VCA. Given what was on offer, it should have been a better synthesizer than it was, but the similar AX60 was easier to use and had a nicer sound, and the more advanced VX600 was streets ahead. Furthermore, the AX73 suffered from some serious shortcomings, perhaps worst of which was that it still relied upon audio tape as its patch storage mechanism.

Happily, Martinic’s AX73 reaches far beyond the original. Each oscillator now offers waveshaping of all five waveforms and has a square‑wave sub‑oscillator. The VCF retains audio‑frequency FM but now offers three modes (LP/BP/HP) and three cutoff slopes, and there’s an additional 6dB/oct LPF to help mould the overall tone. The chorus has four modes derived from the AX73 and AX60, plus a width control. There are also four invertible HASDR contour generators with three triggering modes, seven selectable destinations and independent velocity sensitivities, and four LFOs with a host of new features including nine destinations, a programmable sample & hold mode, various triggering modes, a one‑shot contour mode, and both mono and poly modes. There’s an 11‑mode, MIDI‑sync’able, three‑octave arpeggiator, and new keyboard modes. Oh yes... and much like a Super‑JX10 (which incorporates two JX8Ps) or a DX5 (which incorporates two DX7s), there are two of these synthesizers — called Parts — available in every patch. At the end of the signal path, the output of both Parts is fed to a series of eight effects units (many of which you can sync to MIDI) that you can patch in any order you choose, and any combination of which can be active at any moment.

In Use

I ran the soft synth alongside my VX90 (the AX73’s rackmount sibling) and set up a selection of simple patches to see whether it had the character of the original. The oscillators were close, but filter sweeps had a slightly different sound, even once I had tweaked everything to make it as similar as possible. Was I concerned by this? Not in the slightest. If you don’t have an AX73 or VX90 nearby to make forensic comparisons, why would you care? I then proceeded to create more complex patches, first staying within the range of the Akai, and then straying far beyond it. In truth, it’s so difficult to programme great sounds on the original AX73 and so simple on the soft synth that I found the comparison almost pointless.

Mind you, the soft synth’s GUI won’t be to everyone’s taste. The Keys page (shown above) wastes a lot of space and displays only a tiny subset of the upper Part’s parameters. This means that you have to access the three Settings pages to get into the guts of the synth. These have a grey, two‑dimensional appearance that harks back to the days of the Atari 1040ST so, if you have a hankerin’ for a slick, resizable, rendered GUI, this isn’t the soft synth for you. But once I had grown used to it, I found it to be clear and simple to use, provided that I kept a clear picture in my mind regarding which EG was doing this and that, and which LFO was doing the other.

The Settings page certainly offers a more visual indication of what’s going on than Akai’s AX73 front panel did...The Settings page certainly offers a more visual indication of what’s going on than Akai’s AX73 front panel did...

While creating these sounds it occurred to me that some of the soft synth’s underlying structure is not much different from a Prophet 10’s, so I tried to recreate some of the Prophet’s sounds on it. I didn’t succeed fully but, in pursuing these, I programmed many other patches that I liked very much. I was also able to create some interesting layered sounds that combined an attack phase generated by one Part with a sustained phase generated by the other. In addition, Split mode allowed me to play two sounds (say, bass below the split point and organ above) independently.

Moving yet further from the original AX73, I experimented with the Dual and Unison modes, which play either two or six voices per note respectively. Since the maximum polyphony of the soft synth is four times that of the Akai, the number of notes available in these modes can also be four times greater, so I used Dual mode to create lush, 12‑note polyphonic ensemble sounds, and Unison mode to create huge, detuned four‑note monsters. For obvious reasons, these modes also benefitted monophonic lead and bass sounds, which can be played with low‑, high‑ and last‑note priorities.

Interestingly, there’s no mechanism for simulating the vagaries of analogue oscillators. However, there’s never any obvious phase cancellation in a Part either. This seems to have been accomplished by ensuring that the oscillators are never in tune with one another. The closest that I could get them seemed to be around 0.05Hz — far enough apart to avoid cancellation but close enough to sound like analogue oscillators in tune with one another. Simple, and clever!

Another unusual approach has been employed to avoid aliasing. You can play higher and higher up the keyboard until you reach a note with a frequency of a little over 8kHz (C9 using an 8’ oscillator) and if you then play higher, the notes wrap back down an octave. This means that the fundamental never approaches the frequencies at which aliasing is a risk. Of course, it’s the harmonics of complex waveforms that cause the problem, but some good anti‑aliasing filtering has also been applied, and the sound of the AX73 remains commendably lacking in artefacts.

It has a character that’s rather different from many of the more mainstream soft synths.

So, what of its shortcomings? There are a few. For example, it doesn’t respond to aftertouch or MPE, and MIDI Learn suffers from the common limitation that any given CC can affect only one parameter at a time. It also lacks an audio input so you can’t use it to treat samples, which was an important feature of the original. Elsewhere, despite what the manual says, there’s no fine adjustment mode and many of the knobby parameters are programmable only in integer steps. In addition, there’s no way to allocate the same number of voices to the upper and lower Parts; the only ratios available are 3:0, 2:1, 1:2 and 0:3 and, while these echo the original synth, this is an area that Martinic should have updated. Next, I would like to see a more useful rendering with more controls on the Keys page and the option to resize the GUI. And, finally, there are neither AAX nor stand‑alone versions, which will be a limitation for some users. But all of these (with perhaps the exception of the last) are niggles, and none of them should stop you using the AX73 if you like the sound that it’s making.

...and the Effects page offers even more....and the Effects page offers even more.


While the Akai AX73 was hailed as an alternative to the likes of the first Roland Juno series, it sank almost without trace. So, while I can see why the chaps at Martinic named their soft synth as they did, I might not have done so. Sure, its sound is inspired by the Akai, but its capabilities reach so much further that the association is at best tenuous. Happily, we’re here to judge the soft synth on the sounds that it’s capable of producing, not on its provenance, and here the AX73 scores highly. It has a character that’s rather different from many of the more mainstream soft synths, so it’s certainly worth downloading and testing the trial version. If you like what you hear, you could be tempted to convert it into a full licence. Given the attractive price, you could be very tempted.


  • Given the link to the original AX73, its sound quality and flexibility are far greater than you might expect.
  • It runs on legacy systems running Windows 7 (32‑ and 64‑bit) and Mac OS 10.9 onward.
  • It uses a soft licensing system, so no dongle is required.
  • It’s affordable.


  • The GUI won’t be to everyone’s taste.
  • It doesn’t respond to aftertouch or MPE.
  • There are no AAX or stand‑alone versions.
  • There’s no audio input.


The AX73 is an unusual soft synth that bears only a passing resemblance to the Akai synths that inspired it. Despite its rather bland appearance, it’s a surprisingly competent soft synth and there’s much here to enjoy. If you’re looking for something a little leftfield (or even if you’re not) it’s certainly worth trying.


£78 including VAT.