Arturia iProphet

Virtual vector synthesis app for iPad

By the mid 1980s analog synthesis was being surpassed in popularity by the sonic possibilities offered by new forms of digital synthesis. In 1986 Sequential Circuits released a synthesizer with a completely new form of synthesis called Vector Synthesis. The Prophet VS keyboard (it was also available in rack module form) was not only well-received by many musicians, it was also the direct ancestor of vector synthesis keyboards and modules from Yamaha and Korg. Vector synthesis typically uses four oscillators or wavetables and gives the user the ability to dynamically crossfade and mix between them on a XY axis vector plane, balancing the relative volume levels of each. This can create sounds that are far more complex, with significant movement and changes to the sound over time. Arturia impressed me with their inexpensive and great-sounding iSEM iPad app, so I was eager to check out iProphet, their iPad version of the classic VS synth.

What You Need To Know

• I checked out version 1 of iProphet, as well as the latest update, version 1.1. iProphet 1.1 requires an iPad 2 or newer running iOS 6.0 or later. It adds iOS 8 compatibility and fixes a few bugs that were in the previous version, such as the MIDI channel selector not showing devices opened if iProphet was opened before them, the issue where every third oscillator would be the one before on preset load, and a Frequency knob issue where turning one of them fully clockwise caused it to act as if it was set to zero and turned fully in the opposite direction. Version 1.1 also updated Audiobus to 2.1.5 and added the ability to delete custom presets.

• Right off the bat, let's clear any potential confusion. This isn't a Prophet 5 emulation. Developed by Arturia and Retronyms, it is their iPad app recreation of the Prophet VS. Like the Prophet VS iProphet is a digital synthesizer that uses vector synthesis, with four digital oscillators.

• There are four screens in iProphet, labeled Main, Vector, Mod Matrix and FX. Across the top of the Main screen is a menu bar, with all the tools you need to load and save programs.  Programs are arranged in thirteen categories, including Ambient, basses, brass, chords, efx, instruments, keyboards, leads, moving, pads, sequence, strings and woodwinds, and hundreds of presets are included.

• Near the left side of the Main screen you'll find the four oscillators. Each has frequency and fine tuning controls. You get the expected sine, sawtooth and square waveforms, but there are also many complex waveforms here too, with a total of 95 different waveforms available. They are generally well named to give you a good idea of what to expect. Tapping on the wave display number calls up a scrolling Select Waveform dialog box. There's also a search field where you can start to type in the name of the wave you want and have it come right up, which is a handy and convenient feature that can save you a lot of scrolling.  

• The iProphet's multimode filter occupies the center of the main screen. There are four modes - low pass, high pass, band pass and band reject. Env(elope) Amount, Cutoff and Reso(nance) controls are provided. Right next to the Filter section is the Amp section.  Clicking on the graphic Filter and Amp Env displays in the Main screen opens up the corresponding envelope editors.

• Directly below the Filter and Amp envelope are the two LFOs, each of which includes a Rate knob, Sync button and five-position Shape knob, including triangle, ramp up, ramp down, random and square options.

• Immediately to the right of the four oscillators is the vector joystick. This virtual control functions just like a real joystick and lets you adjust the mix of the four oscillators. Not only can you do this manually, but also with the Envelope Time controls which can be found directly below the joystick.

• Hitting the Edit button in the Envelope Time Control section or the Vector button in the top menu bar opens up the Vector screen, with the oscillators, their controls and their current waveforms displayed on the left and the Envelope Mixer and its time controls on the right, complete with multiple node, loop and repeat options.

• The Mod Matrix screen is where you'll find the controls for iProphet's powerful modulation matrix, which as you can see in the screen shot below, offers a wide range of modulation sources and destinations.  

• Chorus, overdrive and delay effects are included with iProphet, and their parameters can be adjusted on the FX screen. You can also adjust the effects mix from the Main screen, and all three effects can be used simultaneously.

• Regardless of which screen you're on you can call up a variety of controls for the virtual keyboard, including scroll, hold, zoom and legato functions, glide and portamento controls, and the ability to set the virtual keyboard to one of over twenty different scale options.

• Arturia provides a wide range of tools to connect with the rest of the world, including Core MIDI, Audiobus and Tabletop compatibility. I was able to use Inter-App Audio to record iProphet parts directly into Garageband with no problem and the setup was easy and straightforward.

Limitations

• iProphet is compatible with the Prophet VS section of Arturia's Prophet V software, and you can import and export Prophet V presets with iProphet via iTunes as long as you stick to Prophet VS sounds; it won't work with Prophet V's Prophet 5 or Hybrid sounds. Imported sounds are added to the "mypresets" folder on iProphet.

Conclusion

Once again Arturia has provided a surprisingly realistic and faithful rendition of a classic, groundbreaking vintage synth for your iPad that costs a tiny fraction of what the original  sold for back in 1986, or for that matter, what a decent used Prophet VS sells for today. The iProphet's sonic character, like the Prophet VS that its based on is not at all thin or weak, which are characteristics that are sometimes associated with digital synths. It has a punchy, bold character and due to the capabilities of vector synthesis, a lot of complexity, variation and movement is on display in many of its sounds. Bouncing buzzy basses, etherial wandering pads, out of this world sound effects, pseudo loops that evolve over time, brassy leads and pealing bells, iProphet can generate all of them and more, and its voice offers a nice compliment to other synths, loops and samples.  I continue to be amazed by the progression of the technology; the ability to run a powerful synth like this on a mobile device like the iPad is tremendously cool for modern musicians and if you're a musician and own an iPad, there's really no reason not to spend the ten bucks and add this to your sonic arsenal.  

Resources

Arturia iProphet ($9.99 MSRP, available from the Apple iTunes App store)

Arturia iProphet product web page

Arturia iProphet tutorial video: