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Analog Synth X

Aurelius Prochazka has released Analog Synth X, a free app designed to show off the power off AudioKit 3 SDK. MIDI is supported but Audiobus is not supported. It is unclear if AUX or IAA are supported either. They have a weird mishmash of technologies from the Open Source community and Apple, so you'd expect support for AUX and IAA though neither is mentioned on their site. Update: Aurelius commented here that AUX and IAA are indeed supported!

Correction: Developer Matthew Fecher clarified in a comment here that AudioKit 3.0 supports AUX and IAA, but this specific app does not at this time. Well that was all super confusing. He does share some fun hacking tips for anyone with Xcode.

Analog Synth X iTunes Description:

Matt Fecher's analog synthesizer for iPad created entirely with the new AudioKit 3.0 framework.

Get the full source code now from the AudioKit website at audiokit.io.


  • 5-Voice Virtual Analog Polysynth
  • Dual Morphable VCO Oscillators
  • Dedicated Sub Oscillator
  • FM Oscillator w/ Mod
  • Beautiful Sean Costello Reverb
  • Free-running LFO w/ 4 waveforms
  • Multi-tap (Ping-Pong) delay
  • 4-Pole Vintage Modeled Filter
  • ADSR Envelope
  • MIDI in for notes
  • Detune Oscillators by Semitone & Hz
  • Hold & Mono modes for keyboard
  • Noise generator
  • 8-Bit Crusher

Buy Analog Synth X App on iTunes: Free

Reader Comments 8

it sounds great...I just wish you could save sounds

February 01, 2016  | person_outline rayola

Nice design. Looks good. Sounds alright too. Drop that keyboard out the bottom, add some controls there and I could have some fun using it with my midi keyboard.

February 01, 2016  | person_outline Anonymouse

Sounds ok. Very simple interface (perhaps good for noobs). Though I have PLENTY of subtractives that can do all this and more, it is hard to argue with the price.

I wonder what benefits might arise from it being partially open source or shared sourced code. I wonder how that might affect/improve the way it evolves.

February 01, 2016  | person_outline stub

This app is just a demo of what can be done with AudioKit 3 fairly easily. It's free and open source, so you can even tweak anything you don't like directly in the code. We use Apple's AVAudioEngine and CoreAudio tools, but augment that with many open source processors and sound generators. AUX is certainly supported, and I'm guessing IAA too, but neither are the point of this particular example project. The core team is helpful and welcoming, so if you want to contribute, we're all ears! Thanks for this article Tim!

February 01, 2016  | person_outline Aurelius Prochazka

It doesn't show up as IAA in any of my programs and neither as Audio Unit in Garage Band mobile. I got iPad Air 2. Sure these things are implemented in this example, Tim?

February 02, 2016  | person_outline IncarnateX

Thanks everyone for checking it out and for your feedback! (And, thanks Tim for posting this, you rock!) Regarding the question on IAA and AUX, that's supported in the AudioKit library, but is not currently implemented in this app.

We’re working on a new version of the app as I type this. In the meantime, for those of you with it working, here’s some tips:

Sound Tips for Analog Synth X:
* You can get a pure Sine wave by (1) turning the Osc Mix to the left (2) turning off VCO1 (3) Turn the FM up!
* Use the morph knob between square and pulse for basic PWM control.
* The reverse saw LFO (the last wave setting on the LFO) can make a cool simulated note-repeat effect.
* Turn the ADSR Release down to zero and turn the echo on to hear how the echo taps fire.

For those of you with Xcode who want to download the free source code:
* The sub is set to a sine wave for a more powerful bass tone. You can change it to a square if you’d like the synth to have more of a vintage feel. You can also experiment between -12/-24 settings. That’s a fun first exercise for getting in the code.
* Try changing the preset knob bounds (minimum/maximum) in the SynthViewController file to extremes to play a synth with wild settings!

Keep us posted on any apps you make with the code, we’d love to hear from you! You can also follow us on Twitter at @audiokitman and @goFecher. We'll be sure to let Discchord know about any updates as well!

February 02, 2016  | person_outline Matthew Fecher

Thanks for the clarification, Matthew. Since the app is iOS 9 only I was unable to do any personal checking on this one.

This thing has some strannnge behavior.

1. The ADSR has a mind of its own. You can set R to zero and still have a long fade out instead of a solid cut. On top of that, you raise Release a little bit and it is a long tail.

2. Mono keys does not mean mono polyphony. Which is also super weird. If your release is up and you hit one note and then another, or even 5 in a row (of the release is long enough), then you hear all 5 notes at once, when mono is supposed to mean 1 voice max.

The cutoff filter can make a little noise when adjusting (iPad Air 2), the LFO points to one destination as if you can choose, but alas you cannot. The osc morph affects both oscs at once so it is tricky to attempt to blend a steady saw with a pwm (not that the LFO can be redirected to it). Notes get stuck (thank goodness for panic!). The redux cannot be turned all the way to nothing, so you always have some amount (even if the minimum is more than too would prefer).

I do like that it clearly shows the setting of any parameter you are adjusting. Having quick off buttons for oscs/fx/filter is quick and convenient. Some of the controls are limited in options but efficient. Viewing the waveform is always a nice way to feel like there is a kind of energy happening.

It is a nice project though, and I appreciate what it is conceptually. A starting point for learning how to develop synths with an actual example available for free on the App Store.

February 02, 2016  | person_outline Yur2die4

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