There is no explanation for why Cantor is suddenly free, so hurry up and get it while the getting's good! This is Rob Fielding's reincarnation of GeoSynth.

A Microtonal Guitarist's synth, designed for extreme playability on the iPhone and iPad. It is the successor to Geo Synthesizer and Mugician. It does send a specialized MIDI output (requires a multi-timbral synth that can handle independent channels is all but necessary, such as SampleWiz or ThumbJam in OMNI mode, or Arctic Synth). The internal synth is driven by the actual MIDI output, because external MIDI synths are the main point of this project rather than the internal audio engine. It has a basic looper/delay combination, and the loop can be copied out as a sample to the general pasteboard for apps such as GarageBand.

Thank you very much to Hoyas79 for bringing this sale to my attention!

Update - I just got the following message from Rob on Google Plus (I keep telling you all the cool kids are on there! Facebook is full of people I know, G+ is full of people I want to know.)

I am only selling 3 copies [of Cantor] a day, down from a few hundred in the first few days. So I am doing some experimentation to measure its potential. I had this sort of phenomenon with Mugician, and it hit #4 in free music for the 2 days it first went free.

The plan for now: randomly, when Mugician is free Cantor is for sale. I actually did get lots of requests from heavy Mugician users to pay for Mugician when I was actively developing it. I would like to make it an optionally paid app where users can name the price without getting into maintaining and submitting multiple versions, so I am doing it by simply putting in price variations. ﻿

I really like this idea. It is a kind of "Pay What You Like" model, done in the limitations of the AppStore! Rob is a really clever guy, I have such a nerd-crush for him.

Here's a demo from Rob himself! You may also know him as the guy behind Mugician.