KORG recently launched the iDS-10 for iPhone, and in typical KORG fashion, there was not much advance hype about it. The app is a port of sorts of the Nintendo DS version, but with some updated visuals and features.
The app is a dual-synth plus drum machine plus voice synth. Each of the two synths has two separate VCO's, with four different waveforms to use. There is pulse width modulation on VCO1, and you can set the pitch of VCO2 as you wish, giving you the option to tune to a fifth up or down, for example.
Of course you've got the standard VCF cutoff and peak knobs, low-pass/high-pass/band-pass filter types, as well as the envelope generator ADSR and VCA controls. Almost all of these knobs can be automated, which is where things really get fun. Either by manually tweaking the knobs, or drawing in the automation curves, this is really easy to do.
The drum synth allows you to really scuplt your sounds, as this is a synth after all. You've got six instruments to use (kick, snare, two hi hats, a tom, and a percussion). You can record these hits in real-time by using the buttons at the bottom of the screen, or program them in the drum pattern sequencer.
The voice synthesizer is a real gem here. Either by way of "text-to-voice" or by using the internal microphone, you can get a pretty sweet sounding vocoder. There are loads of controls to manipulate these vocals, either by pitch, vibrato, or adding a formant filter, just to name a few. This feature alone makes the iDS-10 a great purchase.
Some standard KORG offerings are here, in the form of the KAOSS pad, "smart" keyboard for scales, and some cable patching options similar to the iMS-20 for iPad. Onboard effects include a delay, chorus, eq, and some reverbs.
One feature that is intriguing is the "mystery bingo" feature. Ostensibly set up as a way for users to discover the many features of the app, there are 25 icons that need to be "completed". What do you "win" if you get them all? I have no idea! Some of them seem obvious on how to achieve them, whereas others still remain a mystery to me. I personally really like this idea, as I think it's a pretty unique way to encourage exploration.
As of right now, the app does not have any Audiobus or IAA integration. However, KORG recently tweeted that they are very close to getting those integrated into the app. That will be very welcome. UPDATE (12/21/15): KORG has just released version 1.1.0, which includes Audiobus, Inter-App Audio (IAA) and Bluetooth headphone support! As is, this app is a great pocket-sized synth that will find a lot of use for me, much the same way I enjoy KORG's iKaossilator or Propellerhead's Figure. Quick, easy-to-use, and great sounding, the iDS-10 is pretty easy to recommend. And, if you're reading this before December 28th, the app has launched at 50% off normal price, so go grab it quick!