Modstep is compatible with any iPad running iOS 7 or greater, and even the relatively ancient iPad 1 supports its MIDI functionality. This is a rarity for modern audio apps, and I could see formerly shelved devices being put back into service for Modstep MIDI sequencing. For those with the fourth generation iPad or one of the newer series, I would also suggest taking a look at some of the AU plug-ins out there on the App Store. The plug-in standard on iOS is much more convenient in use than inter-app audio (IAA), and relative to desktop plug-ins the prices are very reasonable.
When you open Modstep for the first time, you're greeted with a demo song built upon a grid-based view of clips and scenes that's very reminiscent of Ableton. This main view shares the same name as its Live counterpart (Session View) and acts in very much the same way. For instance, you can trigger clips individually or an entire row together as a scene. AppBC built in support for follow actions to their Session View, but unlike Ableton, this works at the scene and clip level. This allows you to build full song structures in Modstep by defining the number of times each scene will loop before moving on to the next one. This is an important feature as there is no Arrangement View. Another important difference in Modstep's version of the Session View is the lack of audio tracks. Essentially, all clips are MIDI clips. There is a somewhat limited workaround to this, thanks to Modstep's Sampler instrument. Load one of these on to a track and you can trigger up to 16 audio loops in one-shot mode.
In addition to Sampler, there's an additive synthesiser with manual waveform shaping called Synth. Besides these two built-in instruments, Modstep allows you to send MIDI out to external apps or hardware with individual In/Out options on each track. Using IAA, you can also add other apps and AU plug-ins from an integrated browser directly on to a track's device chain. In the latter case, the MIDI from Modstep will be sent to the app or plug-in, and audio will be returned back to Modstep. You can add effect apps or plug-ins to the chain to further process audio, and there's an integrated mixer within Modstep for balancing the levels of each track.
Once you're ready to bounce to audio, there are two options: you can record stems from the tracks (including the master) by using the cassette tape icon, or you can route audio to yet another app via IAA. Stems recorded in Modstep can either be exported to AudioShare, or copied to Sampler for playback. As one would expect, sending audio out with the IAA option is the more flexible option. It allows you to route it directly to a computer using StudioMux, or to an iPad DAW app like Cubasis or Auria for arrangement and mixing.
There are two views dedicated to the building of MIDI clips. First is the Piano Roll, which provides the familiar method of managing notes in a clip. Notes are entered by recording incoming MIDI or by tapping notes into the roll. To do more than this, you'll need to make use of the function buttons in the top bar of Modstep. Here you'll find Edit, Transpose and Quantize, allowing you to do things like change the length or pitch of a note, or duplicate it. These buttons aren't limited to MIDI clip functions—they can play key role in almost every aspect of Modstep. Whether you want to duplicate a scene or delete a mapped parameter, you'll need to utilise these three buttons. The other MIDI sequencing view is the Step Sequencer, which gives you a different workflow to accomplish the same task and some additional options like an X/Y pad for parameter automation. Getting used to the way these two views interact is crucial to getting the most from Modstep. Thankfully, there are some relevant tutorial videos that complement the rather underwhelming manual.
The final view in Modstep may be the most powerful: the Template Editor. Here you can set up presets for apps or external hardware, whether it be to define the supported CC names and numbers for parameter automation, or to map drum pads to specific notes for an external drum machine. Having predefined templates that you can save and reuse in future Modstep sessions is a killer feature. Thanks to AppBC and its community of users, there are a load of stock templates already built into Modstep and the list grows with each release of the app.
Modstep is likely the most powerful standalone MIDI sequencing app currently available on any mobile platform. But the complexity does come with some downsides, namely a steep learning curve and a few bugs yet to be squashed. Many folks have complained about stability when using IAA and in some of my tests, clips randomly transposed themselves after being recorded. There's also no true undo/redo functionality built into Modstep, though the session is autosaved at certain points so it's possible to load one of these autosaves as a rudimentary undo. Despite these bugs, Modstep has immense potential and it'll be exciting to see it evolve over time.
Ease of use: 3.7