Audiobus: Use your music apps together.
What is Audiobus? — Audiobus is an award-winning music app for iPhone and iPad which lets you use your other music apps together. Chain effects on your favourite synth, run the output of apps or Audio Units into an app like GarageBand or Loopy, or select a different audio interface output for each app. Route MIDI between apps — drive a synth from a MIDI sequencer, or add an arpeggiator to your MIDI keyboard — or sync with your external MIDI gear. And control your entire setup from a MIDI controller.Download on the App Store
Audiobus is the app that makes the rest of your setup better.
StepPolyArp Unit/App sync and other issues
I desperately try to use StepPolyArp or StepPolyArp with Audiobus and/or AUM. My use case is almost always the same. I define a chord progression in a MIDI sequencer (Xequence2 or Atom), I feed it to StepPolyArp, and it produces a bass line or a keyboard comping using the pattern I define and the chord it eats up. To this, I add a drum track using mostly Lumbeat apps.
At first, I was using StepPolyArp in the « middle slot » of Audiobus MIDI channel. For my use case, I understand that I should use StepPolyArp in ARP mode, and I am syncing it using Ableton Link.
My first issue is that with exactly the same setting, sometime it works (e.g. proper sync and notes going out of SPA), but sometimes it doesn’t (no note going out of StepPolyArp). I should also mention that I don’t have the feeling that the issue is with the upstream software (mainly Xequence), because if I put any other app instead of SPA in the middle slot, it works as expected. On the other hand, if I keep SPA and put another app in the input slot, it doesn’t work (even with ChordPolyPad).
My second issue is that I usually need two instances, so that I can produce the bass line and the chord comping. So I bought the « Unit » version, which was a bit unpleasant due to the price tag of each of this app. If I use the « Unit » version as the app, it seems to have the same behavior as the one I reported in previous paragraph. If I use the Audio Unit, I get another unexpected behavior: the note that should go first, doesn’t, so instead of starting my bass line on the root note, it starts on the second note... Which makes it quite unusable... (which is unacceptable due to the price tag of each of this app).
This is quite surprising, because the workflow I use seems quite straightforward. Does anyone got the same issue? Is there a known workaround?