Quantum is a performance midi sequencer which approaches music composition with an interactive creation processes - sometimes referred to as 'noodling'.

Where pattern or piano-role sequencers are good for music forms (intro/verse/chorus etc) or grid entry, Quantum's approach is built around the idea of a step being the focus - think of the step as a single note or chord written on a music sheet then add a lot of extra notation (like probability of playing or ornamentation say).

These highly detailed steps are then aligned into sequences (think melodies) that loop. You can have any length up to 64, but these can be further split into 4 sub-sequences that have their own set of sequencer parameters (like tempo, play direction, transpose etc).

To enter step parameters such as note pitch, velocity, gated length etc, 16 general faders are available which allow you to draw, drag, select copy/paste, inc/dec & link together to edit values. These are also midi learnable (midi cc or nrpn) to allow you to use control surfaces or midi controllers.

To aid you with faster control Quantum has loop actions which you can program in to carry out tasks when a sequence loops - e.g. transpose, randomise, start or load another sequence etc.

With up to 24 sequences playing Quantum introduces a mixer page allowing you to blend midi velocities. Built on the MidiSequencer engine, midi FX, devices & Controllers are now possible per sequence.

So why would Quantum be good for your setup? There are many midi enabled IOS & hardware synths that produce exotic timbres if you send them fast & varied midi controls that you just would not hear with keyboard playing or slow tempo tunes. Also, Quantum, embraces experimentation in melody creation and by copy/pasting allowing quick setup of arpeggios & counterpoint tunes that you can create & manipulate on the fly!

note : This app sends midi information - you need to use it in conjunction with any midi enabled iOS synth app (e.g. Sunrizer) to hear sounds

What's New

Version 1.4

Bug Fixes
. Select buttons work again
. Options panel resized on iphones
. Green limits bar scaling corrected for iphone devices
. Realtime controls - now sends CCs on + or -

. Step Trigger Conditions - invert button now had 1,n & n & inv as options - the new one n ignores first loop.
. double tap show button now also forces hidden sequences(those on other page) to show notes, vel, gate% etc
. You now have an option to randomise using only selected notes (use Select).
. Undo now works on all shown fader displays (notes to mute) & after a randomise. Increased to 124 undo actions
. Latest Audiobus 3 SDK

Customer Reviews

4.7 out of 5

17 Ratings

17 Ratings



I'm still trying to get a grip on all the amazing possibilities with this sequencing app. It's a multitrack sequencer with SO MANY options and I've read elsewhere about a lot of future plans including a more modern looking interface. I don't really care how it looks as long as I can make some music happen and the fact that's it Universal made this an instant purchase.

Unbelievable App


Out of the gates, this is one of the most creative and fun midi sequencers while still being deep and complex. Just using the basic functions will get you inspiring results, so you don't have to dig you don't want to. But if you do, the rewards are great. Classic 5 star app. Must have.

Among the most powerful

Jack Jack Jack Jack

Among the most powerful step sequencers ever made. Only downside is it accounts for 70 percent of my battery use if I forget and leave it open, even if the clock isn’t running.


anthony saunders
67.9 MB
Requires iOS 9.3 or later. Compatible with iPhone, iPad, and iPod touch.
English, Simplified Chinese
Age Rating
Rated 4+
© anthony saunders


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