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Review of RapidComposer music prototyping software by MusicDevelopments

RapidComposer is a unique, non-destructive, phrase-based music prototyping software designed for composers, song-writers and musicians of all musical styles for both Windows and macOS.

It is available in two versions

  1. Light edition typically priced at $79 +VAT has Core functionality, VSTi and soundfont support, standalone and VST versions (Windows and macOS), all updates until v3.99, more than 200 reusable phrases and product support.
  2. Full version typically priced at $199 +VAT includes all of the light edition features plus 2 Melody Generators, Idea Tool, articulations, phrase morphing, unlimited tempo and signature changes.

Both versions are available direct from the MusicDevelopment website:

This review is for the full license of RapidComposer, version 3.4, the update was released in January 2018.


The basic idea is that you create your composition style and length, add chords, add basses, add melodies and harmonies on as many tracks as you need. You can load soundfonts or VSTs to hear your composition and then export as audio or drag and drop as midi files to a DAW for further processing. The VST that runs inside a DAW is a smaller version that communicates with the standalone version. You can use RapidComposer to control separate VSTs or a multichannel VST such as Kontakt.

In practice, it has so much more depth and is a very powerful composing tool for any style of music. It’s very flexible because it allows you to create your composition to any length and any format. Although it comes with a number of chord progressions built-in, you are not limited to these and can add your own chords and furthermore there are many phrasing options too as well as options for piano and guitar chords.

There are a large number of scales and modes and a number of generators to create musical phrases which can be used as is or you can edit them to suit your needs.

I found there was a learning curve to get to grips with the workflow but once I mastered this, the process of scoping out a song was pretty quick. I’ve been happy using the standalone version and exporting to midi to import into MuLab 7 DAW to use with a number of VSTs to create audio and then mix and master to create the composition. Although I’ve got to grips with basic use, I feel there’s so much more functionality to learn and experiment with that will really enhance RapidComposer’s usability, for example using the VST version to control virtual instruments would speed up the creative process.

In Use

It took me a while to get the hang of the interface and functionality, it’s worth spending a little time to do this because actually, it’s very straightforward once you get the hang of the terminology and icons.

Starting a new composition creates a 4 bar song with a default I IV V I progression. At this point, you have the basics of your song which you need to customise to your requirements.

The important points to note are the terminology. RapidComposer has a hierarchical structure as shown below.

You can set scale, chord, tempo and signature at the global level and lower levels inherit these by default but you can override them on any level. This is presented as a collapsible list accessed by the structure icon where you can set global properties as well as settings for each separate section, name the composition and composer. You can also choose whether to use absolute chords or chords with scale degrees.

In practice, this terminology is actually quite helpful because you can arrange your song as simple or complex as you like from a simple single section with alternating chords to something more elaborate such as introduction, verse, bridge, chorus, verse, chorus structure.

You can also add new parts or lines or delete them using the icons that appear when you click on a part or a line. This brings up a x2 which duplicates the part / line, a plus above which adds a part or line above and the lower plus adds a line below whilst the ‘no entry’ deletes it. It appears when you add a line or a part it replicates that particular line or part so you may need to edit this to your requirements. The default length also seems to be 4 bars and you cannot change this within this section.

Once created you can return to the main screen and zoom in / out to change the view settings and this is where you can change the length of each line to a different number of bars if required.

You now need to start adding notes to the composition and you do this using phrases which are basically a group of notes. This covers chords, basslines, melodies and many more which you add to your track. A lot of the power of RapidComposer comes in its ability to generate phrases which you can then edit, resize and add variations to.

You start with a chord progression, there are a large number of inbuilt progressions which you can drag and drop to the master track. However, you are certainly not limited by these and I tend to use my own progressions – standard ones may be useful for creating backing tracks for example but sometimes they can sound formulaic or contrived in some circumstances.

There are a couple of ways to do this, I added the IIIm chord and then used the circle of fifths to change it to a minor 11th chord. I then used the phrases icon and chord generator to add the chord to the line. You can drop this on whichever starting note you want. At this point I remembered I wanted this line to be 8 bars long and it’s a simple case of dragging the line length to 8 bars and extending the chord by dragging to also increase this to 8 bars length. I then edited the chord so that it’s 8 bars long. This is a simple case of right click to display the menu, select all notes, join all notes and then click ‘apply changes to phrase in composition’ which helpfully changes all chords. You can also click and drag to select notes which is useful to extend or decrease the length of the chord to allow a reverb tail to finish, for instance.

Returning to the structure inspector, when you click on a line, pressing x2 duplicates the line with any chords and phrases you’ve created. This means that you can very quickly start to create your composition by copying, editing and pasting lines and sections.

I’ve kept the lines deliberately short, they seem easier to manage as shorter separate lines rather than longer sections.

At this point I’d also say that RapidComposer saves your composition on exit but I’d recommend clicking the file menu and ‘save composition as’ to ensure you save the most up to date version. You can then use the keyboard shortcut of ctrl+s to save the composition as you go along. It’s also useful to name the different parts and lines into parts of your composition for easy reference.

Duplicating a section creates an exact copy so a very useful aspect of using relative chords is that if you change a chord type, the phrase automatically updates. This is an excellent way to very quickly scope out your composition. If you create sections of your song with different chord phrasings, you can copy these to give variety.

Once you’ve entered the chords, you add other tracks by right clicking on a track, clicking on settings and then add midi track. You can then change colour, instrument and preset as required. You can then add phrases as required and edit them to suit your requirements. For example, clicking on the phrases icon you can change the length at the top of the menu to the desired number of bars and then drag say bass generator to your bass track. The rules mean that the bass will snap to the appropriate root note of your chord.

It would probably be quicker to create one section and duplicate rather than drag and drop for each section but it’s quite a quick process anyway. I’ve then added extra tracks with piccato strings and a melody generator. You can drag and drop into a DAW but I found the best way is to export to midi, you can export as a file which includes all of the tracks or separate tracks. If you find the composition is too long or too short, it’s easy enough to edit the composition and re-export it. I wasn’t keen on the bass that was generated and you’d definitely benefit from playing around with the generators to add variety and variations to the phrases.

The icon for the file menu is which brings up a list of options for saving, exporting etc.

From the composition I made, I kept all of the original parts and used Xpand!2 for sounds, adding a drum loop and extra background sounds using Polygon. As I didn’t like the bassline I processed this with Cryogen (Glitchmachines) to produce a bit crushed / glitchy sound. I also added a quote from William S Burroughs about the cut-up method. I mixed with H3000 Factory, H949 Dual Harmoniser, Octavox, MangledVerb, Blackhole, Ultratap and Ultrachannel all by Eventide. I’ve also a drum loop and also Polygon (Glitchmachines) and Incipit (Inear Display) for percussive elements. The spoken part is taken from ‘William S Burroughs Lecture on Public Discourse’ which was recorded on 11th August 1980 by the Jack Kerouac School of Disembodied Poetics and is contained within the Naropa Poetics Audio Archive

I also created a second song from scratch rather than editing the first one. The process was much quicker second time around, I followed a similar process and exported the midi to MuLab. I used Olafur Arnalds Chamber Evolutions (Spitfire Audio) and then mixed with Blackhole, Tverb, 2016 Stereo Room, H3000 Factory and Ultrachannel by Eventide.

Both tracks were mastered in MuLab using EQ45 (Eventide), Type A (AudioThing), Elevate (Newfangled Audio) and Stage (Fiedler Audio).

The bandcamp link is embedded at the start of this section, the songs appear in reverse order to how they were created.


RapidComposer is a very impressive and inspirational tool. If you’ve ever struggled producing melodies or harmonised parts for chords then this can really help your creativity – in minutes. From scoping out whole songs to providing melodies or piano lines, it’s an amazing powerful and flexible composition tool. The structure is flexible enough to allow you to create a composition for any style, and any length. There are a huge number of chords and scales and although there are a large number of phrases, I like how you are not limited by these with the phrase generators and the random nature of these generators is a great way to see what happens. Understanding the basics of music theory does help to get more out of it.

I also like how you can grow with its functionality, there’s a learning curve to understanding how it works but I soon got to grips with the basics and created the compositions above. You can add variety with chord phrasings, variations to phrases such as humanising, adding swing and velocity. You can be as minimal or in depth as you like.

The flexibility allows you to create and export a composition within the standalone version, use the VST version directly within a DAW to control a number of virtual instruments or create a composition that you can export to midi files to import into a DAW separately for fine tuning instrument and effect settings.

Chord generation is very quick, using relative rather than absolute allows you to change key and still keep the same chords / progressions. Whilst you could use RapidComposer to solely create master chord tracks, you’d be missing a lot of the benefits to help produce your composition. I especially like the melody, ostinato and strings staccato generators because I normally struggle to produce melodies like these from scratch.

The ideas tool is also a superb addition to the full version of RapidComposer, this allows you to create a master track from scratch, use an existing melody track or generate a melody and harmonise with this. You can add chords to the master track by using a scale and specifying rules, absolute chords,progressions or random chords.

You generate the master track chords and then add tracks as required, it’s a simple case of dragging phrases, rhythm patterns adding any required variation and then generating the tracks as required.

I’ve created a song using the ideas tool with an E Neapolitan minor scale. I’ve edited the chords and deleted some of the piano parts and added variation into the bassline. It’s taken just a few minutes to complete the whole song. I’ve done it whilst finishing off this review so haven’t even listened to it yet, will export it to my DAW and see what it sounds like with further processing and effects added.