How to Manipulate Loops in Dr Octorex

Dr Octorex - Propellerhead Reason

Reason’s Dr. Octorex has loop manipulating power to spare – here’s a tour of its many charms

The Reason rack has many powerful tools at its disposal, but the Dr Rex and its replacement, Dr Octorex have to be one of its most ingenious and powerful.

This innocuous rack unit can, and often is, used for little more than playing back loops that can be locked perfectly in sync, regardless of the project’s tempo. This is very useful in itself, but if you go a bit further, this is the perfect tool for manipulating loops in simple but incredibly effective ways.

Here, we’ll take a look at how it works, and how you can exploit its charms without resorting to simply playing back the loop.

Dr Octorex

How REX files work

Firstly, it’s important to understand where REX files (the audio file type used by the two REX players) actually came from.

Propellerhead’s first musical product was piece of software called Recycle. At the time, a major issue when using sampled loops was that, should you change the tempo of the track, you would have to adjust the lengths of any loops used by timestretching. This was a laborious process, and such breaks could hamper creative flow.

Propellerheads ReCycle 2.2

Recycle was a piece of software designed for use with hardware samplers. Essentially, it would analyse the loop, and place slice points where each hit began. From these hit-points it would extract the groove and create a MIDI file, along with a sampler program, with each slice mapped to a different note. The MIDI file would then play back the loop as a MIDI file, such that tempo could be adjusted, and each hit would still be in time.

Recycle is still available, and perfect for creating your own REX files. It is these sliced files that the Dr Rex family exploit.

Dr Octorex, one slice at a time…

You may be familiar with using Rex players in reason to playback these sampled grooves. However, if you switch the ‘enable loop playback’ feature off, you can use these to rearrange REX loops to your heart’s content. And here’s how.

1. Create a Dr Octorex

Dr Octorex - Tool Selection

2. Click the ‘enable loop playback’ light, such that the light turns off

Dr Octorex - Disable Loop
3. Click to small triangle to open the Dr Octorex programmer

Dr Octorex - Open Programmer
4. You’ll see folder button, which is used to select rex files to load, and 8 numbered buttons beside this. These are loops slots. Select slot one, then open the file browser by clicking the folder button

Dr Octorex - Open loop browser
5. Open the Reason Factory Sound bank from the menu on the left, then open the Dr. Rex Drum Loops folder from the window

Dr Octorex - Browser Window

6. Here, you’ll find just about every kind of drum loop you can think of. Pick one- for the sake of this guide, its worth picking one with a variety of different drum sounds within it.

7. Click OK, and this will be loaded to slot 1.

Dr Octorex - Song Arrange
8. In the arrange window, create a 4-bar region on the corresponding track. Click the ‘loop’ button on the transport bar, and adjust the loop locators to the ends of the region. Double click the region, or click the ‘edit mode’ button

Dr Octorex - Edit Mode

9. The first thing you’ll notice is that the edit window is not the piano-roll style editor you see when editing synth or sampler parts. In place of the piano keyboard, you’ll see a list labelled with ‘Slice #1’ at the bottom, and an increasing #number as it moves upwards. These correspond to the slices in your loop

Dr Octorex - Edit Mode
10. Click these individually, and you’ll hear which slice corresponds to which part of your loop.Try finding a kick drum and place it on the ‘1’, or snares and placing them on the ‘2’ and ‘4’. Experiment, using each slice as a drum hit. You’ll find that one of the advantages of using loops in this way is that each hit sounds very natural next to any other. Plus, sequential hits will flow perfectly into each other.

Of course, it doesn’t have to be drum loops, you could use melodic loops, and if you use the ‘copy loop to track’ button, you can load up the loop as it is played and edit it to your heart’s content, adding fills and variations.

Or, you can copy the loop to track, then load up a completely different loop, playing the groove of one loop with the sounds of another. The possibilities are endless, and it’s all so quick and intuitive.

So, there we are- Dr. Octorex: the musical remedy. Stay tuned for more insights into the residents of the Reason rack…

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