Propellerhead Recycle 2.1

Loop-slicing Software (Windows & Mac OS X)

Published in SOS August 2004
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It's been a long wait, but the original slice-and-dice loop editing program has finally made it to Mac OS X. Is it still an essential tool a decade after its original launch?

Derek Johnson

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A typical two-bar drum loop is here easily sliced using the Sensitivity slider. No further fine-tuning of slices was needed, though the Envelope, Transient Shaper and EQ have been manipulated.
A typical two-bar drum loop is here easily sliced using the Sensitivity slider. No further fine-tuning of slices was needed, though the Envelope, Transient Shaper and EQ have been manipulated.

With the high profile of their Reason software studio, it's easy to forget that Propellerhead have another revolutionary piece of programming in their roster. Recycle has been around in one form or another for almost 10 years (version 1.1 was reviewed in SOS May 1995) and represents, as it always has, a lateral approach to tempo- and pitch-matching of unrelated sampled audio, typically of the 'loop' variety. Of course, Recycle's chances of being marginalised are slim: Reason includes the Dr. Rex loop player amongst its device arsenal, and Recycle is the package that generates the required loops.

At the time of Recycle's initial release, real-time pitch and tempo manipulation were a couple of generations away for most studio users, while many engineers used hardware samplers to extend the capabilities of their computer-based audio software. Recycle's approach of 'find the peaks and chop the sample into bits' soon found favour with engineers and remixers of all styles. The bits, of course, could be triggered by a MIDI file generated by the process, or played back in any order at any tempo, with slices having the option of being retuned. The slices were generally sent to the engineer's sampler, to take the load off the host computer. The whole loop could also be quantised, or used as the basis for 'groove quantising' in another piece of music. This approach to the issue has been borrowed by others — most visibly, perhaps, in recent sampling devices from the likes of Korg and Yamaha — and is still an effective alternative to pure DSP-based tricks.

The latest incarnation of Recycle works under Windows XP/2000 or Mac OS X; gone is version 2.0's support for earlier flavours of Windows and Mac OS 9. Operationally, though, there are few significant differences between the versions 2 and 2.1.

Slice And Dice

To explore what Recycle does is to discover its control set. First of all, you load a file, since Recycle has no recording options. This can be a mono or stereo 8-, 16- or 24-bit AIFF or WAV file, with a sample rate between 11.025kHz and 1MHz. Mac Sound Designer II files can also be loaded. The only real limitation is that no sample, mono or stereo, can be longer than five minutes. A very detailed file selector window lists all a sample's parameters and offers pre-loading auditioning.

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Recycle's file loading window. Note the detailed sample information provided, included tempo, size, channels (mono or stereo file) and, since we're looking at RX2 files, size both compressed and expanded.
Recycle's file loading window. Note the detailed sample information provided, included tempo, size, channels (mono or stereo file) and, since we're looking at RX2 files, size both compressed and expanded.

Once loaded, the sample's appearance in the waveform/slice display dominates the screen. Stereo files can be displayed in single- or dual-channel format; I prefer the latter, since peaks might appear more obvious in one side of the signal than the other.

To slice a loop, first try tweaking the Sens(itivity) slider. This causes the program to search for peaks — the more obvious first — and place 'slices' there. The further to the right the slider is moved, the more peaks are detected — at the extreme right, it's definitely detected too many peaks! In some audio, notably speech or impressionistic sounds, it might not find enough peaks, or find the wrong ones. In these cases, you move the Sens slider slowly, let the program do what it can, and then add, or move, slices manually, where you can see or hear the desired points. It's possible to audition individual slices to check for clicks and other unwanted artifacts; a full range of keyboard shortcuts includes options to automatically jump through slices.

Before you can hear the full sliced effect, the Preview button — the strange icon to the left of the playback transport controls on the top row of the window — must be engaged. Two things now happen: first of all, a dialogue pops up asking you to say how long the sample is, in bars. Because the software is mainly aimed at working with loops and rhythmic audio, this information is needed to give Recycle a starting point from which it can calculate new tempos and ensure the correct playback of a loop's slices. There's also an on-screen parameter group that lets you be pretty precise in defining a sample in terms of bars, extra beats, and time signature (choices include 5/4 and 7/8, which is handy), after which the software determines an initial tempo. For audio that's not obviously tempo- or bar-based, such as speech, you'll develop both the knack of adding appropriate slices (especially where syllables in words morph into one another), and making a guess at a number of bars or beats. It's a matter of counting during the loop to get the best feel.

And secondly, once Preview is engaged, you'll be able to not only change the tempo and pitch, but apply several other interesting processes, which we'll discuss in a moment.

Going By The Grid

For a simple rhythmic loop — a one- or two-bar drum pattern for example — with definite peaks and a fixed tempo, there's another, more automated, slicing option. First of all, tell Recycle to Show Grid from the View menu, and then select Add Slices at Grid from the Process menu. The grid divides the sample into 16th-note sections, and adds a slice at every grid point. For much rhythmic audio, this will be all you need to do. Click Preview and tweak the tempo to your heart's content. If your loop comes from a real performance, rather than a drum machine or something similarly rigid, you may have to move some of the slices manually to line up with the real peaks, rather than the grid. Once the Recycle process happens, though, the 'feel' of the original will remain the same.

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Two bars of real guitar playing were sliced in this loop. The Add Slices at Grid option was used since the playing was pretty regular, but several slices had to be moved manually in order to capture the naturally varying feel of the original. Note that in fluid audio such as this, or a full mix, obvious peaks and good slice points don't necessarily coincide!
Two bars of real guitar playing were sliced in this loop. The Add Slices at Grid option was used since the playing was pretty regular, but several slices had to be moved manually in order to capture the naturally varying feel of the original. Note that in fluid audio such as this, or a full mix, obvious peaks and good slice points don't necessarily coincide!

Sometimes, when using the Add Slices to Grid option, you get too many or too few slices; this would be the case if your audio has an eighth-note feel for example. You could manually erase unwanted or add wanted slices, but you can also cheat by telling the software that your sample is half or double the length that you need, and it'll create a grid to match. So, a two-bar loop in normal circumstances would be divided into 32 16-note slices. Tell Recycle that it's a one-bar loop, and the grid will be 16 slices long, offering an eighth-note grid to your two bars. Just don't forget to switch the 'bars' parameter back to 'two' when you're finished, so that everything plays back at the right tempo.

Finally, you can simply look at the audio and place the slices manually. Note that there are two types of slice: locked and unlocked. Locked slices are added during the grid-based and manual processes, and unlocked when using the Sensitivity slider. One type can be changed to the other, and the only difference between them is that unlocked slices won't disappear if you move the Sensitivity slider to the left. Slices can also be muted, though this removes the effect of the slice rather than muting actual audio.

A loop can potentially contain a lot of slices: the program told me I was trying to insert 1000 slices during one test! Be warned, though, that Dr. Rex in Reason can only accommodate files with a maximum of 99 slices.

However you create your sliced-up loop, once you're Previewing it, a number of other processes can be applied to it. The first of the three main processes, Envelope, alters the attack and decay time of each slice. This is handy for smoothing away any intransigent clicks that you can't eliminate by moving slices, and for adding gated effects. Moving the decay parameter to the left causes slices to become more staccato; the effect can be quite dramatic and aggressive when used on a busy loop. The Envelope also has a Stretch parameter, which artificially creates longer slices when a loop is played back at slow tempos. The effect is sometimes like a reverse reverb, but can often help fill in gaps that would otherwise be distracting when a loop is playing much more slowly than its base tempo.

The Transient Shaper is essentially a compressor, with threshold, amount, attack and release controls, and a level meter. The effect is triggered at each slice break rather than by audio peaks, and can, again, be quite aggressive (to the point of distortion), but it really helps level out uneven loops, or add punch and energy — not to mention volume — to slightly lifeless samples.

Lastly, the EQ is a deceptively simple affair. There are four 'bands': high and low cut (centring on 15Hz and 20kHz respectively), and two parametric bands with full control over frequency, bandwidth and gain. The lower parametric band has a centre frequency of 20Hz to 3kHz and the high ranges from 1.5kHz to 16kHz. Whatever you need an EQ to do can be done here, such as removing hiss from a noisy sample or adding a bit of 'oomph' to a drum loop's bottom end.

Beyond these handy processes, the user is also presented with a gain control, a pitch knob variable ±24 semitones in 25 cent steps, and a tempo control. The software always knows what the sample's original tempo is, but you're free to define a default for the finished file, and it will be this tempo that's noted by other applications using the file, such as Reason's Dr. Rex. Last of all, a Gate Sensitivity control applies gating to each slice; the knob simply adjusts the gate's threshold.

In addition, DSP options include normalisation (for the whole loop or each individual slice), sample format change, convert to mono, DC removal and loop cropping. The latter is used in conjunction with the rather tiny loop start and end markers located at the bottom of the display, and discards any audio outside their limits.

Reason Adapted
One major difference between this and previous versions of Recycle is that it's bundled with a stripped-down version of Propellerhead's core application, Reason, known here as Reason Adapted. The Adapted rack features three Dr. Rex loop players into which you can load your Recycled loops, plus one NNXT advanced sampler, an RV7000 reverb, a Remix mixer and the track-based sequencer. The package also includes a specialised Sound Bank that's loaded with samples, drum kits and patches.
There are a number of things that you'll be free to do within Reason Adapted for Recycle: load whatever REX files you'd like into the Dr. Rexes, load samples into NNXT, repatch the supplied devices, save finished songs, and bounce loops and songs as audio. But there's a load of operations that you won't be able to manage, such as saving NNXT and RV7000 patches (any settings you make will be saved as a part of an Adapted Song, though). If you want more devices and effects, you'll have to upgrade to the full version; check out the supplied demo first, and see if your credit card doesn't twitch!
Taking It Further

There are a couple of options when it comes to moving your loop outside the program. First of all, just saving the processed file stores the audio, together with all settings. The data is compressed using a lossless algorithm, so that a Recycled file takes up less disk space than the original AIFF or WAV file. This file can be loaded into the Dr. Rex device in Reason, and can even be directly imported into Steinberg's Cubase SX. A Recycled audio parts sits in a Cubase SX track and stretches or shrinks to match the tempo you select.

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And here's what the first bar of a two-bar loop taken from a full audio mix looks like, sliced on the grid.
And here's what the first bar of a two-bar loop taken from a full audio mix looks like, sliced on the grid.

To import a processed file to other applications, it may be necessary to save each slice individually. As part of this process, you can save a Standard MIDI File that recreates the 'feel' of the original loop by providing triggers for each slice in all the right places. The slices could be loaded into a software sampler, mapped, and triggered from the MIDI file. It would also be possible to load the slices into a MIDI + Audio sequencer and line them up to the hits in the MIDI file — not too elegant, but possible.

One thing it is not possible to do is directly export the slices to an attached hardware sampler. This feature has been removed from Recycle as of version 2.1. The software had a hardware sampler link since its inception, but given that this was based around outdated SCSI or the painfully slow MIDI Sample Dump Standard, its demise is perhaps not surprising. Most hardcore samplists now use computers, and stand-alone hardware studio samplers are not exactly plentiful these days. Still, there are applications — such as i3's shareware DSP Quattro Mac audio editor — which still maintain SDS/SCSI export options, if you need them. And if you're using a sampler-equipped workstation synth, you'll have to transfer the slices via USB connection or media card.

Finally, let's not forget that a Recycled file can be exported as a single sample. If you want to make a piece of audio fit the tempo and/or pitch of an existing session, you could make all the adjustments in Recycle and re-load the processed file into the session, using the software stricty as an editing tool. In this and other cases, it's possible to silence, or gate, individual slices, which is useful to eliminate clicks, breaths, and other noise.


Recycle remains an essential tool for anyone working with loop-based music — though remember that it has no recording facilities, and is not a composition environment like Sony's Acid. You can use it with drum patterns, vocal phrases, bass lines, piano licks, in fact almost anything. Rhythmic audio, or any audio which you know the bar length of, can be sliced really easily and quickly. But it can also be used on any other kind of audio, though perhaps with a little more manual input from the user. I find it effective on sections of mixed audio, rhythmically chopping up loops bounced from within Reason to create new textures for re-importing back into Reason itself. There's hardly a track I've worked on since I started using Recycle that doesn't have some sliced audio in it!

The bottom line is that serious users of Propellerhead's Reason virtual electronic music studio should already have a copy of Recycle. But I daresay any serious samplist would find the software £159 well spent.

System Requirements
PC: Windows 2000 or XP, 300MHz or faster Pentium-compatible processor, 128MB RAM, 800 x 600 display, 16-bit Windows-compatible soundcard.
Mac: Mac OS X 10.2 or later, G3, G4 or G5 processor, 128MB RAM, 800 x 600 display.
Propellerhead Recycle £159
Now runs on Mac OS X and Windows XP.
Classic approach to loop manipulation still a winner.
Easy and fun to use.
No longer provides a direct link to hardware samplers.
It's hard to believe Recycle is nearly 10 years old, but it's still an essential sound-mangling tool, allowing you to manipulate looped audio's tempo, feel and dynamics with ease.
£159 including VAT.
M Audio +44 (0)871 717 7100.
+44 (0)871 717 7101

Test Spec
Recycle v2.1.
Apple G4 450MHz with 896MB RAM, running Mac OS 10.3.3.

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