You are here

Rack & Roll

Propellerhead Reason Tips & Techniques
Published September 2012
By Robin Bigwood

Pausing by the buffet, we check out what Propellerhead have brought to the Rack Extension party.

The diminutive (and currently free) Pulsar isn't just a modulator: with a few clicks it can be turned into an ultra-basic monosynth ideal for lo-fi electronic game-sound emulations — and much more. The diminutive (and currently free) Pulsar isn't just a modulator: with a few clicks it can be turned into an ultra-basic monosynth ideal for lo-fi electronic game-sound emulations — and much more.

As the dust settles following the release of Reason 6.5, the potential of some of the new Rack Extensions is becoming clear. This month, we continue our look at Propellerhead's own offerings, beginning by picking up where we left off with Propellerhead's intriguing Pulsar device.

On the face of it, Pulsar (a free download until October 1st this year) is one of the more workmanlike Rack Extensions available. In last month's column, I looked at how its two LFOs could be pressed into service for simple (and not so simple) modulation of other devices. However, there's another, more unexpected side to it too: the LFOs can work well up into the audio range, and in a few steps you can turn Pulsar into a primitive but distinctive monosynth. Here's how:

1. Right-click on an empty part of your rack and choose Utilities > Pulsar Dual LFO to create the device. Turn down the level knobs on both its LFOs (you'll see why in a minute).

2. Right-click the empty rack once again and choose Utilities > Mix Channel, to route Pulsar's audio into the Reason mixer.

3. On the rear of the rack, drag a cable from one of Pulsar's LFO1 Audio outputs to the L/Mono input of the new Mix Channel.

This combo is already usable, in a sort of 1960s BBC Radiophonic Workshop fashion. Try turning Pulsar's LFO1 rate up to about the three o'clock position, un-tick the Tempo Sync option, and then raise its level. You should hear a continuous tone, which can be pitched with the Rate knob. Go easy with the Level knob (and your overall monitoring level) if you try any of the more spiky or square waveforms: Pulsar has no anti‑aliasing filters, so its output is liable to be filled with tweeter-melting high‑frequency digital artifacts. So far, so crude. To make it more usable, we need to get MIDI input and pitch-tracking going.

4. Right-click an empty part of Pulsar and choose 'Create Track for Pulsar'. Also turn the far right Kbd Follow knob all the way up. This makes MIDI input control the LFOs' frequencies.

5. Next, to achieve accurate pitch-tracking, turn LFO1's Rate knob right up.

6. Now, assuming you don't want a monosynth that never shuts up, turn the LFO1 level knob all the way down but raise (a little bit) the leftmost Level knob in Pulsar's Envelope section.

The overall high pitch of Pulsar can be tamed by retuning its LFO rate knobs using automation data.The overall high pitch of Pulsar can be tamed by retuning its LFO rate knobs using automation data.

Pulsar's envelope will now trigger every time it receives a MIDI note input, and raise the Level parameter for as long as the note is held. You've got basic control over note start and end shapes using the Attack and Release knobs. It's a working synth! But it's all pitched rather high, and you could say the sound quality puts the 'rude' in rudimentary. There's a lot you can do to remedy that, though.

LFO1's Lag knob 'rounds off' the squarer waveforms, so it acts like a kind of low-pass filter. The Shuffle knob acts almost like a pulse-width parameter on a conventional synth, so you can adjust it to tease out different harmonic characters from your basic waveforms. And if you flip the rack around and drag a CV cable from one of LFO2's CV outputs to LFO1's Shuffle CV input, you get a moving PWM (pulse width modulation) effect. Adjust LFO2's parameters to control the effect.

For even more control over the sound quality, try creating a filter in the insert section of Pulsar's Mix Device. The lowly ECF42 half-rack device will do the trick, but I've also been getting some brilliant sounds from FXpansion's Etch Rack Extension. You encounter limitations when using separate filters like this, because they don't track the pitch you're playing, as a more sophisticated synth's filter would. But that's part of the charm of this setup — it's basic, and produces a certain unique character as a result.

What about that overall high pitch? Pulsar screams out (maybe literally) to be used as a bass synth, so you need to tweak the rate knob to find some lower octaves. Even adjusting it with the Shift key held down (to access finer value increments) doesn't give sufficient resolution to do this properly, so instead Alt-click the LFO1 Rate knob to enter an automation value for it in Pulsar's sequencer track. Find that in the Sequencer — switch to Edit mode if necessary — and double-click the 'Static Value' handle to type in a value directly. Values of 524 and 263 (Hz) give a much more suitable lower octave.


Deep and gloriously weird, Polar will keep tweakers and programmers happy for weeks.Deep and gloriously weird, Polar will keep tweakers and programmers happy for weeks.

Polar is one of the weirder new rack extensions. Termed a 'dual pitch-shifter', but taking its cue from harmoniser effects of the '80s, it's a completely new kind of effect device for the Reason platform.

We already have pitch-shifting, of course, directly in sequencer tracks (thanks to the Transpose parameter for audio clips), which is ideal for tuning and repitching loops, and also in a really sophisticated, formant-corrected form, in the Neptune Pitch Adjuster, which is amazing for generating backing vocals and counter‑melodies. Polar isn't meant to replace or duplicate either of these, but rather is a creative pitch-shifter for modifying tone quality and texture, not always in a naturalistic way, and for creating stereo effects and strange pitch cascades.

Let's look at creating an octaver effect for a synth or guitar track. Create an instance of Polar for the track, and initialise its parameters by right-clicking an empty part of its panel and choosing Reset Device. What we're dealing with here is essentially two pitch-shifters (labelled 1 and 2) running in parallel, with their output optionally routing through a filter, so making a simple octaver is easy: just turn the Shift knob for pitch-shifter 1 down by 12 semitones (or one octave), and also enable the Dry Signal section so that you can hear the original audio too.

The quality of the octave-shifted audio is dependent on the settings in the Algorithm section. It's here that Polar analyses the incoming audio. Smooth and Classic are the two algorithms best suited to this sort of straightforward role, with Classic potentially the more dated‑sounding of the two. Choose Fast mode to minimise latency (Med and Slow can give better results, especially for complex and transient-rich audio, but at the expense of latency). Finally, also check that that the Delay knob is turned right down in the Delay Buffer section. Your octaver should now be fully functional.

A sample library in a rack extension: GForce's Re-Tron is a 21st century take on the Mellotron tape-based instrument.A sample library in a rack extension: GForce's Re-Tron is a 21st century take on the Mellotron tape-based instrument.You can adjust the relative volumes of the dry and octave-shifted signals with their separate Volume knobs at the bottom of the front panel. You can also pan them: try positioning the dry signal far left and the shifted signal far right, for example. Now try turning up Shifter 1's Feedback (marked 'F.Back') knob. This injects the octave-shifted audio back into the input, so it's shifted down again — and again, and again, producing massive octave 'stacks'. In fact, for a truly symphonic effect, switch on Shifter 2 (by clicking its red indicator), turn its Shift knob up an octave, and add some feedback. Now you have octave stacks stretching both above and below the notes of the track audio. This can work brilliantly in big, spacious pad sounds, for example.

Polar is capable of more subtle effects too. Check out the default 'Classic Stereo Spread' preset. Here, both shifters apply a tiny amount of pitch change, with a tweak up and down of their Fine knobs. One is panned far left, the other far right, and the dry signal left in the middle. The result is a subtle, chorus-like decorrelation of phase, and an exaggerated stereo image. Adding feedback thickens the effect further.

Here's one final setup to try in this initial examination of Polar.

  • Disable Shifter 2.
  • Set Shifter 1's Shift knob to +2 semitones.
  • Turn up the feedback (you might hear a grim tone-cluster) and the Delay knob in the Delay Buffer.

Now the resulting steps up in pitch are spaced out in time. We've entered the realm of the special effect, but this is something you might consider using low in the mix as a bizarre vocal or pad treatment, once or twice in a song.  

Tron 2012

One of the most exciting Rack Extension releases of recent weeks has been GForce Software's Re-Tron, a slightly cut-down port of their virtual Mellotron, M-Tron Pro, which has been available as an AU/RTAS/VST plug‑in for some time.

Re-Tron offers 25 tape banks, and many ready-to-use patches, covering all the classic Mellotron timbres — strings, flutes, choirs and orchestras — as well as a beautifully grungy piano, some organs, tuned wine-glasses, and more. Two sounds can be layered, tapes can be reversed or played at half speed, and there are independent filters, LFOs and envelope generators, plus on-board delay and chorus/ensemble effects. It's all beautifully implemented, and the sound oozes vibe and character.

Re-Tron costs €59$75 and is available from

Published September 2012

Buy Article PDF