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Wave Sequencing | Vocoder Mod | Lead Synth

I’ll admit it: When I first heard about the new features added to the 3.0 release of Propellerhead Reason, the venerable virtual studio program, I wasn’t exactly breathing hard. Aside from the MClass Mastering Suite (and since I’m not a mastering engineer, that’s not the kind of thing I get excited about), the big news in 3.0 is a device called the Combinator. Trouble is, the Combinator doesn’t do anything. It’s just a big empty box that you put other, older Reason modules into.

That’s what I thought, anyway. I was dead wrong.

When I installed 3.0 and started going through the Combinator factory presets, I was amazed at the creative sound design. And there’s no denying it: Being able to stuff a number of synths and effects into the “big empty box” both speeds up the process of creating new music and makes it easier to archive your visionary sonic experiments. Still, hardware synthesizers have been able to layer sounds and save the settings of built-in effects processors along with the synthesis parameters for more than 20 years.

But wait. There’s more to the Combinator than that. And amazingly, very few of the factory presets take full advantage of the Combinator’s features. Specifically, if you hit the Tab key while auditioning those factory Combis, you’ll discover that the CV (control voltage) inputs to the four rotary knobs are seldom used. Those four jacks turn the Combinator into a very respectable modular synthesizer. When used in tandem with the Combinator programmer window, the CV inputs make it possible to control many more of Reason’s synthesis parameters using envelopes, LFOs, and Matrix patterns.

In this article I’ll outline the concepts you need to grasp in order to take full advantage of the Combinator’s CV inputs. Then we’ll take a quick look at three Combis I cooked up to give you a taste of what you might want to do with your own Combi patches. If you don’t have Reason, consider downloading a free demo from the Propellerhead site.

Combinator Rack Propellerhead Reason offers an infinitely tall rack of music gear. At the simplest level, the Combinator helps you tame that rack by grouping modules into single playable units that you can save as a Combi patch, like the DeDigitalizer here.

CV Basics, Reason-Style

Many of Reason’s devices have CV outputs on their back panels. (The term “control voltage” is not strictly accurate: True control voltages are found only on analog synthesizers. But that’s what Propellerhead calls Reason’s control signals, so we’ll use their term.) Among the sound-producing modules, only the NN-XT sampler lacks CV outputs. They’re also found on the Matrix Pattern Sequencer, the vocoder, the MClass Compressor, and the Scream distortion effect. Even more Reason devices have CV inputs, usually associated with trimpots (small input level knobs) so that the amount of response to the CV signal can be scaled up or down.

Combinator Jacks Here’s the back side of the Combinator module on page 1. You can see the four CV inputs and their associated trimpots at left, labeled Rotary 1–4.

CV signal values in Reason can range from –127 to 127. Some of the CV outputs, such as the SubTractor envelopes, are unidirectional (meaning they go from 0 up to 127), while others, such as the SubTractor LFO, are bidirectional (they go from –127 to 127). The Mälstrom modulator outputs can be either uni- or bidirectional, depending on the waveform selected. The trimpots by the CV input jacks reduce the range of an incoming CV, and the Spider CV Merger & Splitter can invert a CV.

Most Reason parameters can be set between 0 and 127. When driven by one or more CVs whose combined total drops below zero, they will “peg” at zero. Conversely, if sent two or more CVs (for instance, using a Spider to merge two signals) that goes higher than 127, the parameter will peg at 127.

To understand CV range a little better, try this experiment:

  1. Create a Combinator and create a SubTractor inside it.
  2. Connect the SubTractor’s rear-panel LFO 1 output to the Combinator’s rotary 1 CV input:

    LFO to CV

  3. Reduce the LFO 1 rate to about 16 and select the rising sawtooth waveform for the LFO:

    Setting LFO Rate

  4. Open the Combinator programmer, select the SubTractor in the device list, and assign rotary 1 to Amp Env Attack in the target column:

    Mod Routing

At this point, you’ll see the amp envelope attack slider on the SubTractor rise slowly and smoothly from the bottom of its travel to the top, then snap back to the bottom and start over. Note, however, that the CV coming from the LFO is being affected by three settings—the Rotary 1 rear-panel input trim (which is set to 64 by default), the front-panel setting of the Rotary 1 knob (also 64 by default), and the min/max range defined in the programmer (0–127 by default).

Turn the Rotary 1 front-panel knob down to 0. Now the slider will spend half of its time pegged in the minimum position, rise to the center of its slot, and then snap back to the bottom. This is because half of the time the LFO’s output is below zero. When Rotary 1 is set to 127, the slider does the opposite: It starts in the middle, rises to the top, and then pegs there for a while.

Move Rotary 1 back to 64 and turn the rear-panel trim up to 127. Now the slider pegs briefly at both the top and the bottom. This is because a trim setting of 64 is equivalent to multiplying the input value by 0.5. When the trim is at 64, the ±127 range of the LFO is compressed to ±64. The value of the front-panel Rotary knob is then added to this, causing the CV signal to take on a range of 0–127 (the same as the range of the slider). Try some other experiments with these settings to learn how CV signals are processed.

The Combinator Programmer

After patching a CV output into one of the Combinator’s Rotary CV inputs, you’ll need to route the CV to one or more destinations in devices within the Combinator. This is done using the programmer window, as we’ve just seen. The devices in the Combi are listed at left. After selecting a device by clicking on it, you can use the list of signal routings in the column on the right side to route CV signals to any of its available parameters.

Programmer Window The Programmer window gives the Combinator its modular patching prowess. Pick a device on the left, then pick a target and range on the right.

As you’ll see when you examine any of the pop-up menus that show up in the Target column, the parameters available as CV/Rotary destinations are basically the same ones you can automate in the Reason sequencer. For instance, you can modulate an envelope generator’s attack time, a filter resonance setting, or a mixer channel’s aux send level.

However, the parameters for individual samples in the NN-XT are not available, either for automation or for Combinator control. Technically, you could accomplish identical musical results either via Combinator CV control or by automating each knob, slider, or button separately in the sequencer. But in most musical situations, using automation would take a hundred times as much patience; when was the last time you tried drawing a good sine wave freehand with the mouse?

When using a synth module in a Combi strictly as a CV source, you may not want it to receive the MIDI notes that are playing the synth(s) you are listening to. If you want to use an envelope as a modulation source, triggering it from a Matrix rhythm is often a better approach. To shut off note reception, open the Combinator programmer, select the modulation source in the device list, and uncheck the Receive Notes check box in the lower left corner.

Don't Receive Notes This Matrix sequencer is changing the Oscillator 2 waveform in a SubTractor synth, so we’ve disabled note reception. The Matrix output is connected to a Combinator CV input.

Each device in the device list can receive one signal from each of the Rotaries and one signal from each of the buttons. In addition, if you look at the bottom of the source list, you’ll see two blank boxes. These are drop-down menus from which you can select any rotary or button. So in total, it’s possible to use a single CV to modulate three separate parameters in a single Reason device. But once you’ve done that, the other Rotaries and buttons can modulate only one parameter each within a single destination device.

The same CV(s) can also modulate other parameters in other devices within the Combi, and the min and max values are separately programmable for each routing. As a result, it’s possible to use a single LFO, envelope, or Matrix curve output to modulate a dozen sound parameters in different devices, or two dozen, at the same time, and to control the range and direction of the modulation. (If the minimum is set higher than the maximum, the modulation will be inverted.)

Example 1: Wave Sequencing

The SubTractor oscillators’ waveform parameter is available as a CV destination in the Combinator programmer. (The Mälstrom oscillator wavetables, which have to be loaded from disk before they can be used, are not.) The curve CV output on a Matrix, which changes in stepwise fashion from note to note, is a good source for a CV to switch among the SubTractor’s waves.

In the Combinator patch waveseq.cmb (download link below), three Matrix sequencers are used at once. All three send their curve outputs to the Combinator’s rotary CV inputs. The first Matrix is also playing the notes you’ll hear when you click on the sequencer’s start button. (I suggest setting the tempo to about 108 bpm.) The third Matrix controls the SubTractor’s amp envelope attack time, and also the filter envelope’s decay time. The amount of modulation is inverted for the decay time.

A second SubTractor is used strictly as an LFO, modulating oscillator phase on the main SubTractor--again, not a modulation that could be accomplished without routing through a Combinator’s rotary CV input, as there’s no CV input for phase on the SubTractor’s own rear panel. The phase modulation makes the tone a little more interesting. This LFO is also used to control the aux send level on channel 1 of the line mixer. The aux send feeds the two DDL-1 delays.

A fourth Matrix pans the output of the SubTractor. One result of the panning, because the line mixer’s aux send is stereo, is to send some of the notes to the left-side DDL and other notes to the right-side DDL.

The Matrix sequences are different lengths, ensuring that repetitions of the note pattern are articulated with different waveforms and different envelope characteristics. Here’s what the setup looks like:

Wave Sequencing Modulation Routing Wave Sequencing Combinator. Click to magnify the modulation routing screen.

I also added a chorused bass part beneath the Combinator riff to produce a texture vaguely reminiscent of Tangerine Dream:

Example 2: Vocoder Modulation

The vocoder modulation Combi called vocodermod.cmb (download link below) uses two of the band outputs of a vocoder as CV modulation sources. These are routed to the first two rotary inputs of the Combinator, where they control the index parameters of the oscillators in a Mälstrom. A simple Redrum pattern is used as a rhythmic input to the vocoder. To hear the result, start the sequencer and then play notes (preferably one sustained note at a time, in the low range of the keyboard). The CV signals create a more complex rhythm-based index modulation than could be accomplished with the Mälstrom’s Mod generators alone.


Triggering the vocoder with a Redrum pattern.

I chose the two sounds in the Redrum because they are clearly different in frequency. To hear the raw drum pattern, unmute channel 2 in the line mixer. You’ll note that the rhythm is backwards with respect to normal pop music: The snare is on 1 and 3.

Rotary 4 of the Combinator is used to invert the CV output of the Mälstrom’s Mod B. That enables Mod B to modulate the cutoff frequencies of the two filters in opposite directions at the same time, which is not something the Mälstrom can do by itself. (Only one of the filter knobs will appear to be moving, because the other modulation is done internally within the Mälstrom.)

In the musical example, the Combinator patch plays the primary rhythm part, backed up by a throbbing bass coming from a SubTractor and a breathy lead played on another Mälstrom through an RV7000 reverb:

Example 3: Lead Synth

The lead synth Combi called leadsyn.cmb (download link below) is loosely based on the default SubTractor patch. It uses the SubTractor’s own modulation envelope output for several things. First, the envelope controls the SubTractor’s own LFO 2 amount and rate. Rate can be controlled directly within the SubTractor, but as the mod envelope can be given only one output at a time from the front panel, controlling amount and rate at the same time is not possible without the aid of the Combinator. In this case the mod envelope’s direct output is controlling oscillator phase. The mod envelope also controls filter resonance, so that as the note decays the resonance increases.

Next, the mod envelope lowers the Damage parameter of the Scream distortion effect, so that sustaining notes acquire more damage as the envelope decays. At the same time, the mod envelope ducks the output of the Scream, so the damage doesn’t become overwhelming. The SubTractor LFO 1, meanwhile, is moving two stages of the Scream’s EQ in opposite directions to create a subtle timbre shift. The result is that each note you play on the keyboard starts with a great deal of presence and then decays into a swirling, distorted wash.

Screaming Mod Modulating the Damage and EQ in Scream.

In the music example that uses this patch, you’ll need to listen closely to hear the swirling echoes after the lead notes, both because the aggressive drumming covers up some of the sound and because this type of background sound is not well preserved during the data compression process that creates an MP3 file:

Because of this, I also recorded a file in which the lead synth line is soloed:

The pitch-bends and modulation wheel moves (the latter opens the filter in the SubTractor patch) were recorded from the keyboard, not automated. The drums are a stock Dr.REX pattern being mangled by a Scream.

From Many, One

The Combinator encourages Reason users to think of their complex patches as single entities rather than as jumbles of disparate modules. Ultimately this doesn’t just improve the workflow; it can help you to think about your music in more coherent ways. But don’t forget: You can still automate the controls of individual modules within a Combi by assigning them to sequencer tracks in the normal way. You can also patch CV signals directly into a module within a Combi from a module outside the Combi, bypassing the Combinator’s rotary inputs. I don’t recommend the latter, as it will prevent the Combi from working as expected the next time it’s loaded. But Reason doesn’t enforce a rigid way of working. The choices are up to you.

Music Examples: Get Your Combo Workin’

Here in one place are the previous MP3 examples of the Combinator in action. If you have Reason 3.0, you can also download and try the Combi patches and Reason songs (388KB Zip file) I used to make them.

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