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The Thor Synthesizer In Reason 4

Reason Notes & Techniques By Simon Price
Published December 2007

There's a lot to get to grips with in the latest version of Reason - but we begin by looking at the basics of the giant new semi-modular synthesizer, Thor.

The Thor Synthesizer In Reason 4The eminent writer and zoologist Richard Dawkins is often heard to say that, while it's true that one cannot disprove the existence of God, equally one cannot disprove the existence of Thor (or, to use Bertrand Russell's example, the Celestial Teapot). Dr. Dawkins will be delighted to learn that the existence of Thor is now an empirical fact, as anyone who pays their 99 Euros to upgrade to Reason 4.0 will testify. The jury is still out on the Teapot.

OK, that's enough of that! Thor is, of course, the new flagship synth in Reason. Its subtitle of 'Polysonic Synthesizer' hints at the fact that Thor is more like several synths in one, by virtue of the fact that the oscillator and filter sections are 'hot swappable' between several quite different modules. If Reason is a synth rack, Thor is a synth rack within a synth rack.

Basic Architecture

Thor's user interface is divided into four sections. At the top is the Controller Panel, which is the only section displayed when you first create a Thor. (To see the rest of the interface you need to click the Show Programmer button.) The Controller Panel houses several basic controls, such as those for Polyphony, Portamento and trigger sources. As well as the standard Pitch and Mod Wheels, you'll also see two rotary controls, and two buttons. These can be assigned to alter parameters within the patch, for extra performance control.

Thor lets you choose from numerous oscillator and filter types. The Thor device at the top has been completely stripped out, while the patch below uses a variety of different modules.Thor lets you choose from numerous oscillator and filter types. The Thor device at the top has been completely stripped out, while the patch below uses a variety of different modules.The next section of Thor contains all the main synth parameters, divided into modules. To the left are the three oscillator slots, followed by two filter sections, a voice mixer, and a shaper (we'll look more closely at how these fit together in a moment). To the right of these you'll find three envelope generators, an LFO, and a level/pan control.

All these parameters belong to the 'per-voice' side of Thor. Each note played has its own filters, LFO and envelopes from this section, making Thor a true polyphonic synth. All the parameters on the right-hand side of Thor (on the brown panel), are global — they are single modules operating on the mixed output of Thor's voice section.

Below the main Programmer area is the Modulation Bus Routing Matrix, where routing of both control (CV) and audio signals can be defined. One of the unusual features of Thor is that you can interconnect these signals — for example, using an audio signal to modulate a filter, or using a LFO as an audio oscillator.

Finally, at the bottom of Thor's panel you'll find the Step Sequencer, which allows you to sequence notes or modulate any other parameters to add melodic or rhythmic patterns to a patch.

Building A Thor Patch

Thor falls into the semi-modular synth category, in that although you have a very high degree of routing flexibility, there is a pre-defined routing structure. This means that you can get sounds out of the synth without needing to be too much of a boffin, but, if you do, in fact, have patches on the elbows of all your jumpers, you can over-patch the routing in nearly any way you might imagine.

Pop-up menus give access to the six oscillator types.Pop-up menus give access to the six oscillator types.The screen below shows an initialised Thor (see 'It's A Default Patch, Init?' box). Only the Oscillator 1 slot is enabled in the Init Patch, and is set to the Analog Osc type. This is your traditional analogue-style oscillator, switchable between saw, triangle, and sine wave shapes, plus a square wave with PW (Pulse Width) control. Add another oscillator by clicking on the pop-up menu at the top left of the blank Osc 2 panel (as in the screen above). At first you won't hear any change, because you need to route the oscillator somewhere. Each filter has a set of three square, numbered input buttons (which light up in red when active), corresponding to the three oscillators. Click Filter 1's '2' button to route Osc 2 through Filter 1.

Both oscillators are the same at the moment, so tune Osc down by one Octave, using the Oct knob. Now detune Osc 2 down about 10 cents using the Tune knob, for instant fat analogue-ness. The lines and arrows on Thor's panel indicate the default signal routing. Following these you'll see that the oscillators go through the Mixer before hitting the filters. Use the Balance control to adjust the Osc 1/Osc 2 mix.

It's A Default Patch, Init?

In Reason 4, newly created instruments come pre-loaded with a default patch from the Factory Sound Bank. This is a change from previous versions of Reason, where all new instruments defaulted to an 'Init Patch'. For synths, an Init Patch usually meant a simple saw or sine wave, while the samplers and Redrum appeared with no samples loaded. The advantage of a pre-loaded patch is that the instrument's patch browser is immediately pointing at the relevant directory in the soundbank, so you don't need to navigate through various levels of folders to load a patch. Despite the change, each instrument still has an Init Patch, which can be loaded by right-clicking on the device and choosing Initialise Patch.

Filters & Shaper

In the Init Patch, a low-pass ladder filter has been selected at the Filter 1 slot. This is a classic Moog-style analogue filter emulation. Below the ubiquitous Freq and Res controls are three smaller controls that demonstrate some of Thor's pre-defined control routings. The Env control assigns the Filter Env module to the filter frequency, and the Vel knob scales this modulation by note velocity. The Kbd knob links filter frequency to MIDI note pitch.

Thor's Init Patch with a single analogue oscillator and filter.Thor's Init Patch with a single analogue oscillator and filter.After Filter 1, the audio signal passes through the Shaper, where various types of distortion can be introduced. Following the default routing on the panel, you'll see the next junction consists of two arrow buttons. These let you choose whether the audio proceeds on towards the Amp, or is diverted through Filter 2 to use the two filters in series. By default, the output from Filter 2 is disabled, so you'll need to click the red switch that routes it to the Amp. To use the filters in parallel, route the oscillators directly to both filters. You also have the option of routing some oscillators to one filter and some to the other.

From the filters it's on to the Amp, which is modulated by default by the Amp Env, to shape the level of the sound over time. This is the last stage that operates individually on a voice; after the Amp, the voices are mixed for output or processing by the global modules.

Global Section

The first of the global stages is another filter slot, with the same choice of four filters (or none). By default, the Global Env is assigned to this filter. In most cases you will want to turn the Env control off for this filter, as having an envelope controlling a monophonic filter in a polyphonic patch is problematic, as discussed in the last Reason workshop in the October 2007 issue of SOS. This is even true of monophonic patches, as the Global Env is always in Legato mode. (When you've mastered the Modulation Matrix you may see a way to fix this).

This assignment creates PWM (Pulse Width Modulation) of Oscillator, with Rotary 1 adjusting its depth.This assignment creates PWM (Pulse Width Modulation) of Oscillator, with Rotary 1 adjusting its depth.The final modules before the outputs are the Chorus and Delay effects, making Thor the first Reason synth to have these effects onboard. The modulation on these devices is stereo, so as soon as you turn up a Mod Amt (amount) knob, the sound will widen considerably. Prior to this point the signal path is mono, unless you start messing with the routing using the Modulation Matrix.

Modulation Madness

Aside from the interchangeable oscillator and filter modules, the feature that really makes Thor a heavyweight synth is the snappily titled Modulation Bus Routing Matrix. Many synths have a matrix for assigning modulation sources such as LFOs or aftertouch to parameters. Thor's routing matrix goes further and allows you to route audio signals, turning Thor into a fully modular synth.

Let's look at a simple modulation assignment first: setting up an oscillator with PWM (Pulse Width Modulation). Change Osc 1's waveform to pulse, and set the PW knob to the middle. Now, in the first slot in the Matrix, click on the Source field, and choose LFO 2 as the source. Notice that the list of sources is divided among the voice section and global section. Now choose Osc 1 > PW as the destination. To finish the assignment, you need to set the depth of modulation, between -100 and +100, in the Amount field. Set it high and hear the movement this adds to the sound.

Two examples of audio routing in the Matrix. Negative values imply reversed phase.Two examples of audio routing in the Matrix. Negative values imply reversed phase.In the screenshot above, you'll notice that I've also added Rotary 1 in the Scale field. Thor's mod scaling system allows you to adjust, or side-chain, modulation or routing assignments with a third control or parameter. In this example I've assigned the Rotary 1 control to scale the modulation by a factor of 100 percent. The rotary will now provide fast adjustment of PWM between none and the full amount set in the first Amount field.

The first bank of Matrix modulation slots thus allows for simple source and destination assignments with optional scaling. The slots in the second bank have an extra destination field, so you can map a single source to two destinations. The third bank (below the second in the Matrix) have a single destination, but two scale sources, so you could, for example, side-chain a modulation with an envelope and also vary it with the Mod Wheel.

Custom Audio Routing

The Matrix can be used to route audio between Thor's modules if you wish to create patches that deviate from the pre-defined routing possibilities. For example, you might want to route the output of Filter 2 to Filter 1, or route an oscillator directly to the Amp, to bypass the filters and mix a clean version of the signal with the filtered and/or shaped version. Another trick is to create a feedback loop from the Shaper to the input of Filter 1 to overdrive the sound. Both of these tricks are shown in the screen on the left. Notice that you can vary the level of the signals from one module to the next when using the Matrix, whereas the main panel routing controls are just on or off.

Filter 3 has left and right inputs, allowing for panned routing. Here the Scale slots are being used to apply an envelope to the audio signals .Filter 3 has left and right inputs, allowing for panned routing. Here the Scale slots are being used to apply an envelope to the audio signals .Another audio routing application is to create a stereo patch by routing different oscillators or filters to the left and right inputs of Filter 3. This trick is actually described on the back panel of Thor (and shown in the screen below). Notice that the Amp Env has been assigned to scale the signals. This is because you are bypassing the main Amp module, so need to manually patch in an amplitude envelope. The patching allows you to add variation between the left and right outputs, either by routing different oscillators to Filters 1 and 2, or by varying the two filters.

More Thor

Thor is a big modular environment rivalling the Reason rack itself in complexity, and offering enormous scope for experimentation and sound design. We've only had enough space here to cover its signal flow and modulation routing, but there's still plenty left to get our teeth into. We'll no doubt be returning soon to look at the step sequencer, the different oscillator and filter models, routing of external audio and CV signals, the performance controllers and everything else... 

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