#5. Synthesizers in Reason - Subtractor

In the next 3 tutorials we are going to familiarize ourselves with the synthesizers in Reason. I strongly recommend that you take a look at the “Basic Synth Concepts” tutorial first which covers most of the similarities between them, since we are not going to discuss those in the following tutorials.

The Subtractor is the first synth made in Reason. It is a mono device which uses subtractive synthesis for the creation of its sounds. In simple terms, subtractive synthesis is creation of sounds in which different waveforms are processed trough filters. Additive synthesis on the other hand uses a combination of different harmonic basic sine wave tones in order to create the other types like sawtooth, square, etc. For example, if you want to create a sawtooth wave, you need to add many sinewaves – each new added with doubled frequency and amplitude (volume) being 1 / 2, then 1/ 3, then 1/ 4, etc…

Adding different harmonic sine waves together (using the Fruity Loops oscilloscope to show you what changes take place). The ending waveform looks more and more like a sawtooth waveform. The more waveforms are added, the better quality sawtooth we have in the end. The sinewave is the most basic tone (it is actually one dimensional circle).

After that healthy sound creation tip we are going to go back to the Subtractor device.

The Subtractor synthesizer has 2 oscillators with 32 waveforms (including the 4 main sawtooth, square, triangle and sine) and a noise generator. You can select octave transposition, semi-tone (the interval between two adjacent keys, for example C4 and C#4) and cent which divides the semi-tone into 100 fractions.

There was a very neat article in the web from which I`ve print screened all the subtractor waveforms visuals (I can`t find it on a web anymore, so I can`t give the link :( ).

Subtractor`s special weapon is called Phase Offset modulation. When you turn it on, you create a copy of the sound waveform and move it off sync relative to the original one either positively or negatively (using the phase knob). The 0 sign means the effect is off, the "–" sign means that the effect uses subtraction and the "x" knob means that the effect uses multiplication.

Oscillator Mix determines the levels of the two oscillators relative to each other (note that the noise generator and the ring modulator amounts are on the side of the second oscillator in the mix, so if you turn it all the way to the left you won`t hear them).

The noise oscillator is used to create… noises. It has a decay knob determining its duration while the key is pressed, color (from low to bright) and level knobs. On an initialized patch – if you turn the mix knob all the way to the right and turn on the noise generator you will hear it exclusively (alternatively, you can use a little bit of hack – initialize the patch, set oscillator 1 to square wave, make a negative phase offset and turn the phase knob all the way to the left – that will also mute it).

You can use the Kbd tracking button to disable the input of notes from your midi keyboard, making it play a constant pitched sound regardless of the note (for example you may use it if you create a synth percussion sounds requiring constant pitch) .

(Note that the noise generator doesn`t change it`s pitch regardless of whether Kbd tracking is turned on or off).

FM stands for frequency modulation. In it one waveform (modulator (oscillator 2 in Subtractor)) controls another one`s frequency (carrier (oscillator 1 in Subtractor)). It`s a little bit like an LFO although you can hear the sound of the wave that does the modulation. If you don`t want to hear it, simply move the mix knob all the way to the left to hear only oscillator 1 (rather than turning off the oscilliator 2 which will stop the modulation). Since oscillator 1 is the carrier you will not hear the effect if the mix knob is turned all the way to the right which will mute oscillator 1 relative to oscillator 2.

To test that, turn on the FM knob a bit (lets say - half way) and start the second oscillator. Move the mix knob all the way to the left in order to hear only oscillator 1. Now when you play a note and make changes in oscillator 2 you will hear difference in the frequency modulation despite the fact that oscillator 2 is muted. If you do the opposite – mute oscillator 1 relative to oscillator 2 with the mix knob and make changes in oscillator 1, you will not hear any changes in the sound.

Ring Modulation is a type of amplitude modulation in which two waveforms are multiplied (one is usually sine or some other main waveform). The resulting signal contains the sums and the differences of the oscillators` frequencies (ex. - if oscillator 1 has frequency of 11 kHz, and oscillator 2 of 200 Hz, this will output result containing 1,3 kHz and 900 Hz).

In the case of Subtractor, the ring mod is applied only to the second oscillator, therefore you will hear it`s effect only if you can hear oscillator 2 in the mix (unlike the FM case where the opposite happens and the oscillator 1 is the main player). To prove that you can make similar test as we did with the FM synthesis – turn on ring mod and mute one of the oscillators and make some changes to the other one and see if there are differences in the sound output.

The name Ring Modulation comes from the appearance of the diode scheme used to achieve that effect in electronics – they are placed in a form of ring – very similar to the Graetz bridge rectifier trick used to transform AC to DC.

Subtractor has the standard envelopes and filters we have discussed before. The LP12 and LP24 of the low pass filter determines the resolution of the filter in decibels (all the others are at 12 dB). If you link the 24 dB LP filter to the Filter 2 and turn it`s frequency all the way down you will have 36 dB filter. The filter has it`s own kbd knob which modulates it by the note being played. It has amp envelope (for the level), filter envelope and mod envelope affecting selectable target. The last two have amount knob and an inversion option.

Subtractor has two LFOs – the first one has six waveforms which can affect six targets and two knobs – one for the amount and one for the rate. LFO2 has the ability to increase or decrease its rate, depending on the note being played (enabled by the Kbd key track knob). By default it has only a sine LFO wave. It also has a Delay knob which is something like an Attack of the effect determining how long it will take for it to take place when the key is being pressed.

Lo BW (Low Bandwidth) cuts some of the higher, less noticeable sounds in order to save some CPU power. It is located near the patch selector. 

Subtractor can control different targets with received After Touch, Expression Pedal and Breath Control MIDI sources.

If you press TAB and look at the back of the device you will see that it has a single mono output. You can stereo-lize it either by routing it in the left mixer channel or by using audio merger. It has modulation cv and gate inputs and modulation outputs.

P.S. Subtractor has a special "unscrew screws" function which you can do with the left mouse button. 

#2. Basic Synth Concepts

We are now going to get familiar with the synthesizer and it`s components. The most important one is the oscillator. Every synth has one or more. It generates a waveform which we, humans, perceive as noise. It has frequency (cycles per second) and amplitude. The higher the frequency of the waveform, the higher the pitch we hear. Notes are nothing more than specific number of cycles per second - for example the A note above middle C has the pitch of 440 Hz. The amplitude on the other hand determines the loudness of the sound.

The upper two pictures show the difference in amplitude which results in louder sound. The lower two show the difference in frequency resulting in higher pitch.

Amplitude and Frequency modulations

The subtractive synthesizers generally uses four types of waveforms - the sine, square, triangle and sawtooth generating different types of sound (note that some of the synths can have many more, for example Subtractor). Low sinewaveforms for example are pretty good for sub bass tones. The combination of different oscillators creates an unique sound.

The filters are used to filter certain frequencies from the sound. The Low Pass Filter (LP) is used to filter high frequencies while passing the lower ones. The more it`s knob is positioned to the left (or down in the case of Subtractor, Dr Rex etc...), the lesser high frequencies are being passed. The High Pass Filter (HP) does the opposite. The Band Pass Filter (BP) passes only frequencies in between while the Notch Filter filters the middle frequencies (automating that is great for creating the Reese basses used in the drum and bass genre).

Filter and Resonance in Subtractor and Thor`s State Variable Filter

The different types of filters. The frequency spectrum is presented horizontally (from low (left) to high (right)). The volume is presented vertically. The first filter keeps high volume for the low frequencies, and reduces it for the high ones. The second does the opposite - reduces the low frequencies. The third reduces the frequencies surrounding the center while the forth reduces the middle ones.

Resonance in simple terms is a boost near the cutoff frequency of the filters - the higher the boost, the lesser the Q (in other words... the horizontal thickness of the hill) and vice versa. Turning that knob up will add acidic property to the sound, it sounds great when moving the LP filter next to it.

Picture of resonance added to the cutoff of the low pass filter and the different types of "Q" depending on how high it is.

"Q" bandwidth visual... More about that when we discuss the EQ section. It describes the quality of the curve band passed by the filter.

LFO (low frequency oscillator) is a pretty low waveform (below 10 Hz, humans can`t hear it) which is used for controlling different parts of the synthesizer based on the waveform`s rule (loudness, pitch, filter frequency for tremolo, vibrato or sweep effects). It has amount and rate parameters (which can be tempo synchronized or key synchronized, the latter resets the LFO every time you trigger a note key). It has great variety of waveforms controlling the effect.

LFO examples in Reason

Another part of the synthesizer is the ADSR envelope. This abbreviation stands for Attack, Decay, Sustain and Release. It automates different properties of a sound (loudness, pitch, timbre). All of them are time parameters, except Sustain which is an amount parameter.

Thor`s amp envelope example (regulating the loudness of a sound)

ADSR envelope visual. The third parameter (Sustain) is always moving up and down horizontally since it is an amount parameter.

Thor has an advanced  DAHDSR filter.

Lets imagine that we use ADSR envelope to regulate the loudness of a sound...

Attack determines how long it will take for the sound to reach maximum volume after you hit the key on the keyboard. The higher the slider is, the slower the sound reaches maximum loudness (good for slowly progressing pads for example). If the slider is at it`s lowest point, the sound starts right away with full volume after hitting the key.

Decay starts right after the Attack has reached it`s maximum point. It fades the volume of the sound to the level set by the Sustain (the third slider). The shorter the Decay, the faster the sound diminishes to the level set by Sustain.

The Sustain level is the level of the sound you are going to hear as long as you keep the key pressed. If it`s slider is at it`s highest point, the Decay value loses meaning, since there is no lower value to decay to.

Release determines how long the sound is going to continue playing after you have released the key.

Synths have also Pitch Bending Wheel with Range determining option.

There is also a Mod Wheel thing. It`s purpose is to trigger the effects (set by different knobs) in the "Mod Wheel" section (or the nearest ones to it, in the case of the Subtractor).

Pitch Bend and Modulation Wheels in Reason

The Portamento is used when you want to gradually slide between the notes (bending the pitch so to speak).

You can select the amount of Polyphony (how many notes can the synth play in the same time) or you can make it monophonic by selecting Mono Legato (or set the polyphony to 1). Mono Retrig option does the same, but it also resets the envelopes every time you play a note, even if it flows into another one. The Release Polyphony determines how many notes can be playing at once when you have released the key.

Those are the basic synthesizer concepts. Make sure you understand them well before moving to the next lesson.

#1. Basic Audio Wiring

Have you ever seen one those Moog modular monsters? One may ask himself: "What kind of crazy evil minded genius you have to be to know how this monstrosity works?". Well, the complexity is just an illusion - the whole system is composed of many, often repeated simple things. And the Propellerhead Reason wiring is no different.

Open a new, empty rack. Now the only thing you see is the Hardware Interface device on the top. This device is always presented and is basically the final destination of the audio signal. This is the device connected to your midi and audio hardware also you can use it as a connector to other programs (Like Fruity Loops Studio, Ableton Live, etc...) via ReWire.

The hardware interface has both Midi In and Audio Out devices (more about midi in and rewire - later...). For now, we are interested only in the Audio Out section. It transfers the audio signal to your sound card or rewires Reason to other programs.

Most probably, you are going to have only the first two audio output channels (one for the left and one for the right speaker) present, but you may have more depending on your sound card.

The available channels are colored yellow, when you make the connection, they become green.

Now right click on the black area below and create Thor Polysonic Synthesizer (you can also create it from Create on the upper menu, or from the tool window accessed with F10).

Hit TAB to look at the back of the rack. You can see that the output cables of Thor have been automatically connected to the input of the hardware interface:

Now you can play the synthesizer with your keyboard or you can write notes in the sequencer (which is either below the devices and needs to be dragged up, or is using another window, if you have hit Detach Sequencer Window from the Window of the menu above). You might have noticed that the wiring has been made automatically (Reason always auto connects the newly created device to the nearest one), but you are often going to need to do the connection manually. Let`s try that. Right click and while holding shift create RV-7 Digital Reverb. OK, now look at the back of the devices again... You will see that because of the holding shift action the effect has not been connected automatically to the synthesizer. Our goal is to put some reverb effect on Thor - drag the cables from the Thor`s left and right outs and put them in the reverb`s left and right ins accordingly, then put the reverbs left and right outs back to the hardware interface`s ins. It is simple as that, now the effect is affecting the synthesizer successfully:

1 - The Thor`s outputs; 2 - The Reverb`s inputs; 3 - The Reverb`s outputs; 4 - The hardware interface`s inputs.

The newly created reverb (by holding shift) is not connected automatically...

When finishing the connection, this is the result you should get.

Let`s do another interesting thing. Begin with a new, empty rack (from File -> New). Hold SHIFT and create tree new devices - a Thor Polysonic Synthesizer, a RV-7 Digital Reverb. and a DDL-1 Digital Delay Line. Now put the left out of the Thor in the left in of the reverb. It will automatically connect both left and right cables, but you need to remove the right one.

When you connect the left cable it automatically connects the right one as well...

You need to remove the right one.

Then connect the left out of the reverb to the left in of the hardware interface. It will also connect both cables and you need to remove the right one again. As you may have guessed, we are going to create different effects for the left and the right outputs of Thor. Take the right out of thor and put it in the left input of the delay (you might intuitively put it in the right input, but it should be the left one), then connect the left out of the delay to the right input of the hardware interface. What you are going to get in result is reverb in the left speaker and delay in the right speaker.

This is the final result you should get. Notice how even if we output the right cable of Thor, we still need to put it in the left input of the delay. Then we connect the left out of the delay to the right in of the hardware interface. Single cables are connecting always to the left channel of a device.

This is the basic audio wiring tutorial. You can connect all kinds of devices to different effects, than connect them into more effects, connect also only the right or lefts outs in different ones in an endless progression. All the devices have their inputs and outputs in similar places (if you can`t exactly see where they are in a particular device, create it without holding shift to see how it auto connects). Spend a little time experimenting with those concepts, be sure that you understand everything presented here well before moving to the next tutorial.