Synthesizers - part 1 (Subtractor)

There are basically 2 categories of instrument in Reason. For the next few classes, we're going to take a look at the first one: synthesizers.


What is a synthesizer?

Wikipedia says:

A synthesizer is an electronic instrument capable of producing a wide variety of sounds by generating and combining signals of different frequencies. There are three main types of synthesizers, which differ in operation; analog, digital and software-based. Synthesizers create electrical signals, rather than direct sounds, which are then processed through a loudspeaker or set of headphones.

So, basically, you've got a device that electronically generates one or more audio signals. And then by combining and processing those signals, you can create completely orignal sounds. There are several ways that different types of synthesizers operate. The simplest one is called analog, or "subtractive synthesis".

We are actually already familiar with the sounds of subtractive synthesis though working with our friend...

...the Subtractor!

So, obviously there is a lot going on with all these knobs and sliders and stuff. But once you know how to look at it, it really isn't so overwhelming. Today we're just going to focus on three sections, and from there you should know a lot about almost every instrument in Reason. The three sections are:

1. Oscillators
2. Filters
3. ADSR Envelopes.

We'll start with the first: Oscillators.

Oscillators are basically the heart of the instrument. This is where the sounds originate from. The Subtractor has a handful of very basic types of sound waves that it uses as the raw material for creating instrument sounds. Think of these as the block of stone that a sculptor starts with before he/she starts chiseling it into a specific shape. Any guess what those sound waves might be?

That's right: Sine waves, Square waves, Triangle waves, Sawtooth waves, and some others that are variations of these guys.

Subtractor has two different oscillators that it can combine to create more complex sounds. Let's check this out for a second...(demonstration)

OK, so besides being able to play back two sound waves at the same time, Subtractor lets you adjust the pitch of each each one. What do you think that does to the sound? It also lets you add noise, if you're into that.

Next, we have the Filters.


So, if the sound waves are the block of stone that a sculptor starts with, then the filters are like the chisels and other tools that he/she uses to shape it into what he/she wants. Now filters are what put the "subtractive" into subtractive synthesis, and they are a really common audio production tool in general. Think about it, what does a filter do?

We've got four basic types of filters to choose from, and they all reject different parts of the frequency spectrum. They are:

• Low Pass (LP)
• High Pass (HP)
• Band Pass (BP)
• Band Stop (aka "Notch")

Remember, the key word here is "pass"; what frequencies are being allowed to pass through the filter? In a Low Pass filter, the "lows" are being allowed to "pass". In a High Pass filter, the "highs" are being allowed to "pass". Here, let me just show you... (demonstration).

So, in Subtractor, you can select whichever filter you want to work with by clicking on the red dot. Then you can adjust the Cutoff frequency (the point where the filter starts working) by dragging the slider called Freq.

OK, so the last section of the synth we're going to cover today is the ADSR Envelope.

ADSR just stands for: Attack, Decay, Sustain, Release, and it's referring to the way the volume of a sound evolves over time. Check out this picture of a waveform:

What it is showing is the different parts of the total sound. Briefly:

• Attack - the quick rise of the volume up to the highest level.
• Decay - the drop from the highest peak to the average level of the sound
• Sustain - the average level of the sound
• Release - the fade out

Here is a common diagram of an ADSR Envelope:

Now, every sound has these four basic qualities, but with synthesizers, you can actually control the points that these things are happening. You can do this in the section called Amp. What do you think "Amp" is short for?

OK, so if your mind isn't completely overloaded yet, know that you can actually use ADSR Envelopes for more than just the volume of the soundwave itself. One of the most common things is to connect it to the Filter and have the filter moving in a completely different way than the Amplitude envelope. Bottom line: more interesting sounds.

OK, we'll cut the lecture off here today and get into actually making a patch from scratch.