Roland SH-201 specifications Basic Structure of a Synthesizer, Analog Synthesizer

Chapter2 The Basic Structure of a Synthesizer

Atypical synthesizer will have a signal flow-chart similar to the one pictured below.

To start, let’s understand the fundamentals.

		Audio signals
OSC 1	LFO 1	Control signals

PITCH	MIX/	FILTER	AMP
ENV	MOD

OSC 2	LFO 2	FILTER	AMP
		ENV	ENV

OSC Oscillator (➝ P. 9)

This is the basis of the sound, where the waveform and pitch are selected. It is indeed

AMP (➝ P. 13)
Sound generated in OSC and processed through the FILTER is amplified here.
On analog synthesizers, it is called the VCA(*3). The VCA is used to change
the volume (level) of sound signal through changes in voltage.	Chapter
LFO Low Frequency Oscillator (➝ P. 15)	2
	The of a
This is a sound generator capable of producing low frequencies. On analog	BasicStructure Synthesizer
synthesizers, it is also called the LFO(*4). The LFO affects the OSC, FILTER, and
AMP individually as it adds modulation. LFO is a “must have” for producing
synthesizer-like effects.

Examples of LFO

	applied to OSC	Vibrato
LFO	applied to FILTER	WahWah (Growl)
	applied to AMP	Tremolo

ENV Envelope Generator (➝ P. 10, 12, 13)

An envelope generator controls the initiation and termination of sounds.

On analog synthesizers, it is also called ENV(*5). Every time you play

the keyboard, ENV affects the volume and timbre on OSC, FILTER, and AMP individually as it processes its time-varied elements.

Examples of ENV

	applied to OSC	Pitch becomes higher or lower
ENV	applied to FILTER	Sound becomes brighter or darker
	applied to AMP	Sound becomes louder or softer

the heart and soul of a synthesizer. On analog synthesizers, it is called the VCO(*1). A VCO is a sound generator capable of changing frequency through changes in voltage. The SH-201 has two oscillators (OSC1 and OSC2). It’s like having two synthesizers in one.

FILTER (➝ P. 11)

This is where the sound signal generated from the OSC is processed through the emphasis and rejection of a selected frequency range. On analog synthesizers, it is called the VCF(*2). A VCF is used to continuously change the characteristics of a filter (cutoff frequency) through changes in voltage. The SH-201 houses three separate filters, each designed

PITCH ENV

pitch

DEPTH

time

Key-on A D

FILTER ENV
cutoff frequency			Key-off
		S	DEPTH
	A D		time
Key-on			R

AMP ENV

volume			Key-off
			S
	A	D	time
Key-on			R

for a specific purpose.

LPF Low Pass Filter	HPF High Pass Filter	BPF Band Pass Filter
level	level	level
partials which are cut	partials which are cut	partials which are cut

frequency frequency frequency

5

Analog Synthesizer

Once considered relics, analog synthesizers are attracting attention once again. The simple and easy-to-understand OSC ➝ FILTER ➝ AMP structure enables real-time control

to achieve dynamic sound variation. Moving knobs and faders to create your own unique sound can be a very exciting experience indeed. The SH-201 is recommended not only for keyboardists,

but for any artist or producer who desires a new outlet for creativity expression.

(*1) Voltage Controlled Oscillator (*2) Voltage Controlled Flter (*3) Voltage Controlled Amplifier
(*4) Low Frequency Oscillator (*5) Envelope Generator	6