Analog Synthesizer Block Diagrams
An analog synthesizer is made up of various number of 6 basic types of blocks.
- VCO - Voltage Controlled Oscillator - create a sine, triangle, square wave from a control voltage
- VCF - Voltage Controlled Filter - A low pass, bandpass or high pass filter, to add timbre to the sound
- Envelope - ASDR - Attack, Sustain, Delay, Release - Envelope generator controls event from point of key stroke
- VCA - Voltage Controlled Amplifier - modifies the volume as key stroke event progresses
- LFO - Low Frequency Oscillator - Can be used to vary pitch or volume at slow speed
- Audio Mixer - Used to sum up signals from various blocks, to send out to power amplifiers
In a typical analog synthesizer, there are usually two VCO's, an LFO, at least one filter, one VCA, one or more envelope generators, and mixers. The envelope generator is triggered by the down key stroke, and modifies the synth signals as the key stroke event progresses. It usually affects the Volume, but can also swing some parameters of the Filter in real time, or other blocks. Different modles of synthesizers simple combine various numbers of these block, with the same basic pattern, and a few tricks thrown in.
Each function in these block diagrams can be implemented with an Alfa Rpar integrated circuit, in an OEM analog synthesizer product. Each chip may cost in the neighborhood of around $5. Please scroll down in the iframe, to see more description of various real world synthesizers.
Synth VCO/VCR/VCA/ADSR Block Diagrams
Moog Grandmother synth at Sweetwater
Ambika