180 likes | 422 Views
Subtractive Synthesis. Subtractive Synthesis. Subtractive synthesis is the method used to create sounds in most of the classic synths of the 1970s, such as the MiniMoog, ARP 2600 and Oberheim.
E N D
Subtractive Synthesis Subtractive synthesis is the method used to create sounds in most of the classic synths of the 1970s, such as the MiniMoog, ARP 2600 and Oberheim. As opposed to additive synthesis, subtractive synthesis starts with a complex waveform and removes frequencies. Most synthesizers and samplers use the basic concepts of subtractive synthesis to some extent. Subtractive synthesis is also known as analog synthesis, though most are now virtualanalog, in other words, digital.
Subtractive Synthesis Signal Path Oscillator Source Modifier Filter Amplifier Power Modulator Modulator Modulator Dynamic- sound changes over time Static- sound remains the same
Oscillators • Oscillator are the basic sound source for subtractive synthesis • Most synthesizers include more source waves than the basic ones listed • Modulation - frequency Dull Triangle Wave Sine Wave Hollow tube Square (Pulse) Wave Sawtooth Wave Woody Buzzy
Filters • Used to remove frequencies from basic wave • Primary means of shaping a sound • Types • Low Pass filter (LPF) • High Pass Filter (HPF) • Band Pass Filter • Band Reject Filter (Notch) • Special – Formant, Comb
Filter Terms • Cutoff Frequency – point at which filter begins to remove frequencies • Poles – Each pole removes frequencies at a rate of 6 db per octave • Resonance – Accentuation of frequencies around the cutoff frequency
Low Pass Filter • Removes frequencies above the Cutoff Frequency • 2-pole (12 db/octave) or 4-pole (24 db/octave) • Resonance available • Creates fat sounds • Modulate – cutoff frequency, resonance amt
High Pass Filter • Removes frequencies below the cutoff frequency • 2-pole (12 db/octave) • Creates thin, nasal sounds • Modulation – cutoff frequency
Band Pass and Band Reject Filter • Band Pass removes frequencies above and below the cutoff frequencies • Band Reject removes frequencies between the cutoff frequencies Two Cutoff Frequencies Modulation – Cutoff Hz 1, Cutoff Hz 2
Modulation Means to change a parameter in a device • LFO – Low Frequency Oscillator • Envelope Generator - ADSR • Keyboard - Pitch • Keyboard - Velocity • Oscillators • Controllers In advanced synthesizers virtually any device can modulate another
LFO • Continuous device- always on • Uses various waveforms or shapes • Triangle or Sine wave • Ramp up or down • Random • Modulates device parameters in time • Can be synced to tempo/meter
Envelope Generator (ADSR) • Attack time • Decay time • Sustain level • Release time • One-shot • Envelope generators use a trigger and gate. • The trigger is usually a depressed key. • The gate remains open and the EG remains at Sustain level until the key is released. • The envelope then moves to zero based on Release time. • Any parameter can be modulated
Subtractive Synthesis Signal Path Oscillator Filter Amplifier ADSR Keyboard LFO