Subtractive and sample based synthesis

Question 1

What is subtractive synthesis?

Answer 1

Subtractive synthesis refers to a type of synthesis where the partials of a harmonically rich sound are attenuated using a filter.

Question 2

What is the result of filtering out harmonic overtones?

Answer 2

The result of filtering out your harmonic overtones (also called sidebands) allows the synthesist (the person using the synthesizer) to form and sculpt any desired sonic texture or timbre of their choice from their sound source.

Question 3

What does each instrument or voice produce?

Answer 3

A combination of various overlapping waveforms (harmonic overtones) that are unique to the source of the sound.

Question 4

What makes up the note AND timbre of a sound?

Answer 4

The dominating frequency is what we perceive as a note, sung or played. All other frequency vibrations are what “colors” the note with the particular characteristics, or “timbre” of sound.

Question 5

What is an example of early analog sampling?

Answer 5

The mellotron.

Question 6

How does the mellotron work?

Answer 6

Used sounds recorded onto individual strips of tape,
which were played back
when each key is pressed
Notable users: The Beatles.

Question 7

What are some early digital samplers?

Answer 7

Farlight CMI (1979), Akai samplers (1986)

Question 8

Why was creating samples inconvenient?

Answer 8

Creating samples was difficult and time-consuming and RAM (writable memory) was very expensive, so sizes were limited.
- But ROM (Read Only Memory) was much cheaper…

Question 9

What is a sound module?

Answer 9

A sample-based synthesiser,
pre-loaded with samples and voice presets.
 (e.g. Emu Proteus (1989) and Roland JV/XV series (1994-)

Question 10

What is interpolation used to calculate?

Answer 10

The value between samples

i. e. resample the wave
- This allows a sampler to step 
through the wave at any rate
(even fractions of a sample)

Question 11

What are the 4 different types of interpolation?

Answer 11

• No interpolation
• Linear interpolation
• Cubic interpolation
• Sinc interpolation

Question 12

Describe no interpolation.

Answer 12

• use nearest-neighbour

- ‘noisy’, but fastest

Question 13

Describe linear interpolation.

Answer 13

• draws a straight line

- good and fast

Question 14

Describe cubic interpolation.

Answer 14

• draws a curved line

- better but slower

Question 15

Describe sinc interpolation

Answer 15

• ‘ideal’ but slowest

Question 16

What does changing the rate of playback do?

Answer 16

Changing the rate of playback changes the duration.

Higher pitches become shorter; lower notes become longer.

Question 17

What happens if you stretch the sound?

Answer 17

The timbre becomes less natural.

• whole frequency spectrum is shifted
• acoustic characteristics are increasingly lost

Question 18

What are the 2 most common elements in multi-sampling?

Answer 18

• Multiple pitches

- Multiple velocities

Question 19

Give examples of other sample mappings or variations?

Answer 19

• Articulations
• Note actions (alternative sustain and release samples)
• Note transitions (samples that bridge between notes)
• Ensembles (different recordings for solo and ensemble voices)

Question 20

What are 4 common sampling techniques?

Answer 20

• beat ‘mungling’/ loop recycling (breakbeat)
• sampling old film quotes
• sampling music excerpts
• augmenting acoustic sounds