Distortion

Question 1

What is impedance mismatching?

Answer 1

When the impedance of an output signal produces a signal that has a high impedance value compared with the impedance value of a mic input

A high impedance results in a distorted sound on an input not designed to accept high impedance signals. The signal is usually distorted and contains unwanted noise

Question 2

What is clipping?

Answer 2

The type of distortion most common when overdriving an input or output. It occurs when the signal goes above of the maximum level of a capacity, generally 0dBFS

When the signal clips, the parts of the signal above 0dBFS are lost.

In a DAW, the parts of the signal above distortion threshold will be squashed, clipping the waveform, turning a sine wave into a harsh square wave

Question 3

What is Truncation distortion?

Answer 3

Caused by dropping bits when playing or rendering an audio signal that can produce a low level distorted signal

Question 4

What is tape saturation?

Answer 4

• Lacks warmth of analogue technology
• When magnetic tape is overloaded by a signal, it produces a rich, harmonically-driven distortion
• Can be re-produced in DAWs with plug-ins

Question 5

What is fuzz?

Answer 5

• A style of distortion that harks back to early guitar amps, especially broken ones
• It was discovered that broken amps could sound pretty interesting and fuzz pedals were soon created
• Fuzz created by hard clipping analog transistors
• Has been used by hard rock and lo-fi indie bands
• Can make an overly muddy sound that needs a low-cut or shelf filter

Question 6

What is a fundamental tone?

Answer 6

• The pitch of a tone is determined by its fundamental, the loudest and lowest frequency in a waveform
• If the fundamental is 100hz, the next wave that forms will be 200hz. This is the first overtone in relation to the original fundamental or the second harmonic

Question 7

What is harmonic distortion?

Answer 7

• Do not add to the harmonics surrounding the fundamental
• The total harmonic distortion indicates the difference between the harmonics present in the outgoing signal produced by an amp compared to the pure incoming signal

Question 8

What is overdrive?

Answer 8

• A type of analog style soft clipping that doesn’t add many extra harmonics, but drive the signal
• Replicate the effect of running a signal through an analogue tube amp. Great for adding thickness but not fundamentally changing too much of the timbre

Question 9

What is non-harmonic distortion?

Answer 9

• Similar to clipping and is the result of additional frequencies being added to the signal that aren’t multiples of the fundamental tone.
• The non-harmonic distortion of an over-driven solid state amp is a part of the heavy metal sound

Question 10

What is linear distortion?

Answer 10

• A change in amplitude or phase with no new frequencies added
• Signal isn’t fundamentally altered
• Doesn’t colour the sound
• Changes in the wave amplitude or phase can lead to cancellation of certain frequencies or increase volume levels for others.

Question 11

What is non-linear distortion?

Answer 11

• Non-linear distortion occurs when new frequency components are generated
• Frequencies present in the outgoing sound that are not from the original audio are elements of distortion
• All amps produce slight non-linear distortion
• Diodes, transistors and amps will all contribute to slight distortions

Question 12

What is bitcrushing?

Answer 12

• The higher the bits the more information the audio can contain
• Once bits start dropping from 16, there will be very audible differences
• Downsampling is similar to bitcruchung but is reducing the sample rate instead of the bit depth