Week 9 - Compression

Question 1

How does a compressor function?

Answer 1

1. A signal is inputted to the compressor.
2. The compressor senses the level of the incoming signal and compares it to the threshold level set by the users
3. The compressor then adjusts the signal’s output level based on the threshold.

Question 2

What are the two inputs involved with the compressor?

Answer 2

1. The first input is for an audio signal to pass through the compressor
2. The second input is for a control signal to determine how the device will adjust the gain of the signal.

Question 3

What is the second input of the compressor, that determines how the device will adjust the gain of the signal, called?

Answer 3

The secondary input is called the sidechain or key input.

Question 4

What are the three types of compressors?

Answer 4

1. VCA (Voltage-Controlled Amplifier)
2. FET (Field-Effects Transistor)
3. Opto-Electronic Photocell

Question 5

What are the controls that are included in the compressor? What do each of the controls control in the compressor?

Answer 5

1. Threshold (The signal level above which compression kicks in)
2. Ratio (The ratio of input to output level above threshold, in dB)
3. Attack (How fast the compressor fully kicks in, once the threshold has been broached)
4. Release (How fast the compressor returns to unity gain once the signal level has fallen back below threshold)
5. Output Level or Gain Makeup (To make up for the gain reduction imposed on the signal)

Question 6

What is peak limiting?

Answer 6

Peak limiting is when you set a high threshold just under the maximum allowable output level, and then severely “squash” any portion of the signal that tries to go above that level. It uses:
-Fast Attack
-High Ratio
-Fast Release

Question 7

What factor determines whether audio is compressed or limited?

Answer 7

Limiting means that a high ratio of 10:1 or over has been chosen.

Question 8

What is dynamic limiting?

Answer 8

Dynamic limiting is when the entire dynamic range of the signal is greatly reduced.

Question 9

What factors are used to accomplish dynamic limiting?

Answer 9

Dynamic limiting means that there is a low threshold and a high ratio. This means that there is a large amount of gain reduction as a result.

Question 10

What is the goal of dynamic compression?

Answer 10

The goal of dynamic compression is to bring up the lowest level passages so there is less discrepancy between them and the loudest passages.

Question 11

What settings are used to achieve dynamic compression?

Answer 11

The settings that are used for dynamic compression are:
-Low threshold
-Low ratio