Basic Guide to Audio Compression

1. Compression
A compressor is a
device for automatically
controlling the level of
an audio signal

2. Compression
The use of compressors can
make recordings sound more
polished by controlling
maximum levels and maintaining
higher average loudness.

3. Compression
Additionally, many
compressors will have a
signature sound that can be
used to add coloration and
tone into otherwise lifeless
tracks.

4. Compression
If a ratio of 2:1 is set, an input
signal exceeding the threshold
by 2dB will be output with a
level of only 1dB over the
threshold
It 'turns down' the audio when the level exceeds a
threshold set by the user

5. Compression
To make the effect of compression smooth and natural-
sounding, compressors often allow attack and release time
parameters to be set by the user
attack release
The output control is used
to restore the peak level of
the compressed signal to that
of the uncompressed input
signal

6. Valve Compression
Valve (or Tube) compressors have a slower
response than other forms of
compression. Because of this, they have a
"vintage" sound that is nearly impossible
to achieve with other compressor types.

7. Optical Compression
Optical compressors affect the dynamics
of an audio signal through a light element
and an optical cell.As the volume of an
audio signal increases, the light element
emits more light, which causes the optical
cell to lower the volume of the output
signal.

8. FET Compression
FET or “Field Effect Transistor”
compressors emulate the tube sound with
transistor circuits.

9. VCA Compression
VCA or "Voltage Controlled Amplifier”
compressors use solid state circuits.They
are usually cheaper than tube or optical
compressors.VCA's also tend to have less
"colour" compared to optical or tube
compressors— similar to digital vs. analog
tape comparison in recording.

10. Noise Gates
A noise gate mutes the signal
when it falls below a certain
threshold
the rate or release time
determines how slowly the
gate re-opens