Fostex 3070 - Page 11

By adjusting attack and release characteristics, these
typical compression curves can be altered radically, as in
Figure 5, below. A small, mV signal produces the same maximum
output level as a large signal. This effect similar to automatic
gain control (AGC), can be quite useful for live recording and
PA applications.
Fig. 5
Expansion is simply the inverse equivalent of compression.
The algebraic addition of the two curves shown in Fig. 6 would
be linear.
Fig. 6