The "One Knob Squeezer"
There were two primary goals in designing the "One Knob Squeezer" circuit. The first was, obviously,
that it sound good in those applications where compressors are usually employed. The second was
that it provide an interface simple enough for even a novice user to tune. A third (implicit) goal was
that the circuit be inexpensive and practical.
The first goal was achieved by careful listening and tweaking of the circuit. The third was by achieved by
using a single-chip dynamics processor, the THAT 4301 Analog Engine , and being diligent about
minimizing the parts count.
Tuning simplicity was achieved by an innovative design wherein threshold, compression ratio, and
makeup gain were implemented with a single adjustment by taking advantage of the soft-knee
threshold's signal-dependent compression ratio characteristic. As was discussed previously, any
compression ratio from 1:1 to near :1 is readily achievable with the soft-knee threshold circuit. The
compression ratio that will result at any given input level is dependent on the threshold setting, and as
such, the compression ratio adjustment can be omitted. To account for the changing output signal
level, a variation of the complementary gain and threshold sidechain was designed. After auditioning a
number of variations, the best approach was found to be a make-up gain adjustment that complied with
the soft-knee curve.