Wikipedia: dbx, Inc.
is an American producer of professional audio recording equipment. It
was founded by David E. Blackmer in 1971. The original company goal was:
"To get closer to the realism of a live performance." Its early products were based on the concept of using decibel expansion which gave the company its name. dbx is best known for the dbx noise reduction system.
The dbx noise reduction system used compression while recording an
audio track and symmetric expansion when playing it back. They also
manufactured the Model 700,
a unique but short-lived studio recording system, briefly popular in
some circles as a mastering format. Another early product was the
eXpanded range DeciBel meter, a little solid-state meter that measured
audio voltages both weaker and stronger than other bigger contemporary
voltmeters, built into an aluminum extrusion that was about the size of
the meter itself, which was an earlier source of the company initials.
The most important inventions of David Blackmer and dbx are the dbx voltage controlled amplifier or VCA and the dbx RMS
detector. The original dbx 202 VCA was based on the Blackmer gain cell
and was referred to as the dbx 202 "Black Can" VCA. They were built
using discrete transistors that were hand matched while running at an
elevated temperature in an oven. While noisy and having significant
distortion, they exceeded by far the performance of other VCAs of the
 These VCAs were used in most early automated mixing boards.