The development of the Duplex traces its roots to Jim Lansing's
involvement in the Shearer Horn project of 1934. That system set
the standard for wide-bandwidth, accurate, sound reproduction.
After its introduction, Jim Lansing began a decade long quest to
bring the same level of sound quality to monitoring
applications. His first attempt was in 1936 when Lansing
Manufacturing introduced a scaled down version of the Shearer
Horn known as the Monitor System 500A. He followed that up in
1937 with an even more compact system called the Iconic It
retained the multicultural horn of previous designs but used a
smaller, ported bass section. It became the standard of its day
for monitor quality, but even its relatively small size was
inappropriate for many control rooms. The solution to high
quality sound in a compact package lay in a coaxial speaker
driver. The idea of a coaxial system for monitoring was
suggested by an Altec Lansing dealer named Art Crawford. James
Lansing immediately picked up on his suggestion as