Universal Audio UAD Plug-Ins ver.7.5 - Manual (Page 475)

UAD Powered Plug-Ins Manual - 475 - Chapter 48: Teletronix LA-2A Leveler Collection
Historical Background
In the 1950s while at Parsons Electronics, Electrical Engineer Jim Lawrence
was quietly asked to join the Titan Missile Program based at Cal Tech's Jet
Propulsion Lab and was assigned to develop optical sensors for the program.
Fortunately for everyone, the technology developed from Lawrence's work
lead back to a more peaceful deployment of the optical sensor, as the detec-
tor in his future Leveling Amplifier. The interactions of the luminescent panel
with the photo resistors in his T4 design are predominantly what gives the
Teletronix Levelers their signature sound.
Lawrence later broke out on his own to start Teletronix, setting up shop in his
hometown of Pasadena, California in 1958. Among the Teletronix line of
products were transmitter tubes, multiplex generators, to full-scale radio trans-
mitters. Jim's first pass at his Leveling Amplifier was realized as the Teletronix
LA-1; Around 100 units were made. Lawrence then updated the design to the
LA-2 with improved specs and circuit layout, then moved quickly to the indus-
try standard LA-2A. In 1965, just three years after the incarnation of the LA-
2A, Jim Lawrence sold the company to Babcock Electronics. Enter Bill Putnam.
Putnam picked up Babcock's broadcast division including Teletronix, and
rolled it into his parent company, Studio Electronics in 1967. From there, Uni-
versal Audio resumed manufacturing of the LA-2A, and Putnam began using
the optical detector for new designs.
Whether serendipity or by intent, Jim Lawrence’s Teletronix Levelers and his
T4 design had the right musical response that allowed the LA-2A the sonic
and technological longevity it still retains. Universal Audio spent a long time
getting the T4 right for their hardware LA-2A reissue and the plug-in. But what
was special about it wasn’t fully understood until UA began the research to
model the LA-2A for the UAD-1. Modern photocells are designed to be as fast
as possible, but they don't have the right multi-stage response they need to
sound like a Teletronix design. Our DSP research helped us understand how
the original T4 worked at the quantum physics level. This not only allowed us
to develop an accurate DSP model of the gain reduction behavior, it also
helped us make our hardware T4 more consistent. This involved studying the
original photocell formula, working with both modern device physicists and
the people who developed the original photocells, locating the special equip-
ment originally used to manufacture these back in the '60s, and re-qualifying
the manufacturer. Whether hardware or DSP, it is this special qualified man-
ufacturing process and “recipe” UA re-established that gives the LA-2A its
unique, musical sonic quality to this day.