Origins of the Teletronix LA-3A

How a 1960’s “secret weapon” audio compressor bridged the gap between tube and solid‑state sound.

Designed by Brad Plunkett, inventor of the wah wah pedal and long-time associate of UA founder Bill Putnam Sr., the Teletronix^® LA-3A Audio Leveler combined vintage opto-style compression with quickness, clarity, and punch thanks to its solid-state design.

Here, we uncover the origins of this studio workhorse and reveal how it differs from its iconic predecessors — the Teletronix LA-2A and UA 1176 compressors.

Modeled from a unit in UA’s vintage collection, the Teletronix LA‑3A Audio Leveler plug-in gives you all the tone, attitude, and quickness of the rare hardware.

The Birth of Optical Compression

The Teletronix® LA-2A Leveling Amplifier revolutionized audio recording upon its release in 1958. Widely considered the greatest vocal compressor ever made, it remains a go-to by pro engineers and producers, and can be found in recording studios around the world.

The LA-2A is often referred to as the "big brother" of the LA-3A — as both units use a T4 electro-optical cell to control gain reduction.

“The LA-3A is essentially a solid-state version of the tube-driven LA-2A,” explains Will Shanks, UA Product Designer. “It has the same basic controls — Gain, Peak Reduction, and a Comp/Limit switch. But most importantly, they both use a T4 ELOP, the component responsible for converting an audio signal into an optical signal. This offers a smooth, natural compression sound."

But the LA-3A’s controls and shared electro-optical element are where its similarities with the LA-2A end, says Shanks: “Even though they both use that T4 cell, the LA-3A has a much faster attack.”

For over 50 years the Teletronix LA-2A has been revered for its smooth, natural, musical compression.

Getting Faster Compression with FETs

As audio recording technology advanced into the late 1960’s, UA founder Bill Putnam Sr.’s desire to create a modern compressor with “exceptionally fast attack” was realized with the UA 1176 Limiting Amplifier.

The 1176 was a departure from the LA-2A and other optical tube designs that came before it. With its quickness and immense flexibility, it remains a ubiquitous tool in pro studios. And its distinct sonic fingerprint, owing to its solid-state design, can be found throughout the LA-3A.

“The 1176 was the result of many years of research and development. It was the first true peak limiter with all-transistor circuitry and fast FET (field effect transistor) gain reduction.” - Bill Putnam Sr.

Teletronix LA-3A: The Best of Both Worlds

Released in 1969, the LA-3A borrowed from design concepts used on the 1176. Sharing many of the same components, both compressors ultimately deliver the same quick attack and musical compression.

“The LA-3A is fast and bright,” says Shanks. “It opened up uses that vintage levelers like the LA-2A were not as well-suited for — cymbals and room mics, as well as close mic’d snares, kicks, and toms.”

Along with drums and percussion, many producers enjoy the LA-3A’s midrange character, making it useful on acoustic or electric guitars and bass.

“The Teletronix LA-3A gives you smooth, optical compression, but with the aggression of a transistor circuit.”

—Joe Chiccarelli (The Strokes, Morrissey)

The LA-3A features a simple control panel, making it easy to find a sound quickly. And the Teletronix^®LA‑3A UAD plug-in offers added versatility — with a HF sidechain filter for use with low-frequency sources, as well as a Dry/Wet Mix control for easy parallel compression.

A unique hybrid between its tube and solid-state predecessors, the LA-3A has stood the test of time for more than 50 years. This “secret weapon" audio compressor is sure to lend punch and presence to recordings for many years to come.

Want to try the Teletronix LA-3A UAD plug-in? You can demo it for free, along with dozens more at the links below!

— McCoy Tyler

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