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Advanced compression techniques—history and application: a thread
*The text that follows is excerpted from my forthcoming book “Audio Dynamics” (releasing worldwide Oct. 8, 2021)*
Compression and painting have one major similarity: applying everything all at once produces a gloppy mess while applying one layer after another yield superior results. One of the secrets to achieve perfect-sounding compression is applying the process several times.
Adding compression in small increments at various stages of the production process can produce a wondrous result. For example: applying a minimal amount of compression during recording; adding more compression on the channel during mixdown; then more compression on final mix.
The serial compression process can be enhanced by choosing different parameters. Different ratios, attacks and releases can be used for the separate layer. This approach ensures that gain reduction does not impact heavily on a single position all at once, or over and over.
Parallel compression—also known as “Exciter compression” or “New York compression”—is an advanced compression technique used in audio recording and mixing.
This process reduces the dynamic range of the signal by raising the softest sounds instead of doing it by reducing the extreme peaks. Parallel compression is commonly used on individual tracks (e.g., vocals, drums), group and stereo mix buses, in mastering, and live sound mixing.
Before 1960, records were usually mixed with vocals that were significantly louder than the backing tracks. The backing track was reinforced by reverb to make it blend with the dry vocal. Popular recordings from Frank Sinatra and Nat King Cole are prime examples.
In 1960, Berry Gordy Jr. founded the Motown record label in Detroit, whose in-house audio engineers would adopt a revolutionary approach to traditional mixing.
Gordy founded the Hitsville USA recording studio on West Grand Street in Detroit, Michigan, and outfitted the recording studio with cutting-edge recording technology. Hitsville upgraded to a 3-track recorder by 1961 before moving to 8-track by 1966.
By then, Motown’s head of engineering Michael McLean had already innovated the “Motown EQ” (a lush 2-band equalizer) as well as the “Motown direct box” (the first DI for studio use). Through these innovations, the output of Hitsville was already becoming more distinctive.
The volume of the rhythm section (drums and bass) became louder over the course of the 1960s, resulting in a sound that audiences found to be more appealing and danceable.
“Exciter compression”, pioneered by Motown in the early 1970s, was the first parallel compression technique used in popular music. McLean got the idea from engineers at classical music label Deutsche Grammophon, which was then adapted by Motown’s Lawrence Horn.
Horn used his analog console to split a lead vocal into two channels. Next, Horn added reverberation and equalization to the first channel. He then compressed the second channel and added high-shelf EQ at 5 kHz. This process produced two separate channels with lead vocals.
The first vocal channel had EQ and reverberation while the other was heavily compressed with more highs. Horn combined the original channel with the second one, the final result being a natural-sounding vocal that was clearer and brighter, hence more “exciting” to listeners.
(Thanks for reading the excerpts—I'll post more as we get closer to the official book release date in October)
