Compressors – The Unsung Heroes of the Recording Revolution

The Compressor: Transforming Audio History

Imagine the early days of radio, where the dynamic range of voices and instruments often exceeded the limits of the technology, resulting in distorted peaks and inaudible lows. Enter the compressor—a revolutionary device that not only solved these issues but also paved the way for new creative possibilities in music production. Let’s delve into the fascinating journey of compressors, from their groundbreaking role in early broadcasting to their indispensable presence in today’s recording studios. Discover how this essential tool has shaped the sound of iconic albums and continues to innovate the audio landscape.

The Birth of a Necessity

In the early days of radio broadcasting, engineers faced a daunting challenge: the dynamic range of the human voice and musical instruments was simply too vast for the primitive technology of the time to handle. Peaks would overload the system, causing distortion and clipping, while quieter passages would be lost in the ether, buried beneath the ever-present hiss and crackle of the airwaves.

It was a problem that threatened to undermine the very essence of audio transmission, rendering the fledgling medium little more than a cacophony of noise and distortion. But necessity, as they say, is the mother of invention, and it was this very need that gave birth to one of the most groundbreaking devices in audio history.

The Western Electric 110 Limiting Amplifier

Introduced in 1937, this vacuum tube-powered marvel was the first of its kind, a device capable of automatically attenuating the gain of an audio signal when it exceeded a predetermined threshold. By taming the wild dynamics of the audio signal, the 110 prevented overmodulation and ensured a more consistent, intelligible transmission.

While crude by today’s standards, the 110 was a revelation, a beacon of hope in a world where audio fidelity was often sacrificed on the altar of technological limitations. It was the first step on a journey that would lead to the creation of the modern compressor, a tool that would forever change the way we experience and create sound.

Western Electric 110A Compressor

From Radio to Recording: The Evolution of The Compressor

As radio technology continued to evolve through the 1940s and 1950s, so did the compressors used to manage audio signals. Engineers soon recognized the potential for these devices beyond broadcasting, seeing their value in the burgeoning field of audio recording. The ability to control dynamic range became essential not only for radio but also for capturing performances in a studio environment.

The Universal Audio 175B and 176

The Universal Audio 175B and 176, introduced in the late 1950s, were among the first compressors explicitly designed for studio recording and mixing. These early workhorses, designed by Bill Putnam, Sr., were primarily used for controlling the dynamic range of vocals and instruments, preventing overloads and allowing for a more consistent overall level. The 175B was particularly notable for its variable-mu tube design, which provided smooth and musical compression, making it a favorite among engineers for its ability to add warmth and character to recordings.

The 176, an evolution of the 175B, offered additional features such as variable attack and release times, which gave engineers even more control over the compression characteristics. This made the 176 highly versatile and suitable for a wide range of applications, from subtle leveling to more aggressive dynamic control. Both the 175B and 176 compressors were integral to the sound of many classic recordings of the era, cementing Universal Audio’s reputation as a leader in audio innovation.

These compressors were not only pivotal in professional studios but also influenced the design and functionality of future compressor models. Their legacy continues as they remain highly sought after in the vintage audio equipment market, and modern recreations of these units are still used in studios today for their distinctive sonic qualities.

The legacy of the Universal Audio 175B and 176 lives on through the UAD 175B & 176 Tube Compressor Collection, which offers authentic plugin emulations of these classic compressors, providing modern engineers with the same warmth and musical compression as the original hardware.

universal audio 175b compressor

The Holy Grail – Fairchild 660 and 670

The introduction of the Fairchild 660 (mono) and 670 (stereo) compressors in the late 1950s marked a significant leap forward. These tube-based units offered variable attack and release times, providing engineers with more control over the compression process. Their distinct sonic qualities were partly due to the use of up to 20 vacuum tubes and four massive transformers in the circuitry, which contributed to their unique, smooth, and musical compression.

The Fairchild compressors quickly became studio staples, revered for their ability to add warmth and character to recordings while maintaining a balanced dynamic range. According to Wikipedia, the first Fairchild compressor was purchased by Rudy Van Gelder, who utilized it to cut lacquer masters for Blue Note Records and Vox Records. The second unit was installed at Olmsted Sound Studios in New York City, while the third unit was bought by Mary Ford and Les Paul. Not a bad start!

The Fairchild is still widely coveted today and has been modeled in many clones and plugins. There is even a new reissue that faithfully recreates the tone and vibe of the original, under the Fairchild brand name.

Fairchild-670 Compressor

The Altec 436B

The Altec 436B also emerged during this period and became a prominent tool in the recording industry. Introduced in the late 1950s, the Altec 436B was a tube-based compressor that gained popularity for its unique sound and reliable performance. It featured a straightforward design with fixed attack and release times, making it user-friendly for engineers. The 436B was widely used in both broadcast and recording studios, and its distinctive compression characteristics contributed to the sound of many classic recordings. The Altec 436C, an improved version released in the 1960s, offered adjustable threshold and release times, providing greater control and flexibility for audio engineers. The legacy of the Altec 436 series continues, as these compressors remain sought-after pieces.

Altec 436C

The Golden Age of The Studio Compressor

As the recording industry blossomed in the post-war era, so too did the demand for more sophisticated compression tools. Engineers, ever the alchemists of sound, began experimenting with different compression techniques, using multiple compressors in series or parallel to achieve unique tonal characteristics and creative effects. It was during this golden age that some of the most revered compressor designs were born, each with its own distinct personality and sonic signature.

Studio Staple – The LA-2A

The LA-2A, with its distinctive gray “suitcase” styling and electro-optical attenuator, quickly became a studio staple, renowned for its ability to impart a warm, musical compression that seemed to caress the audio signal rather than simply squashing it. Its gentle, almost transparent compression made it a favorite for vocals, adding a silky smoothness that would become a hallmark of countless hit records.

LA2A-Leveling-Amplifier / Compressor

The Iconic 1176

Among the giants of compressor design, the Universal Audio 1176 stands tall. Introduced in 1967, the 1176 was the first true peak limiter with all-transistor circuitry, delivering ultra-fast attack times and a wide range of tonal possibilities. Its distinctive FET (Field Effect Transistor) design allowed engineers to achieve aggressive, punchy compression that could bring out the character in any instrument or vocal track. The 1176’s versatility and signature sound have made it a studio staple, used on countless classic recordings.


Glue! The SSL Master Buss Compressor

Another legendary compressor that emerged from this golden era is the SSL (Solid State Logic) Master Buss Compressor. Known for its ability to “glue” a mix together, the SSL compressor became famous for its use on the master bus in mixing and mastering applications. Introduced as part of the SSL 4000 console series in the late 1970s, it provided a smooth, cohesive compression that enhanced the overall sound of a mix, making it a go-to tool for many top engineers and producers.


These compressors were more than mere tools; they were instruments in their own right, capable of imparting a unique character and warmth to the recordings they graced. Engineers quickly discovered that by pushing these devices to their limits, they could achieve a range of creative effects, from the gentle caress of subtle compression to the aggressive pumping and breathing that would become a hallmark of many iconic recordings.

Classic Examples of Compression

Geoff Emerick and the Revolver Sessions

One of the most innovative uses of compression came from Geoff Emerick during the recording sessions for The Beatles’ Revolver. As the chief engineer, Emerick employed radical techniques, using heavy compression on Ringo Starr’s drums and Paul McCartney’s bass to create unprecedented punch and clarity. This approach not only defined the album’s groundbreaking sound but also set new standards for creative compression in music production.

Joe Meek and “Telstar”

Another pioneer in the use of compression was Joe Meek, a legendary British producer known for his experimental techniques. His work on The Tornados’ 1962 hit “Telstar” showcased innovative use of compression to achieve a distinctive, futuristic sound. Meek’s aggressive compression settings on the drums and keyboards gave the track a punchy, compressed feel that was ahead of its time.

Bruce Swedien and “Thriller”

Bruce Swedien’s work on Michael Jackson’s Thriller album is another landmark in the history of compression. Swedien utilized compression creatively to achieve a tight, polished sound that became the hallmark of Jackson’s music. Notably, Swedien used compression on Jackson’s vocals and rhythm sections to create a powerful, driving sound that helped propel the album to legendary status.

Bonham’s Drums!

One of my favorite examples is the legendary drum sound on Led Zeppelin’s “When the Levee Breaks.” By running John Bonham’s thunderous kick drum through a heavily compressed signal chain, engineer Andy Johns was able to capture a sound that was massive and punchy, with a sense of weight and presence that seemed to defy the laws of physics.

Freddie’s Vocals!

We are all familiar with the incredible vocal performance of Freddie Mercury on Queen’s “Bohemian Rhapsody.” By carefully layering multiple compressed and uncompressed vocal takes, producer Roy Thomas Baker and engineer Gary Lyons were able to create a vocal sound that was both intimate and larger-than-life, a tour de force of dynamic control and sonic sculpting.

These are only a few examples of the countless ways in which compression has been used to shape the sound of some of the most iconic recordings in history, a testament to the power and versatility of the compressor.

The Digital Compressor Revolution

As the 20th century drew to a close, the world of audio engineering was forever transformed by the advent of digital audio workstations (DAWs). Suddenly, the power of compression was no longer confined to the realm of hardware; it had been unleashed into the digital domain, accessible to a new generation of engineers and producers.

Software developers wasted no time in incorporating compression plugins into their DAW offerings, democratizing these powerful tools and making them available to a wider range of creators. What had once been the exclusive domain of professional studios could now be harnessed by anyone with a computer and a passion for audio.

But the digital revolution did more than just make compression accessible; it also ushered in a new era of innovation and experimentation. One of the most significant advancements in compression technology during this period was the introduction of multiband compression. This technique allowed engineers to apply different compression settings to different frequency bands, providing unprecedented control over the tonal balance and dynamics of a mix.

Suddenly, the once-monolithic compressor had been transformed into a surgical instrument, capable of precisely sculpting the sonic landscape with a level of precision that would have been unimaginable just a few decades earlier. Want to tame the boomy low-end of a kick drum while preserving the attack? No problem. Need to add some punch and presence to a vocal without squashing the delicate high frequencies? Multiband compression has you covered.

Fab Filter

The Art of Compression – Sculpting Sound, Shaping Emotion

Today, compression remains an essential tool in the audio engineer’s arsenal, with a vast array of hardware and software options available to suit every need and creative vision. While traditional compressor designs like the LA-2A and 1176 are still widely used and revered for their unique sonic characteristics, modern compressors offer an unprecedented level of flexibility and control.

Techniques like parallel compression, where an uncompressed and compressed signal are blended together, have become a staple in the pursuit of a punchy, dynamic sound that still maintains overall loudness. By carefully balancing the two signals, engineers can achieve a sense of impact and presence that would be impossible to achieve through traditional compression alone.

And advanced techniques like sidechain compression, where the compressor’s gain reduction is triggered by an external audio source, have opened up new realms of creative possibility in music production and sound design. Want to create a pumping, rhythmic effect that follows the kick drum? Sidechain compression is your friend. Need to carve out space in a dense mix for a vocal or lead instrument? Sidechain compression can help you achieve that, too.

But perhaps the most remarkable aspect of compression is its ability to transcend its original purpose of level control and become a true artistic medium. In the hands of a skilled engineer or producer, a compressor can breathe life into a recording, imbuing it with a sense of energy, emotion, and character that would be impossible to achieve through any other means.

From the gentle caress of a vocal performance to the relentless pumping of a pulsating bassline, compression has the power to shape the very essence of a recording, transforming it from a mere collection of sounds into a living, breathing entity that resonates with the listener on a visceral level.

As the demand for louder and more consistent audio levels continues to grow, compressors will undoubtedly remain a crucial component in the audio signal chain. But their role has evolved far beyond mere level control; they have become instruments in their own right, capable of sculpting the very fabric of sound and elevating the art of audio engineering to new heights of expression and creativity.

In the ever-evolving landscape of music and audio production, the compressor stands as a testament to the power of innovation, a reminder that even the most humble of tools can profoundly impact the way we experience and create sound. And as we look to the future, one thing is certain: the legacy of these unsung heroes will continue to reverberate through the annals of audio history, shaping the sonic tapestry of recorded music.

Dennis Martin

Dennis Martin is a music producer, manager, composer and founder of Trend & Chaos. Follow him on Instagram & Twitter.