A pair of vintage Spectra Sonics Model 610 Complimiters in the Vintage King Tech Shop.

At the Vintage King Tech Shop, we're no strangers to rare and revered pieces of analog gear. But when a pair of vintage Spectra Sonics Model 610 Complimiters recently arrived for restoration, they had everyone in the shop talking. 

The Model 610's unique "Complimiter" design combines compression and limiting in one versatile, ultra-fast circuit. Unlike conventional compressors that can sound heavy-handed, the 610 offered a level of control and transparency that was revolutionary when it debuted in the late 1960s. 

Continue reading to learn more about what makes the Complimiter so special and check out some exclusive photos of these classic compressors.

A pair of vintage Spectra Sonics Model 610 Complimiters in the Vintage King Tech Shop.

The History of the Spectra Sonics and the Model 610 Complimiter

Although William G. Dilley had a history of designing advanced tube preamps, mixers, and power amps under the name "Custom Engineering by Dilley," he founded Spectra Sonics in 1964 to focus on discrete solid-state designs.

Originally, Spectra Sonics provided individual amplifier modules, card frames, power supplies, and equalizers for small manufacturers and in-house engineers who wanted to build custom consoles. In a few short years, some of the world’s biggest studios built custom consoles using Spectra Sonics components, including Muscle Shoals, Ardent, Stax, Atlantic Records Studio C, and the Record Plant.

The heart and soul of these desks was Spectra’s 101 preamp design, which can be heard on classic records by Led Zeppelin, Aerosmith, Elton John, and more. Many of these consoles also featured Spectra’s 601 limiter circuit, the fastest analog limiter ever made. This fixed-timing, fixed-threshold peak limiter has an attack time of less than 90 nanoseconds, offering unparalleled transparency both for the time and still to this day. 

In 1969, Spectra Sonics combined these two circuits to create the legendary Model 610 “Complimiter,” the first compressor/limiter that allowed compression and limiting circuits to be used together or separately. This dual functionality made the Complimiter a versatile tool for recording and mixing engineers, but it quickly became a staple for mastering engineers thanks to its fast, transparent response. 

When it first hit studios, engineers were amazed by its ability to deliver smooth, musical compression without the dreaded pumping effect that plagued other units of the era, even at extreme ratios up to 100:1. Not to mention its remarkably clean signal path. With noise and distortion specs that rival premium microphone preamps, the Complimiter delivers true audiophile-grade performance where most compressor-limiters fall short.

The Legendary Spectra Sonics Model 610 Complimiter Returns

In 2007, two former Spectra Sonics employees, Bill Cheney and Jim Romney, resurrected Spectra Sonics’ legendary designs under the name Spectra 1964, using the same designs and components as the original products.

In 2019, 50 years after the release of the original Complimiter, Spectra 1964 announced it would be reviving the legendary 610 Complimiter with two new models. The V610 is a faithful recreation of the original, while the new C610 includes updated features like higher bandwidth cinemag transformers, external power supply, selectable input padding, and more. 

A pair of vintage Spectra Sonics Model 610 Complimiters in the Vintage King Tech Shop.

A closeup of the input knob on a vintage Spectra Sonics Model 610 Complimiter.

A closeup of the output knob on a vintage Spectra Sonics Model 610 Complimiter.

A closeup of the serial numbers on the back of a pair of vintage Spectra Sonics Model 610 Complimiters.

A closeup of the inspection sticker on a vintage Spectra Sonics Model 610 Complimiter.

A pair of vintage Spectra Sonics Model 610 Complimiters in the Vintage King Tech Shop.

Frank VerschuurenIf you’re interested in purchasing any vintage or used gear for your studio, we're here to help! Contact a Vintage King Audio Consultant via email or by phone at 866.644.0160.