Analog Obsession
ITI, Sontec, and the History of Parametric EQ
by Will Shanks

If Pultec wrote the book on how to make a great sounding EQ, Sontec penned a stellar sequel. Developed from technology developed by Burgess MacNeal and George Massenburg, the Sontec EQ was among the first parametric EQs and remains a beloved staple in many studios, particularly mastering studios throughout the world for its musicality, ease of use, and remarkable features.

The revered Sontec Mastering EQ
Sweep-Tunable EQ
Parametric EQ was birthed from Burgess MacNeal and George Massenburg's original idea for an EQ that would avoid inductors and switches, which were expensive and often unreliable at the time. While at ITI, MacNeal and Massenburg developed the workings of what would soon set the standard for EQs from mixers to mastering. The parametric, or "Sweep-Tunable", EQ's major advancement was the implementation of a bandwidth control.

ITI was to launch into the console market, and the technology for the parametric was to be implemented as part of ITI's flagship mixer. 1968 through 1970 was the major development thrust. The final result featured three bands of fully parametric EQ, with a 10kHz high shelf and a selectable 50Hz/100Hz low shelf. This first EQ had no fixed stops, making it practical only for tracking and mixing. But as word spread of the new technology, ITI and the audio community soon realized the potential for the mastering market; the seed was planted for what would become the Sontec. The mixer never went beyond prototype, but the MEP-130 EQ was sold as a console module and was repackaged and released as a stand-alone rack mount product in 1971, thus making the MEP-130 module and MEP-230 outboard unit the first commercially available parametric EQs. Massenburg presented his paper on the parametric EQ at the 42nd AES convention in 1972; it was never patented.

In 1971 the first mastering unit was built for in-house use (ITI also had a recording studio and vinyl pressing plant). Positive detented switches were incorporated to add repeatability. The unit featured three paramedic bands per channel as well as high and low cut filters. All control characteristics were based on the experience of ITI cutting engineers and never changed. It was then decided to make the mastering EQ commercially available. The product was the MES-430. These early units were sold through Gotham Audio and bear the reseller's logo on the faceplate.

Launch of Sontec
Financial difficulty befell ITI in 1975, and its assets were auctioned off. Fortunately MacNeal was able to purchase the original drawings and some original parts. Production was re-established under the Sontec name and the MES-430 continued on to establish itself as the most popular mastering EQ ever produced. Different models gradually appeared with added features tailored for specific uses, but wavering only slightly from the circuit architecture derived from the original designs.

The most amazing feature of the original parametric EQ is musicality. Unlike many parametric EQs, which can have as much negative as positive effect on your audio, the parametric EQs made by ITI and Sontec are hard to get a bad sound out of.

As the Sontec was made specifically for mastering, it has some features that were designed with disk cutting in mind. The MES-430 can conveniently equalize program and preview material simultaneously as it is "dual stereo". Moving one knob moves the preview channel as well as the master channel for the cutting lathe. Also, the EQ bypass can be linked to the cutting system. Additionally, two units can be cascaded and automatically switched, allowing the ability to jump back and forth between set ups for the various tunes on a record side; a breakthrough feature, considering the lathe was unable to stop for making changes.

In addition to the Sontec EQs produced by Burgess MacNeal, George Massenburg has his own EQs under his GML brand: one for tracking and mixing called the 8200, and one specifically for mastering called the 9500. These units also adhere closely to the original parametric and are highly respected. Another fantastic mastering EQ called the Maselec MEA-2 is produced by Prism Sound. The Maselec was collaboratively designed with audio engineer and producer Leif Mases, hence the name. For the most part, all of these EQs and many others adhere to a similar design-the same layout that was thoughtfully created for the first parametric EQ. Why not? Good design tends to last!

Special thanks to Ron Kramer,
Bob Ludwig and Don Grossinger

Ron Kramer of Sontec can be contacted at:
P.O. Box 1583
Nokomis, FL. 34274

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