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Pulse Techniques EQP-1A

Analogue Passive Equaliser
Published February 2019
By Hugh Robjohns

Pulse Techniques EQP-1A

Is this, as the manufacturers claim, the most authentic recreation of the venerable PulTec EQP‑1A?

As a standard facility of most mixing consoles and DAWs, we all tend to take EQ for granted, even though there are many different types of equaliser with varying levels of sophistication and application. While the true origins of the first audio equaliser are shrouded in the mists of time, two names stand out for me as pioneers of audio equalisation: Peter Baxandall from the UK, and the American, Eugene Shenk. Baxandall was an electronics engineer (and friend of our esteemed Editor In Chief) who came up with a very elegant circuit for an active bass and treble equaliser. He published his design, royalty-free, in 1952 and it has subsequently been employed almost universally in mixing consoles and hi-fi amplifiers, bearing his name as the Baxandall equaliser or 'tone control'. Amazingly, at around the same time in America, Gene Shenk developed a passive design which has become the legendary studio equaliser — the PulTec EQP-1.

The PulTec name is an abbreviation of Pulse Techniques Inc, the full name of the company Shenk established with his business partner Ollie Summerlin at the start of the 1950s. Both Shenk and Summerlin (or Summerland, as many articles claim) were skilled electronics engineers, Shenk having spent 14 years working at RCA on radio telegraphy, while Summerlin had worked as an engineer for Capitol Records and later sold Ampex tape recorders, so brought a good knowledge of the flourishing recording studio industry.

Initially, PulTec made things like adjustable power supplies for valve equipment and audio oscillators, but one of Summerlin's former colleagues at Capitol had moved to MGM to build a mastering studio, and he commissioned PulTec to build a bespoke mastering...

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Published February 2019