The Pultec EQP-1A is a passive equaliser considered by many engineers to the holy grail of EQ processors. Though light on features, sporting only two bands of EQ, it is an incredibly powerful tool and unsurpassed in the way it adds weight and sheen to a source.
The EQP-1A is one of the most sought after audio processors ever made. Introduced in 1956, it was the flagship product of Pulse Techniques (shortened to Pultec), what was then a garage operation between two electrical engineers. Pultec would go on to leave a profound legacy of standard and design, though in its thirty years in business, never exceeded a three-man team. Despite six decades of technological advances since its first release, many believe that the original EQP-1A design remains the benchmark for equalisation.
The EQP-1A is said to be something of a perfect storm of design. Its wide EQ curves, the particular frequency selection points, its tube-based output amplifier and transformers work in harmony to create a beautifully-sounding tool. As is characteristic of passive EQ designs, it is a broad strokes tone-shaping device rather than a surgical or corrective tool. The EQP-1A is capable of applying large gain boosts without sounding artificial and harsh, making it a stand-out for adding large amounts of air to vocals or huge bottom end to low-frequency sources. Although the original manual specifically advises against this, engineers found that utilising both the boost and attenuation controls over the low band simultaneously yields a particular EQ shape with a resonance peak that creates a powerful yet controlled bottom end, which is ideal for kick drums. The high-band can also be used in a similar way, bringing down the low-pass filter while boosting the high peak with a bandwidth wide enough to extend above the filter cut-off point. This can result in pulling back some harshness while restoring sheen and air.
In 2011, Pultec started offering once again a reissue of the EQP-1A, amongst with other units, following over a decade of meticulous collaboration with the original designers. These modern units are not enhanced to leverage any modern technology, instead being faithful recreations equal to the original design.
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