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Pultec EQP-1
Pultec
The Pultec EQP-1 is a passive, tube-amplified equalizer introduced in 1956 in a 3U 19-inch rack chassis, designed specifically for professional recording studios to overcome noise issues in existing film-industry equalizers. It features a low-frequency shelving filter with three bands (30, 60, 100 Hz) and a parametric high-frequency section with boost frequencies at 3, 5, 8, 10, and 12 kHz plus adjustable bandwidth. Its design enabled simultaneous boost and attenuation of adjacent low frequencies — a technique later adopted despite being discouraged in the original manual.