Pultec EQP-1A3 Program Equalizer

Pultec EQP-1A3 Program Equalizer in its standard version is a tube passive equalizer in a 2U chassis with a brushed aluminium front panel. In 1971 Gene Shenk and Ollie Summerlin rearranged the controls and components of the 3U model to fit a chassis a third shorter without altering the circuit. The original brochures said it outright: same parts, same specs. This was the first model Pulse Techniques put back into production.

Eight channels of Pultec where six used to fit

The difference between 3U and 2U stops being cosmetic the moment you count rack space. A room that wants passive equalization on every bus channel fits a third more units into the same rack at 3.5 inches of height. That matters for stereo work, where every band needs a matched pair, and it matters when the equalizer lives permanently in one bus insert. The circuit and the 12AU7, 12AX7 and 6X4 tube complement are identical to the EQP-1A, so the choice comes down to space and which panel you prefer looking at.

Curves that do not fight each other

The low section boosts and attenuates at the same frequency, and most of what this equalizer is used for rests on that behaviour. Up to 13.5 dB of boost at 60 or 100 Hz against up to 17.5 dB of cut leaves a bottom end with mass and a visibly cleared band above it, which tidies kick and bass without reaching for a high-pass filter. The high section works independently: seven peak centres from 3 to 16 kHz with a bandwidth control, plus a separate shelf attenuator at 5, 10 or 20 kHz. You can lift presence at 5 kHz and pull excess air above 10 kHz in the same pass.

KEY FEATURES

• Passive equalization network with a tube line amp restoring level
• 2U chassis with brushed aluminium front panel
• Same components and specifications as the 3U EQP-1A
• Simultaneous low-frequency boost and attenuation at the same frequency
• Four low-frequency centres: 20, 30, 60 and 100 Hz
• Seven high-frequency peak centres from 3 to 16 kHz with bandwidth control
• High shelf attenuation at 5, 10 and 20 kHz
• 600 Ohm input and output transformers

TECHNICAL SPECIFICATIONS

• Type: passive program equalizer with tube line amplifier
• Low shelf boost: 20, 30, 60, 100 Hz, 0-13.5 dB
• Low shelf attenuation: 20, 30, 60, 100 Hz, 0-17.5 dB
• High peak boost: 3, 4, 5, 8, 10, 12, 16 kHz, 0-18 dB
• High shelf attenuation: 5, 10, 20 kHz, 0-16 dB
• Input impedance: approx. 600 Ohms
• Output impedance: approx. 50 Ohms
• Noise: 92 dB below +10 dBm
• Distortion: 0.15% max at +10 dBm into 600 Ohms
• Amplifier response: 20 Hz to 20 kHz, +/- 0.5 dB
• Tubes: 12AU7, 12AX7, 6X4 (one each)
• Height: 2U (3.5 inches)