Pultec EQM-1S Mastering Equalizer

Pultec EQM-1S Mastering Equalizer is the mastering version of the EQP-1S in a 3U chassis, fitted with stepped ELMA switches on a full-range progressive taper. Beyond the controls, Pulse Techniques made one change to the curves themselves: the 6 kHz peak centre gives way to the 16 kHz centre familiar from the 1A family. The result is the only Pultec that combines a 16 kHz air band with full 5 and 10 kHz shelf boost in one chassis.

Air and shelf without choosing between them

The 1A family has the 16 kHz peak but no high-frequency shelf boost. The 1S family has the 5 and 10 kHz shelf but originally carried a 6 kHz centre where the 16 kHz would be. For mastering that forced a choice between two ways of opening the top: a gentle tilt across the whole band, or air added above the material. The EQM-1S has both on the same panel, and both sections work at once, so you can raise the shelf by half a decibel across the top and add 16 kHz separately wherever the mix reads dark.

Half a decibel you can repeat in both channels

The switches give 0.5 dB per step through the first half of rotation, with step size growing beyond 50%, so the full 16-20 dB range stays available for more aggressive track work. In mastering, though, what counts most is that a setting is a number: you can write it down, return to it after checking a reference, and dial it identically into the second unit of a pair. With nine peak centres, two shelf corners and a separate attenuator, the number of combinations is large enough that working on potentiometers without documentation stops being repeatable after the first day.

KEY FEATURES

• Mastering version of the EQP-1S in a 3U chassis
• 16 kHz peak centre in place of the original 6 kHz
• 5 and 10 kHz high shelf boost available alongside the 16 kHz peak
• 21-position ELMA switches instead of potentiometers, 11-position bandwidth switch
• Full-range progressive taper: 0.5 dB per step across the 0-5 dB range
• Nine high-frequency peak centres, including 1 and 2 kHz
• Low curves at 30, 40, 70 and 100 Hz with simultaneous boost and cut
• Repeatable settings and unit-to-unit matching for stereo work

TECHNICAL SPECIFICATIONS

• Type: passive program equalizer with tube line amplifier, stepped controls
• Low shelf boost: 30, 40, 70, 100 Hz, 0-13.5 dB
• Low shelf attenuation: 30, 40, 70, 100 Hz, 0-17.5 dB
• High peak boost: 1, 2, 3, 4, 5, 8, 10, 12, 16 kHz, 0-18 dB
• High shelf boost: 5, 10 kHz, 0-14.5 dB
• High shelf attenuation: 5, 10, 20 kHz, 0-16 dB
• Controls: 21-position switches, 11-position bandwidth switch
• Input impedance: approx. 600 Ohms, output 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: 3U (5.25 inches)