Pultec EQP-1S3 Program Equalizer

Pultec EQP-1S3 Program Equalizer in its standard version is the most curve-rich tube Pultec in a 2U chassis. The line amp is identical to the EQP-1A3, while the passive section adds peak centres at 1 and 2 kHz, moves the low curves to 30, 40, 70 and 100 Hz, and introduces high-frequency shelf boost with 5 and 10 kHz corners. The originals carried a 6 kHz centre where the 16 kHz now sits, but demand for 16 kHz was clear enough that Pulse Techniques builds them with that centre today.

Shaping the top with two independent tools

The peak and shelf curves operate at once, which separates two jobs that always interfere inside a single filter. A shelf at 5 or 10 kHz tilts the whole top end and holds that level upward, so it suits adding air to a vocal or to an entire bus. The peak, with its bandwidth control, gets placed independently wherever presence is needed, at 3 or 5 kHz. On top of that sits shelf attenuation at 5, 10 or 20 kHz for pulling back excess without undoing what the shelf just added.

The 1-2 kHz band in half the rack height

The 1 and 2 kHz centres decide whether a vocal reads clearly and whether a guitar cuts through a backing track, and the 1A family cannot reach that band at all. The EQP-1S3 gives access to it in a 2U chassis, so a room does not have to choose between the full curve set and rack space. The low section keeps simultaneous boost and attenuation at the same frequency, with 13.5 dB of lift against 17.5 dB of cut, enough to sort out the bottom of kick and bass in one setting. All equalization stays passive, with level restored by a tube stage on 12AU7, 12AX7 and 6X4.

KEY FEATURES

• Passive equalization network with a tube line amp restoring level
• 2U chassis with brushed aluminium front panel
• The widest curve set in the tube Pultec line
• High-frequency shelf boost with 5 and 10 kHz corners
• Nine high-frequency peak centres, including 1 and 2 kHz
• Low curves at 30, 40, 70 and 100 Hz with simultaneous boost and cut
• 16 kHz centre in place of the original 6 kHz
• 600 Ohm input and output transformers

TECHNICAL SPECIFICATIONS

• Type: passive program equalizer with tube line amplifier
• 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 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)