DarkPultec

DarkPultec — Pultec EQP-1A Style Passive Program EQ

A schematic-accurate emulation of the legendary Pultec EQP-1A — the 1951 American passive program equalizer that defined an entire era of recording. Hand-built tube tone-shaping with the famous “boost AND cut at the same frequency” trick that gives Pultec its impossibly silky, anchor-the-mix character. The original mastering EQ.

Authentic Pultec topology:

• 12AX7 triode tube stage with authentic vintage bias point (0.2, more colored than the Tube-Tech 0.08)
• Dynamic bias shifting — program-dependent envelope (1 ms attack / 50 ms release) modulates bias depth (0.22), giving the Pultec its lively, “breathing” character
• HF pre-emphasis at 700 Hz — pushes more high frequencies into the saturation stage for that distinctive Pultec air and edge
• Authentic frequency interaction — boost and atten interact like the real passive LC network
• Up to 8× oversampling (Kaiser FIR)

Low Frequency Section:

• Low Boost (0–10 dB) — independent boost amount
• Low Atten (0–10 dB) — independent attenuation amount
• Low Freq selectable: 20 / 30 / 60 / 100 / 150 / 300 Hz
• The famous Pultec trick: boost AND cut at the same frequency simultaneously — the harmonic interaction creates the unmistakable Pultec “thump and air” curve

High Frequency Section:

• High Boost (0–10 dB) — independent boost amount
• High Atten (0–10 dB) — independent attenuation amount
• High Boost Freq: 3K / 4K / 5K / 8K / 10K / 12K / 16K / 20K / 24K
• High Atten Freq: 5K / 10K / 20K
• Bandwidth (0–10, Sharp ↔ Broad) — Q control for the high boost band

Global controls:

• Tube Drive (0–1) — push the 12AX7 stage for that classic Pultec saturation and harmonic content
• Output (-12 to +12 dB) post-EQ trim
• Oversampling (1× / 2× / 4× / 8×)
• Bypass