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NIVIEM EQP-1

Name: NIVIEM EQP-1
Brand: NIVIEM
SKU: niviem-eqp1
Price: 35 USD
Availability: InStock

Classic Passive Program Equalizer

Hardware-faithful emulation of the 1961 Pultec EQP-1A Program Equalizer. Passive parallel LC shelves with the famous Pultec trick, ECC83 / ECC82 tube make-up amplifier with three transformers, swappable input valves, M/S routing, opt-in HPF / LPF helpers, Auto Gain, and a Hardware Accurate master mode.

$35

Save 30%Intro Price (30% Off)

Regular $50

Manual Quick Start

Version

1.0.0

Released

May 2026

Formats

VST3, Audio Units

Platforms

macOS, Windows

Features

What Makes It Special

Hardware-Faithful Pultec EQP-1A Emulation

Component-level recreation of the 1961 passive LC topology — every coefficient derived from the schematic. The LF parallel-shelves network folded into a single biquad whose pole-zero structure matches the analytical solution; the HF Boost as RBJ peaking with bandwidth-coupled Q; the HF Atten as a first-order shelf cut.

The Famous Pultec Trick

Parallel low boost + cut around the same dial frequency for tight, punchy bass — impossible on conventional EQs. The LF Boost shelf turns over at ≈6× dial; the LF Atten shelf at ≈13.5× dial. Engaging both lifts the band's centre and dips the mud just above — the canonical mix-bus engineering technique.

ECC83 / ECC82 Tube Make-Up Amplifier

Two-stage push-pull cascade. ECC83 input pair runs the Maillet six-term polynomial fit to a measured RCA 12AX7 plate-current curve. ECC82 output pair runs the Koren 1996 space-charge model fitted to the Philips datasheet (4.1% mean error). Three transformer cores deliver the warm character that defined sixty years of mastering EQ.

Swappable Input Valves

12AX7 (the original, µ=100), 5751 (µ=70, more headroom, cleaner), or 12AY7 (µ=45, vintage Fender voice, cleanest). Each option is a real DSP model with its own load-line solve and ADAA-1 antiderivative lookup — not cosmetic, the saturation character actually changes.

Modern Niviem Extensions

M/S routing with full per-side parameter divergence, opt-in 12 dB/oct Butterworth HPF + LPF helper filters, continuous-frequency CON mode on all three rotaries, A/B settings slots, smart Auto Gain with 64-point pink-weighted loudness scan for honest bypass A/B.

Hardware Accurate Master Mode

One-click switch that pins every Niviem extension back to its schematic-faithful value — purist 1961 EQP-1A signal path with no creative knobs in the way. Toggle off to unlock M/S, helpers, tube swaps, voltage, wear, transformer headroom, and CON mode.

Specifications

Inspired ByPultec EQP-1A Program Equalizer (1961) by Gene Shenk / Pulse Techniques

Low Frequency Stops20, 30, 60, 100 Hz + CON (continuous 20–100 Hz)

High Frequency Stops3, 4, 5, 8, 10, 12, 16 kHz + CON (continuous 3–16 kHz)

HF Atten Stops5, 10, 20 kHz + CON (continuous 5–20 kHz)

LF Boost / Atten0–13.5 dB / 0–17.5 dB (parallel shelves at ≈6× and ≈13.5× turnover)

HF Boost / Atten0–18 dB peaking + 0–16 dB high shelf cut (corner at dial÷7.5)

Make-Up AmplifierECC83 (12AX7 / 5751 / 12AY7 swap) → interstage → ECC82, global NF loop

TransformersInput + Interstage + Output cores, tanh-knee + ADAA-1 antiderivative

Helper FiltersHPF 20–800 Hz + LPF 1–20 kHz, 12 dB/oct Butterworth (opt-in)

RoutingSTEREO (linked pair) or M/S (per-side parameter divergence under LINK off)

OversamplingPolyphase halfband cascade, ~352 kHz internal, Kaiser β=12, ~120 dB stopband

Anti-AliasingADAA-1 antiderivative reads on every nonlinear stage

Factory Presets52 across 9 categories — Init, Vocal, Drum, Bass, Guitar, Mix Bus, M/S, Creative, Helper Filters

Nivipedia65-entry built-in encyclopedia, searchable, every control linked

Sample Rates44.1 kHz – 384 kHz

Highlights

Hardware-faithful component-level emulation of the 1961 Pultec EQP-1A
The famous Pultec trick — parallel low boost + cut for tight, punchy bass
ECC83 / ECC82 push-pull tube make-up amplifier with three transformers
Swappable input valves (12AX7 / 5751 / 12AY7) — each a real DSP model
Modern M/S routing with per-side parameter divergence
Opt-in HPF / LPF helper filters for surgical cleanup
Continuous-frequency CON mode on all three rotaries
Smart Auto Gain — honest bypass A/B without louder-equals-better illusion
Hardware Accurate master mode pins everything back to the 1961 schematic
Mains voltage, tube wear, transformer headroom — vintage-condition knobs
52 factory presets calibrated against the Auto Gain reference
65-entry Nivipedia built-in encyclopedia (controls + theory + history + workflow)

Under the Hood

LF parallel shelves folded into single biquad — pole/zero structure derived from LC topology

HF Boost as RBJ peaking with gain-coupled Q (mechanical loaded-Q preserved from LC tank)

Maillet six-term polynomial fit (RCA 12AX7) for ECC83 input pair, ~140 V / 1 mA operating point

Koren 1996 space-charge model for ECC82 output pair — Philips datasheet, 4.1% mean error

Newton load-line solve per-sample at bake, 2048-point LUT × 7 supply-sag curves

ADAA-1 antiderivative read on every valve + transformer block — band-limited by construction

Polyphase halfband FIR cascade (taps 127/61/25), Kaiser β=12, ~120 dB stopband attenuation

Per-band Hardware Accurate turnover ratios fitted from EQP-1A3 / DIYRE EQP5 cap-bank measurements

Global negative feedback loop wraps the two valve stages + interstage transformer

Click-free transitions throughout — 8 ms coefficient smoothers + 11 ms wet-path mute envelopes on topology flips