KH-EQ1

About the KH-EQ1

The KH-EQ1 is a semi-parametric equalizer that doesn't behave like the surgical, clinically clean EQs everyone already owns. It's a five-band, engineer-designed tool built to add colour, not just remove problems — five ear-selected frequency ranges, each with its own harmonic saturation, wrapped around a stepless Mid<->Stereo<->Side router. We built it with multi-platinum mix engineer Koen Heldens as the second release in his signature series, and the brief was simple: make an EQ that flatters a modern mix instead of fighting it.

What a semi-parametric EQ gives you here

Semi-parametric means each band has a sweepable frequency and a gain control, but no separate Q knob to fuss over — the bandwidth is voiced for you so you stay in musical territory. The KH-EQ1 spreads five symmetrical bands across 20Hz to 33kHz with ±18dB of gain each: the Low End and High End are shelving filters, the three middle bands are bells, and the ranges deliberately overlap so you're never stuck. Low End covers 20–250Hz for weight and sub. Low Mids run 100Hz–2.5kHz, the zone that turns muddy first. Mids sit at 250Hz–5kHz, where vocals and guitars live and center stage is won or lost. High Mids reach 1–15kHz for clarity, presence and de-essing. High End stretches 5–33kHz for air and sheen. Click the LED above any band for instant A/B, or hit Auto Listen to solo the frequency you're moving so you can place it by ear.

Per-band saturation and the M/S router

Here's where the KH-EQ1 stops being "just another EQ." Every band has its own Saturation dial that adds even- and odd-order harmonic distortion to that band's isolated signal — so you can drive presence into a dull high-mid without smearing the low end, or thicken a bass band while the top stays clean. It's the analog vibe of pushing a console strip, but surgically placed. Then the stepless Mode router morphs the whole processor from Mid through Stereo to Side. Cascade two instances (one full-mid, one full-side) for a full-blown M/S EQ, widen a mix by shaping only the sides, or tighten a bass by EQing the middle. A Dry/Wet control lets you parallel-blend the processed signal back in for gentler, mastering-grade moves.

Using the KH-EQ1 on vocals, bus and masters

On lead vocals, a lift through the Mids and High Mids with a touch of per-band saturation pulls the singer forward and adds presence that never turns brittle. On the mix bus, small moves in Stereo mode plus a hair of High End saturation add the "finished record" gloss. Mastering? Switch to Side, widen the top end, keep the low end mono-tight, and blend to taste with Dry/Wet. Each license ships with custom presets built by Koen himself, so you can start from his settings and make them yours. If you want the matching dynamics, pair it with the KH-COMP1, the compressor that opened the signature series.

KH-EQ1 Features

Semi-parametric 5-band EQ (20Hz–33kHz)

Five symmetrical, ear-selected bands — Low End, Low Mids, Mids, High Mids and High End — each with a sweepable frequency and ±18dB of gain. The overlapping ranges mean any move you need is always within reach, without a Q knob to babysit.

Per-band harmonic saturation

Every band carries its own Saturation dial that adds even- and odd-order harmonic distortion to that band's isolated signal. Drive presence into a high-mid or thickness into a low band while the rest of the spectrum stays clean — analog colour placed exactly where you want it.

Stepless Mid<->Stereo<->Side router

The Mode control morphs continuously from Mid through Stereo to Side, blending the decoded middle and sides against the original stereo image. Cascade two KH-EQ1s (full-mid + full-side) for a complete M/S EQ, add width, or tighten the low end.

Dry/Wet parallel blend

Blend the processed (wet) signal against the original (dry) for parallel EQ and saturation — ideal for subtle, mastering-grade moves where you want colour without heavy-handed shaping.

Input and output gain staging (±24dB)

Dedicated Input and Output controls, each with ±24dB of range, let you drive the EQ and saturation stage "hot," then correct the amplitude afterwards for clean, level-matched gain staging. A switchable VU meter reads either the input or the output.

Per-band bypass and Auto Listen A/B

Every band has its own on/off so you can audition one move in isolation, and the LED above each band gives instant A/B. Engage Auto Listen and the band you are adjusting solos itself so you can find the exact frequency by ear.

Custom Koen Heldens presets

Each license includes original presets built by Koen Heldens, giving you tested starting points drawn straight from his own hip-hop and pop mixing sessions.

SSE2-optimised code

DSP operations are pipelined on the SSE2 instruction set for high-performance operation, even under complex per-band processing.

HighDPI / Retina support

Crisp, high-pixel-density rendering on macOS and Windows for a sharp interface on modern displays.