Three-Body Tech Kirchhoff EQ

Kirchhoff-EQ is a 32-band parametric EQ plugin built for all critical professional applications.

It has refined sound quality, analog-matched curves, 11 filter types with continuously variable shape, and 30 vintage EQ types modeled from real-world devices.

The built-in dynamic processing functions are highly flexible and have ultra-low distortion. All these push Kirchhoff-EQ to a next-generation standard.

Robust Nyquist-matched Transform

Through originally developed "Robust Nyquist-matched Transform", Kirchhoff-EQ has made digital-domain frequency response more approximate to its analog counterparts without high-frequency cramping as in regular IIR(infinite impulse response) equalizers. This technique is applied to all filter types in Kirchhoff-EQ.

High-Precision Processing

64-bits is mandatory and it's not negotiable. The internal processing of Kirchhoff-EQ is always in 64-bits (or 117-bits), regardless of the host DAW's current working precision.

Psychoacoustic Adaptive Filter Topologies

All linear filter structures should have same sound on paper. However in a real-world application, round-off errors make every filter structure sound differently: some better in low frequency, some better in high frequency.

A technology called "Psychoacoustic Adaptive Filter Topologies" has been deployed in Kirchhoff-EQ. Filter structures change themselves to a "best fitting" state along with corresponding band frequency changes, making optimized sound quality in both low and high frequency.

Switchable Ultra-High 117-bits Processing

Since there are already 64-bits, why not go further? Kirchhoff-EQ uses a technique called "Double-Double" to make precision of internal processing reach 117 bits!

This is the first equalizer in the world to reach such precision. You can switch between 64-bits and 117-bits at any time. It satisfies the most demanding ears.

*Linear-phase mode always uses 64-bits as it is an FIR(finite impulse response) filter, and does not support 117-bits.

11 Unique Filter Types

• low pass, high pass, band pass: continuously variable from 0 dB/oct to 96 dB/oct;
• bell, notch: continuously variable from 12 dB/oct to 96 dB/oct;
• low shelf, high shelf, tilt shelf: continuously variable from 6 dB/oct to 96 dB/oct;
• flat tilt and flat top;
• sword: has a sharper slope than bell, specifically designed to "dig" out resonances.

Continuously Variable Slopes Filters

The slope of most filter types can be continuously changed from 0 dB/oct, 6 dB/oct, or 12 dB/oct, up to 96 dB/oct. Would you like to try a 8.125 dB/oct high pass?

30 Filter Types Modeled from Historic Vintage EQs

Get vintage and modern at the same time! We modeled 8 vintage EQ hardware units into Kirchhoff-EQ, for a total of 30 EQ types.

Benefit from Robust Nyquist-Matched Transform, every EQ type precisely matches the original hardware and won't cramp near Nyquist frequency.

For a further step, unlike the original hardware that only allows you to choose between several frequency positions, we modified the DSP model to make adjustable frequency points for all these types!

Every type in these models can be used together with regular EQ types or other modeled types, and can be applied with dynamic functions (except lowpass and highpass types).

This brings you more freedom and convenient operations.

*No non-linear behaviors were modeled. All vintage filter types only contain ideal linear parts of their physical model.

Zero-Latency/Analog/Linear/Mixed Phase Modes

The phase mode of Kirchhoff-EQ is switchable between zero-latency mode, analog mode, linear phase mode, and mixed-phase mode. To meet all your Phase relationship needs.

*No matter which phase mode is currently in, if dynamic functions are turned on for a filter band, it will work on minimum-phase mode (won't affect other bands).

Mixed Phase Mode

The zero-latency and linear phase modes have very different sounds.

Kirchhoff-EQ provides a mixed mode that uses zero-latency when the band frequency point is low and uses linear phase when it is high.

Each band could smoothly change between minimum and linear phase mode according to their frequency.

* There is no noticeable crossover between filter types while in mixed-phase mode, the transition is seamless.

Flexible Dynamic EQ Functions

Dynamic functions in Kirchhoff-EQ are not just a bonus, They provide the richest functions you have ever seen.

Enabling you to achieve unlimited possibilities of dynamic EQ functions.

All filter types (except low/high pass, bandpass, and notch), even these vintage-modeled ones, can be applied with dynamic functions.

Harmonic Shifted Envelope

All dynamic EQ have odd- and non-integral harmonics, that's the laws of physics.

By using advanced DSP techniques, Kirchhoff-EQ now "shift" most energy of odd-harmonics into even-harmonics, making an ultra-low noise floor and enhanced sound.

Now you can use dynamic functions with freedom without worrying about smashing your sounds.

Two-Way Threshold

You can now control how dynamics react to the portion of signal above/below threshold concurrently.

In Kirchhoff-EQ, the "Above" stage works as a compressor or upward-expander, and the "Below" stage works as an expander or upward-compressor.

For example, you can raise the signal below the threshold AND compress the signal above the threshold to "stabilize" a band.

Detect/Relative Envelope Detection

Let us imagine a simple case: we are playing an audio clip in which sounds around 1khz are 9dB.

You may think "The 1khz range is overpowering, we should reduce the 1khz,but we should also consider the overall level.

If the whole audio is 30dB, you would not feel that 1khz is too much, instead, you may feel it's not enough.

The better criteria to determine whether a band's volume is high or low is its relative portion in the overall volume envelope, instead of only its absolute dB value.

Thereby we introduce "Detect/Relative Envelope Detection" in Kirchhoff-EQ.

The dynamics are affected by both current frequency band and relative portion to a "Relative" band.

The contribution of Relative Envelope Detection to dynamics is also adjustable: when set to 0%, it degrades as a normal dynamic EQ; and when set to 100%, the amount of dynamics is fully calculated from the relative portion.

The "detect" band is set according to the frequency and Q of the band by default, "Relative" is the whole audio envelope by default. But they can be set freely.

The detecting band and relative band have a freely adjustable frequency point and Q value. Or enable "S.C." mode to make "Detect" or "Relative" to a sidechain signal.

Onsets Detection Mix

By turning on "Onsets" mix, the envelope detector reacts more specifically to transients inside of the envelope, so you can fine-tune the tone of transients.

For better adjustability, you can "mix" envelope detector and onsets detector. For example, you can compress the high frequencies just a little bit whilst compressing the sudden increase of high frequencies more aggressively.

More Features

Spectrum Grab

Kirchhoff-EQ allows you to locate a specific frequency peak rapidly by directly grabbing on spectrum.

Switchable 2x Oversampling

Kirchhoff-EQ has built-in 2x oversampling that can be freely turned on/off.

Per-Band Directional EQ

Each band can be set as mid/side or left/right processing, so you can pan a band Left or right, or adjust Mid/Side, or just left, right, mid, and side separately.

Extreme CPU Optimization

Through hand-written assembly code commands, Kirchhoff-EQ achieves ultra-low CPU workload. Never fear using hundreds of instances!

Low Clicking Noise

We made our best to reduce clicking noises while performing parameter changes, type switching, bypass on/off and enter/leave solo listening mode.

GPU Accelerated GUI

We are dedicated to smoothness in operating, speed to open/close UI, and operation latency. To achieve better rendering efficiency, the GUI of Kirchhoff-EQ is rendered using OpenGL.

Visual-Comfort Spectrometer

The spectrum panel of Kirchhoff-EQ is carefully optimized for visuals and is freely configurable. You can adjust its decibel range, refresh speed, resolution, frequency scaling, and brightness. You can even directly specify its center frequency.

User-Customizable Settings

To help speed up your workflow, Kirchhoff-EQ provides a rich set of options allowing you to cast it to your own handy tool.