Elysia Xfilter

The xfilter is a true Class-A stereo equalizer in a 1U rackmount format, designed to deliver exceptional analog sound quality, combining openness, precision, and impact.

Its ability to project transients with punch and naturalness makes it a tool of choice for both recording and mixing.

Stereo operation relies on stepped potentiometers and computer-selected film capacitors, ensuring a perfectly coherent stereo image.

Extremely versatile, the xfilter combines flexible active filters and a dedicated passive LC stage for high frequencies, resulting in a sonic signature that is both musical and refined.

Architecture and Sound Processing
Resonant High-Pass and Low-Pass Filters

The Low and High bands offer great flexibility. In standard mode, they function as low-shelf and high-shelf filters, ideal for quickly adjusting the depth and airiness of a signal.

They can also be independently switched into resonant high-pass or low-pass filters, with:

12 dB/octave slope

Resonance peak at the cutoff frequency

The resonant low-pass filter adds a crisp, punchy character to low frequencies, while the resonance in the high frequencies allows you to highlight a specific frequency without overemphasizing the entire high-frequency spectrum.

Parametric midrange bands with switchable Q factor

The xfilter incorporates two parametric midrange bands, each with a switchable Q factor based on the proportional Q principle:

Wide Q (0.5): gentle and musical corrections

Narrow Q (1.0): more precise and targeted processing

This intentionally limited selection prioritizes the musicality of the processing. Ultra-surgical corrections are left to digital tools, while the xfilter excels in analog sound shaping.

Passive LC High Band – “Passive Massage”

In addition to the four active bands, the xfilter features a switchable passive LC filter dedicated to high frequencies.

Slight resonance peak at 12 kHz

Gradual attenuation from 17 kHz

Natural coil saturation concentrated in the useful range

The inductors are individually shielded, effectively reducing hum and interference.

Result: an elegant and natural high-frequency opening, activated with a simple button.

Design and Manufacturing
Individually Selected Potentiometers

In a coupled stereo equalizer, the precision of the potentiometers is essential.

Gain controls use dual-layer potentiometers, while frequency adjustments rely on four-layer models, increasing the risk of differential tolerances.

Each potentiometer in the xfilter is measured, analyzed, and selected using Audio Precision equipment and dedicated computer routines to ensure identical behavior on both channels.

Dedicated Ground Shielded PCB

The xfilter's PCBs consist of four layers:

2 audio layers

1 power supply layer

1 dedicated ground shielding layer

This design effectively protects the filter networks—which are particularly sensitive to low frequencies—from electromagnetic interference, guaranteeing a clean and stable signal.

Key Features

100% Class-A Topology

True Stereo Equalizer (coupled controls)

Resonant High-Pass/Low-Pass Filters

Dedicated Passive LC High-Frequency Filter

Switchable Q Factor on the Midrange

Individually Selected Low-Tolerance Components

Detented Potentiometers for Precise Recall

Made in Germany