Elysia xfilter Mastering Edition

From the original xfilter to an edition designed for finalization

Part of the same family as the museq, the xfilter combines Class A analog design with a lightweight rack format. The xfilter Mastering Edition builds on this foundation and adapts it for delicate work on a complete mix: adjusting the low-end foundation, clearing space in the midrange, or opening up the highs without disrupting the musical balance.

Compared with the standard xfilter, this edition offers a finer operating range of -5 to +5 dB and extended operating headroom, with a maximum level of +27 dBu at both the input and output. These changes make measured corrections easier and facilitate integration into an analog mastering chain.

For mastering engineers and producers attentive to mix balance

This stereo analog equalizer is intended for studios that want to shape the color and tonal coherence of their mixes with precision. On an acoustic production, it helps preserve the nuances of the performance; on an electronic track, it helps structure the low end and control the presence of the upper spectrum.

Its coupled stereo operation allows the left and right channels to be processed with a single set of controls. You can therefore adjust the entire program without having to reproduce each setting on two separate channels. The detents and graduated controls also make it easier to recall a session and compare different settings.

Four active bands and passive high-frequency finishing

Fine corrections, with filters suited to musical work

The four active bands feature a deliberately narrow gain range. The low and high bands operate as low shelf and high shelf filters to adjust the foundation and openness of the mix. They can also be switched independently to high-pass and low-pass filters, with a slope of 12 dB per octave and a resonance peak at the cutoff frequency.

This resonance provides an additional way to shape the extremes of the spectrum: tightening the low end while retaining definition near the cutoff, or emphasizing a high-frequency area without boosting the entire top end. The two parametric mid bands offer a switchable Q factor between 0.5 and 1.0, for broad or more targeted interventions.

Their proportional-Q behavior favors musical corrections over ultra-narrow frequency cuts. The bandwidth can be switched independently of the gain setting, allowing you to adapt the treated area to the sonic material and the mastering intent.

An LC circuit for opening up the top end

In addition to the four active bands, a fixed, switchable passive LC filter adds another texture to the high frequencies. It features a slight resonance peak at 12 kHz, followed by attenuation beginning at 17 kHz. Its action is concentrated around this area rather than indiscriminately accentuating all the highs.

This “passive massage” makes it possible to achieve greater openness with a single control. The coils feature individual shielding to limit external influences, including hum and unwanted noise.

A construction focused on stereo precision

The multilayer potentiometers are measured and selected using Audio Precision equipment and dedicated computer routines. This selection limits channel discrepancies caused by component tolerances. The film capacitors also benefit from a tolerance that is twice as tight as the specified industrial standard for this design.

The inputs, outputs, and discrete mixing stages are part of a fully Class A audio path. The four-layer printed circuit boards include a ground plane dedicated to shielding, positioned close to the audio traces to reduce electrical interference, particularly when the filter networks become more sensitive to low-frequency adjustments.

Technical specifications

Category	equalizer	Rack unit	1
Number of channels	2	Analog outputs	jack, XLR
EQ	4 channels	Color	Black

Type	rackmount stereo analog equalizer.	Passive filter resonance	slight peak at 12 kHz; attenuation begins at 17 kHz.
Version	xfilter Mastering Edition, optimized for mastering.	Potentiometers	41 detented positions and detailed scale.
Topology	fully Class A audio path.	Two four-layer printed circuit boards	two audio layers, one power supply layer and a dedicated copper ground plane for shielding.
Inputs, outputs and mixing stages	discrete design.	Bandwidth at -3.0 dB	lower limit below 10 Hz, upper limit of 400 kHz.
Operation	coupled stereo, with a single set of controls for both channels.	THD+N at 0 dBu, from 20 Hz to 22 kHz	0.01%.
Number of active bands	4.	THD+N at +10 dBu, from 20 Hz to 22 kHz	0.008%.
Gain range of the four bands	-5 to +5 dB.	Noise level, from 20 Hz to 20 kHz, A-weighted	-92 dBu.
Outer bands	low shelf and high shelf.	Dynamic range, from 20 Hz to 22 kHz	120 dB.
High-pass and low-pass filter slope	12 dB per octave.	Maximum input level	+27 dBu.
Mid bands	2 proportional-Q parametric filters.	Maximum output level	+27 dBu.
Switchable Q factor	0.5 for broad correction and 1.0 for narrower correction.	Input impedance	10 kilohms.
Additional high-frequency filter	fixed, switchable passive LC circuit with individually shielded coils.	Output impedance	68 ohms.