Elysia xfilter qube

elysia stereo processing in a compact format

The elysia xfilter 500 brings the sonic approach of Class-A equalization to the 500-series modular format. Its principle: to offer musical stereo processing that is flexible enough to shape a signal without multiplying the controls. The left and right channels share the same settings, with component selection designed to maintain consistent response between them.

It naturally fits alongside an xpressor, but can also complement another analog processing chain during recording or mixing. Please note the integration requirements: the module requires an elysia qube rack or an API 500-series-compatible rack to operate. This rack is not included.

To add weight, presence and air to your mixes

This studio stereo equalizer is aimed at musicians, producers and audio engineers who want to sculpt their signals with physical controls and a musical response. It can rebalance a stereo source, give an ensemble more weight or add openness to the top end.

Its two Q factors favor broad corrections and targeted but natural boosts. The xfilter 500 is therefore not intended to replace a digital equalizer for removing a resonance on an extremely narrow band. Its ideal applications remain shaping color, tonal balance, punch and the perception of transients.

Complementary filters for precise sound shaping

Switchable shelves with resonant filter modes

The two outer bands initially operate as low shelf and high shelf filters. They allow you to adjust the low-end weight and brightness directly. Each band can be independently switched to a high-pass or low-pass filter, with a slope of 12 dB per octave and a resonance peak at the cutoff frequency.

This resonance expands the possibilities beyond simple spectral cleanup. It allows you to emphasize the area close to the cutoff while attenuating the frequencies beyond it. You can therefore combine control of the extremes with emphasis on a specific area, without uniformly boosting an entire section of the spectrum.

Two mid bands with switchable Q

The parametric mid bands offer a choice between a broad Q of 0.5 and a narrow Q of 1.0, based on a proportional-Q design. The broad setting is suited to gradual balance changes; the narrower setting focuses the action more closely on the selected area. Both behaviors remain geared toward musical rather than surgical equalization.

Passive finishing for the high frequencies

In addition to the four active bands, a fixed, switchable passive LC filter adds another texture to the highs. Its slight resonance peak at 12 kHz is accompanied by attenuation starting at 17 kHz. The inductor's action is thus concentrated around this area, adding openness without indiscriminately boosting the entire high-frequency range.

The inductors have their own shielding to limit the influence of external fields, hum and unwanted noise. This stage provides accessible sonic finishing at the press of a button, making it easy to compare according to the needs of the track.

A design focused on stereo consistency

In an equalizer with coupled controls, component matching is crucial. The gain potentiometers have two sections, while the frequency potentiometers have four. To reduce channel-to-channel deviations, each potentiometer is measured and then selected using Audio Precision equipment and dedicated computer routines. Computer-selected film capacitors also contribute to this precision.

The stepped controls make it easy to recall settings. The circuit boards feature four layers, including one dedicated to ground shielding positioned close to the audio traces. This construction protects the filter networks from electrical interference, particularly when their impedance increases at the lowest frequency settings.

Technical specifications

Frequency response - start	20 Hz	Number of channels	2
Frequency response - end	22 kHz	EQ	4 channels
Category	equalizer

Type	500-series stereo analog equalizer.	Noise level, from 20 Hz to 20 kHz, A-weighted	-98 dBu.
Topology	100% Class-A.	Dynamic range, from 20 Hz to 22 kHz	120 dB.
Channels	two, with a shared set of controls.	Maximum input level	+21 dBu.
Active equalization	four bands.	Maximum output level	+21 dBu.
Outer bands	low shelf and high shelf, independently switchable to resonant high-pass and low-pass filters.	Input impedance	10 kOhm.
High-pass and low-pass filter slope	12 dB per octave.	Output impedance	68 Ohm.
Resonance	additional peak at the cutoff frequency.	Four-layer printed circuit boards	two for audio, one for the power supply and one for ground shielding.
Mid bands	two parametric filters with switchable Q and proportional-Q operation.	Manufacturing	Germany.
Q values	0.5 in wide mode and 1.0 in narrow mode.	Dimensions of the 500 module	76.2 x 152.4 x 134.6 mm.
Additional filter	switchable fixed passive LC stage with individually shielded inductors.	Dimensions of the qube	101.6 x 188 x 134.6 mm.
Passive filter response	slight peak at 12 kHz, attenuation begins at 17 kHz.	Weight of the 500 module	0.5 kg.
THD+N at 0 dBu, from 20 Hz to 22 kHz	0.0018%.	Weight of the qube	1.4 kg.
THD+N at +10 dBu, from 20 Hz to 22 kHz	0.005%.	Module operation	requires an elysia qube or compatible API 500-series rack, not included.