The SPL Qure is a fully parametric, dual-channel equaliser developed for the most demanding studio applications, including detailed tonal shaping of individual instruments, vocals and complex stereo programme material. The design centres on musical control and perceived sound quality rather than purely numerical performance, resulting in an equaliser that combines precision with a highly refined tonal character. Each channel provides three fully parametric bands, additional high-cut and low-cut filters, and independent input and output gain stages, allowing the SPL Qure to operate equally effectively in tracking, mixing, mastering and cutting environments.
At the heart of the SPL Qure is an advanced analogue circuit topology in which each filter band is mounted on its own circuit board and connected in series, with individual op-amps for every stage. This approach delivers exceptionally low noise and distortion figures while maintaining maximum signal integrity. Every filter band, along with both cut filters, can be completely removed from the signal path via hard bypass switching, and a master relay hard bypass ensures full signal continuity in the event of power loss. Balanced XLR and balanced stereo jack connections are provided for flexible integration into professional studio systems.
A defining characteristic of the SPL Qure is its use of proportional-Q filtering rather than conventional constant-Q designs. As bandwidth is widened, the amount of boost or cut is automatically reduced, preserving musical balance and preventing exaggerated emphasis of adjacent frequencies. Narrowing the bandwidth increases the level at the centre frequency without the need for continual gain readjustment. This behaviour makes the equaliser far more intuitive to use and allows subtle tonal nuances to be identified and shaped with ease. The resulting bell-shaped response curves emphasise frequencies close to the centre point while gently reducing the influence on more distant frequencies, producing natural and musical results across the entire spectrum from 15Hz to 21kHz.
The mid band incorporates a non-reciprocal boost and cut characteristic that allows it to function effectively as a notch filter, with deep attenuation available at high Q settings. This design delivers a wide dynamic response and maintains an open and transparent sound even under heavy processing. High-cut and low-cut filters on each channel further enhance flexibility, enabling precise control over unwanted extremes while preserving the integrity of the remaining signal.
The SPL Qure also introduces the proprietary Qure control, a unique tonal enhancement circuit based around inductors and an LCR network integrated into a tube output stage. The signal passes through a 12AX7 double triode operating in a mixed current and voltage coupling mode, chosen for its high headroom and musically pleasing harmonic structure. Engaging the Qure circuit subtly influences phase response and harmonic content, producing a smoother top end, a more refined midrange and enhanced spatial imaging. This makes it particularly effective for reducing digital harshness, placing vocals more clearly within a mix, and adding depth to layered or background elements without artificially increasing ambience.
For accurate recall and consistent results, all controls on the SPL Qure are implemented using stepped potentiometers, with step counts tailored to each function. Bandwidth, frequency, boost and cut, input gain, output gain, cut filters and the Qure control are all precisely stepped, making the unit well suited to mastering and other recall-critical applications. The internal construction employs SPL’s central grounded shield layout to maximise rejection of interference, along with Super-Balancing hybrid circuitry that provides excellent common-mode rejection. A generously specified internal toroidal power supply and tube warm-up circuitry further contribute to long-term reliability and consistent sonic performance.
Features
- Dual channel three band fully parametric equaliser
- Proportional Q filter design
- High cut and low cut filters on each channel
- Unique Qure tonal and spatial enhancement control
- Independent input and output gain controls
- Stepped potentiometers for precise recall
- Hard bypass switching for each filter band
- Hard bypass switching for high cut and low cut filters
- Master relay hard bypass for the entire unit
- Balanced XLR and balanced jack inputs and outputs
- Tube output stage using a 12AX7 double triode
- Central grounded shield layout construction
- Super Balancing hybrid circuitry
- Internal toroidal power supply