SPL Qure

The Qure gives a silky sheen and an unmistakable presence to vocals and guitars.

The classic sound of coil filters, that are operating in proportional-Q mode, and the inimitable Qure function make this equalizer a very special one.




The Qure is a fully parametric equalizer, specially designed to meet the most demanding studio applications. It is a 3-band, two-channel system with input and output gain controls, high-cut and low-cut filters as well as the new Qure control for the enhancing presence and room imaging of vocals, instruments and complex stereo material.

Both balanced XLR and balanced stereo jacks are provided for signal connections to and from the Qure. The proportional-Q principle provides precise control over a frequency range, from 15Hz to 21kHz, while the low noise level of -99dB (A-weighted), and the enormous dynamic range of 113dB make the Qure ideally suited for mastering and cutting. By employing circuitry designed around the principles of perceived sound, rather than simply designing by numbers, the Qure overcomes the limitations of conventional parametric equalisers.

The Qure circuitry

The Qure circuitry is a SPL development which gives the name for the unit and also represents a new technology, which uses coils to influence the presence and the spatial imaging. At the same time it is ideally suited to “cure” recordings from digital harshness.

The signal runs through a tube circuitry featuring an 12AX7-LPS double triode tube in a mixed current/voltage coupling mode. This stage is extremely clip-resistant and produces a pleasant and musical sounding tube-THD spectrum.

The Qure On switch puts a coil/condenser/resistor filter network (LCR) into the tube output stage. This network is integrated into the coupling path of the tube and reacts on the dynamic response of the input signal by influencing THD spectra and phase response.

The Qure potentiometer changes the frequency response and produces a fresh and silky top-end and a mid-range free of sharpness and harshness. For example, vocals can be “placed” in the front of a mix without having to provide more “space”, also background or layer sounds can gain improved spatial depth.


Unlike most other equalisers which use constant-Q filters, the Qure adopts the proportional-Q principle to realise maximum musicality. Conventional constant-Q designs keep the amplitude constant, regardless of the adjusted bandwidth (Q). The disadvantage of this is, when it comes to sound creation, frequencies above and below the centre frequency are often boosted so intensely that they lose their musicality.

With proportional-Q it is quite different; the amplitude of the processed frequency band is reduced as the bandwidth broadens. Adjusting the bandwidth back to a narrow bandwidth (high Q), will increase the amplitude of the centre frequency to its former level. Furthermore, with proportional-Q, there is no need to constantly readjust the boost/cut control when varying the bandwidth as is usually necessary with constant-Q equalisers. It is generally perceived that equalisers based upon constant-Q designs produce acoustically comparable results, and suffer from limitations in the areas of sound flexibility and musicality. Often there is only one truly usable position on the Q-control. The proportional-Q principle offers a wide range of possible potentiometer settings and makes it easier to identify the desired frequencies within the sound spectrum even subtle nuances become clearly audible. Equalising with proportional-Q is therefore more intuitive and subjectively musical than with constant-Q equalizers.

The Qure forms its response curve around the centre frequency with a bell-like response, so that frequencies closer to the centre frequency are emphasised slightly more; frequencies further from the centre are less affected. The development of these filter curves was the result of extensive listening tests, and the result is an equaliser that combines technical excellence and precision with unsurpassed musicality.


Instrumentation amplifier, electronically balanced (differential), transformerless
Nominal input level: +6dB
Input impedance: = 22 kOhms
Output impedance: < 600 Ohms
Max. input level: +14dBu
Max. output level: +20dBu
Minimum load ohms: 600 Ohms
Relay Hard Bypass
Power Fail Safety
Frequency response: 10Hz 100kHz (100kHz = -3dB)
EQ frequency range: 15Hz 21kHz
CCMR: > -80 dB @ 1 kHz
THD & N: 0.01855% @ 1kHz
S/N CCIR 468-3: -85dBu
S/N A-weighted: -99dBu


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