| The Qure is a 2-channel, parametric, 3-band EQ, ideally suited for demanding tonal shaping of individual instruments, voices and complex musical signals. Mastering
applications benefit from the unique tonal potential and the sophisticated
filtering design that perfectly complements the fine details of the sound being
processed.
The highly sophisticated circuitry of the Qure forms the basis for
its outstanding tonal qualities: each filter is serially connected on separate
boards with individual op-amps, resulting in excellent noise and distortion
values, with a hard bypass available for each individual filter.
Features
- 2 x 3-band fully parametric EQ
- Proportional Q operation
- Variable HF and LF cut filters
- Unique QURE control
- Variable input gain (-12dB to +18dB)
- Variable output gain (-7dB to +4dB)
- Hard-Bypass for each filter band and both cut filters
- Master relay hard-bypass for entire unit
- Central Grounded Shield Layout
- SPL's Super-Balancing Hybrids (CMRR > 80dB)
- Tube warm up circuitry for prolonged tube-life
- Overrated internal toroidal power supply
- OPTION: Lundahl I/O transformers
Concept
The Qure
is a fully parametric equaliser, 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 control
The Qure
circuitry is a new 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.
Proportional Q
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 equalisers. 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.
The Frequency Bands
The Qure
is configured as a two-channel, 3-band equaliser with a separate hard-bypass
switch for each band. The filters are connected in series. The three filters
bands cover a frequency range from 15Hz to 21kHz. In addition each channel is
equipped with high- and low-cut filters. Tuning the equaliser is very intuitive
because the frequency control law has been designed to match the characteristics
of the human hearing system. The perfectly linear phase response of the Qure
circuitry, combined with its wide bandwidth, contributes to the sonic excellence
of this esoteric equaliser. The mid-band features the "non-reciprocal
response" of the Boost/Cut control which qualifies this band to operate as a
notch filte, too. Cutting is allowed to -36dB at high Q (Q5) whereas the low and
high band offer cutting of -15dB. The sonic advantage of the "non-reciprocal
response" design is the vast dynamic response making the filter sound very open
and clear.
General Features
To allow
easy recall of all control settings the Qure is equipped with stepped
potentiometers throughout. The number of steps is optimised to the control
function: 11 steps for bandwidth, 31 steps for frequency and boost/cut, and 41
steps for input gain, HF/LF Cut filters, and Qure control. Each band can
individually be switched in and out of the signal path making comparison easy
and avoiding the need to nullify the boost/cut control. Each filter is mounted
on a separate printboard featuring a "central grounded shield layout(CGSL) for
maximum rejection of interfering frequencies. Single op-amps are used throughout
to minimize noise and THD. The tubes in use are the well-acclaimed Sovtek 12 AX
7. Furthermore selected custom made condensers are used to produce harmonical
and pleasant sounding THD spectra. The frequency controls are also custom made
featuring a control characteristic that is designed to realise a gentle
frequency sweep with a musically optimised control range.
Specifications
Input & Output
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
Measurements
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
Power Supply
Toroidal
transformer 35 VA
Fuse (primary) 500 mA (230V/50Hz), 1000 mA (115V/60Hz)
Ground-Lift switch, Voltage selector 115V/230V
Dimensions
Housing
Standard EIA 19"/2U, 482 x 88 x 237mm
Weight 4,9 kg
Note: 0dBu = 0.775
V
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