SPL 9738, QURE 9738 User Manual

Model 9738

Manual

Dual Channel Parametric Tube/LC Equalizer

By Hermann Gier and Paul White

Version 2.2 - 1/1999

The information in this document has been
carefully verified and is assumed to be correct.
However Sound Performance Lab (SPL)
reserves the right to modify the product
described in this manual at any time. Changes
without notice.This document is the property
of SPL and may not be copied or reproduced
in any manner, in part or full without the
authorisation of SPL.

Limitations of Liability:

In no event will SPL be liable for any
damages, including loss of data, lost profits,
cost of cover or other special, incidental,
consequential or indirect damages arising
from the use of the unit, however caused and
on any theory of liability. This limitation will
apply even if SPL or an authorised dealer has
been advised of the possibility of such
damage.

SPL electronics GmbH

P.O.Box 12 27

D- 41368 Niederkruechten, Germany

Phone +49 - 21 63 / 98 34-0

Fax +49 - 21 63 / 98 34-20

eMail: [e-mail]

© 1999 SPL electronics GmbH. All rights reserved. QURE® is a registered trademark of SPL electronics GmbH.

Qure

Model 9738

Manual

3

Contents

Dear customer,

Thank you for the confidence you have shown towards SPL

electronics GmbH by purchasing the SPL QURE.You have decided to
use a tool of high performance which sets you in the position to
have faster success and a better sound quality in your music
productions and pre-masterings. As a typical SPL unit the Q

URE

combines exemplary specifications and high manufacturing stan­dard with excellent sound quality to provide you a precious
component for recording purposes. Please read this manual
carefully to ensure you have all the information you need to use
the Q

URE. We wish you every success with it.

Your Sound Performance Lab-Team

I would like to start with my thanks to all our staff, who created
what is to be described here.The importance of their exceptional
qualification and talents cannot be overestimated.Special thanks
to Wolfgang Neumann for his exceptional creativity in EQ and
filter design.

Our products are often tested and compared in many publica­tions and by our customers themselfs and constantly valued with
best results. I would like to pass on this broad appreciation to
those,who deserve it – my excellent colleagues.

Hermann Gier

Foreword

Thanks

Foreword............................................................................................... 3

Thanks.................................................................................................... 3

Introduction......................................................................................... 4

Operation Safety................................................................................. 7

Connections.......................................................................................... 8

Applications......................................................................................... 9

CONTROL ELEMENTS

WARM UP & READY .......................................................................... 10

MASTER ............................................................................................... 10

IN ........................................................................................................... 11

HF/LF CUT ON .................................................................................... 11

HF CUT.................................................................................................. 11

LF CUT .................................................................................................. 11

LF ........................................................................................................... 12

MF .......................................................................................................... 12

HF........................................................................................................... 13

BW.......................................................................................................... 13

B/C ......................................................................................................... 15

LF/MF/HF ON ..................................................................................... 17

QURE ON ............................................................................................. 17

QURE ..................................................................................................... 18

SHIFT QURE ......................................................................................... 20

OUT........................................................................................................ 20

Power supply........................................................................................ 21

Specifications....................................................................................... 22

Warranty................................................................................................ 23

4

Congratulations on purchasing the QURE, one of the most
advanced and musical sounding parametric equalizer currently
available.

The Q

URE is a fully parametric equalizer, specially designed to

meet the most demanding studio applications.It is designed as 3­band, two-channel system with input and output gain controls,
high-cut and low-cut filters as well as the new Q

URE-circuitry for

the creative and corrective sound shaping of vocals, instruments
and complex stereo material. Both balanced XLR and balanced
stereo jacks are provided for signal connections to and from the
Q

URE.

Its musically optimized parametric filters, based on a sophisti­cated refinement of state-variable-filter technology (SVF),include
proportional bandwidth, tube technology for a warm and fat
sounding mid-range, LC filtering for clear and transparent upper
frequencies,transistor and semi-conductor technology for a volu­mious low end.

The proportional-Q principle provides precise control over a
frequency range,from 15 Hz to 21kHz, while the low noise level of

-99dB (A-weightened), and the enormous dynamic range of
113dB, make the Q

URE ideally suited for mastering and cutting. By

employing circuitry designed around the principles of perceived
sound, rather than simply designing by numbers, the Q

URE over-

comes the limitations of conventional parametric equalizers.

The QURE circuitry

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 increase the presence of vocals and the depth of the
music.At the same time it is ideally suited to cure recordings from
digital harshness. The name is derived from ‘cure’in combination
with Q from EQ.

The signal runs through a tube circuitry featuring a Sovtek
12AX7 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 filternet­work (LCR) into the tube output stage.This network is integrated
into the coupling path of the tube and reacts on the dynamic
reponse of the input signal by influencing THD spectra and phase
response. The Q

URE potentiometer changes the frequency

response and produces a fresh and silky top-end and a mid-range
free of sharpness and harshness.The presence and ‘aura’of vocals
is largely improved.

The Q

URE is a parametric

equalizer for creative
sound design

The Q

URE combines a

technology-mix of five
decades of audio engineering

Exemplary specification
contribute to the excellency of
this EQ

The QURE circuitry improves
presence,clarity and depth.
It can also be used to cure
recordings from digital
harshness.

A new LCR network combined
with a 12AX7 tube reacts on
the dynamic response of the
audio and alters THD and
phase response.

Introduction

5

Proportional Q

Unlike most other equalizers which use constant-Q filters, the

Q

URE adopts the proportional-Q principle to realize 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 center 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 center 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 equalizers. It is generally perceived
that equalizers 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.Equalizing with proportional-Q is therefore
more intuitive and subjectively musical than with constant-Q
equalizers. The Q

URE forms its response curve around the center

frequency with a bell-like response, so that frequencies closer to
the center frequency are emphasized slightly more; frequencies
further from the center are less affected. The development of
these filter curves was the result of extensive listening tests, and
the result is an equalizer that combines technical excellence and
precision with unsurpassed musicality.

The Frequency Bands

The QURE is configured as a two-channel, 3-band equalizer 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 equalizer 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
Q

URE circuitry, combined with its wide bandwidth, contributes to

the sonic excellence of this esoteric equalizer.

The mid-band features the ‘non-reciprocal response’ of the
BOOST/CUT control which qualifies this band to operate as a
notch filter, too. Cutting is allowed to -36 dB at high Q (Q 5)
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.

With the musical

proportional-Q principle the

amplitude of the processed

frequency band is reduced

as the bandwidth broadens.

Equalizing with

proportional-Q is more

intuitive and subjectively

musical than with

constant-Q equalizers.

The Q

URE is a two-channel,

3-band equalizer with the

filter bands connected

in series

The mid-band features

a ‘non-reciprocal response’

of the BOOST/CUT control

6

Stepped potentiometers for
easy recall; individual bypass
for each filter band

Central grounded shield
layout,single op-amps,
Sovtek tubes,custom
made condensers
and potentiometers

General Features

To allow easy recall of all control settings the QURE is equipped
with stepped potentiometers throughout. The number of steps is
optimized 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 realize a gentle
frequency sweep with a musically optimized control range.

Overview

• 2x 3-band EQ with variable HF and LF cut filters

• QURE circuitry (Tube + LCR)

• Variable input gain (-12 dB to + 18dB)

• Variable output gain (-7dB to + 4 dB)

• Hard-bypass for each filter band and both cut filters

• Master relay hard-bypass for entire unit

• Central Grounded Shield Layout

• SPL super-balancing hybrids (CCMR -90dB)

• Tube warm up circuitry for prolonged tube-life

• Overrated internal toroidal power supply

• PREMIUM-Version (recommended):
LUNDAHL in- & output transformers (LL1539 & LL1540)

7

Important security advices

Operation Safety

The housing of the QURE has the standard 19"-EIA format and
occupies 2U (88.9 mm) in your rack. When installing the unit in a
19"-rack, the rear side of the unit needs some support, especially
in a touring case.

Choose the installation location of your unit carefully:

The Q

URE should not be installed near units which produce

strong magnetic fields or extreme heat. Avoid placing it in direct
sunlight.

Also avoid locations subject to vibration and excessive dust,
heat,cold, or moisture.

Keep it away from sources of hum such as transformers or
motors.

Do not install the Q

URE directly above or below power ampli-

fiers.

Check that the voltage details quoted on the back panel are the
same as your local mains electricity supply. Use a minus (-)
screwdriver to set the voltage selector to the voltage for the area
in which the unit will be used.

Never cover up the ventilation slots on the top of the unit. If,
during operation,the sound is interrupted or indicators no longer
illuminate, or if abnormal odor or smoke is detected, or if liquids
are spilled on the unit, immediately disconnect the power cord
plug and contact your dealer.

WARNING: Do not open the cabinet of this unit, because to do
so might result in damage to the unit,or injury by electric shock.If
any foreign object or substance enters the unit, contact your
dealer for assistance.To reduce the risk of electric shock, do not
expose this appliance to rain or moisture.

To prevent damage by lightning, disconnect the power cord
from the household AC outlet during an electrical storm. When
disconnecting the power cord from the household AC outlet,
grasp the plug; do not pull the cord. Refer servicing to qualified
personnel only!

Do not apply excessive force when using switches and controls.
When moving the unit, be sure to first disconnect the power cord
from the household AC outlet, and disconnect cords connected
to other equipment.

Do not attempt to clean the unit with chemical solvent as this
might damage the finish. Only clean the Q

URE with a clean, soft,

lint-free cloth.

8

THE QURE is fitted with both XLR connectors and TRS stereo jacks
for balanced operation,though the jacks may be used with unba­lanced connections simply by plugging in mono jack-plugs. The
level difference that normally occurs when a balanced input or
output is used unbalanced is automatically compensated for.

Should the need arise to use the XLR connectors in an unba­lanced system, pin 3 of the XLRs should be grounded. Inserting a
mono jack also unbalances the XLRs.

Both output stages operate in parallel, so it is possible to
connect two different destination units simultaneously, for
example to record to two different media at the same time or split
the output between a mixer and effects processor. However, only
one type of input (jack or XLR) should be connected at a time –
the Q

URE is not intended to be used as a mixer!

To ensure optimal signal quality, SPL has developed a super­balancing hybrid input/output stage using all laser-trimmed resi­stors with a tolerance of 0.01%.This approach has resulted in high
CCMR (common mode rejection) values better than -90dB at
1 kHz.

As a precaution, before connecting the Q

URE switch off the

power to the unit and to all connected units.

Connections

1

2

3

Pin wiring: XLR connectors

1=GND 2=Hot(+) 3=Cold(-)

Pin wiring: Stereo Jack plug

Tip=Hot(+) Ring=Cold(-) Sleeve=GND