Apex Digital dBQ-zero User manual

www.apex-audio.eu
dBQ-zero
User Manual

APEX NV
Schoebroekstraat 62
3583 Beringen (Paal)
BELGIUM
Tel: + 32 (0)11 28 61 91
Fax: + 32 (0)11 25 56 38
e-mail: [email protected]
website: www.apex-audio.eu
Trademarks
The APEX trademark is owned by APEX N.V. All other brand, product and company names and any other registered names or trade marks
mentioned in this manual belong to their respective owners.
Disclaimer
APEX N.V. has taken all possible steps to ensure that the information given here is both correct and complete. In no event can APEX accept any
liability or responsibility for any loss or damage to the owner of the equipment, any third party, or any equipment which may result from use of
this manual or the equipment which it describes.
The information provided in this document may be modied at any time without prior warning. Specications and appearance may differ from
those listed and illustrated. Any complaint against APEX N.V. shall be governed by the laws of Belgium.

dBQ-zero 2 x 30-band graphic equaliser
June 2010
Serial number of this product:
©2010 APEX N.V. All rights reserved.
This manual may not be reproduced or transmitted, either in part
or as a whole, by any means, be they mechanical or electronic,
without the express written permission of APEX N.V.

4
CAUTION: to reduce the risk of electric shock, do not
remove cover (or back). No user-serviceable parts
inside. Refer servicing to qualied service personnel.
The lightning ash with arrowhead symbol,
within equilateral triangle, is intended to
alert the user to the presence of uninsulated
“dangerous voltage” within the product’s enclosure that
may be of sufcient magnitude to constitute a risk of
electric shock to persons.
The exclamation point within an equilateral
triangle is intended to alert the user to
the presence of important operating and
maintenance (servicing) instructions in the literature
accompanying the appliance.
Instructions
Before installing or operating the equipment, read all
safety instructions, warnings and operating instructions.
Heed all warnings. Follow all instructions. Keep all
safety, installing and operating instructions for future
reference.
Installing and operating location
Do not use this apparatus near water. Do not expose
this apparatus to drips or splashes. Do not place
any objects lled with liquids, such as vases, on the
apparatus.
Do not install near any heat sources such as radiators,
heat registers, stoves, or other apparatus (including
ampliers) that produce heat. No naked ames, such
as lighted candles, should be placed on the apparatus.
Do not install the apparatus in a conned space such as
a book case or similar unit. Do not block any ventilation
openings.
Ensure that foreign objects and liquids cannot get into
the equipment.
Installinaccordance with the manufacturer’sinstructions.
Only use attachments/accessories specied by the
manufacturer.
Use only with the cart, stand, tripod, bracket or
table specied by the manufacturer, or sold with the
apparatus.
When a cart is used, use caution when
moving the cart/apparatus combination to
avoid injury from tip over.
The apparatus should be located close enough to the
AC outlet so that you can easily grasp the power cord
plug at any time.
The mains plug, the appliance coupler or the mains
switch is used as the disconnect device. Either device
shall remain readily operable when the apparatus is
installed or used.
Power source and grounding
This product should be operated only from the power
source indicated on the apparatus or in the operating
instructions. If you are not sure of the type of power
supply to your home, consult your product dealer or
local power company.
Do not defeat the safety purpose of the polarised or
grounding-type plug. A polarised plug has two blades
with one wider than the other. A grounding type plug
has two blades and a third grounding prong. The wide
blade or the third prong is provided for your safety. If
the provided plug does not t into your outlet, consult an
electrician for replacement of the obsolete outlet.
Connect Class I construction apparatus to an AC outlet
with a protective grounding connection.
Do not overload wall outlets, extension cords or integral
convenience receptacles, as this can result in a risk of
re or electric shock.
Protect the power cord from being walked on or pinched,
particularly at plugs, convenience receptacles and the
point where they exit form the apparatus.
Unplug this apparatus during lightning storms or when
unused for long periods of time.
Batteries (battery pack or batteries installed) should not
be exposed to excessive heat such as sunshine, re or
the like. Never dispose of batteries in a re as they may
explode and cause injury.
CAUTION: Danger of explosion if battery is incorrectly
replaced. Replace only with the same or equivalent
type.
Important safety instructions
Important safety instructions

5
Customer participation is important to minimize the
potential affects on the environment and human health
that can result from hazardous substances that may be
contained in this product.
Please, dispose of this product and its
packaging in accordance with local and
national disposal regulations including those
governing the recovery and recycling of waste electrical
and electronic equipment. Contact your local waste
administration, waste collection company or dealer.
Cleaning, maintenance and servicing
Unplug the apparatus from the wall outlet before
cleaning. Do not use liquid cleaners or aerosol cleaners.
Use a damp cloth for cleaning.
Do not attempt to service this product yourself, as
opening or removing covers may expose you to
dangerous voltage or other hazards. Refer all servicing
to qualied service personal.
Servicing is required when the apparatus has been
damaged in any way, such as power-supply cord or plug
damaged, liquid has been spilled or objects have fallen
into the apparatus, the apparatus has been exposed to
rain or moisture, does not operate normally or has been
dropped.
Intended use
The equipment may only be used for the purpose
described in the operation instructions. Never carry out
any work on the equipment other than as specied in
the operating manual.
Never push objects of any kind into this product through
openings, as they may touch dangerous voltage points
or short-cut parts, which could result in a re or electric
shock.
Children should never use the apparatus without close
adult supervision.
WARNING: excessive sound pressure levels can cause
hearing loss.
Environmental precaution
Electrical and electronic equipment may contain hazar-
dous substances for humans and their environment.
The “crossed out wheelie bin” symbol present
on the device and represented above is there
to remind one of the obligation of selective
collection of waste. This label is applied to
various products to indicate that the product is not to
be thrown away as unsorted municipal waste. At the
end of life, dispose of this product by returning it to the
point of sale or to your local municipal collection point
for recycling of electric and electronic devices.

6
Registration 7
Introduction 8
Product highlights 8
Foreword 8
Before you get started 9
About this manual 9
Inspection and unpacking 9
Operating environment 9
Power requirements 9
Installation 9
Front and rear panel description 10
Front panel 10
Rear panel 11
Overview 12
Wiring the unit 12
dBQ-zero Block diagram 13
Using the dBQ-zero 14
Technical specications 16
Electrical specications 16
Mechanical specications 17
Limited Warranty 18
Table of contents
Table of contents

7
Registration
Register your product
Please take the time to register your product on-line by typing the following URL in your browser:
http://productregistration.apex-audio.eu/
As well as registering the product on-line, please take the trouble to record the serial number of the unit in the
space provided on page 3 of the manual, and keep the manual in a safe place.

8
Introduction
Foreword
On both equaliser channels, the 30-band Constant-Q graphic
EQ is complemented with a lter section consisting of a high-
pass lter, high and low shelving equalisers and two notch
lters. Shelving lters add ‘warmth’ and ‘colour’ to the mix.
A typical application for the frequency adjustable high-pass
lter is to remove hum or vibration transmitted by turntables.
Notch lters provide a quick and simple method of removing
noise or potential feedback frequencies.
The Constant-Q design preserves lter bandwidth independently
from amplitude and therefore minimises adjacent band-
interaction. The use of Constant-Q lters also ensures that the
composite lter response of the graphic EQ accurately follows
the physical positions of the front panel faders.
Front panel legending and controls are clear and straightforward.
Two 10-segment LED level indicators, each with dedicated
signal present and clip LEDs are available.
For convenience and to simplify installation in any application,
the dBQ-zero comes with balanced inputs and outputs on XLR,
6.35 mm jack and screw terminal connections.
Dear customer,
Thank you for buying the Apex dBQ-zero. The dBQ-zero is a no-compromise 2-channel graphic equaliser with
supplementary lter sections. It is an excellent choice for live or installed sound reinforcement applications. A typical
application of the dBQ-zero would be to equalise monitor wedges.
As well as registering the product on-line, please take the trouble to record the serial number of the unit in the space
provided on the front cover of the manual, and keep the manual in a safe place.
Product highlights
• Constant-Q design for an accurate graphic representation
• Selectable boost/cut scale ±6 dB or ±15 dB
• 45 mm precision faders
• Equaliser bypass switch and automatic bypass in the event of
power failure
• Swept high-pass lters for removing unwanted low frequency
content
• Precise and deep notch lters for accurate feedback
suppression
• High and low shelving lters for smooth frequency adjustment
• Clear 10-segment level indicator with dedicated signal present
and clip LEDs
• Electronically balanced inputs
• High-quality, servo-balanced output stages, capable of driving
long cables

9
Before you get started
About this manual
Carefully read all instructions and warnings before operating
this appliance. Keep this manual in a safe place so that it can
be referred to when required.
Latest manual revision can be downloaded from:
http://www.apex-audio.be/manufacturing/support/downloads/
Inspection and unpacking
This appliance has been carefully packed in the factory and the
packaging was designed to withstand rough handling. Should
the unit appear to have been damaged in transit, do not discard
any of the packing material and notify the carrier immediately
as they would be responsible.
Save all the packing materials for future use if you ever need to
ship the unit again.
Please check the list below against the contents of the
packaging. If any items are missing or damaged, contact the
Apex dealer or distributor where you purchased the unit.
• dBQ-zero unit
•IEC AC power cable with mains plug
•This manual
Operating environment
This appliance is designed to operate in moderate climates at
a temperature between 5 and 40°C (41 - 104°F) with relative
humidity no more than 60 %.
Should the unit be installed in an equipment rack, it is important
to ensure that the operating temperature inside the rack does
not exceed the upper limit. This could be the case where the
rack contains power ampliers. A cooling fan may be necessary
in such installations.
Power requirements
BEFORE you connect any unit to the mains, please make
sure that your local AC supply is within the range of voltages
required by the unit.
The dBQ-zero is designed to work from an AC supply between
100 V and 240 V, at a frequency between 50 and 60Hz. No AC
voltage selector is provided as the device automatically adjusts
to the incoming AC voltage.
Precautions should be taken so that the appliance is properly
grounded at all times. This unit must be earthed.
Installation
If the unit is brought into a warm room from a cold environment,
internal condensation may occur. Wait an hour or two before
switching it on so that it can reach the ambient temperature.
Although this unit is intended for installation in a standard
19-inch rack it can nevertheless be used freestanding. If the
unit is installed in a ight-case or in an equipment rack, x the
unit with all four screws through the front panel holes.
For normal use no extra support is needed, but in more
extreme conditions, such as on the road, we recommend the
unit is supported at the rear.
Allow at least 10 cm (4 inches) at the back, front and sides of
the unit for sufcient ventilation.

10
Front panel
Front and rear panel description
Front panel
Input Controls:
Front panel controls for channel A and channel B are identical.
30-band graphic equaliser section; centre frequencies
follow the ISO standard.
Input level control with range from -10 to +10 dB. The con-
trol is centre-detented at unity gain (0 dB).
6/15 dB scale switch changes the maximum boost/
attenuation of the graphic EQ. The green LED indicates
that the ±15dB range is active.
High-pass lter frequency selection control.
High-pass lter on/off switch. The green LED indicates the
lter is active.
Low-shelving lter gain.
High-shelving lter gain.
Low frequency notch lter frequency selection.
Low frequency notch lter on/off switch. The green LED
indicates the lter is active.
High frequency notch lter frequency selection.
High frequency notch lter on/off switch.The green LED
indicates the lter is active.
Bypass switch; disables input level, graphic EQ and all
other lters in the channel.The green LED indicates that
level and lters are bypassed.
LED peak meter with separate signal present and clip
LEDs. The clip LED indicates that the signal level is within
1 dB of clipping.
Other front panel features:
The green Power LED illuminates when AC power is
applied to the unit. The dBQ-zero’s power switch is on the
unit’s rear panel.
3
4
2
1
5
6
7
8
9
10
11
12
13
14
12
3
4
5
67
8
911
12
13
10
14

11
Output connector pinouts are as follows:
IEC receptacle for AC mains.
A ‘POWER’ switch of the ‘rocker’ type applies power to the
unit.
Mains fuse holder. The fuse size is 20 x 5 mm, type T500mA
(slo-blo). Only replace a fuse with one of an identical size,
type and rating.
The unit’s serial number can be found on the rear of the
unit. Please record this number in the space provided on
the rst page of this manual.
Rear panel
Rear panel connections for channel A are described; those for
channel B are identical.
Channel A balanced input - female XLR
Channel A balanced input - 6.35 mm TRS jack
Channel A balanced input - screw terminal
Input connector pinouts are as follows:
Channel A balanced output - screw terminal
Channel A balanced output - male XLR
Channel A balanced output - 6.35 mm TRS jack
Rear panel
3
41
52
1
2
4
5
6
6
3
978
10
7
8
9
10

12
EARTH
J9
J2
EARTH
EARTH LIFT
J4
EARTHEARTH LIFT
EARTH LIFT
EARTH
J10
EARTH LIFT
Wiring the unit
Overview
The use of twin-and-screen cable is recommended for both
inputs and outputs.
Inputs
Preferred wiring for both balanced and unbalanced sources is
illustrated below:
Balanced
Unbalanced
Outputs
Preferred wiring for both balanced and unbalanced destinations
is illustrated below:
Balanced
Unbalanced
12
3
1 2
3
1 2
3
12
3
A ‘ground lift’ facility is available on the dBQ-zero’s inputs and outputs, which may be useful in resolving earth hum issues.
Normally the XLR’s pin 1 is connected to ground, but this connection may be broken by moving an internal PCB jumper.
groundlift jumpers on PCB
Connection Jumper
Input A J2
Input B J4
Output A J9
Output B J10

13
dBQ-zero Block diagram

14
Using the dBQ-zero
Operation of the dBQ-zero is straightforward. However, if you
would like to know the ner details of this equaliser, then we
invite you to read on.
Graphic EQ section
The graphic EQ section consists of 30 faders adjusting the gain
of 30 band-pass lters, each spaced by a 1/3rd of an octave.
These lters have a xed centre frequency, as dened by the
ISO standard, and a xed Q-factor.
The Q-factor of a lter is dened as the ratio of its centre
frequency to its bandwidth: Q = f / Bw. The greater the Q, the
smaller the bandwidth. The bandwidth is measured between
the ±3 dB points on either side of the band-pass centre
frequency. With Constant-Q designs, such as that found in the
dBQ-zero, the bandwidth of each of the band-pass lters stays
constant no matter what the boost or cut of the lter is. The use
of Constant-Q lters ensures that the composite lter response
of the graphic EQ accurately follows the physical positions of
the front panel faders. This is achieved by the lters minimising
frequency band interaction.
To obtain good results quickly, and to keep the program material
as clean as possible, we advise you to start from the lower
frequencies and work your way up to the higher frequencies
(from left to right). All sounds consist of a fundamental
frequency and harmonics (depending on the nature and origin
of that sound). When working from low frequencies to high you
should aim to change the fundamental rst and then its higher
harmonics.
Other advice is that it is better to cut than boost. When boosting,
you will reduce the overall headroom of the system. If, for
example, there is a lack of high frequency content, you can
boost those frequencies, but it would be better to cut some of
the lower frequencies instead.
Also, try to avoid extreme differences in gain between adjacent
bands as this will create large phase shifts. Try to make your
equalisation curve as smooth as possible.
Using the Scale switch enables the fader gain range to be
changed. In its normal position (LED off) the scale is ±6 dB: this
scale is suitable for minor adjustments but with great precision.
When the Scale switch is in, the LED will light and you will have
access to a range of ±15 dB.
Adjusting the overall gain
If you have applied gain to multiple frequencies, the signal
level may become very high and hence may clip, or cause the
Using the dBQ-zero
next item of equipment to clip. Use the input level to adjust the
overall dBQ-zero gain to keep the signal in an optimal range.
Similarly, if multiple frequency bands have been cut use this
input gain to amplify the overall level back to normal.
High-pass lter
By using the high-pass lter you can remove unwanted low
frequency content/noise, such as hum, rumble or microphone
handling noise. This lter has a xed slope of 12 dB/octave
and a cut-off frequency which is adjustable between 20 Hz and
250 Hz.
The high-pass lter may be switched on or off using the switch
adjacent to the HPF frequency control. The LED indicator lights
when the lter is enabled.
Low and high shelving lters
The low and high shelving lters are used to add or remove
excess ‘warmth’ or ‘brightness’ respectively. The frequency
of both lters is xed. The low shelving lter has a corner
frequency of 100 Hz and the high shelving lter is xed at 14
kHz.
Using the rotary controls enables you to adjust the level of cut
or boost applied to each lter (between ±9 dB).
Notch lters
The dBQ-zero offers two notch lters per channel, with
independent frequency selection and on/off switch. When a
notch lter is switched on, the corresponding LED will light.
The rst notch lter is adjustable between 25 Hz and 1.5 kHz
and the second is adjustable between 700 Hz and 18 kHz.
The principle function of the two notch lters is to attenuate
any problem frequencies that may be causing feedback or
any other unwanted noise. Feedback is most likely to occur at
frequencies between the xed lter bands on the graphical EQ.
This is why the notch lters are useful. Furthermore, the notch
lters have a higher degree of attenuation than the graphic EQ
lters and are therefore more efcient at preventing feedback.
Only the centre frequency of the notch lters may be adjusted by
the user. The Q-factor and attenuation have been intentionally
xed for ease of use. The attenuation is 20 dB and the Q-factor
is 4. These settings are sufcient to remove major sources of
feedback without altering too much of the program spectrum.
Similarly to the graphical section, when trying to remove
unwanted frequencies start with the notch lter frequency

15
selection fully counter-clockwise and then gradually increase
the frequency. Feedback mostly consists of more than one
frequency, but starting at a low frequency ensures you nd the
fundamental rst.
Bypass switch
When enabled, the bypass switch connects the equaliser’s
input directly to its output, bypassing the input gain and all
lter sections. In case of power failure the bypass feature is
automatically activated.
LED level meter
The LED level meter consists of a signal LED which illuminates
when the signal level is above -40 dBu; an 8-segment peak
meter (each segment represents a 3 dB increment in level) and
a multipoint monitoring clip LED.
The peak meter measures the signal at the output of the
equaliser, after the input level and all lter sections. It monitors
signal peaks as opposed to traditional VU-meter monitoring
RMS level. Peak level meters are better adapted to working
with today’s range of audio equipment.
Both the signal and clip LEDs monitor level at three different
points in the signal chain; at the input, after the graphic EQ
section and at the output.

16
Technical specications
Electrical specifications
Balanced line level input
Connectors ¼ TRS jack / 3-pin XLR / screw terminal
Impedance >10k ohms, balanced
Max. input level +21 dBu, balanced, 1 % THD+N
CMRR +21dBu, balanced, 1% THD
Balanced line level output
Connectors ¼ TRS jack / 3-pin XLR / screw terminal
Impedance < 50 ohm, balanced
Max. output level +21dBu into 600 ohms, balanced, 1% THD+N
Audio performance (unity gain, all settings at)
Frequency response 20 Hz - 20 kHz, ±0.5 dB
THD+N less than 0,005%, +4 dBu, 20Hz- 20 kHz, 22 kHz BW
Signal to Noise ratio >94 dB ref 4 dBu, 22 kHz BW, un-weighted
Crosstalk -75 dB, 20 Hz - 20 kHz, +4 dBu, channel-to-channel
Functions
Gain control: ±10 dB
Graphic EQ: 30 x 45 mm faders, switchable boost/cut ±6 dB or ±15 dB,
ISO frequencies, constant-Q
High pass lter: 12 dB/octave variable 20 Hz – 250 Hz
HF shelving lter: ±9 dB at 14 kHz
LF shelving lter: ±9 dB at 100 Hz
Two notch lters: Fixed Q factor of 4, xed depth of –20 dB, variable frequency
control: rst 25 Hz–1500 Hz, second 700 Hz–18 kHz
AC power requirements
Voltage Auto-detect 100 - 240 V - 50/60 Hz
Power consumption 30 VA
Environment
Operating
Temperature 5° to 40° C
Relative humidity up to 60 %
Storage
Temperature -20° to 60° C

17
Mechanical specifications
In the interest of product development, Apex reserve the right to modify or improve specications of this product at any time,
without prior notice and without any obligation to change or update equipment already delivered.
Dimensions
Unit
Width 482 mm (19-inch)
Height 133 mm (3U)
Depth 183 mm
Package
Width 560 mm
Height 215 mm
Depth 310 mm
Weight
Unit (Nett) 4.2 kg
Package (Shipping) 5.6 kg

18
Limited warranty
Limited warranty
Apex N.V. (“Apex”) warrants you, the original purchaser, or any party that purchases the device from you,
that its products are free from defects in material and workmanship under normal use for a period of two
(2) years from the date of original purchase. The date of purchase is the date which appears on the rst
invoice or any other proof of purchase provided by an Apex approved dealer.
Subject to the conditions and limitations set forth below, Apex will, at its discretion, either repair or replace
any part of its products that prove to be defective, provided that the product is returned with proof of
purchase, shipping prepaid, to an authorised Apex approved service facility.
Warranty cover of any repairs will only extend to the end of the original warranty period.
We will be happy to provide you with a list of authorised dealers to whom you can return the defective unit
or who will give you a returns note to enable you to send the unit to the factory.
Service turn-around time will be as fast as reasonably possible. If you are not satised with the repair,
contact Apex.
Exclusions and limitations
This limited warranty covers only repair or replacement for defective products manufactured by Apex.
Apex is not liable for, and does not cover under warranty, any loss of data or any costs associated with
determining the source of system problems or removing, servicing or installing Apex products. This
warranty excludes 3rd party software, connected equipment or stored data. Apex does not warrant
that the operation of the product will be uninterrupted or error-free. In the event of a claim, Apex’s sole
obligation shall be replacement of the hardware.
This limited warranty does not cover:
(1) any damage to this product that results from improper installation, accident, abuse,
misuse, natural disaster, insufcient or excessive electrical supply, abnormal mechanical or
environmental conditions or other external causes;
(2) any damage caused by operating the product outside the permitted or intended uses described
by Apex;
(3) any damage caused by any unauthorized disassembly, repair, or modication;
(4) consumable parts, such as batteries;
(5) any cosmetic damage.
Apex is not liable for consequential damages.
This limited warranty also does not apply to any product on which the original identication information
(including serial number) has been altered, obliterated or removed or any product that has not been
handled or packaged correctly.
Warranty services will be furnished only if the product is accompanied by a copy of the original retail
dealer’s invoice.
Warranty claims other than those indicated above are expressly excluded.

w w w . a p e x - a u d i o . e u i n f o @ a p e x - a u d i o . e u
Copyright
© 2010 APEX N.V. All rights reserved. This manual may not be reproduced or transmitted, either in part or as a whole, by any means,
be they mechanical or electronic, without the express written permission of APEX N.V.
Please recycle