Apex Digital dBZ-48d User manual

www.apex-audio.eu
dBZ-48d
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.

dBZ-48d Stereo zone mixer with with built-in DSP
March 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.
Installin accordance 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
Overview 12
dBZ-48d Block diagram 13
Using the dBZ-48d 14
Mono operation 14
Menu system and navigation 14
Preset submenu 15
Audio submenu 15
Settings submenu 17
Menu flowchart 18
Applications 19
Small bar-type venue 19
House of Worship 20
Audio to video synchronization 21
Technical specifications 22
Electrical specifications 22
Mechanical specifications 23
Limited Warranty 24
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.
In memory of our friend Robert Van Aenroyde, electronic audio engineer.

8
Introduction
Foreword
The Apex dBZ-48d can be used in any situation where one
or two stereo audio signals need to be routed and mixed at
different levels to up to four destinations.
Common areas of application are as zoners/distribution
ampliers in installed audio situations, as time alignment
devices for sound reinforcement systems, and to provide audio/
video synchronisation.
Dear customer,
Thank you for buying the Apex dBZ-48d. The dBZ-48d is a professional quality, DSP-equipped 2-into-4 stereo zone
mixer designed to manage audio distribution and time alignment in a variety of sound reinforcement applications
including live PA and installed sound systems.
Product highlights
• Two stereo input channels
• Four stereo output channels
• Electronically-balanced inputs
• High-quality, servo-balanced output stages, capable of driving
long cables
• Stereo/mono switch on each input and output channel, with
LED indication
• Mute button on each input and output channel, with LED
indication
• LED signal metering for L & R on each input and output channel
• Integral DSP (Digital Signal Processing) section, providing:
• Adjustable delay for each output channel, 0 – 1 second
• Hi- and lo-pass lters in each output channel
• Polarity (phase) switching for output channel
• Delay can be specied in units of ms, distance or
video/lm frames
• Temperature compensation for delay calculations (°F/°C)
• 8 presets for storing all DSP settings
• DSP by-pass for each output channel
• Simple menu system with LCD display
• Rugged all–metal chassis
• Professional quality XLR connectors throughout
• 1U 19” rack-mounting unit
When used as a zoner, any of the four outputs may receive
either of the two inputs at any level, or a mix of them.
Mono/stereo switching on both the inputs and the outputs
makes matching the unit to a variety of sources and speaker
systems simple. Filtering can be applied to individual outputs to
tailor the signal to suit the acoustics of the area being driven.
An alternative installed sound application is to use the unit as a
distribution amplier (DA), to drive rows of loudspeakers in an
auditorium. It is common practice to drive speakers further from
the stage at a higher level, and to introduce delays to time-align
the speaker rows accurately.
When used with a sound reinforcement system, the dBZ-48d
can be used as a simple electronic crossover. The lters may
be set to congure any two output channels as a two-band
crossover; two pairs of outputs may be set differently to suit
different speaker systems.
Another live sound application is to use the dBZ-48d to
derive the feeds for a system’s delay towers; time delays
can be accurately added to each output channel, calculated
automatically from distance and temperature data.
The dBZ-48d is also extremely useful in providing nely-
adjustable audio delays to enable accurate audio/video
synchronisation at live events. Video processing generally
introduces signal delays in discrete numbers of video frames;
the dBZ-48d’s delays can be adjusted in frames to simplify this
process.

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.
This manual describes dBZ-48d internal software version v1.0.
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.
• dBZ-48d 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 dBZ-48d 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 IN A are described: those for IN B are
identical.
IN A LEVEL is a stereo control adjusting input stage gain,
with range from -∞to +6 dB.
The control is centre-detented at unity gain (0 dB).
Pressing the latching MUTE button removes Input A’s signal
from all outputs.
Red LED indicates Input Mute [2] is active.
The Left and Right channels of the Input may be summed
with the MONO button. A 6 dB pad is inserted in mono mode to
maintain mono/stereo level compatibility.
Green LED indicates Input Mono [3] is active.
Three LEDs indicating signal level for each channel of the
stereo input: the green sig LED illuminates at -20 dBu; two
further yellow LEDs illuminate when the input level is +4 dBu
and +10 dBu respectively, with the LEVEL control set to zero.
The meters are post the input level control [1], and therefore
can be used when this is adjusted. However, they are pre the
mute button [2], and thus will continue to indicate the presence
of an input signal even when the mute is active. The meters
possess PPM-style ballistics (fast attack, slow decay).
A separate red Peak LED indicates that the signal level is
within 1 dB of clipping. The signal is monitored before the level
control [1] as well as at the metering point.
Output Controls:
Front panel controls for OUT 1 are described: those for OUTS
2 to 4 are identical.
OUT 1 MIX A is a stereo control adjusting the level at which
Input A signal is fed to Output 1. The range is from -∞to +6 dB.
The control is centre-detented at unity gain (0 dB).
OUT 1 MIX B has an identical function to [8] for Input B.
Pressing the latching MUTE button mutes Output 1
completely.
Red LED indicates Output Mute [10] is active.
The Left and Right channels of the Output may be summed
with the MONO button. As with the input mono function, a 6 dB
pad is inserted to maintain mono/stereo level compatibility.
Green LED indicates Output Mono [12] is active.
A set of meters is provided with characteristics identical to
those of the input meters [6]. The output metering point is post
both the Mix controls [8 & 9] and the Output Mute button [10].
A separate Clip LED indicates that the signal level is within
1 dB of clipping. The signal is monitored before the Mix controls
[8 & 9] as well as at the metering point.
If the unit is being used purely as a zoner or distribution
amplier with no DSP functions being required (delays, ltering,
etc.), the DSP section for the output section may effectively be
switched out of the signal path with the DSP BYPASS button.
Yellow LED indicating that the DSP section is bypassed.
Other front panel features:
The 2-row x 16-character LCD display allows control of the
dBZ-48d’s DSP section.
Rotary control for menu navigation, data entry, etc. The
control can also be pressed inwards, to perform an “Enter”
action in the menu system.
The Menu/Undo button gives entry to the menus, and
also performs an ‘Undo’ function in certain parts of the menu
system.
Navigation between menu items is with the rotary encoder/
Enter control and the Up/Down buttons. Pressing and holding
these buttons simultaneously also activates a front panel
lockout function. A full description of the menu system is given
later in this manual.
The green Power LED illuminates when AC power is
applied to the unit. The dBZ-48d’s power switch is on the unit’s
rear panel.
The dBZ-48d may be mounted in a standard 19” rack
housing. Please observe the guidance regarding ventilation.
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11
Rear panel
3 4
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Rear panel
All connections to the dBZ-48d are made via the rear panel.
Rear panel connections for IN A are described: those for IN B
are identical. Similarly, the details of the output connections are
identical for all four channels.
Input A L & R. Inputs are on latching 3-pin female XLRs,
with separate connectors for left and right channels. The inputs
are electronically balanced. The pinout is as shown below:
PIN XLR (female)
1 GND
2 ‘Hot’ ( + )
3 ‘Cold’ ( - )
Output 1 L & R. Outputs are on 3-pin male XLRs, with
separate connectors for left and right channels. The outputs
are electronically balanced. The pinout is as shown below:
PIN XLR (male)
1 GND
2 ‘Hot’ ( + )
3 ‘Cold’ ( - )
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.
A 9-pin D-type connector (RS-232) is tted for the purpose
of updating the dBZ-48d’s rmware. This procedure should only
be performed by an Apex distributor. Note that this connector
has no other function.
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.
7
6

12
The Apex dBZ-48d can be used in any situation where one
or two stereo audio signals need to be routed and mixed at
different levels to up to four destinations.
See Block diagram on next page. Each of the two inputs is
provided with electronic balancing, RFI ltering, mono/stereo
switching, level control, a muting circuit and LED metering.
After A-to-D conversion, the inputs are routed through the DSP
section, where they are split to the four output channels.
Delay, ltering and polarity (phase) are implemented by DSP
on a per-output channel basis. After D-to-A conversion, the
level of each input signal fed to each output channel may be
Wiring the unit
Overview
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
A ‘ground lift’ facility is available on the dBZ-48d’s inputs, which
may be useful in resolving earth hum issues. Normally the input
XLR’s pin 1 is connected to ground, but this connection may be
broken by moving an internal pcb jumper.
individually set. Again, mono/stereo switching, muting and LED
metering are available for each output. The servo-balanced
output stage design results in a very low output impedance,
making it possible to drive long balanced lines (e.g., from a
FOH mix position to stage amp racks).
Note that the DSP processing (delay, ltering and polarity...)
precedes the mixing stage (where inputsA and B are combined),
and that the mixing is in the analogue domain. This architecture
allows rapid level/mix adjustments in “real-time”, without any
delay between making the adjustment and hearing its effect.
Outputs
Preferred wiring for both balanced and unbalanced destinations
is illustrated below:
Balanced
Unbalanced
groundlift jumpers on pcb

13
dBZ-48d Block diagram

14
Using the dBZ-48d
Operation of the dBZ-48d’s analogue input and output sections
is entirely straightforward, and requires only correct adjustment
of the respective level controls.
Start with all the front panel rotary controls fully anticlockwise.
Connect the stereo input source(s) to IN A and IN B and the
stereo outputs to their respective ampliers (or other signal
processing) as appropriate. With the programme material
present, rotate the input level controls until the second (+6dB)
LEDs ash on the loudest peaks, but so that the red CLIP LEDs
do not illuminate. Then rotate the output level controls for each
output channel in turn to obtain a similar display on each pair of
output LED meters.
All DSP parameters are adjustable from the front panel via the
menu system and alphanumeric display. The dBZ-48d also
provides eight memory presets enabling congurations to be
stored and recalled from the front panel.
Mono operation
The MONO buttons on the input channels should be used if the
input in question is being fed from a mono source. In this case,
the input signal may be applied to either the L or R input.
If any of the outputs are to be used in mono (e.g. with the
dBZ-48d in use as a zoner, it may not be practical for some
room areas to support effective stereo operation), the output
channel MONO buttons may be used to make an L+R sum of
the stereo input signals available at both L and R outputs of a
channel. This does not compromise the other output channels
being used as stereo, of course.
Menu System and Navigation
The dBZ-48d’s DSP functions (delay time, ltering, polarity
etc.) are all controlled through the menu system, using the front
panel LCD display, rotary encoder and the three associated
push buttons.
After initial boot-up (during which the display shows the version
number of the unit’s rmware), the LCD display goes to the
Home Page, shown below:
This is the display state during normal operation.
The ‘house’ symbol in the display conrms that the menu
is either at the Home Page or at the top (‘Home Menu’)
page of one of the three submenus (see below).
The ‘closed padlock’ symbol indicates that the front
panel DSP controls are locked and adjustment is not
possible.
An asterisk after the Preset number indicates that the
Preset currently in use has had its stored parameters
modied, but not saved.
The menu system comprises three submenus:
• Preset submenu
• Audio submenu
• Settings submenu
To access the submenus from the Home Page, press the
rotary encoder knob (the “Enter” function) or the MENU/
UNDO button. The Preset submenu’s Home Menu item is rst
displayed; pressing Enter will enter the actual submenu. The
other two submenus (Audio and Settings) may be accessed in
a similar manner by rotating the encoder from the Home Menu
and pressing Enter.
To exit any of the submenus, press MENU/UNDO to return to
the submenu’s Home Menu page, and MENU/UNDO again to
exit the submenus and return to the Home Page.
Using the dBZ-48d

15
Audio submenu flowchart
Preset Submenu
Once the rst submenu item is displayed, the rotary encoder
can be used to step through the others; to select an item, press
Enter while it is displayed.
Recall Preset
The dBZ-48d has eight Presets; these are memories which can
be used to store sets of parameters for the unit’s DSP section.
Preset 1 is selected initially; use the UP (K) and DOWN (J)
buttons to select another of the 8 available. Pressing Enter
opens an Are you sure ? screen, with No as the default
response; rotating the encoder clockwise changes this to Yes.
Pressing Enter then recalls the Preset and loads the stored
parameters. Pressing Enter with No displayed reverts to the
Preset submenu Home Menu page.
If the Preset is empty – i.e., nothing has been previously saved
in it – the display also reverts to the Preset submenu Home
Menu page.
Store Preset
The process of storing the unit’s set of current DSP parameters
to a Preset is similar to recalling them. Preset 1 is the default;
use the UP/DOWN buttons to select another. Pressing Enter
opens the Are you sure? screen as above, press Enter to
store the settings.
Erase Preset
This submenu option may be used to clear the Preset whose
number is displayed, erasing its contents. Operation of the
submenu option is the same as Recall Preset above.
Audio Submenu
Once the rst submenu item is displayed, the rotary encoder
can be used to step through the others; to select an item, press
Enter while it is displayed.
Preset submenu flowchart

16
Delay Time
A delay of up to 1 second can be introduced in each of the four
outputs, as required.
Output No.1 is selected initially; use the UP (K) and DOWN
(J) buttons to select another. Delays in different outputs can
easily be compared using these buttons.
To vary the delay, press Enter and use the rotary encoder.
Default units are milliseconds; alternatives are available (see
Settings Submenu). A choice of coarse or ne adjustment of the
delay time (when in milliseconds) may be made by using the UP
and DOWN buttons; UP adjusts the time in 1 ms increments,
DOWN in 20,83 µs increments (1 sample at 48 kHz sample
rate). To set the displayed value, press Enter. To cancel the
change press MENU/UNDO.
Note that once a delay setting has been entered, if the delay
units are set to anything other than milliseconds, the screen
will alternate between the value set in the chosen units and
the equivalent in milliseconds (with the value in brackets).
However, while its value is being adjusted, the delay setting
remains shown in the selected units.
High-Pass Filter
A high-pass lter may be inserted in any of the dBZ-48d’s
outputs. Output No. 1 is selected initially; use the UP (K) and
DOWN (J) buttons to select another.
The lter is a fourth-order (slope of -24 dB/octave) Linkwitz-
Riley. The cut-off frequency (-3 dB point) is selectable from a
range of twenty-one; available frequencies are at the standard
ISO 1/3-octave spacing in the range 25 Hz to 2.5 kHz. The
default setting is Bypass.
Press Enter to adjust the lter frequency; use the rotary
encoder to select a frequency, pressing Enter again to set it.
Press MENU/UNDO to cancel the change.
Low-Pass Filter
A low-pass lter may be inserted in any of the outputs in exactly
the same way as the high-pass lter. The lter is a fourth-order
(slope of -24 dB/octave) Linkwitz-Riley.
The range of frequencies available is from 16 kHz down to 40
Hz. Default setting is Bypass.
Selection and operation of the Low-Pass Filter is identical to
that for the High-Pass Filter.
Polarity
The signal available at any output may be phase-inverted
relative to the input signal. Additionally, it is possible to phase-
invert either the L or R channel on each output independently.
The default state is for neither the L nor R channels of any of
the outputs to be inverted.
Output No. 1 is selected initially; use the UP (K) and DOWN
(J) buttons to select another. The display will indicate the
current polarity of the L and R channels of the selected output
with a plus sign (+) to indicate non-inversion or a phi (Ø) to
indicate inversion. Press Enter to alter this; a cursor appears
under the currently-selected channel. Use UP (K) to select
the Right channel and DOWN (J) to select the Left channel.
Then use the rotary encoder to change the polarity, pressing
Enter again to accept the setting and exit.
Note that if MONO is selected, both Left and
Right channels must have the same phase (either
in-phase or inverted), otherwise the channels will
cancel and result in a strange-sounding and attenuated output.
Remember that level adjustment and the mono function are
performed after the digital processing !

17
Delay Units
This menu item sets the units used for delay time in the Audio
submenu. The default units are milliseconds; if preferred, delays
may be adjusted in meters or feet, an internal calculation being
performed to translate the physical distance into time.
As a further option, delay time may be expressed in terms
of video frames, with frame rates of 24, 25 or 30 fps being
selectable. This option should be used when the dBZ-48d is
being used as an audio-video synchroniser.
Press Enter to alter the setting, use the rotary control to select
an alternative unit if wished, press Enter again to select it.
Settings submenu flowchart
Settings Submenu
Once the rst submenu item is displayed, the rotary encoder
can be used to step through the others; to select an item, press
Enter while it is displayed.
Temperature
This parameter is only relevant if the delay units selected are
of distance (feet or meters). The speed of sound in air varies
slightly with temperature, and adjustment is necessary if the
ambient temperature is different from the ‘standard’temperature
of 21°C.
Use the rotary control to alter the reference temperature; the
display shows this both in °C and °F. Press Enter to select it
LCD Contrast
It may be necessary to alter the characteristics of the LCD
display under extreme ambient lighting conditions. Use the
rotary control and Enter to adjust.
Front Panel Lock
To prevent inadvertent alteration of DSP parameters, the DSP
section of the front panel may be locked. This includes the DSP
BYPASS buttons in the output channels.
To lock the panel, press and hold both the UP (K) and DOWN
(J) buttons simultaneously. The screen displays the message
Front panel lock and the closed padlock symbol, and a timing
bar of full stops moves from left to right. At the end of the timing
period, the screen conrms Front panel is locked ! If the
buttons are released before the time period is expired, the front
panel does not lock, and the lock sequence exits.
To unlock the front panel, press and hold the UP (K) and
DOWN (J) buttons again; the unlocking procedure is identical
to that for locking except that the word Unlock(ed) replaces
Lock(ed).
DSP bypass
There are many applications (i.e. when used as a zoner) where
delay, ltering or polarity control are not required. In such
cases, these functions may be overridden in any or all of the
output channels with the DSP BYPASS buttons.
Note that the DSP BYPASS buttons are disabled by the Front
Panel Lock function. Although the buttons are non-latching,
each output channel retains its BYPASS state when the panel
is locked.

18
Menu flowchart

19
Small bar-type venue with multiple areas, featuring both live and recorded music
This application uses the dBZ-48d as a 3-way zoner, with two
outputs being used to derive LF and HF feeds for a two-way
speaker system in one area. The set-up would be suitable for
a small venue which features live music in a main area, while a
CD player, music server, TV sound or similar is made available
at different levels in other rooms.
The stereo output of the live music mixing console is connected
to In A, while the stereo recorded music feed (probably via a
switcher of some kind) is connected to In B.
Out 1 feeds the live area sound system, with Out 1 Mix A being
used to control the ultimate sound level. Out 1 Mix B is set to
minimum.
Out 2 and Out 3 feed the sound system in a secondary area
(bar or restaurant, e.g.), and it is assumed that a speaker
system with a separate subwoofer is being used.
Out 3 feeds the subwoofer, and the hi-pass lters and lo-pass
lters are set to 25 Hz and 125 Hz respectively, thus allowing
only bass frequencies through to the LF unit. Out 3 is also set
to mono as stereo imaging can be dispensed with for LF (and
commonly, only one unit is used). Out 2’s hi-pass lter is set to
reject frequencies below 100 Hz, and is connected to the main
speaker system in the area.
Out 2 Mix A and Out 3 Mix A are set to minimum as only
recorded music is required at this moment in this area.
Out 2 Mix B and Out 3 Mix B are used to control the overall in
the area independently of other outputs.
At any time, the user may decide to feed the live music to this
area by changing the Out mix of A and B accordingly.
Out 4 feeds TV sound or recorded music to a quieter area, which
might have a plasma/LCD screen or projector, for example.
Mono is used, this being adequate for TV, and the hi-pass and
lo-pass lters are set at 80 Hz and 16 kHz respectively, to reject
any extreme frequencies, as it is likely that the speaker system
in such a room would not be able to handle them.
Out 4 Mix A is set to minimum as live music is not required in
this room, and Out 4 Mix B is used to set the volume.
Applications

20
House of Worship sound system
It is common practice in many churches and other places of
worship for two mixers to be used; a small simple one, allowing
control of perhaps one or two mics plus a music source, and
a larger mixing console, used with live musicians and choir,
etc. This would generally be operated by a dedicated sound
engineer.
The dBZ-48d may be used in this context to send the outputs of
the two mixers to several banks of loudspeakers, with a specic
time delay inserted in each output to time-align the various
banks.
Each of the four stereo outputs is routed to its own stereo
amplier. The output of each amplier channel drives a pair
of loudspeakers, the pairs being mounted at an increasing
distance from the front of the church. Signal path lengths of
20 m, 30 m and 40 m have been assumed as the distance of
each Rows 2, 3 and 4 respectively from the front of the church.
Inserting delays corresponding to these distances (delays
maybe entered into the dBZ-48d directly in units of distance)
ensures that the sound from each speaker row arrives at a
listening position at the same time.