BX30 subwoofer
Owner’s Manual
- and Safety Instructions
Preliminary Version 990209
455 490 A
EXPLANATION OF GRAPHIC SYMBOLS
The lightning flash with arrowhead symbol, within an
equilateral triangle, is intended to alert the user to the
presence of uninsulated “dangerous voltage” within the
product’s enclosure that may be of sufficient 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.
This product conforms to the following Product Specifications:
EN 60065
EN 55103-1
EN 55103-2
EN 60065 (LVD)
Safety requirements for mains operated electronic
and related apparatus for household and similar
general use.
Use only in environments where humidity is between
30 and 70%rh and temperature between 5° and 40° C
EN 55103-1 (Emission)
Electromagnetic compatibility – Product family
standard for audio, video, audio-visual and
entertainment lightning control apparatus for
professional use
EN 55103-2 (Immunity)
Electromagnetic compatibility – Product family
standard for audio, video, audio-visual and
entertainment lightning control apparatus for
professional use
Copyright 1999 by DYNAUDIO ACOUSTICS A/S. All rights reserved. No part of this manual may be reproduced,
stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, or otherwise
whatsoever, without the prior written permission of DYNAUDIO ACOUSTICS A/S.
The information contained in this document is subject to change without notice.
Important Safety Instructions
Safety
Read these instructions before any connection to the apparatus.
Please keep these instructions in a convenient place.
CAUTION
To avoid electric shock, do not open the subwoofer.
There are no user-serviceable parts inside.
Installation
If the BX30 have been stored for a longer period in an environment, where temperature was low or
humidity high, we recommend that the BX30 is disconnected for at least three hours before use.
Do not operate this apparatus near water.
Do not install near any heat sources such as radiators, heat registers, fireplaces, stoves, or other items
that produce heat.
Do not cover the apparatus. Keep it ventilated, minimum 3 cm all around the cabinet.
Power connection
Do not defeat the safety purpose of the grounding-type plug. A grounding-type plug has two blades
and a third grounding prong. The third prong is provided for your safety. If the provided plug does not
fit into the wall outlet, consult an electrician for replacement of the obsolete outlet.
Protect the power cord from being stepped on or pinched, particularly at plugs, convenience
receptacles, and the point where they exit from the apparatus.
Unplug this apparatus during lightning storms or when unused for long periods of time.
Attachments
Only use attachments/accessories specified by the manufacturer.
Servicing
Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been
damaged in a way such as power supply cord or plug is damaged, liquid has been spilled or objects
have fallen into the apparatus, the apparatus has been exposed to rain or moisture, has been dropped,
or does not operate normally.
Maintenance
To prevent fire or shock hazard, clean only with a damp cloth. Never use cleansers or chemicals.
Sound pressure level
Please note that excessive listening at high sound pressure levels may cause permanent hearing
damage.
Warning
This equipment can produce
sound pressure levels in excess of
90 dB(A)
Please follow all instructions and heed all warnings
CONTENTS
SAFETY ................................................................................................................................................ 3
Installation .................................................................................................................................................. 3
Power connection........................................................................................................................................ 3
Attachments ................................................................................................................................................ 3
Servicing ..................................................................................................................................................... 3
Maintenance................................................................................................................................................ 3
Sound pressure level ................................................................................................................................... 3
BX30 OWNER’S MANUAL ................................................................................................................... 5
Unpacking................................................................................................................................................... 5
INTRO .................................................................................................................................................. 5
INLET SECTION .................................................................................................................................... 6
OPERATING PANELS ............................................................................................................................. 7
BX30 PLACEMENT .............................................................................................................................. 9
COOLING ............................................................................................................................................. 9
MOUNTING .......................................................................................................................................... 9
5.1 SYSTEMS ..................................................................................................................................... 11
SOUND CALCULATOR ........................................................................................................................ 12
BX30 TECHNICAL DESCRIPTION ........................................................................................................ 13
System topology........................................................................................................................................ 13
FLOW DIAGRAMS ............................................................................................................................... 14
BOX DATA ......................................................................................................................................... 15
BX30 Owner’s Manual
BX30 Owner’s Manual
Unpacking
Every loudspeaker leaving DYNAUDIO ACOUSTICS A/S has been carefully and thoroughly inspected and tested.
When unpacking the subwoofer, be sure to check if any physical damage has occurred to the subwoofer due to shipping.
In case of damage, please contact the selling dealer immediately.
When unpacking the subwoofer, verify that the voltage switch is positioned according to area voltage requirements.
Intro
The BX30 is a sophisticated and versatile low frequency monitor speaker, which satisfies all the demands of the
recording and postproduction facilities.
As a stand-alone unit it can be used to provide the sub bass channel of a 5.1 multi speaker system.
It can be used as the bass-extension-section of a small full range monitor, in single mono, dual stereo or multiple
applications, where a large amount of low frequency energy is required.
The BX30 features an innovative electro-acoustic system which optimises bass output power for the music spectrum,
giving an advantage of up to 18 dB over conventional bass reflex designs.
Figure 1. The BX30 driver has a –6 dB point at 17 Hz, which results
in superb reproduction of the most demanding material.
An electronic filter limits the response to 22 Hz in order to prevent large excursion by sub sonic signals and rumble.
This filter can be removed when the BX30 is used for reference listening purposes. This is a factory modification, which
must be ordered through an authorised agent.
A single BX30 is a perfect match to any of the smaller dynaudio acoustics  monitors, such as the BM5, BM6, BM6A
or M1. The integrated 95 Hz high-pass crossover combined with the variable level and phase adjustment allows perfect
matching in any position, giving complete freedom of movement and placement of the BX30; very useful in confined
spaces!
Two BX30s will be more than a match for the BM15A and BM15, while four will rival the output of very large monitor
systems; the BX30 can, thanks to its flexibility, grow with your requirements and give a lifetime of service.
5
BX30 Owner’s Manual
Inlet section
Figure 2. AC inlet
AC inlet
Power switch
This is a grounding-type plug.
Do not connect to a convenient AC outlet on a sound system or non-grounding AC
outlet.
0:
1: There is voltage on the amplifier.
The Protection LED lights up, red.
Voltage switch
115/230: The amplifier’s power supply can be used with various voltages, 115/230 V ~, and
frequencies, 50/60 Hz.
The voltage selector switch on the back panel of the subwoofer shall be positioned
according to the required voltage in your area. The manufacturer fixes the setting
prior to shipping.
Caution Do not try to alter the voltage setting, as doing so will result in a blown fuse. Wrong
settings may result in damaged electronics.
Fuse-drawer
The main fuse for the subwoofer is located in the Fuse-drawer.
Replace For continued protection against risk of fire, replace only with same type of fuse.
115 V:
230 V:
6
8 A / 125 V Slow-blow
4 A / 250 V Slow-blow
BX30 Owner’s Manual
Operating panels
Figure 3. Subwoofer control panel
LED
Limiter: Lights up when the limiter circuits start protecting the woofer. The limiter does not
affect the signals on the XLR OUT.
Detect: When the input signal is above – 20 dB it lights green. If the line signal increases to
0 dB it turns red.
The protection circuit also measures signal levels inside the subwoofer amplifier. If
the level calibration is turned clockwise and the signal in one of the measuring
point surpass –20 dB.
Protection: Switch on the subwoofer, and the LED turns red, and for the next 5 seconds the
protection circuit checks the amplifier. When everything is all right, the protection
circuits switch the signal- and speaker relays on.
LEVEL
Calibration: Adjustment of the subwoofer level.
Sensitivity: Level attenuation of input signal.
–10 dBm consumer level signal
+4 dBm pro level signal
Mute for muting the subwoofer. The signal on XLR OUT remains.
PHASE
Calibration: Changes the phase alignment IN versus subwoofer.
Polarity: Invert the IN proportion subwoofer phase.
CROSSOVER
Low Pass: Changes the crossover frequency subwoofer itself. To fit the BX30 to your main
speakers.
7
BX30 Owner’s Manual
Figure 4. Output control and connectors
CROSSOVER
High Pass: Changes round the OUT line signals between :
Direct: The signal on XLR IN connectors is directed to the XLR OUT.
95 Hz: The signal on XLR IN runs through a 95 Hz high pass filter, before it is
send to the XLR OUT.
IN
L and R : Balanced line signal input.
Pin 1 : Ground
Pin 2 : Non inverted (hot)
Pin 3 : Inverted (cold)
OUT
L and R: Balanced line signal output.
Pin 1 : Ground
Pin 2 : Non inverted (hot)
Pin 3 : Inverted (cold)
If CROSSOVER High Pass is set on 95 Hz and the BX30 is turned off, the relays
in the amplifier will change and thereby the OUT signal will disappear.
8
BX30 Owner’s Manual
BX30 Placement
Single Unit (Stereo)
The correct location and phase alignment of the BX30 is essential to achieve accurate performance with any given
system. The best results are usually achieved with the BX30 floor standing and at the same distance from the listening
position as the main speakers. The unit should be placed at the centre point of a line between the main speakers if used
as part of a stereo system. The polarity and phase can be adjusted so that there is the maximum cut in bass at 95 Hz
when the unit is switched ‘out of phase’. This should ensure the optimum coupling with the main speakers when ‘in
phase’.
Double Units (Stereo)
The optimum stereo performance will be achieved with one BX30 directly beneath each main speaker. This will ensure
correct panning and image location of signals when mixing. If performance is affected by the presence of a solid
console or equipment furniture, it may be necessary to place the BX30 units at the same level as the main speakers in
which case suitable, mechanically adequate stands should be employed. In any event the BX30s should always be
placed equidistant to the mixing position in order to avoid phase cancellations.
Single Low Frequency Effects Channel (.1)
In this mode the BX30 will reproduce only the low frequency content of a discrete multi channel format and the
positioning is usually asymmetrical to the room. This is done to avoid direct coupling to standing waves which results
in better frequency response. The internal filter should be set to 120 Hz for film mixing or as required by the medium
being used. Several BX30 units may be daisy chained using the input and output XLR connectors.
Large Active Systems
The BX30 can be used as part of a large sound system to handle bass frequencies up to 120 Hz. The phase adjustment
allows combination with any mid range device and the integrated signal and power management makes the BX30
suitable for club and sound system installations. It is also suitable for mobile use but it should not be used outdoors or
anywhere prone to damp or moisture, for electrical safety reasons.
The cabinet is designed for free standing or stand mounting; flying or rigging will require a suitable cradle or full
supporting bracket. No fixing should be made directly to the MDF panels or rear electronics panel.
Cooling
The BX30 has full logic thermal control, which will shut the amplifier down in the event of the inner heat sink reaching
60 degrees Celsius. Always allow sufficient air flow, around the rear panel, especially if the unit is mounted in a front
wall baffle or similar enclosure.
Under normal circumstances the BX30 should not be mounted with the heat sink fins horizontal, as this will impede
convection cooling.
Mounting
Under some conditions it may be desirable to place the BX30 on anti vibration mounts so as avoid direct transmission to
a floor or shelf unit. Special damping units may be ordered from your dynaudio acoustics  agent who will facilitate
this without compromising bass performance. Placing the unit on soft foam or carpet may reduce audible buzzing or
vibration.
The design of the amplifier lead to the possibility of rotating the amplifier to horizontal or vertical. Disconnect the
BX30, then remove the eight fixing screws. Lift the amplifier carefully out of the mounting hole. Then rotate it in the
direction which suits you. Place it again and mount the eight fixing screws.
9
BX30 Owner’s Manual
Figure 5. Shows the standard 1/3 octave response in active bass
extension mode with the crossover pre set to 95 Hz.
The response offers a seamless match to any high quality monitor system but it is particularly well suited to smaller
models with limited bass output capability.
Figure 6. The flexibility of switching low pass and match high pass x-overs means
the BX30 can be matched to any system with ease and accuracy.
Figure 7. The impulse response of the BX30 is almost perfect
for a two octave, 100 Hz band pass filter.
The impulse response Figure 7 shows the superior transient response of direct radiating systems compared to narrow
resonant cavities and chambers.
10
BX30 Owner’s Manual
5.1 Systems
Dolby AC3 format.
The specification for each channel is strictly defined and the BX30 conforms carefully and accurately to that standard.
The agreed sound level capability for the sub bass channel in film theatres is 115 dB in any one-octave band, in any
seat. The BX30 can deliver this output with clean, undistorted power, which is equally suited to small rooms, or in
multiple (modular) formats in much larger spaces. Our design chart gives SPL predictions for different rooms. Please
note these are narrow band or single frequency predictions, not broad band levels which are much higher.
For example a single BX30 will produce 112 dB at 63 Hz at one metre, enough to match nearly all near-field monitors,
while eight units can satisfy the requirement for THX theatres of 1000 cubic metres at a distance of 10 metres.
By comparison the Dolby requirement for calibrated 5.1 systems is only 105 dB and so the BX30 is well equipped to
deal with the future demands of digital multi channel audio, especially in the professional dubbing theatre.
11
BX30 Owner’s Manual
Sound Calculator
ONE BX30 AT VARYING DISTANCE D FOR 100WRMS POWER
Freq. L W H Lw(1W) Lw(Rqd) EPR
Q
D
S
V
63
63
63
63
63
63
63
20
20
20
20
20
20
20
10
10
10
10
10
10
10
5
5
5
5
5
5
5
100
100
100
100
100
100
100
120
120
120
120
120
120
120
100
100
100
100
100
100
100
2 1,0 700
2 2,0 700
2 3,0 700
2 4,0 700
2 8,0 700
2 12,0 700
2 16,0 700
1000
1000
1000
1000
1000
1000
1000
a
T60 Lp calc Dc
0,4
0,4
0,4
0,4
0,4
0,4
0,4
1 TO 8 BX30 UNITS WITH 1, 10 AND 100W AMP POWER EACH
L W H BX30
Lw
EPR
Q
D
S
V
a
20
20
20
20
20
20
20
20
20
20
20
20
L
W
H
Lw
Q
D
EPR
10
10
10
10
10
10
10
10
10
10
10
10
5
5
5
5
5
5
5
5
5
5
5
5
1
1
1
2
2
2
4
4
4
8
8
8
100
110
120
103
113
123
106
116
126
109
119
129
1
10
100
1
10
100
1
10
100
1
10
100
2
2
2
4
4
4
8
8
8
16
16
16
length
width
height
sound power of source speaker
directivity index
distance to point of measurement
electronic power required (amplifier)
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
0,50
0,50
0,50
0,50
0,50
0,50
0,50
112
107
104
103
101
100
100
3,21
3,21
3,21
3,21
3,21
3,21
3,21
T60 Lp calc Dc
10,0
10,0
10,0
10,0
10,0
10,0
10,0
10,0
10,0
10,0
10,0
10,0
700
700
700
700
700
700
700
700
700
700
700
700
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,4
0,50
0,50
0,50
0,50
0,50
0,50
0,50
0,50
0,50
0,50
0,50
0,50
S
V
a
Sa
T60
Lp
Dc
room surface area
room volume
average absorption
total absorption
reverb decay time
sound pressure at D
critical distance Ld=Lr
81
91
101
84
94
104
88
98
108
93
103
113
3,21
3,21
3,21
4,54
4,54
4,54
6,42
6,42
6,42
9,08
9,08
9,08
BX30 Sound Calculator
120
power and Spl
100
80
EPR
60
Lp calc
40
20
0
1
1
1
2
2
2
No. of BX30
12
4
4
4
8
8
8
BX30 Owner’s Manual
BX30 Technical description
System topology
The BX30 is fully active with a sophisticated signal management system. The following features are provided as
standard.
Dual inputs and outputs fully balanced with automatic bypass in the event of power loss. The outputs are buffered and
filtered with a 24 dB/ octave high pass network which forms a perfect 24th order crossover (Linkwitz-Riley) when the
BX30 is set at 95 Hz Low Pass mode. A direct through switch is also provided for multiple BX30 linking.
•
All inputs and outputs are relay switched for full protection of system. There is a voltage protection limiter on each
input to protect the balanced line level amplifiers.
•
A full logic management and protection system controls all switching functions with LED indication of fault
conditions.
•
Switchable –10 dB, +4 dB or mute gain with level control.
•
Three precision low pass networks, calibrated to meet international standards;
• 80 Hz for critical listening applications using high quality small monitors.
• 95 Hz for most subwoofer applications in stereo or part of a multi channel system.
• 120 Hz for full 5.1 systems requiring a separate low frequency effects channel. This mode is designed to meet
Dolby, DTS and THX criteria for theatres.
•
Additionally there is an internal spectrum equaliser and subsonic filter (17 Hz) to ensure optimum sensitivity and
maximum output from 20 Hz to the cut off frequency.
•
Full 360 degrees of phase adjustment allows room positioning and alignment for optimum summing with a main or
satellite speaker. This promotes mutual coupling of multi speaker systems for perfectly solid imaging.
•
VCA controlled power limiting ensures overload conditions cannot occur. Driver protection is achieved without
compression and misleading changes in the sound spectrum. A relay offers instant protection of the driver in a
condition of fault or overload.
We believe the BX30 is the most advanced low frequency speaker system available. It can work alone or as part of a
larger modular system.
The 140 W power module is an extremely efficient unit with virtually no quiescent current. The unit can be operated
indefinitely in standby mode. Distortion is negligible under normal operating conditions.
13
BX30 Owner’s Manual
Flow diagrams
IN XLR
Input relay
Passiv limiter
High pass 95 Hz
Line receiver
Line driver
Output relay
Output switch
L+
24 dB/oct
L+
Left
Left
OUT XLR
Left
Left
L-
L-
b
b
R+
24 dB/oct
R-
Right
Right
Right
Right
R-
R+
b
b
Buffer
Low pass
24 dB/oct
80 Hz
Fix level
Left
Temperature
sensor
+4 dBm
-10 dBm
Mute
d
Level
24 dB/oct
95 Hz
h
a
60°
f
e
24 dB/oct
120 Hz
Right
= also adjustable with a tool
Limiter
Equalizer
Subsonic
Phase 0°-180°
c
Phase +180°
Power Amplifier
Speaker
Speaker relay
24 dB/oct
10 Hz
a
VCA
g
b
Figure 8. Flowchart preamplifier
Comparator
V++ ±10%
Timer
Reset
V-- ±10%
0 = fault
AND
0 = fault
VCC ±5%
3 seconds
0 = fault
0 = fault
VEE ±5%
1 = no fault
0 = fault
DC at amplifier
g
Red
Green
Protection
indicator
0 = fault
Front of cabinet
Temperature > 60°
b
h
Startup
0 = fault
Comparator
Timer
attack 3s
hold 10s
Input level right
d
OR
Comparator
Red; input overload
Input level left
VU
indicator
e
Green; input
Bass level
f
Front of cabinet
Limiter
indicator
Buffer
Comparator
= also adjustable with a tool
Limiter active
c
Red; limiting
Figure 9. Flowchart protection circuit
14
OR
BX30 Owner’s Manual
Box data
Power Amplifier
:
collector coupled quasi
complementary BJT
Phase Shift
:
20-150 Hz, variable
Frequency Response
:
+/- 3 dB
Internal cabinet volume
:
inner
Bass Principle
:
reflex
Weight
:
net
Dimensions
:
w×h×d
Crossover
:
Linkwitz-Riley
crossover frequencies
input
output
140 W
0-180 °
17-80/95/120 Hz
76 litres
29,9 kg
41 × 619 × 547 Mm
80, 95, 120 Hz
crossover slope
12 dB/Oct
crossover frequencies
95 Hz
crossover slope
12 dB/Oct
Connections
:
input
output
Impedance
:
input
output
Woofer
:
30 cm polypropylene cone
100 mm pure aluminium
wire voice coil
Cabinet
:
front baffle 22 mm MDF
cabinet 22 mm chip board
XLR female 3 pole
XLR male 3 pole
20 kΩ
50 Ω
internal bracing structure
15