Dynaudio BM User manual

BM
User manual

▪Introduction
▪Important safety instructions
▪WARNING:
▪Setting Up
▪Mains Power Connections
▪Audio Connections
▪Positioning
▪Operation
▪Controls
▪Indicators
▪Running in
▪Protection
▪Miscellaneous
▪Troubleshooting
▪Care
▪Service
▪Warranty
▪Technical Specifications
▪Schematic Diagram
2BM User manual

3

Introduction
Congratulations on your purchase of the Dynaudio BM15A monitor. With the right care and attention it will give
you many years of trouble free audio reproduction. It is most important, however, that you take a few minutes at
this early stage in your BM15A’s life to read the safety instructions. They contain essential information to enable
you to get the best from your monitors.
4BM User manual

Important safety instructions
1. Read these instructions.
2. Keep these instructions.
3. Heed all warning.
4. Follow all instructions
5. Do not use this apparatus near water.
6. Clean only with dry cloth.
7. Do not block any ventilation openings. Install in accordance with manufacturer’s instructions.
8. Do not install near any heat sources such as radiators, heat registers, stoves, or other apparatus (including amplifiers) that
produce heat.
9. Do not defeat the safety purpose of the polarized or grounding-type plug. A polarized 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 are
provided for your safety. If the provided plug does not fit into your outlet, consult an electrician for replacement of the
obsolete outlet.
10. Protect the power cord from being walked on or pinched particularly at plugs, convenience receptacles, and the point
where they exit from the apparatus.
11. Only use attachments/accessories specified by the manufacturer.
12. Use only with the cart, stand, tripod, bracket, or table specified 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.
13. Unplug this apparatus during lighting storms or when unused for long periods of time.
14. Refer all servicing to qualified service personnel. Servicing is required when the apparatus has been damaged in any way,
such as power-supply cord or plug is damaged, liquid has been spilled or object have fallen into the apparatus, the
apparatus has been exposed to rain or moisture, does not operate normally, or has been dropped.
WARNING:
To reduce the risk of fire or electric shock, do not expose this apparatus to rain or moisture.
The apparatus shall not be exposed to dripping or splashing and that no objects filled with liquids, such as vases,
shall be placed on the apparatus.
An appliance coupler is used as the disconnect device, the disconnect device shall remain readily operable.
This symbol is intended to alert the user to the presence of uninsulated dangerous voltage within the product’s
enclosure that may be of sucient magnitude to constitute risk of fire and electric shock.
This symbol is intended to alert the user of the presence of important operating and maintenance instructions in
the literature accompanying this product.
Important safety instructions 5

Setting Up
Mains Power Connections
Mains power is applied via a fused IEC inlet. The unit must be earthed. The voltage selector switch is used to
match the unit to the mains voltage in your territory. The mains fuse must be the correct value for the voltage
selected. 115 V requires a T4A fuse while 230 V requires a T2A fuse. The “T” signifies a slow blow type fuse.
You must ensure that the correct voltage and fuse have been selected before switching the unit on.
Audio Connections
Audio input is via a female XLR connector. The input is electronically balanced with +ve on pin 2, -ve on pin 3 and
ground on pin 1. If your signal source is unbalanced it is usual to connect the unused signal pin (i.e. Pin 3) to
ground. This is normally done inside the connecting cable. For best results use only good quality screened cables
and connectors.
Positioning
The BM15A is designed as a “nearfield” or “mid-field” monitor and would normally be positioned 1-3 m from the
listener. It can be mounted on stands or on the meter bridge of the console (providing this is substantial enough).
For best results, the speakers should be “aimed” at the listener in both vertical and horizontal planes.
This monitor can be used in a horizontal orientation – i.e. lying on its sides. However, the acoustic dispersion has
been optimized for vertical use. Also the heatsink will provide improved cooling when used vertically.
In any situation ensure that there is adequate space for ventilation around the heatsink.
6BM User manual

Operation
Controls
Level switch
This sets the input sensitivity of the unit. The +4 position is intended for professional use and means that full
power is reached with an input level of +4dBm (balanced). The -10 position is intended for semi-professional or
domestic use and means that full power is reached with an input level of -10dBm (unbalanced).
HF Trim
This control allows the high frequency level to be adjusted. The HF Trim circuit is a low-Q equalizer which reaches
a maximum range of 6dB @ 15kHz (see graph).
LF Trim
This control allows the low frequency level to be adjusted. The LF Trim circuit is a low-Q equalizer which reaches a
maximum range of 6dB @ 50 Hz (see graph).
The trim controls are intended to allow the user to make some adjustment of the speaker response to
accommodate personal tastes and variations in acoustic environment.
Figure 1: Trim Control Response
Indicators
There are two LED indicators on the front bae of the BM15A.
The right LED is the power/fault indicator. On switching the unit on this will shine red for about five seconds and
then turn green to indicate normal operation. If for any reason the amplifier protection circuitry is engaged the LED
will turn back to red.
The left LED is a “true-clip” indicator and lights if the low frequency amplifier clips. It is acceptable to have this LED
light up occasionally, but avoid running your system with this LED on most of the time.
Running in
The drivers in your BM15A must be run in before optimum performance is achieved. Avoid using the system at
high levels for the first 24 hours of operation. Full run-in is usually achieved after about one week of normal
operation.
Operation 7

Protection
The BM15A has a comprehensive electronic protection system. Thermal overload or DC voltage on the outputs
will cause the system to engage. This will disconnect the drive units from the amplifiers and change the power
LED to its red/fault condition. In addition the HF amplifier has an optical limiter in circuit which prevents excessive
long term power reaching the tweeter whilst allowing transients to pass uncompressed.
8BM User manual

Miscellaneous
Troubleshooting
If the speaker stops working and the power LED turns red (fault condition) switch the mains power o and leave it
for a moment. If the unit fails to operate again when you switch back on the fault may be due to overheating,
switch o again and allow it to fully cool down before powering up. Ensure the heatsink is clear of obstruction and
has free air circulation around it. If however the fault condition persists the unit should be inspected by qualified
personnel.
If the speaker stops working and no LEDs are alight then the mains fuse on the back panel should be checked
and replaced if necessary. If this does not rectify the problem the unit should be inspected by qualified personnel.
Care
Components of the highest quality are used in the BM15A and should ensure a long trouble-free life. Here are a
few hints to help them on their way.
Avoid running the system into clipping or distortion. When an amplifier clips it can send potentially damaging DC
components to the drive units. They may not fail at once but prolonged exposure to this will result in eventual
failure.
If you need to switch o or unplug equipment connected to the monitor, turn o the monitor first. Large voltage
spikes are often generated when equipment is switched o which will be amplified to a potentially damaging level.
Do not touch the drive units. The tweeter especially uses a very fine fabric diaphragm which is easily damaged.
Miscellaneous 9

Service
There are no user serviceable parts inside the BM15A so consult your dealer if service is required or contact one
of the addresses below.
Dynaudio A/S
Sverigesvej 15
8660 Skanderborg
Denmark
10 BM User manual

Warranty
This product is guaranteed against defects in materials and workmanship for 1 year from date of purchase. This
warranty is void if the unit has been tampered with or modified in any way, or in our opinion has not been used in
accordance with the instructions above.
Warranty 11

Technical Specifications
Parameter Value
Type 2 way active near/midfield monitor
Frequency Response 40 Hz to 22 kHz (-3 dB)
SPL (Peak/Cont.) 119 dB / 109 dB one cabinet @ 1m
Drive units 240 mm bass driver, 26 mm high frequency driver
Internal amplifiers
200 W + 100 W discrete MOSFET power amps.
Convection cooled.
1.7 kHz electronic crossover, 5th order phase aligned.
Instrumentation type balanced input section, with input
overload protection.
Protection DC, Thermal on both channels, opto-electronic limiter
on HF
User Controls Variable HF and LF trim, Input sensitivity
Dimensions 455 x 290 x 387 millimeters (H x W x D)
(Allow 35 mm for rear connectors clearance)
Positioning Free standing near/mid-field, desktop mounting.
Rigid high performance stands recommended.
Accessories Power cable supplied
12 BM User manual

Schematic Diagram
Instrumentation type
electronically balanced
input stage
200 W Hexfet Amplifier
100 W Hexfet Amplifier
DA D260
DA 24W100
Fixed EQ 5th order crossover Driver protection
Clip indicator
HF
Limiter
Schematic Diagram 13

BM
Designed and engineered by Dynaudio Labs in Denmark
Dynaudio A/S
8660 Skanderborg
Denmark
dynaudio.com
© 2022 Dynaudio A/S
All text and image copyrights reserved.
Subject to change without notice.
14 BM User manual