d&b 24C User Manual

24C/24C-E

xC

Manual 1.3 en

General information

24C/24C-E Manual

Version: 1.3 en, 02/2015, D2618.EN .01

Copyright © 2015 by d&b audiotechnik GmbH; all rights
reserved.

Keep this manual with the product or in a safe place
so that it is available for future reference.

When reselling this product, hand over this manual to the new
customer.

d&b audiotechnik GmbH
Eugen-Adolff-Strasse 134, D-71522 Backnang, Germany
T [phone], F [phone]
[e-mail], www.dbaudio.com

Contents

1. Safety precautions......................................................... 4

1.1. Information regarding the use of loudspeakers......... 4

2. 24C / 24C-E cardioid column loudspeaker........... 5

2.1. Product description...................................................... 5

2.1.1. 24C cardioid column loudspeaker......................... 5

2.1.2. 24C-E cardioid column extender............................ 5

2.1.3. Cardioid dispersion................................................. 6

2.1.4. Dispersion characteristics........................................ 7

2.1.5. Directivity index (dB)................................................ 7

2.1.6. Aiming of the beam................................................. 8

2.2. Connections................................................................. 9

2.3. Operation.................................................................... 9

2.3.1. Controller settings.................................................. 10

2.4. Technical specifications............................................ 11

3. Attaching the 24C-E extender.................................. 13

4. Manufacturer's declarations.................................... 15

4.1.

EU conformity of loudspeakers (CE symbol)........... 15

4.2. WEEE Declaration (Disposal).................................. 15

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1. Safety precautions

1.1. Information regarding the use of loudspeakers

Potential risk of personal injury

Never stand in the immediate vicinity of loudspeakers driven at a
high level. Professional loudspeaker systems are capable of
causing a sound pressure level detrimental to human health.
Seemingly non-critical sound levels (from approx. 95 dB SPL) can
cause hearing damage if people are exposed to it over a long
period.

In order to prevent accidents when deploying loudspeakers on the
ground or when flown, please take note of the following:

– When setting up the loudspeakers or loudspeaker stands,

make sure they are standing on a firm surface. If you place
several systems on top of one another, use straps to secure
them against movement.

– Only use accessories which have been tested and approved

by d&b for assembly and mobile deployment. Pay attention to
the correct application and maximum load capacity of the
accessories as detailed in our specific "Mounting instructions"
or in our "Flying system and Rigging manuals".

– Ensure that all additional hardware, fixings and fasteners used

for installation or mobile deployment are of an appropriate
size and load safety factor. Pay attention to the manufacturers'
instructions and to the relevant safety guidelines.

– Regularly check the loudspeaker housings and accessories for

visible signs of wear and tear, and replace them when
necessary.

– Regularly check all load bearing bolts in the mounting devices.

Potential risk of material damage

Loudspeakers produce a static magnetic field even if they are not
connected or are not in use. Therefore make sure when erecting
and transporting loudspeakers that they are nowhere near
equipment and objects which may be impaired or damaged by an
external magnetic field. Generally speaking, a distance of 0.5 m
(1.5 ft) from magnetic data carriers (floppy disks, audio and video
tapes, bank cards, etc.) is sufficient; a distance of more than 1 m
(3 ft) may be necessary with computer and video monitors.

d&b 24C/24C-E Manual 1.3 en4

2. 24C / 24C-E cardioid column loudspeaker

2.1. Product description

2.1.1. 24C cardioid column loudspeaker

The 24C is a passive 2-way column loudspeaker housing six 4”
neodymium drivers and an HF array comprising six 1.1” dome
tweeters.

The 4" drivers are arranged in a unique cardioid setup radiating
through waveguide elements at the front and damped ports at the
rear of the cabinet. This design provides a constant directivity
pattern of 90° in the horizontal plane with an average broadbad
attenuation to the rear of approx. 18 dB.

In the vertical plane, the beam produced by the low-mid drivers is
tilted downwards by –5° and provides significant directivity down
to 370 Hz.

The HF array has a nominal vertical dispersion of 20° and its main
axis can be adjusted continuously between 0° and –14° (when
using ArrayCalc, adjustment in 1° increments).

The loudspeaker cabinets are based on an extruded aluminum
profile with a metal grill protecting the front of the loudspeaker.
Two continuous rails (8 mm T-slot profiles) are provided at the rear
for attaching a wall mount bracket.

2.1.2. 24C-E cardioid column extender

The 24C-E is a passive column extension to be attached directly to
the 24C. The cabinet houses six 4” neodymium drivers, providing
an extension of vertical directivity down by a further octave to
190 Hz.

The acoustic design is based on the same principles as the 24C,
thus offering the same cardioid dispersion pattern in the horizontal
plane. The extender is electrically connected through the 24C
without the need for an additional amplifier channel.

Note: The 24C-E loudspeaker is not intended to be operated
as a stand-alone system.

d&b 24C/24C-E Manual 1.3 en 5

2.1.3. Cardioid dispersion

Due to their dimensions, conventional column loudspeakers
provide no significant horizontal directivity below 2 kHz.

At low and mid frequencies, the resulting polar pattern is almost
omni-directional (dotted line).

The cardioid patterns of the 24C and 24C-E show a much higher
directivity resulting in much less energy radiated into the room
(continuous line).

Typically, column loudspeakers are mounted onto walls or other
hard plane surfaces. Hard surfaces act as an acoustic mirror. That
means, the room is not only covered by the sound of the actual
column loudspeaker but also by the sound produced by its virtual
mirror source from "behind".

In the case of conventional column loudspeakers with their low
horizontal directivity, the mirror source radiates at a similar level as
the loudspeaker itself.

The combination of both sources results in a dipolar characteristic
where the main energy is radiated along the walls (dotted line).
The 24C and 24C-E, however, with their cardioid dispersion
patterns provide an even dispersion characteristic and a useful
directivity when mounted onto a wall.

2.1.3.1. Flush mounting

If architecturally required, xC-Series cabinets may be partially flush
mounted.

Please note that this will render the cardioid ports ineffective and
as a result, may change the dispersion pattern.

In conjuntion with 24C cabinets, care must also be taken to ensure
that the dispersion of the rearmost horn of the HF array is not
obstructed by the edges of the wall recess. Otherwise, this will
create reflections which will have a negative impact on the
frequency response in front of the cabinet. The same applies when
the cabinet is mounted in a corner of the room. Reflections of the
adjacent side walls will cause deviations in both, the frontal
frequency response and the dispersion pattern.

d&b 24C/24C-E Manual 1.3 en6