User’s Manual Hardware K&F CD 44 Digital System Controller
KLING & FREITAG GMBH ©2006 - 2009 Version 10.1, 22.04.2009 Page 7 of 63
6. Product Description
The signal processor CD 44 is a digital 4 in 4-way speaker controller that can process both
analogue and digital signals in the AES/EBU format up to 192 kHz.
The controller is equipped with the finest AD and DA state-of-the-art converters as well as 3
micro-controllers and 8! integrated signal processors (DSP). It not only offers excellent audio
results, but also a multitude of special features and novel functions:
Multi-level memory concept for parameter management
The parameter sets for almost all K&F speaker systems are saved in the form of macros in the
device (the so-called ‘LSBlocks’). They can be copied as a complete set of data and
independently of one another into each of the 4 output channels.
The specification of one K&F phase reference for multi-way operations is advantageous
because of its high level of compatibility. Without requiring phase adjustments, the various K&F
tops can be combined with all K&F subwoofers.
Additional LSBlocks ‘Flat’ facilitate the integration of third-party products (with limitations) or
the processing and linking of signals to speakers with integrated filters and amplifier
electronics.
14 pre-configured routings allow every reasonable configuration from up to 4 different input
signals to the 4 output channels.
Frequently used combinations of routings and ‘LSBlocks’ can be saved along with further
parameters (such as Gain / Delay / PEQ) in up to 64 set-ups.
Two-step limiter concept
Two limiters work in each of the 4 output channels. A quick reacting “peak limiter”
limits the peak level and, thus, the cone excursion of the connected speakers is kept at
non-critical levels.
A slow reacting ‘RMS Limiter’ reduces the level when there is a risk that the permissible average
power will be exceeded, thus resulting in the voice coils overheating.
The pre-set values have been established in extensive series of tests. With excellent sound
qualities, they provide an outstanding compromise with regard to the peak levels and
protection of the speaker systems.
Automatic determination of gain using sense technology
The CD 44 calculates the gain of the connected amplifiers in real-time and automatically
corrects the limiters’ thresholds as soon as the gain of the connected amplifier should be
changed (i.e. by using the input potentiometer or similar). Compared to conventional devices
this results in a clearly improved reliability when adjusting the limiter thresholds.
Limiter reduction
The preset limiter thresholds can be reduced in fine increments for specific purposes. This
function is advantageous when the connected speakers are to be subjected to a particularly
long-lasting high load. In this case, the reduction of the limiter thresholds reduces the maximal
thermal and mechanical stress, thus significantly extending the product life of the speakers.
Furthermore, these functions can also be used to limit the sound levels of the speakers.
The integrated limiters and the function ‘Limiter Reduction’ can also be used for speakers with
integrated amplifier electronics. For this, the gain values of the utilised power amplifiers can be
edited manually in the CD 44.
Operating with 'Shortcut' buttons
Four buttons with ‘Shortcut’ functions make it possible to directly jump to often-used functions
without having to navigate through the menu. By pushing these buttons repeatedly, you
access the functions of all input and output channels.
In doing so, the functions ‘Gain’, ‘Delay’, ‘Filter’ and ‘PEQ’ can be quickly and easily adjusted.
Additionally, the LEDs which are integrated into the respective buttons indicate if these
functions have been changed as compared to the original settings.
31 Band One-Third Octave EQs
A separate 31 band one-third-octave EQ is assigned to each of the CD 44’s four input
channels. Up to 16 different EQ setups can be saved and administrated in an individual EQ
setup library. These EQ setups can be loaded in addition to the setups.
