CBT36K Assembly Manual
12. CROSSOVER SETUP:
I
NTRODUCTION
:
This section describes setup of the recommended Behringer DCX2496 DSP Crossover which is sold by
Parts Express (
http://www.parts-express.com/pe/showdetl.cfm?partnumber=248-669
, about $250).
Other DSP processors may be used. We have experience with two other units: the DEQX HDP-
EXPRESS (
, about $2,000), and the miniDSP 2x4 DSP processor
Here is an interesting diyAudio forum comparison of the three units
http://www.diyaudio.com/forums/minidsp/176544-minidsp-vs-dcx2496-vs-dcx2496-modded-vs-deqx.html
.
Dayton
Audio bears no responsibility for the opinions expressed in these forum posts.
Refer to the “Crossover Filter/EQ Settings Table” in section 12.3 on pages 81 and 82 for help in setting
these units.
12.1. S
ETUP OF
B
EHRINGER
DCX2496
U
LTRADRIVE
P
RO
DSP
C
ROSSOVER
:
The primary function of a crossover is to divide the frequency spectrum into bands and route these bands
to the driver(s) within the loudspeaker optimized to reproduce those frequencies. In addition, modern
crossovers equalize response irregularities in each of the bands to better approximate an ideal speaker.
Fig. 18. Front panel of Behringer DCX2496 Ultradrive Pro DSP crossover.
The Behringer DCX2496 is a very versatile crossover based on Digital Signal Processing (DSP) that
has 3 input channels and 6 output channels and may be configured to divide the spectrum in many
different ways. For instance you can configure it to drive three 2-way speakers, or two 3-way speakers
or two 2-way speakers plus a subwoofer.
A table at the end of this section has a complete list of all the crossover filter and equalization settings
that are required for the CBT36. This table can be used as a starting-off place if you desire to use another
DSP crossover other than the ones we recommend. Remember however, you are on your own here!
12.1.1. Simplified CBT36 Crossover Signal Flow:
CBT36 is designed to be a two-way speaker, meaning that the spectrum is divided into two bands, one
for the mid-bass drivers and one for the tweeter drivers, the remaining two output channels can send the
low frequencies to an optional subwoofer amplifier. Initially the crossover is set up so that CBT36 can be
used without a subwoofer but with only simple changes you can add a subwoofer of your choice and
mate it with CBT36.
The following figure shows a typical signal-flow setup when an optional subwoofer is used. The frequency
response transfer-function curves in the boxes are the actual curves used in this setup, not dummy data.
The first block in the diagram contains the lift compensation that equalizes the power rolloff of the CBT36
(for an explanation of this power rolloff refer to the section “CBT36 Power Rolloff” later in APPENDIX 2:
“CBT THEORY OF OPERATION”). The compensation starts at 200 Hz and then rises at 3 dB/octave (10
dB/decade) up to 20 kHz. This EQ equalizes the axial and power frequency responses of the CBT36 to
be flat to 20 kHz. Refer to the section “The Flat Energy Response Debate” later in APPENDIX 2 for more
information on this equalization and it’s effects. See also section titled “Check your Crossover Work” later
in this section for overall crossover transfer-function curves.
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