86 Silicon chip Australia’s electronics magazine siliconchip.com.au
DSP Active Crossover and
8-channel Parametric Equaliser
In this third article, we test the DSP Crossover modules, then finally
connect them together and power the whole unit up. Once it has been
tested and assembled into its case, you can then set it up before hooking
it up between your preamplifier and power amplifier(s), so that it can
process the sound as required.
A
s mentioned in the previous ar-
ticles, this DSP Active Crosso-
ver is built from six different
modules: a power supply/signal rout-
ing module, a CPU board, an analog-
to-digital converter (ADC) board, two
identical digital-to-analog converter
(DAC) boards, a front panel control
board and a graphical LCD with a small
adaptor so that it can connect directly
to the CPU board.
Those previous articles described
how the circuits of each module
worked and how they join together.
We also gave the assembly instructions
for all the aforementioned modules.
So if you’ve been reading along and
working as you go, at this stage, you
should have a complete set of modules,
but you will not have connected any
of them together or applied power yet.
So now we get to the fun part: pow-
ering everything up, plugging the mod-
ules together, and seeing if it works
(fingers crossed!).
Once we’ve verified that everything
is working, we can mount all these
modules in a case and then we’ll ex-
plain how to use the resulting device
and what sort of performance you can
expect from it.Testing
The first thing to check is that the
power supply board is working prop-
erly. Regardless of whether you are
planning to power the final unit us-
ing a plugpack or mains transformer,
the easiest way to test it is by wiring
a 12V AC plugpack to CON13 on thepower supply board, either between
pins 1 & 2 or pins 3 & 4.
Don’t plug anything else into this
board for now.
If you don’t have such a plugpack,
mount the mains transformer, mains
input socket and fuseholder in a metal
case (it’s usually easiest to place these
all in one corner).
Complete and insulate all the mains
wiring before powering it up, and en-
sure that the metal case is Earthed di-
rectly back to the mains input socket
or cord.
If using a captive mains power cord,
ensure it is adequately clamped to
the case using a cord grip grommet or
P-clamp, so that pulling on the cord
won’t allow any internal conductors
to come loose.Part III – Design by Phil Prosser... Words by Nicholas Vinen