1446 Chapter 38
frequency to the midrange speaker. This may often be
followed by a multiband parametric equalizer used to
smooth the response of the woofer. Lastly will come a
limiter to keep the power amplifier from clipping and/or
provide some degree of protection for the woofer. The
midfrequency processing chain will have a high-pass
filter to set the crossover frequency from the woofer,
and a low-pass filter to set the crossover frequency to
the high-frequency speaker. It might also have a multi-
band parametric equalizer and a limiter. The
high-frequency processing chain will have a high-pass
filter to set the crossover frequency from the midrange,
and might have a low-pass filter to set the high-
frequency limit. It may have a shelving equalizer to
compensate for the high-frequency response of the
driver. It will also have a multiband parametric equal-
izer and a limiter.
Some of these fixed configuration audio processors
can allow quite complex systems to be built. For
example the BSS ProSys ps-8810 provides eight inputs
and ten outputs. Each input has filtering, delay, gating,
AGC, compression, automatic mixing, more filtering,
polarity, and muting available. This is followed by and
eight in by ten out matrix mixer. Each output has delay,
filtering, ambient level control, and limiter available.
The combination of all these facilities allows quite
complex systems to be built, Fig. 38-4.38.3 Virtual Sound ProcessorsAt times, however, even the most complex fixed configu-
ration processor will not meet the needs of a project. In
1993, the Peavey MediaMatrix system introduced the
concept of the virtual sound processor. It allowed the
designers to choose from a wide variety of virtual audio
processing devices, and wire them in any configuration
they desired. Integrated digital sound systems could now
be designed with the same flexibility of configuration
formerly enjoyed in the analog world, and with much
greater ease of wiring. Changes to the configuration
could be rapidly made on screen and loaded into the pro-
cessor at the click of a button. Complex systems, which
would not have been possible using analog technology
due to circuitry drift or cost, now became routine. Sys-
tems with as many as 256 inputs and 256 outputs, and
70,000 or more internal controls became practical, Fig.
38-5. More recently, BSS came out with the Soundweb
digital audio processor with similar capabilities but a dif-Figure 38-4. BSS control software for the ProSys ps-8810 showing the signal flow diagram. There is a limited ability to
configure the function of the various signal processing blocks. This is a part of the IQ for Windows software package and
can use CobraNet for digital I/O.