BSS Audio FCS-960 Owner's Manual - Manual (Page 13)

13
Using the FCS-930/960
The FCS-930/960 Graphic equaliser is the result of a detailed study of
sound engineers and contractors requirements plus many hours of voice
and music program listening tests to carefully optimise the benefits of
controlling equalisation in this ergonomically efficient and familiar
manner.
The filter sets chosen are arranged in the alternate summing mode to
reduce interaction, and utilise a multiple-feedback band- pass topology
rather than the more generally used gyrator topology. This assures
excellent high frequency fidelity by placing less demands on the
associated electronics. The resulting filter shape is ‘constant Q’ giving a
constant bandwidth regardless of the amount of boost or cut selected.
This produces consistent selectivity over the whole range of fader
movement.
The extra long 45mm faders are centre detented for accurate zero
setting, as well as being centre tapped. This electrical centre tap, which
is grounded, ensures each filter set is properly removed from the circuit
at the faders central position. This will give you added confidence during
use, as well as reassurance that, if a filter is not being used, it is absent
from the signal path.
Analysis has shown that the filter shape requirements depend to a large
extent on the final application for the equaliser and for this reason the
FCS-930/960 is provided with a MODE selector which re configures the
filter sets.
Here the Q value of the filter is set to allow groups of faders to be set in a
pattern which represents fairly closely the actual amplitude response
obtained. The combining effect is smooth whilst still retaining a degree
of selectivity normally associated with a graphic equaliser. The constant
Q design allows predictable and precise control over the whole range of
fader movement.
This Normal mode would be used for all sweetening type of work where
boosts and cuts are combined to provide an overall smooth contouring
response.
Here the filters are reconfigured to offer a higher Q value, and hence
produce less adjacent filter interaction. This requirement is consistent
with applications where high selectivity is required such as for correcting
room resonances and where a number of notches are required to be
inserted to avoid feedback. Again the filters produce a constant Q shape
which allows high selectivity for small amounts of cut or boost. A feature
hard to realise on many other graphic equalisers.
6.0 Using the FCS-930/960
Normal Mode
Mode Switch Out
Fine Mode
Mode Switch In