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.
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