Klark Teknik DN370, Руководство оператора

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The most important design decision for the DN370 was determining the equaliser response. Proportional-Q equalisation, as
used on previous Klark Teknik analogue graphic equalisers, offers some key advantages over the more numerous Symmetrical-Q
equalisers on the market, namely at low amounts of cut or boost the width of the filter is relatively broad and becomes narrower
as the amount of boost or cut is increased, giving a more 'focused' response. This differs from a Symmetrical-Q response which
boosts or cuts an increasingly wide band of frequencies, and is an important consideration in applications such as cutting
particular problem frequencies, as more of the frequency spectrum is scooped out when using Symmetrical-Q equalisation;
proportional-Q equalisers are much better at cutting just the problem frequency band. Symmetrical-Q equalisers are frequently,
but inaccurately, termed Constant-Q as the Q is measured 3 dB up from the point of maximum attenuation when in cut, rather
than the correct definition of 3dB down from the point of maximum gain (0 dB when cutting), which results in a notch filter
response.
In all types of graphic equalisers, one of the key issues is how the summing of adjacent EQ bands alters the frequency response.
Lower-Q filters will blend together more smoothly, but higher-Q filters provide more selective control of problems - at the
expense of more frequency response ripple. A weakness of the Symmetrical-Q approach is that for small amounts of boost and
cut (a very typical situation), the EQ bands have to be comparatively broad to blend smoothly to avoid excessive ripple in the
frequency response, however as the Q of the EQ bands remains constant, larger amounts of boost or cut will affect an
increasingly wide range of frequencies, limiting the precision and usefulness of the equaliser.
and show the responses of a leading Symmetrical-Q equaliser in both its 'wide' and 'narrow' modes of
operation for 2dB of boost and cut, which is typical of the small adjustments made in corrective EQ applications. The 'wide'
response gives a very smooth combined response for the three bands shown, however the 'narrow' response shows significant
ripple in the combined response which will lead to audible artefacts such as phase distortion.
Figure 1 Symmetrical-Q equaliser “wide” mode ±2dB boost and cut
Figure 2 Symmetrical-Q equaliser “narrow” mode ±2dB boost and cut
Figure 1 Figure 2
The DN370 proportional-Q response
-15
+15
-10
-5
+0
+5
+10
d
B
u
300 4k 400 500 600 700 800 900 1k 2k 3k
Hz
-15
+15
-10
-5
+0
+5
+10
d
B
u
300 4k 400 500 600 700 800 900 1k 2k 3k
Hz
DN Operators Manual - 370 Page 14