XTA dp200 Operator's Manual - page 14
DP200 Page 14
Parametric Equalisation and Limit Modes.
Three modes are provided :-
Quad 5 band + limit (2 In 4 out), Dual 14 band + limit (2 in 2 out) and Stereo 14
band + limit (2 in 2 out with 'ganged' parameter control). In dual and stereo modes
outputs 3 & 4 still operate, with signal being derived post e.g. but pre-delay : (useful
for feeding the main stacks in a delay tower installation).
Quad mode features 5 bands of fully flexible parametric equalisation for each of 4
outputs, with sections 1 & 2 of each output selectable respectively to L.F. and H.F.
shelving response. Delay time and output gain is adjustable for each output and a
limiter is provided for each output.
Dual and Stereo modes feature 14 bands of parametric equalisation for each
output; all other output functions are the same as for Quad mode.
Equalisation
(see page 29 for more information)
Each identical parametric section can be positioned at any frequency 20Hz to
20kHz and features a wide range of 'Q's to produce response curves ranging from
broad to notch. 15dB boost and 30dB cut is provided with 0.1dB resolution.
Frequency parameter features 1/24 octave resolution for precise control. Since all
filtering is achieved in DSP all settings are re-settable with absolute accuracy and in
stereo mode parameters track identically, Very narrow band notch filters can
achieved, (maximum Q=128). Unlike analogue filters these 'tight' Q filters are
entirely stable, maximum notch depth is 30dB.
Parametric filters are carefully implemented using Double Precision processing.
This method is costly in terms of processing power but yields substantial benefits in
terms of the DP200's exceptional noise performance and greatly improved low
frequency stability.
Output Limiters
High performance digital limiters are provided for each output with control over
attack time, release time and threshold level parameters ( see page 22 ). This level
of control allows the user to balance the required subjective quality of the limiter
against the driver protection requirements. It does also mean that an incorrectly set
limiter may sound awful!. In particular, as with all limiters, using too fast an attack or
release time will result in excessive low frequency distortion. Please therefore
ensure that all limiters are bypassed during initial set-up and use the table on page
as a starting point.
Once set, the limiter view screen can be set ( see page 23 ) this simultaneously
displays the amount of gain reduction for all outputs on four separate 'over limit'
meters.
If required the limiter-link function can be selected via the menu system. Once
selected, if any one limiter's threshold is exceeded, equal gain reduction will be
applied to all limiters, so avoiding a dynamic change in system frequency response.