Phase-Adjustment With The Dn9848E - Klark Teknik DN9848E Operator's Manual

10.2. Phase-adjustment with the DN9848E

To meet the demands of a wide range of situations, the Klark Teknik DN9848E provides two all-pass
filters with complementary control parameters for fine-tuning the phase response on each output.
Although some crossover filter designs, e.g. Linkwitz-Riley types, are inherently phase-aligned at
crossover, others such as Butterworth or Bessel responses may require manual phase alignment.
Even Linkwitz-Riley filters may not produce accurate phase coherence when HPF and LPF are
combined to produce a band-pass output. In addition, the phase response of the drive units and
cabinets (especially horn-loaded types) may require compensation to achieve correct acoustic phase,
even if the electrical phase is correct. The DN9848E filters provide straightforward tuning control in
all cases.
The first filter of the DN9848E is presented as a "phase shifter" for which you can specify a particular
phase shift at a reference frequency , namely a HPF or LPF (typically the crossover point) or one of the
6 PEQs. The plots in the graph below show the effect of these controls on the filter response when
set to a 90 ° phase shift at references points equivalent to 20Hz, 300Hz, 1kHz and 20kHz. Referring to
the figure, the overall response always remains the same shape i.e. tending from +180 ° at low
frequencies to 0 ° at high frequencies, but is shifted along the frequency axis to achieve the required
phase shift at the specified reference point.
Audio Precision
+150
+100
+50
d
e +0
g
-50
-100
-150
20
C olor Lin e Style
Gree n Solid
Ye llo w Solid
Ye llo w Solid
Response of the phase shifter filter for a phase shift of 90° at
reference points equivalent to 20Hz, 300Hz, 1kHz and 20kHz
The second filter, presented to the user as an "all-pass filter", enables the user to set the Order and Q
of the phase shift, at a particular Frequency. The Order can be switched to Off (no filter), 1
nd
(90 ° shift) or 2 Order (180 ° shift).
The graph over the page shows the response of the filter for a 1
control is disabled. As can be seen, the filter behaves in an identical manner to the phase shifter, i.e.
the response tends from +180 ° at low frequencies to 0 ° at high frequencies, shifted along the
frequency axis according to the chosen frequency. In effect, this is a phase shifter for which the
frequency is entered directly, rather than being referred to a HPF/LPF or PEQ section.
90 deg phase shift @ 20, 300, 1K, 20K
50 100 200
Th ick D ata Axis
1 An lr.Pha s e Left
1 An lr.Pha s e R igh t
1 An lr.Pha s e Left
Application Notes
500 1k 2k
Hz
ph as e.a t1
st
order shift. In this mode, the Q
39
01/19/01 15:52:45
+150
+100
+50
d
+0 e
g
-50
-100
-150
5k 10k 20k
st
order