Operation Manual

851Dazur
13
ENGLISH
Minimum phase lter
-80
-60
-40
-20
0
20
-200
-180
-160
-140
-120
-100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Magnitude (dB)
Frequency response
frequency/FS (input sampling rate)
The Minimum Phase lter is another highly regarded audio lter that
offers even lower ripple in the pass and stop bands. Unlike the Linear
Phase lter, group delay is not constant; however, phase shift is low and
the particular benet with this lter is that the impulse response exhibits
no pre-ringing.
0
0 20 40 60 80 100 120 140 160 180
Impulse response
Time (samples)
Amplitude
Steep lter
Magnitude (dB)
Frequency response
frequency/FS (input sampling rate)
-80
-60
-40
-20
0
20
-200
-180
-160
-140
-120
-100
0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1
Steep lter
Linear phase lter
Our Steep lter is a linear phase lter that has been optimised for stop
band attenuation of close-in aliasing images. Here we have traded a
little attenuation of the very highest frequency response (-2dB at 20kHz
for 44.1kHz material) and a little more pre- and post-ringing for a very
steep attenuation just outside the pass band. The Steep lter is able
to attenuate aliasing at 22kHz by some 80dB for 44.1kHz material for
instance.
0
0 20 40 60 80 100 120 140 160 180
Impulse response
Time (samples)
Amplitude
Note: All lters exhibit the same ultimate roll-off of approximately 140dB.
The following table shows the lter stop band attenuation for 44.1kHz
material:
Linear Phase Minimum Phase Steep
Roll-off at
20kHz
-0.1dB -0.1dB -2dB
Roll-off at
22kHz
-10dB -10dB -82dB
Ultimate roll-off 140dB 140dB 140dB
We encourage you to experiment with the lters to determine which
sound best to your ears and using your source equipment/programme
material. The 851D remembers and recalls the selected lter type for
each input individually, making it possible, for example, to select Steep
for the USB input and Linear Phase for Digital Input 1, and so on.