User`s manual
12
Operating instructions cont.
Filters
The 851C DSP has three different Filter functions: Linear Phase,
Minimum Phase and Steep. All three lters are highly sophisticated
audiophile topologies, optimised specically for audio playback. In our
opinion, these lters offer excellent sound quality but differ subtly in
optimisation, hence we’ve made all three available to you.
Note: For clarity, all diagrams show the theoretical response of the DSP
itself, excluding any analogue ltering at the DAC output or the anti-
aliasing lter applied during recording and/or mastering of the digital
source.
Linear Phase Filter
-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 response
The Linear Phase lter is a highly regarded audio lter offering low ripple
in both the pass and stop bands, and what is known as constant group
delay. Constant group delay means that audio signals of all frequencies
are always delayed by the same amount when passing through the lter.
All audio is therefore fully time-coherent at the output.
The trade-off with this type of lter is that due to internal feed-forward
in the DSP, its impulse response will exhibit some pre-ringing. In other
words, when excited with a theoretical impulse, the output has both
a small amount of pre- and post-spike amplitude ringing (albeit well
damped).
0 20 40 60 80 100 120 140 160 180
0
Frequency response
Frequency response
Amplitude
Setup
Menu structure
Auto Off Auto
Play
USB
Class
Input
Naming
S/W
Version
Front IR Digital
Volume
Ch.
Balance
The 851C menu structure has a variety of setup parameters that can
be adjusted to suit both specic installation requirements and personal
preferences. The setup parameters are accessed and modied through
a menu driven interface that uses the 851C display along with its front
panel or handset Menu, Select, Skip ( ) and Stop () buttons.
To enter the 851C setup menu, rst press the front panel or handset
Menu button. The rst setup parameter (Auto Off), will be shown on the
display. To select further parameters for adjustment press the one of the
front panel or handset Skip ( ) buttons.
With the required parameter selected, press the front panel or handset
Select button. Pressing one of the Skip ( ) buttons will now scroll
through the options available for that parameter. When the required
option is displayed, press the front panel or handset Select button.
The setup option is now stored. To exit from the setup menu interface
press the front panel or handset Menu button to step back through the
interface.
Note: The 851C will automatically return to normal play mode if it is left
inactive in setup menu mode for more than a minute.
Each setup parameter and its options is described following paragraphs.
Auto Off – When Auto Off is engaged the 851C will switch to standby
after a preset time if no audio is playing. The Auto Off options are Off, 5
minutes, 10 minutes and 15 minutes.
Auto Play – WIth Auto Play engaged a CD will begin to play as soon as the
disc drawer is closed. The Auto Play options are Off and On.
USB Class – USB Class options enable 851C compatibility with both USB
Audio 1.0 and USB Audio 2.0 interface formats. The default setting is
USB Audio 1.0 which will work driverlessly with most operating systems
for 16-24 bit content at 32-96kHz. Note USB Audio 2.0 requires a driver
to be loaded for Windows. Without this selecting USB Audio 2.0 will
normally give no output . See section on USB Audio for advanced users.
Input Naming – Input Naming enables the display name of the Digital 1,
Digital 2 and AES/EBU inputs to be changed. Use the Skip ( ) and
Select button to select the input name to be changed. Once selected
a ashing cursor will appear beneath the rst character to the existing
name. The Play/Pause and Stop () buttons can then be used to scroll
through the available characters. When each desired character is
displayed, use the Skip ( ) buttons to move on to the next character.
Press the Select button to store the new name.
S/W Version – Selecting S/W Version displays the player’s internal
operating software version number and some additional build
information. This information is primarily provided for service personnel.
Front IR – Selecting Front IR enables the 851C front panel infrared
receiver to be switched on or off (if you are using an external IR system
and the IR emitter Input or Control Bus. In the majority of installations
the infrared receiver should be left switched on.
Digital Vol – Digital Volume enables the 851C to operate as a digital
preamplier and be connected directly to a power amplier. With Digital
Volume engaged, the remote handset volume buttons (symbols) will
control the 851C analogue output level. Digital Volume is disengaged
(Off) by default and should remain off in most 851C installations. It
should only be engaged (On) if the 851C is installed in an appropriately
congured audio system without a further downstream volume control.
Ch. Balance – Only enabled when Digital Volume is used. A balanced
control is implemented.
(Note: Only available
if Digital Volume is
enabled)
Off 5m 10m 15m Digital 1 Digital 2 AES/EBU
On Off Off OnOn OffAudio 2 Audio 1
Downloaded From Disc-Player.com Cambridge Audio Manuals