7 - Advanced operations
TASCAM DA-78HR
44
(for instance 16, the DA-78HR’s non-HR tape word
length) to improve quantization.
Paradoxically, this technique of adding noise
removes quantization noise and distortion at low sig-
nal levels a nd im proves the overall disto rtion fig-
ures.1
Though quantization noise is reduced, there is a loss
of a few dB in the signal-to-noise ratio. For this rea-
son, the DA-78HR does not implement dither as a
standard, but allows you to c hoose between no dither,
rectangular or triangular (the shapes refer to the dis-
tribution of values in the digital noise). Rectangular
gives about 3dB better signal-to-noise ratio than tri-
angular, but there is noise modulation, whic h may be
audib le when r ecordi n g and pla ying ba ck low-l eve l
progra m so ur c es.
NOTE
Dither can be turned on and off while recording is
taking place. How ever, there will probably be an audi-
ble change in the sound quality. We suggest making
a test recordin g before a session. In thi s way you will
be able to make a n instant assessment of the effects
of th e d iffer e nt dith er set tings on your pr ogram mate-
rial.
7.11.1Selecting dither setting s
1Press the SHIFT key so that th e SHIFT indicator
is flashing, and then press the MENU key until
the display show s Audio . 1-- (AUDIO1--).
2Press the S UB MENU key until the display
shows DITH. ;;; (DITH xxx where xxx
is the
curr ent s etti ng) .
3Use the ▲ and ▼ to select the dither function
you want ( either OFF (OFF), RECT (RECT)
(rectangular) or TRI (TRI) (triangular)).
7.12Advanced output options7.12.1Output word length
The output word length from the TDIF-1 (and t h e
SPDIF (COAXIAL
)) outputs can be set to either 16 or
24 bits.
1Press the SHIF T key so that the unit is in shift
mode (SHIFT indicator is flashing).
2Press the MENU key until the display shows
Audio. 2-- (AUDIO2--).
3Press the SUB MENU key until the display
briefly shows Out. bit. ;; (OUT BI T xx),
where xx is the current setting.
4Use the ▲ and ▼ keys to change between 16
and 24 bi t s.
NOTE
Simp ly changing th e output wo r d length to 24 bi ts w il l
not automatically provide better sound quality, if the
equipment being fed by the DA-78HR is not capable
of accepting 24-bit audio.
7.12.2 Output patchbay
In addition to the integral input patchbay, the DA-
78HR also features a patchbay which allows t racks to
be routed to different output channels.
This routing is carried out in parallel to both the
TDIF dig ital a nd t h e anal og sets of ou tputs .
The default setting is NORMAL (NORMAL), i .e.
tracks are output to their correspondingly-numbered
output channels.
To make an output patch setting:
1Press the SHIF T key so that the unit is in shift
mode (SHIFT indicator is flashing).
2Press the MENU key until the display shows
Audio. 2-- (AUDIO2--).
3Press the SUB MENU key until the display
briefly shows Out. Patch (OUT PATCH), fol-
lowed by the current setting.
4Press any of the RE C F UN CTION
keys to select
an output channel ( not a track) which will have
a track as sign ed to it.
5The display shows the current setting of this
output channel, e.g. Ch. 1 Tr. 3 (Ch1 tr3)
means that output channel 1 is fed by tape
track 3. Use the ▲ and ▼ keys to change the
track number.
1. A full discussion of dither and other digit al
audio techniques is outside the scope of this
manual. However, a good starting point f or
learning about this, and other aspects of digital
audio, is John Watkinson’s The Art of Digital
Audio, pub Focal Press.