Tascam RC-898 - Manual (Page 43)

Section 7.2 - Unit-related functions
7-5
2) Use the LEFT and RIGHT keys to select a unit,
and the UP and DOWN keys to change the
setting between Digital and Analog .
See p15 and pp25-26 of the DA-88 manual for fur-
ther information regarding this facility.
7.2.8 Varispeed (pitch control)
The DTRS design allows for
±
6.0% speed control,
in 0.1% increments.
1) From menu group 0, move the cursor to Vari
Spd , and press SELECT :
2) Use the UP key to change Fix to Vari , or
the DOWN key to change Vari to Fix .
The VARI indicator [10] will light if Vari is
selected, even if the setting is 0.0% , and will go
out if Fix is selected, even if the setting is not
zero.
3) Move the cursor to the right (numeric) field,
and use the UP and DOWN keys to set the
value.
7.2.9 Input selection
DTRS units can accept either digital or analog
inputs. The choice of which inputs are to be used
for each machine is made in the following way:
1) From menu group 9, move the cursor to
InputSel and press SELECT :
2) Use the UP and DOWN keys to select between
the digital and analog input sources for each
unit.
In the screen above, units 1 through 4 are accept-
ing analog signals, while 5 and 6 are using TDIF -
1 digital inputs.
7.2.10 Word length
The DA-38 and DA-98 units are able to
accept digital data at their digital I/O connectors at
either 16-bit, 20-bit or 24-bit word lengths. These
settings are made in the following way:
1) From menu group 2, move the cursor to Word
Len , and press SELECT :
2) Use the UP and DOWN keys to select between
16 , 20 and 24 bit word length of incoming
data, which will be converted to 16 bits for
recording purposes.
If you select a value higher than 16 , you may
want to experiment with the Dither settings (see
7.2.11, “Dither”, below), as this may help with dis-
tortion, though a little may be lost from the signal-
to-noise ratio.
7.2.11 Dither
Dithering, in digital audio, is the tech-
nique of adding a known noise signal to a low-
level input signal, especially when converting
from a word length with a higher number of bits
than the destination (see 7.2.10, “Word length”
above).
Paradoxically, this technique removes quantiza-
tion noise and improves overall distortion figures,
though at the slight expense of the signal-to-noise
ratio. The DA-38 implements an “on/off” dither
function, and the DA-98 allows two “shapes” of
dither. See section 4-8 of the DA-38 manual or
8.13 of the DA-98 manual for further details.
1) From menu group 1, move the cursor to
Dither and press SELECT :
2) Allowable values for DA-38 units are on and
off . The DA-98 allows the following settings
to be made: off , triangular and
rectangular .
See the section 8.13 of the DA-98 manual for a
discussion of rectangular vs. triangular dither
modes.
V a r i S p e e d
M a c h i n e 1
F i x + 0 . 0 %
NOTE
The varispeed function is only available if the unit clock has
been set to internal (see 7.2.6, “Clock selection”) and the
video resolve function (
see 8.2.10, “Video resolve” ) is
off.
I n p u t S e l e c t
D i g i t a l » »
A n a l o g » » » »
M a c h i n e 1 2 3 4 5 6
T D I F W o r d L e n g t h
M a c h i n e 1
1 6 b i t
D i t h e r
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o f f
38 98
38 98