Tascam DA-38 - Manual (Page 20)

SECTION 4: RECORDING
4-8. Dithering the Re-quantization Noise
The DA-38 has a 18 bit A/D converter, a quantizer for
changing analog data into its digital equivalent.
The DA-38 can also receive digital data of up to 24 bits,
but it records and plays using 16 bit patterns, which means
that it is necessary to further convert the 18 or 24 bit data
into 16 bit data, a process called re-quantization.
2 Access the dither menu by pressing MENU as many
times as necessary, which looks like "d it h. o f f " .
^ Press either the A or the T key and the " o f f " will
change to "o n ".
d I t h. n
The simplest solution may be rounding of the data, which
neglects data past the 16th bit.
This rounding may produce noise correlated to the origi­
nal input signal, because of the difference in resolution
between 18/24 bit data and 16 bit data.
Press SHIFT and the associated LED will turn off, the
display being switched back to show the ABS time.
• To switch off the dither, change the "o n " display
to "o f f " by means of either A or T ,
The dithering process overcomes re-quantization noise by
masking it with a low-level random signal (a kind of
noise).
The DA-38 is designed to allow you to monitor the input
with as high a definition as possible, so the dithering
process takes place only when the input signal is actually
recorded onto tape. The effect of dithering is thus percep­
tible only on playback.
The dithering function is enabled or disabled in a menu, as
follows :
3 2
1 4
Press SHIFT and the associated LED will start blink­
ing to show that all the double function keys are
switched to offer their lower blue-labelled functions.
4 * 1 4