Description Of Technology - JVC AX-Z1010TN Service Manual

AX-Z1010TN
Description of Technology
1. Digital Pure-A
The ''Digital Pure-A'' is an operation system materialized based upon the new concept of "signal prediction''. In
a conventional digital amplifier, the input digital signal is decoded by the built-in digital decoder and is applied to
the D/A converter as it is. In the ''Digital Pure-A'', however, the input digital signal is once stored in a memory cir-
cuit and, after the large lapse of a certain period, is output to the D/A converter, in which way the signal is delayed
so that signal prediction is thus made possible by the preceding signal. In the AX-Z1010TN, the Digital Pure-A ope-
ration is performed by varying the bias current according to the level of the signal preciding 10 msec.
2. Prediction Signal Generation Circuit
(1) Preceding signal (H.O, DZ)
Of the serial data output from pin 17 of C106 (YM3623B), two bits of MSB and 2SB are latched by IC 261 in to
an EX-OR circuit, the output of which becomes ''H'' when the playback signal level exceeds — 6 dB and is held
at C262 on the way for a certain time and is emitted from pin 1 of J403. (Half Over signal)
In addition, concurrently with this, the serial data is held at C269 for a certain time and is emitted from pin 3 of J403.
(Digital Zero signal)
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Figure 1. Prediction Signat Generation Circuit
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