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CDJ-500G, CDJ-500
1.5 CIRCUIT DESCRIPTION
AUDIO
DATA
AUOIO OUT
DECODER
ICXD2500 BQ
SYSTEM CONTROL[
|_|" | JOG
DIAL |
237)
8-bit CPU
cee
1
" 7 p
SLIDER VR
"--4
EXT. CONTROL
The above circuit achieves the following functions.
(1) Starting playback immediately
(2
—
As jumping of signal tracks is repeated when the CD is
paused, a time lag of about 0.3 seconds at the most oc-
curs when rewinding (when sound begins to be output
after shift from pause to play).
This time lag must be
eliminated to make an instant start in order to join songs
together by a cut-in. This instant start (about 0.03 sec-
onds) is achieved by storing about the first 0.7 seconds of
the song to memory, and playing the data in memory
when pause is canceled. From 0.7 seconds onwards, the
song data is continuously added to the end of this
memory and is used as ring memory in order to continu-
ously play the song. Memory management is executed
by a high-performance DSP under the control of an 8-bit
microcomputer.
Beat search by jog controller
When joining songs together, it is extremely difficult to
match the rhythm (speed and timing) with the BPM of
two songs by adjusting the tempo using the slider. A jog
controller is used to achieve the operation of manually
accelerating or decelerating the disc slightly on an ana-
log turntable.
The pulse generated by the pulse encoder according to
the rotation of the jog controller is computed by a micro-
computer to control the varipitch function of the decoder
LSI.
Turning the dial clockwise accelerates the playback
speed up to +12.7%. Turning the dial counterclockwise
decelerates the playback speed up to -12.7%.
Stopping
the dial restores the playback speed to its original set
speed.
(3) Master tempo
(4
~
The slider voltage is converted to digital values by an A/
D converter.
A microcomputer controls the varipitch
function of the decoder LSI to change the playback
speed to +10% in 0.1% steps.
The playback pitch (interval) simultaneous with changes
during variable speed, which results in vocals sounding
unnatural.
So, key control is processed by the DSP to
eliminate interval changes from the original pitch.
Loop playback
"Break beats" are generated by the DJ (Disk jockey) by
repeatedly playing the same phrase on two turntables.
The same effect as this can be achieved on a single CD
player. This is called "loop playback."
First, the initial 0.7 seconds or so of the song data to be
loop-played is stored to memory. The search time can be
aurally eliminated by outputting the data stored to
memory during searching from the end address to the
start address during loop playback, which allows repeat
playing without any break in sound.
(5) Relay play
vcc
CONTROL
SYSTEM
TER
CONTROL
8-bit CPU
Relay play is achieved by alternately connecting the
player control terminals of two players to which auto cue
is set.
Though terminal-1 is normally in an input standby state,
the play start command (Low pulse) is output when the
song being played ends, and terminal-1 stands by for in-
stant start at the beginning of the next song.
Instant start is executed when the play start command is
received during instant start standby.
Note : The relay play does not operate correctly unless
the audio input jacks of two players are connected
to the audio input jack of one audio mixer or one
amplifier.
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