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RG-2 TECHNICAL
OUTLINE
'The basic funetion of the RG-2 is to expand the
level variations of the input signal (see Fig. 5: in-
pul-output transfer characteristics), Due to the ex-
pander circuit composition, the input and output
clreults are not necessarily linear.
'The block diagram is shown below. The circuit,
consists mainly of a flat frequency response gain
control amplifier (GCA) and
sensor section
which produces the signal to control the gain of
the gain control amplifier, After passing through
the input level
control and buffer amplifier, a
portion of the input signal goes to the sensor
section. At the sensor section, the signal first passes
through an energy distribution filter, which
possesses a slope of ~6dB/octave above and below
a 2, 5kHz, center frequency. This effectively reduces
noise components, such as motor rumble, bum and
tape hiss, yielding only the center frequeney com-
ponent, At the RG detector, a peak detector
(ripple cancelling type) produces a DC output pro-
portional to the peak values of the AC input signal.
The output from this RG detector becomes the
gain control signal for the GCA.
Current from the sensor section determines the
opentoop gain of the gain control amplifier, The
gain therefore increases as the control current in-
creases in accordance with the input signal. 'The
characteristics of this signal undergo changes sue
as those in Fig. 6: input-gain
characterissics. To
provide this characterisiivs, an NFB (negative
back) circuit returns a portion of the GCA output
to the input, and the dynamic expansion selector
selects the NFB elements to control the feedback
ratio, thereby determining the total gain (Fig. 6).
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Econo
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PIONEER
Loft and right channels are mixed by a blending re-
sistor at the sensor seetion input, to provent e:
cessive gain difference between the channels from
producing an unnatural effect during stereo play-
back.
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Fig. 5: RG processor input-output transfer
characteristics
Ell
Fig. 6: RG processor input-gein characteristics
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