Akai Reference Master GX-75 - Page 22

On the tape counter
The
digital
tape
counter
shows
the
amount
of
tape
that
has
been
played
back
or
recorded
in
minutes
and
seconds
(up
to
99
minutes
and
59
seconds).
Press the RESET button to reset the COUNTER to “00:00”.
Counter notes :
® Thetape counter is intended as a guide only andis notan ex-
act measurement of reali time.
®. The tape counter will be reset to “00:00” when the power is
turned off or if the RESET button is pressed.
The peak level meter
The peak level meter shows the peak (maximum) level of re-
cording and playback signals. By monitoring the peak level, itis
possible to set the recording controls of this deck to realistically
reproduce the dynamic characteristics of the original source.
The standard recording level of this meter is indicated at 0 dB at
a level of 250 nWb/m.
The peak level meter conforms to IEC standards.
Peak hold indication
The
peak
level
of
the
recording
signal
can
be
held
to
help
guide
.
you when setting the REC LEVEL controls.
Dolby NR system
Set the proper Dolby Noise Reduction
system before all recording and playback
operations
When playing back a tape, set the noise reduction selector
switch to the setting that was used when the tape wasrecorded.
Set the noise reduction selector switch to OFF for tapes that
were recorded without the use of the Dolby NR system.
What is the Dolby Noise Reduction (NR)
System?
The DOLBY NR system is anoise reduction system designed to
reduce tape noise caused when high frequency soft sounds are
recorded. The DOLBY NR system does this by lowering the
noise floor in order to increase the dynamic room in the high fre-
quency range above 5.kHz.
During recording, the DOLBY NR encoder circuit boosts soft
high frequency sounds, and then during playback the DOLBY |
NR decoder circuit lowers what was boosted by exactly the
same amount to restore the high frequencies to their original
levels. At the same time, tape noise is lowered by the same
amount.
The result is reduction of up to 10 dB in unwanted tape noise in
the high frequencies.
What is the difference between Dolby
B-type and C-type NR systems?
B-type: This is the conventional Dolby NR system. It boosts or
lowers the low-level signals at high frequencies only
(more than 5 kHz) and reduces tape. noise by 10 dB.
C-type: Compared to Dolby B NR, it operates at lower fre-
quencies (from 500 Hz) for uniform noise reduction
across more of the audible spectrum. Tape noise is
reduced by as much as 20 cB.
Doiby NR system
Recording
Source
Result
Loud Encoded tape
sounds
Boosted
soft
sounds
Playback
Loud
sounds
Restored
soft sounds
Encoded tape
Decoder
Tape noise Lowered tape noise
Double process noise reduction system
In a conventional noise reduction system, one circuit acts both
as an encoder and decoder, and is switched to one or the other
accordingly..
The double process noise reduction system has an encoder
circuit in the recording amplifier section, and a decoder in the
. playback amplifier section. The double process noise reduc-
tion systemis used in cassette decks with 3 independentheads
(recording, playback, and erase). Therefore, when recording
with a noise reduction system, you can immediately confirm the
effect of the noise reduction by monitoring the just recorded
_music.