Denon DN-780R - Manual (Page 12)

12
ENGLISH
DOLBY B AND C NOISE REDUCTION SYSTEM
2 The Dolby noise reduction system substantially
reduces the tape background noise (hiss) inherent
in the cassette medium. Dolby B NR is most
widely in use. However Dolby C NR is a much
more recent development and represents
significant improvements over Dolby B NR.
2 Tape background noise consists primarily of high
frequency information, which is particularly
annoying during soft passages. The Dolby NR
system increases the level of low volume mid-
and high-frequency signals during recording and
reduces the level of these signals by an identical
amount during playback. As a result, the playback
signal is identical to the original source, but the
level of background noise generated by the tape is
greatly reduced.
2 The operating principle of Dolby C NR is similar to
that of Dolby B NR except for the encoding
/decoding response curves. The noise reduction
effect obtained with Dolby C NR is up to 20 dB,
compared to 10 dB with Dolby B NR. In addition,
Dolby C NR uses an anti-saturation network and
spectral skewing circuitry for a significant
improvement in the dynamic range of the mid- to
high-frequencies.
DOLBY HX-PRO HEADROOM EXTENSION SYSTEM
This deck is equipped with the Dolby HX-PRO
headroom extension system. Since the system
functions automatically during recording, no switching
operation or adjustment is required. The system is
effective with any type of Normal, CrO
2 and Metal
tape.
The Dolby HX-PRO headroom extension system
functions during recording to raise the saturation level
in the treble range. Therefore, most of the treble
range components distorted or lost during recording
on conventional cassette decks are more faithfully
recorded on the new DENON cassette deck.
Features of the Dolby HX-PRO Headroom
Extension System
(1) Performance of Normal and CrO
2 tapes can be
improved to very close of that offered by Metal
tape.
(2) The dynamics in the treble range are improved
significantly.
(3) Since no decoding is necessary during playback,
the improved sound can be enjoyed on any type of
tape deck, including portable players and car audio
systems.
(4) The system functions whether the Dolby B/C NR
system is engaged or not.
MAINTENANCE
2 Head cleaning
After long usage, tape coating or dust may adhere
to the heads, causing deterioration of sound.
Therefore, the parts depicted in the illustration
should be cleaned regularly. Use a cotton swab
moistened with a tape head cleaning solution
(such as alcohol).
NOTES :
1. Some cleaning cassettes on the market have a
strong abrasive effects and may scratch the
heads. Always use cotton swabs instead of
cleaning cassettes.
2. Since the use of metal tape is apt to collect
more dust on the heads, the heads should be
cleaned more often to enjoy the best possible
sound.
2 Cleaning the Pinch Rollers and Capstans
If the pinch rollers or capstans accumulate dust,
tape transport may become unstable, as a result
from slippage, during recording or playback. The
tape can also be damaged if it gets entangled in
the capstan.
Clean these parts with a cotton swab or a soft
cloth moistened with a tape head cleaning solution
(such as alcohol).
2 Demagnetizing the Heads
The heads will become magnetized after long
usage or if strongly magnetized objects are
brought near them. The result is a generation of
noise, loss of the high frequency range, and in
extreme cases erasure of treble components on
pre-recorded tapes in combination with added
noise.
Thus, the heads should be demagnetized at regular
intervals. (Head demagnetizers are separately
available from your dealer.)
2 How to Demagnetize the Tape Heads
1. Turn off the power.
2. Turn on the demagnetizer while it is at least 30
cm away from the heads. Bring the demagnetizer
near the heads and slowly move it in small
circles four or five times in front of each head,
making sure you do not touch them.
3. Slowly move the demagnetizer away and turn
it off when it is at least 30 cm away from the
heads.