Dolby NR with which the tape was originally recorded
for playback. Select the Dolby NR position with
which you wish to make a recording before starting a
recording. Refer to chapter “Getting the best perfor-
mance from your NAD 613”, section “Dolby NR Noise
Reduction systems B & C” for more details. Dolby NR
will default to OFF after the deck has been switched
off.
18. MPX FILTER.
When recording off-air with some tuners an inaudi-
ble high frequency signal can cause mis-tracking of
the Dolby NR noise reduction circuit which results in
dull sound when the recording is played back. The
MPX filter blocks these high frequencies (above
15kHz).
Press the MPX button if you are experiencing such
problems; MPX FILTER will light up in the display. If
you don’t record from radio you do not need to select
the MPX filter.
19. DISPLAY.
Various functions of the deck are displayed,
Recording, Play, Pause, Dolby NR OFF/B/C/, Repeat
OFF/FULL/BLOCK, Record level and Tape Counter.
GETTING THE BEST PERFORMANCE
FROM YOUR NAD 613 CASSETTE
DECK.
The numbers in the text refer to the controls in fig-
ure “FRONT PANEL CONTROLS” unless mentioned
otherwise.
THE DOLBY NR NOISE REDUCTION SYS-
TEMS B & C.
The deck is equipped with two types of Dolby NR
noise reduction. Dolby C NR provides the greatest
quieting of tape hiss, important when taping “live”
musical performances or recordings with a wide
dynamic range (digital Compact Discs, for example).
Dolby B NR provides optimum compatibility with
older tape recorders, portable and car stereo tape
players. Dolby B NR should also be used when play-
ing most pre-recorded music cassettes.
Each Dolby NR system is active both during
recording and play-back. Thus if a tape is recorded
with Dolby C NR, it must be played back with Dolby C
NR in order for the benefits to be obtained. Similarly,
if Dolby B NR has been used during recording, than it
should be used in play-back as well.
To avoid confusion, it is recommended that you
label each cassette B or C when it is recorded, to
indicate the type of noise reduction used.
NOTE: After switching Power off, the Dolby NR cir-
cuits will be switched off. Make sure you select the
appropriate Dolby NR setting again after switching
the deck on.
Tape sensitivity is constantly changing as record-
ings are made due to the biasing effect of high fre-
quency audio signals. dolby HX Pro is a system that
compensates for these undesirable fluctuations dur-
ing recording. It does not operate during playback, so
cassettes recorded with Dolby HX Pro can be played
back on decks not equipped with the system.
NOTE: Dolby HX Pro operates independently of
Dolby B and C NR, and only during recording.
THE BIAS CONTROL.
Matching the recorder’s bias to the tape is especial-
ly important when Dolby NR noise reduction is used,
because any departure from flat high-frequency
response will be magnified in the Dolby NR NR circuit
during play-back, making the sound excessively
bright or dull. The “Bias” control (14) allows you to
compensate for brand-to-brand tape differences. The
procedure for fine tuning the bias is as follows:
1. Load an unrecorded tape and fast forward for a
few seconds to get past the blank leader tape at the
beginning.
2. Set the “Play Trim” (15) control at “0” (the centre
detent position) and press the “Multiplex Filter” but-
ton (18) to engage the filter (indicated in display).
3. Press “Dolby NR” (17) to select “C”.
4. Set the “Bias” control (14) at “0” (the centre
detent position).
5. Press the “Reset” button (11) and record a brief
sample of music at peak level of about -8dB.
6. Rewind the tape to approximatily to 0000.
7. Play back the sample of music and evaluate its
tonal balance in comparison to the original.
8. If the recording sounds duller than the original,
turn the Bias control DOWN (counter clockwise) to
boost the highs (less bias). If the high frequencies are
exaggerated in the recording, turn the control UP
(clockwise) to reduce the treble response (increase
bias).
9. To test the new bias setting, make another brief
trial recording and check the results. Fine tune again
if necessary.
NOTES:
• The Bias control affects tapes only while a record-
ing is being made. It cannot be used to improve the
quality of tapes after they are recorded.
• We recommend you consistently use the same
brand and type quality tapes to get the best and most
consistent performance from the recorder. Set the
Bias control to match that particular tape.
RECORDING LEVEL.
The two horizontal segmented bars display the
peak level of the source’s signal in each channel.
Adjust the recording level by turning down (counter
clock-wise) or turning up (clock-wise). There are vari-
ous tape formulations - normal (I), CrO2 (II) and
Metal (IV) - available, each with its own specific char-
acteristics such as saturation level. The NAD 613
senses automatically which tape type is used and
adapts its settings accordingly. Too low a recording
GB
NAD
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