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Making Good Sounding Recordings
Dolby Noise Reduction Systems
Dolby B NR is the system used in most cassette tape decks to reduce the background noise that is inherent in all cassette tapes. Dolby
Laboratories then developed an even more effective noise reduction system, Dolby C NR, in response to the demand for increasingly
better sound quality from cassette tapes.
Both Dolby noise reduction systems operate by boosting signals during recording that fall below a certain input level. Dolby B and C
NR operate on the higher portions of the frequency spectrum using what is called a "sliding band'' technique. This is because tape hiss is
most prominent during the quiet, high frequency portions of a recording. These same signals are then reduced back to their original
strength during playback, thereby reducing the background noise by the same amount. In order to operate only when necessary, the
Dolby NR system has a varying effect depending on the input level and frequency of the material being recorded.
Dolby C NR is capable of reducing tape hiss by 10dB more than Dolby B NR. In addition to its noise reduction function, Dolby C
NR has an anti-saturation network that lowers high input levels before recording them and returns the signals to their original strength
during playback. This raises the high-frequency saturation level of cassette tapes to allow you to record signals that would normally
cause distortion. This system raises the maximum output level of cassette tapes by more than 4dB at 10kHz.
The Dolby HX Pro System
Tape sensitivity is constantly changing as recordings are made due to the biasing effect of high frequency audio signals. Dolby HX Pro is
a system that compensates for these undesirable fluctuations during 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.
Setting the Proper Recording Level
The recording level has an important effect on the sound quality a tape will have when it is played back. A recording level that is too high
will cause distortion while one that is too low will lower the signal-to-noise ratio resulting in a tape with excessive "hiss noise.'' It is
particularly important to set the recording level correctly with cassette tapes since they have a much thinner magnetic coating than open
reel tapes. The thin coating gives the tape a comparatively low saturation level which can easily be surpassed if the recording level is set
too high.
The optimal recording level varies depending on the type of the tape being used. With this tapedeck, adjust the REC LEVEL knob so
the PEAK LEVEL indicator occasionally hits the “+6dB” line with “Metal” tapes and “+4dB” line with “Normal” or “High” position
tapes, respectively. It should be noted that the peak level may change from one track to another on some recording sources.
The recording level indicators feature a peak-hold function for the indicators from -10 dB through +10 dB. This can come in handy
when setting the recording level.
CD Synchro Recording System
Once the TA-6711 is connected to a CD player bearing the
zz
zz
z mark (see page 5.), pressing the
s s
s s
s button of the CD player will cause
recording to commence automatically on the TA-6711.
1. Insert a cassette with the side to be recorded facing out.
2. Start the CD player.
3. Press the
gg
gg
g PAUSE button while holding down the
oo
oo
o REC button to put the unit into the recording standby mode. Adjust the input
level. When the recording level has been set, stop the CD player.
4. Start the CD player again, and recording will begin simultaneously.
Notes:
1. Even if the CD player is stopped during recording, the cassette deck will continue in the record mode.
2. If the cassette deck is in the recording standby mode when CD play starts, the deck will begin recording. When setting recording
levels, always start the CD first.
MPX Filter for Recording FM Broadcasts
When recording FM broadcasts using Dolby NR, the 19kHz pilot signal and the 38kHz subcarrier signal included in the FM broadcast
signal can cause the Dolby circuitry to malfunction. This deck is equipped with an MPX FILTER button to prevent this from occurring.
Press the MPX FILTER button to turn on the MPX filter. The [MPX FILTER] indicator lights. The MPX FILTER button should be ON
when recording FM broadcasts using Dolby NR and OFF at all other times.