Teac R-919X Bedienungsanleitung Seite 12

DOLBY HX PRO
Dolby HX Pro is an "active bias" technique
that can improve the quality of audio tape
recordings. High-level high frequencies can
be recorded more accurately, without
sacrificing signal-to-noise ratio, while such
side effects of tape saturation as distortion
are reduced.
What Is Bias?
Bias is a very high-frequency signal generat-
ed within a tape deck and recorded on the
tape simultaneously with the program
material. This inaudible signal allows a low
noise, low distortion recording and flat
frequency response. Different magnetic tape
formulations require different amounts
of bias for optimum performance. If the
bias level is too high, high-frequency
Maximum Output Level (MOL) decreases.
The Problem of Self-Bias
Unfortunately, bias level is often influenced
by the signal being recorded. The high fre-
quencies contained in some music act as
bias. This unpredictable source of bias is
added to the existing bias, resulting in a loss
of high-frequency response. As the high-
frequency content of the signal increases,
the ability of the recorder to record high
frequencies (MOL) decreases. This pheno-
menon is called self-biasing.
How Dolby HX Pro Solution
The Dolby HX Pro monitors the high-
frequency content of the program material
and adjusts the recorder bias oscillator to
maintain a constant total bias level. The
result is improved high-frequency response
and lower distortion. Depending on the type
of tape, the improvement in headroom can
be 6 dB or more.
The Benefits
With Dolby HX Pro, it is easier to make
More accurate recordings of the kind of
music which contains high-level high fre-
quencies. The improvement is similar to
that of high-performance tape over conven-
tional tape, so regardless of the type of
tape used, the results will sound better.
Most important of all, Dolby HX Pro
requires no-decoding process. Once the
tape is recorded with it, the improvements
will be realized when playing the tape back
on any machine.
+10/- T
dB
0
-10
250nWb/m
I
HX PRO on
-20
-30+- +
-40 1
20Hz SO 100 200
Ik 2 5 10 20k
Example of improved frequency response using Dolby HX Pro function
Three-Head System
SE
A three-head system means that you can
record on the tape and monitor from it at
the same time (see illustration). Conven-
tional combination record/playback heads
permit only recording or playback. With
the three-head system, you can check the
quality of your recordings as you make
them.
ae =
Record Playback
Head Head
Erase
Head Record Playback
Signal Signal
Record and Playback Heads
Side Panel Installation
(V-970X U.S. Military Version Only)
(Fig. 10)
eee
1. Remove the three screws on both sides
of the deck using a Phillips screwdriver
(cross-tipped).
(After removing, retain the removed
screws for the future.)
2. Mount the side wood panels provided on
both sides of the deck, using the exclu-
sive screws (three for each side), as
shown in the figure.
If required, use the washers provided
together with the mounting screws.
* Additional accessories for the V-970X
U.S. Military Version
Side wood panel x 2
Mounting screw x 6
e Washer x 6
aA? =
Maintenance (Fig. 4)
A
The heads and tape path should be cleaned
and demagnetized periodically.
Cleaning Tape Path
eApply head cleaning fluid* to special
cotton swabs or a soft cloth, and lightly
rub the heads, capstans and all metal parts
in the tape path.
e Also clean the pinch rollers using rubber
cleaning fluid*.
*Both are available in TEAC HC-1 and
RC-1 in the U.S.A. or TEAC TZ-261
Tape Recorder Cleaning Kit in other
areas.
Demagnetizing Heads
Be sure that the power is off, then demag-
netize the heads using a TEAC E-3 demag-
netizer or equivalent. For details of its
use, read its instructions.
Troubleshooting
ee Oe
Basic troubleshooting of a cassette tape
deck is similar to troubleshooting any other
electrical or electronic equipment. Always
check the most obvious possible causes first.
To give you a few ideas of what to look for,
check the following:
e No power: Is the power cord connected?
e Tape begins running when power is turned
on. Is the TIMER function on?
eNo audio output. Are all connections
properly made?
e Degraded sound quality: Are the heads
dirty or magnetized? Are you using
good quality tape? Is the proper NR
System select switch on?
e Unable to select record mode: Are the
record protection tabs on the tape in
place?