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See the operating instructions for the TD 20A for
a complete description.
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Range
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Right bread
ingut Right
Remote Controt
Input Right
Input Left
Mic
Line 2
Line 4
Input Left
'Mic Lett
Correction:
Normal
Special
Equalization selector
Normal:
This position is used for playback of tape which
has not been recorded with special-correction, and
for recording on tape which will be played back on
tape recorders without special-correction.
Special:
This position is used for playback of tape recorded
with special-correction, and for recording on tape
which will be played back on tape recorders with
special-correction. This position gives a improved
signal/noise ratio.
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[re
Equalization
record EQ
Playback
50 us
50/25 us
25 us
35 us
35/10 us
10 us
50 us
Normal
Special
Normal
15 ips IEC
Special
Normal
15 ips NAB
Special
Choice of tape
When your TD 20A—SE leaves the factory it is
adjusted to give the best performance with tape
types Maxell UD XL, TDK GX, and Ampex Grand
Master 456. Maxell UD XL is used for the factory
adjustment.
Tape such as e.g. Agfa PEM 369, Agfa 468, BASF
SPR 50 HL, Scotch 226, and Scotch 227 can be
used after a small re-adjustment of the machine.
Special correction
Until now the tape noise on analog open-reel tape
recorders has been limited by the standard record
and playback correction curves. By changing the
correction curves so that the TD 20A—SE can take
full advantage of the latest tapes, the tape noise is
reduced to as low as — 80 dB.
The record electronics
The excellent record quality on the TD 20A—SE is
due to two techniques originally developed by
Tandbergs — the DYNEQ® and ACTILINEAR®
systems.
Because of its treble lift, a conventional record
amplifier will give a linear frequency response and
acceptable distortion at middle and low signal
levels. On the other hand, at high signal levels
treble lift will produce overloading and distortion.
This is unfortunate since distortion-free reproduc-
tion is more important than a linear frequency
response.
It is precisely to combat this problem that Tandberg
engineers have recently developed the DYNEQ®
and ACTILINEAR® recording systems.
The DYNEQ® circuit automatically adjusts the
gain at the high frequencies and prevents the tape
from being overloaded. This means that inter-
modulation distortion is substantially reduced and
the record level on the line and microphone inputs
can therefore be increased.
The ACTILINEAR® amplifier is an active current
generator with more than 20 dB overload reserve.
Intermodulation distortion caused by the slew rate
is reduced because the amplifier operates at a low
voltage level. The ACTILINEAR® amplifier also
provides electrical isolation between the correction
amplifier and the bias signal. This also reduces the
intermodulation distortion. Altogether this ampli-
fier significantly reduces distortion and improves
the transient response in the record mode.
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