Sansui QS D1 Brochure

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WE ULTWATE DECODER/SYNTHW

Three TYPE-A QS Vario-Matrix Decoders in Gas

Sansuis new'OSD-i is not for just any
4-channel tan. This extraordinarily ad-
vanced OS 4-channel decoder/synthesizer
was created specifically for professional
and semi-professional applications only.
And like any line audio instrument it
deserves to be incorporated wrthin a total
system of the highest quality- from source
components and preamplifiers right on
through to power amplifiers and speaker
systems.

The QSD-i is the culmination of Sansui's
original 08 4-channel technology for the
discriminating audiophile. Thanks to its
three separate OS vario-matrix decoders.
each constructed of tour custom-designed
le and each responsrble for a particular
frequency band. it delivers unparalleled
OS 4-channel decoding performance.
plus the proven ability to produce musrcally
accurate 4-channel sound signals from
ordinary 2-channel sources.

It is the most technically advanced
4-channel matrix decoder and 4-channel
synthesizer available to the consumer
today. The following technical details will
support this claim.

QSD-1 FEATURES AND
PERFORMANCE

Distortion 0.1% or Less

As numerous independent lab examina
lions have established beyond doubt. the
OSD-i delivers technical and musical
performance equal to and in most cases
tar surpassing those of 2-channel.
In terms of distortion. for instance. months
of Sansui research and development
have resulted in reducing the distortion
factor to 0.1% or less at tkl-lz (see graph),
while at the same time actually extending
dynamic range. frequency response and
other measurable and unmeasurable
criteria of tonal quality.

Inter-Channel Separation 20dB to 30:13

Effective separation of the sound signals
in each of the four channels is vital to the
believability of a 4-channel sound field.
And today the Sansui OS System delivers
this necessary separation- equal even to
that produced by discrete 4-channel
master tapes.

in theory the OS vario-matrix can be
made to provide infinite inter-channel
separation. In practical terms. the QSD-t.
representing as it does the peak of the
OS vario~matrix technique. offers a proven
20dB separation between adjacent chan-
nels and 30:13 separation across the
diagonally opposite channels. Prove it to

yourself. This means that the QSD~1 never
compromises the 4-channel sound field
concept. At the same time it ensures
optimum tonal quality during the actual
appreciation of music,

TYPICAL INTER-CHANNEL
SEPARATION OF TYPE-A
OS VARIO-MATRIX

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High-Performance QS Synthesizer
Your ears will tell you that what you

have thought to be a myth is actually true.

It is possible to derive a 4~channel sound
field from ordinary 2-channel sources.
and there is no more effective way to
achieve this miracle than with the OS
Synthesizer. The synthesizer encoder" in
the QSDJ works together with the three
separate OS vario-matrix decoders to
derive the "hidden" or unexpressed phase
relationships in conventional 2-channel
records. tapes and FM stereo signals. and
convert them into a multi-channel sound
field. It differs greatly trorn other so-called
"stereo expanders" in technical aspects
as well as in actual performance effec-
tiveness. and it offers two separate modes:

Surround: Sound images are clearly
and distinctly located in each of the four
channels with the same 20dB separation
between adjacent channels as offered
from a OS 4-channel source played
through the OSD-t.

Hall: The 2«channel signals are repro-
duced through the front channels as in
ordinary stereo. while the OSD-t sends
ambience signals to the back channels to
result in the same kind of rich musical
sound you would hear in a concert hall.

Professional Monitor Decoder
Application

The OSD-i is being applied at this very
time to professional monitor decoder uses
in recording studios and FM stations.
It has the same design and standards as
the expensive professional OS encoder

OSE-4/decoder OSD~4. and is easily
mounted in the standard 19-inch (480mm)
studio equipment rack.

Function Controls

in addition to the volume, level and
balance controls. the OSD-t has six front-
panel pushbutlon switches: four are for
functions. including 2rchannel. OS Synthe-
sizer-Surround. OS Synthesizer-Hall.
and OS decoding. The other two select
4-channel inputs and a 2-channel tape
monitor.

TYPEA- VAROMTRl-AIX
TECHNOLOGY

Type-A QS Vario-Matrix Technique

The OS variomatrix technique is a
Sansur innovation to decode OS-encoded
signals with the same high inter-channel
separation as discrete 4-channel tape.
it works this way:

When two sounds of different levels
reach the human ears simultaneously
from different directions. the ears are
known to perceive the directionality of the
louder sound very clearly. But their sensi-
tivity to the directionality of the weaker is
momentarily lost or weakened, resulting
in an apparent broadening of location for
that soundThe louder sound is masking
the directionality of the weaker sound.
and hence this phenomenon is called
directional masking."

Taking advantage of this. the OS
vario-matrix circuit works to emphasize
the directionality of the loudest sound at
each moment. while broadening those ot
the weaker sounds. It does this by retriev»
mg from the input encoded signals the
information on the directionality of the
loudest sound. creating signals that reflect
this information. It then uses these
signals to control the operating parameters
of the decoding matrix in such a way that
the latter will increase the separation of
the channel containing the loudest sound
at each moment. while reducing that of
the other channels.

Note that this is a fundamentally different
approach than the so-called gain control
logic. in the latter, the gain (volume) of
the playback amplifier is instantaneously
adiusted to cancel the weaker sounds at
each moment to achieve spurious separa-
tion for the loudest sound. in the OS
vario-matrix circuit. however. oniy the
directionality of the weaker sounds is
broadened; all the weaker sounds. so
very important in the original live sound
field and so essential to recreate its full