Aphex Studio Dominator 700 - Model 703 - with Pre;De-Emphasis

obvious but are interesting. The first notable effect is that
the recovered left and right channels will not necessarily be
well peak limited. For this reason, FM stereo broadcasting
cannot fully utilize this type of limiting without serious
overmodulation difficulties. (Due to the modulatiori vector
summation of all signal components in the FM stereo multiplex
signal, it is necessary to limit the discrete left and right
channels to properly control modulation.)
Another result of matrixed limiting is that the stereo
separation may become greatly enhanced if the limiters are not
opera ted in "Tracking" mode. This is because the di f ference
component, which is usually small compared to the sum component,
can achieve higher relative signal level through separate
limiting. The effect is usually desirable for AM stereo
transmission, because increasing the relative difference energy
level does not reduce the monaural amplitude modulation and
improves the stereo signal-to-noise ratio. In this case, the AM
radio listener who switches his receiver to stereo mode or tunes
from a mono station to a stereo station with a stereo tuner
hears the stereo signal become louder, with the center audio
approximately as loud as the previous mono audio but with
significant additional left and right audio level. The
"hole-in-the-middle I' effect produced by this type of opera t ion
is usually not noticed since the center is not perceived to
diminish as much as the sides are perceived to increase.
It should be noted that if the Studio Dominator is placed
in "Tracking" mode, the sum and difference information will
always remain in normal proportions, and therefore the
de-matrixed stereo will not obtain enhanced separation . The sum
signal, being usually the greater in level, will thus control
the gain reduction of both the sum and difference channels. In
the unlikely case that the difference channel should contain the
greater signal, the sum channel will track the difference, and
thereby remain in normal proportion. Operating in this mode
will not usually diminish the sum amplitude since it is normally
always in control of the limiter gain. Thus, monaural AM will
not be sacrificed. The AM stereo signal may not achieve the
greatp.st possible loudness, but the stereo sound will resemb:e
the original separation. The studio Dominator provides simple
front panel selection of the "Tracking" mode.
Some applications other than AM Stereo which make use of
matrixed limiting are satellite stereo transmissions, and tape
recording.
The chief advantage of matrixed recording is that azimuth
errors 11pon playback show up as ster~o high frequency separ~tion
reductions rather than monaural high frequency loss. Some radio
stations reco~d music tape ca~tridges in the matrixed format
often with noise reduction to improve 'the reproduced consistency
and quality. Using the matrixed Studio Dominator in the
recording system can allow higher average recorded levels
withol1t distortion or compressed sound. This can eliminate the
need for noise reduction and the attendant loss of d~tail and
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