Sony G90 - Manual (Page 24)

ment. A “Bass Split” feature takes bass infor-
mation filtered from the center channel
(assuming you have a small center speaker)
and directs it to the left and right channels.
Inside, the MC-1 uses AD converters and
DACs from a company called AKM. Both are delta-sigma
devices that are supposedly better performing than the con-
verters used in most controllers. Note that both are always in
the signal path, meaning that all analog signals are converted
to digital upon entering the MC-1 and then converted back to
analog at the output. If you have a High End turntable or dig-
ital source (I used a Krell KPS-25s and a Mark Levinson
No.31.5 transport and No.360s processor), the MC-1’s digital
conversions will degrade the sound quality. There’s no
“bypass” mode that directs an analog signal to the output
unaltered. This is, in my view, a serious shortcoming.
I’ve used many controller and A/V receiver remotes;
this is one of the best. The MC-1 needs a good remote
because the machine is extremely complex. There are four
layers of menus incorporating 17 submenus. This opera-
tional complexity goes with the territory on a controller
with as many features as the MC-1. No fewer than 24
effects are provided, including simulated acoustic spaces
(Concert Hall, Night Club), various film-soundtrack modes
(Dolby Digital, THX 5.1, DTS), Lexicon’s Logic 7 process-
ing, and music surround.
Logic 7 Digital Signal Processing for
Movies and Music
Logic 7 is Lexicon’s proprietary technique for generating multi-
channel playback from two-channel sources. Logic 7 processing
can also “enhance” existing 5.1-channel programs such as Dolby
Digital and DTS for seven-channel reproduction. Lexicon pro-
motes Logic 7 as a universal format for distributing multi-chan-
nel music over two-channel formats such as CD and television or
radio broadcasts. These programs can be Logic 7 encoded to
achieve the full surround-sound effect, or unencoded (such as on
existing CDs) and still create surround-sound playback.
When reproducing 5.1-channel sources (Dolby Digital and
DTS) with Logic 7 and seven loudspeakers, the MC-1 sends
the right surround signal to the right side and right rear speak-
ers, and the left surround signal to the left side and left rear
speakers. This is identical to wiring two surround speakers to
each surround channel. But as sound effects pan toward the
rear, the Logic 7 algorithm uses equalization to “steer” sur-
round signals between the two side and two rear speakers.
Specifically, effects moving from the left to rear pan smooth-
ly from the left front loudspeaker to the left side, then from
the left side to both left and right rear speakers. When effects
are moving toward the rear, Logic 7 adds a 3dB treble cut
(shelf filter) to the side speaker. As the sound further pans to
the rear, the frequency at which the shelf filter begins attenu-
ating is lowered, further reducing the treble sent to the side
speaker. When the sound is fully to the rear, a 6dB per octave,
400Hz low-pass filter is applied to the side speakers. The
result is an apparent separation between the side and rear
channels that heightens the feeling of envelopment, and of
sounds in motion.
Lexicon’s Music Surround Modes
The music-surround modes are as innovative as Logic 7. The
music modes are divided into two categories, ambiance
extraction and ambiance generation. In the latter modes, the
MC-1 generates new signals (reverberation) that drive the
side and rear speakers. In the extraction modes, the MC-1
simply recovers ambiance information from the existing sig-
nal for reproduction by the side and rear speakers. The
extraction modes are much more subtle, and, in my view,
more musically appropriate. Nonetheless, the ambiance-gen-
eration modes driving seven loudspeakers can produce some
startling results.
The music modes use a variety of processes to increase
the sense of spaciousness and create a feeling of being
enveloped in an acoustic larger than that of your listening
room. Some of the MC-1’s modes use a crosstalk-cancellation
trick to widen the soundstage. Crosstalk occurs when sound
from the left speaker reaches the right ear, and vice versa.
L e x i c o n ’s booklet that accompanies the MC-1 explains
crosstalk cancellation: “Imagine there is a sound coming from
the left channel only. This sound will travel to the left ear of
the listener, then diffract around the listener’s head and be
heard by the right ear. If we take the left-channel sound, delay
it just the right amount, invert it in phase and feed it to the
right speaker, it will arrive at the right ear just in time to can-
cel the crosstalk from the left speaker.”
Although crosstalk cancellation has been used in other
products (where it has been called a variety of trade names),
the MC-1’s implementation is considerably more sophisticat-
ed. The simple technique described above can introduce col-
orations because the cancellation signal becomes audible.
Lexicon uses a multi-order cancellation technique in which
the cancellation signal is itself canceled by a second signal,
and that signal canceled by a third, and so on. Reducing this
“inter-aural crosstalk” by adding cancellation signals can
make the sonic presentation appear wider.
These are just a few of the processes, used individually or
in combination, by which the MC-1 creates multi-channel sur-
round playback from two-channel sources. Other equally
interesting techniques are also employed that space restric-
tions prevent me from describing.
Listening to Movies
For starters, the MC-1 in straight decoding mode (Dolby Pro
Logic, Dolby Digital, and DTS), or those formats with THX
processing, was superb sounding. The MC-1 had outstanding
dialog clarity and intelligibility, even with the center- c h a n n e l
level perfectly matched to the other channels. With lesser
products, I find myself increasing the center-channel level a
couple of decibels to make the dialog easier to hear. The MC-
1 ’s good resolving power and image solidity seemed to
anchor the dialog right on the screen (it helps to have a
superlative center-channel speaker like the Revel Vo i c e ) .
This impression of tight center-channel focus and clarity
was particularly impressive with matrixed Dolby Surround
sources, which often lack the image specificity and clarity of
discrete multi-channel sources. The MC-1’s Pro Logic
decoding made matrixed sources sound more like discrete
soundtracks, with greater apparent channel separation,
smoother pans, and increased clarity compared with other
Pro Logic decoders.
Even without any additional processing, the impression of
envelopment from the surround channels was exceptional. The
MC-1 seemed to create a spaciousness behind me, along with a
smooth transition between the front and rear speakers. More-