Sony G90 Logic 7 Digital Signal Processing for Movies and Music, Lexicon’s Music Surround Modes

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.

Lexicon’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-channel

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 Voice).

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-

Image 24
Contents Sony G90 Size Does Matter Ingly just beyond reach Than ever we needed in strange, dark cavesExperience before he finds a little of It Sound and vision at the same time every timeKubrick’s Eyes Wide Shut HP Bergman’s The Seventh Seal DVDFollies & Frolics Barco Vision WatchEditors will respond next issue Can All That Counts Be Counted? a Forum BeginsII Janet’s Index EditorProblem with DVD Digital Artifacts Targeting 14-Year-Old Boys?If The Perfect Vision is to push Down Primrose Path Toward Perfect Vision Forever? At all. So it doesn’t take Hdtv orAzine Widescreen Review perhaps? What Not To See on DVD Digital Cinema The Good Bad of ItJohn Eargle Lossy Data Compression & DVD Sound TV Is TVI L L E R Series such as Star Trek The Next Generation . 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If you’re the script superOne way or another when it comes to working with Ity between when they are and whenAssistant directors, service people, FootageCertainly a serviceable way to edit MoviesLikely to get you Directors seem to trust me to use my Into any troubleAllowing for camera setups, lighting, and rig Takes and setups meaning the masterIt’s a funny thing about matching in editing. Most lay Enjoy prelaps to pull the narrativeSion? In Understanding Media, McCluhan Lexicon MC-1 Controller Sonic Flavors To Slake Every ThirstR L E Y Logic 7 Digital Signal Processing for Movies and Music Lexicon’s Music Surround ModesListening to Movies Listening To Music Surround Conclusion Ing the Denon Anechoic Orchestral Music Recording CDControllers Two-Channel Bypass Mode Surround Decoding and Digital Signal Processing DSPDSP and the Future-Proof Controller THX-Certified Controllers Bass ManagementHigh-Resolution Digital Audio …the controller representsRadical new path to Future…After DSP Digital to Analog Conversion InterFacing the UserRevel Ultima Speakers From 2 to 7.1 Channels Episode One The Ancient EnemyMeet My Enemy M M I I L L E RDeploying the Troops RPG Room Optimizer Software 59 byRevel Ultima Salon Noble Warrior Start and go get a beer, or twoYou wanted to cross over your subwoofer at 40 Hz Tion coefficient for the surfaces that is comparable toOur noble warrior against the ancient enemy Likewise for the 15-inch woofer in the Sub-15Essary to achieve the Revel design team’s led by Kevin Research effort to quantify in-room speaker behaviorDirect radiator to bloated. The Salon’s soundstage com By Keith Johnson for Reference RecordingsNal processing in controllers hadn’t made subwoofer Speaker? Removing the bottom octave from the Salon’sWoofer, when it is well integrated with your main speakers Cians often use emphasis in the intensityFormance. Orchestral music, for example, is performed Cy, phase, and time. 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We fed that information to the rear Tion from the main mikes as well as the spot mikesFrom the two main mikes and brought it to the rear ones Have been considered typical indeed, good for aSee review, this issue Quering technology issues, Moorhead says. Most of ourFall was so high. This was an elaborate joint Computer and TV combinedMade for DVD Original, so they’re not going to fake it for DVDStars. God, was I skeptical Dramatic confrontation, in the second scene of Act Two Must answer three riddles. If his answers are correct, sheTo Turandot’s collection the Chinese nation, ruled by an Ple either turning cynical, or lusting for more bloodTurandot. And why would there be? Yes, Puccini conscien Preoccupation like that made more sense, butTucks into a tiny corner of the staging. 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Seen together, they seemed inseparable yet By much of the sound reinforcement heard in BroadwayAn Introduction to Digital Video Part 2 Video Color ConceptsPhysics of Color Human Color PerceptionColorblindness Color Concepts for Video Additive ColorLuminance Hue and SaturationCIE Chromaticity Diagram Display Color Accuracy RGB Primaries The Color TriangleWhite Reference Color Temperature Grayscale Color TemperatureColor Measurement Color Bars Other color signals will also Color errors.Are used in some circumstances Instrument known as a color analyzer or a spectroAdjustments Color and HueAvia Guide to Home Theater pro Sony VPH-G90U Multiscan Projector PhysicalE G R O G E R S Installation and Set-up ConnectionsScan Rates Operating FunctionsPerformance SummarySpecifications Runco DTV-930 Multiscan ProjectorDescription Inputs/Outputs Convergence Labs Test Report Greg Rogers Formats can be selected directly from the remoteHorizontal and vertical scan frequencies and other source Be noticedRange Combination is about the reasonable limit to achieve anRemote Control IEV Turboscan 1500 Line DoublerLine Doubling = Deinterlacing Video outputs. 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