Almost everyone has experienced the enveloping,
electrifying effect of 5.1-channel surround sound in the cinema and at home.
Surround sound is addictive. Once you get used to it, you'll never want to go
back to plain stereo sound. And now you don't have to.
|A Listener's Guide To
Pro Logic II
Pro Logic II from Dolby Laboratories gives you
multichannel surround sound from any stereo source—CDs, tapes, videocassettes,
TV broadcasts, AAC files, you name it. No matter if you're listening to
Stravinsky, the Stones, or a Schwarzenegger movie, you'll get the realistic,
involving sound you'd expect from a 5.1-channel system.
How Pro Logic II Works
Pro Logic II is a dramatically improved, updated
matrix surround system, based on the principles used to develop the original
Dolby Pro Logic decoding back in the 1980s. The original Pro Logic features four
channels—front left, center, and front right, plus a mono surround channel
that's usually split between two rear speakers. The surround channel is also
"band-limited," reducing the treble frequencies. Pro Logic II further
enhances the sound with a full-range stereo surround output and a greatly
improved steering logic, resulting in high channel separation and an
exceptionally stable soundfield.
Pro Logic II offers expanded surround capabilities.
Simpler Circuits, Cleaner Sound
Many surround sound processors have attempted to
improve on Pro Logic by adding increasingly complex detection, steering, and
decorrelation circuits. Not only do these circuits usually produce unnatural
effects, but they can also degrade the sound by running audio signals through
additional processing circuits. Pro Logic II strips away most of this
processing, instead relying on simple but highly effective servo circuits to
derive the output channels. You can hear the same detail and subtlety you
experience from your stereo music system—but in full surround sound.
Pro Logic II is not like the synthetic
"hall," "jazz club," and "stadium" DSP modes found
on many A/V receivers. It adds no reverb, no tonal colorations, and no
delay-induced echoes. Instead, Pro Logic II naturally extracts all of the
ambience and directionality that already exists in the recording.
Pro Logic II–for Movies and Music
All Pro Logic II receivers offer a Movie
mode optimized for movies or programs with Dolby Surround soundtracks. This mode
is also appropriate for use with video games. Movie mode retains the
important features of Pro Logic, but with a full-bandwidth stereo surround
output, the listening experience is much closer to the sound you get from Dolby
Probably the most innovative feature incorporated
in most receivers is the Music mode, which creates a rich and enveloping
surround ambience from stereo sources such as CDs.
In Music mode, most systems also include
three new controls to fine-tune the soundfield. Center Width allows you
to gradually spread the center channel sound into the front left and right
speakers. At its widest setting, all the sound from the center is mixed into the
left and right. This control may help achieve a more spacious sound or a better
blend of the front image.
Panorama wraps the sound of the front left
and right speakers around you for an exciting perspective. There's also Dimension,
which adjusts the front/back balance to suit your taste.
An optional Matrix mode can be included to
produce surround sound from mono material.
Pro Logic II receivers operate in two modes.
What Do I Need to Get Pro Logic II?
All you need is a Pro Logic II receiver or
processor and five speakers (plus a subwoofer, if you wish). Since Pro Logic II
gives you full-range sound in the front and rear speakers, good quality speakers
all around give the best performance. Speaker systems tailored for Dolby Digital
are ideal for Pro Logic II.
Pro Logic II system with left, center, right, left
surround, right surround, and optional subwoofer.
How Do I Set Up a Pro Logic II System?
A Pro Logic II system is set up just like the
original Pro Logic system or a Dolby Digital system. Simply tell the receiver if
you're using large or small speakers (if this option is offered), and then
balance the channel levels using the decoder's test tone.
Pro Logic II in the Car
Pro Logic II's natural surround sound makes it
perfect for use in car audio systems. Whether you're listening to FM radio,
digital radio, cassette, CD, or downloaded digital music files, Pro Logic II's
five channels wrap you in sound as you drive.
Placement of Pro Logic II speakers in an automobile.
With Pro Logic II in the car, manufacturers can
add a center speaker to provide a solid, natural-sounding center image for both
front-seat passengers. You get a sound that's more like a stage full of
musicians sitting in front of you, instead of hearing only the speaker next to
you, as you would with most car audio systems.
If the car includes Pro Logic II's controls for Center
Width, Dimension, and Panorama, you can optimize the sound
specifically for your car, your music, and your taste.
Pro Logic II is available in standalone
processors that can be added to existing car audio systems, or as a feature
built into OEM and aftermarket car audio systems.
Pro Logic II brings all of your old audio
software into the 21st century, giving you many of the benefits of Dolby Digital
from ordinary stereo software. With its elegantly simple circuitry and the
smoothest steering logic ever, it's a very rare processor indeed—the kind
you'll want to leave on all the time, so you can always enjoy surround sound, no
matter what the source.
Dolby Digital related content is Copyright © 2002 Dolby Laboratories, Inc. All
Dolby and the double-D symbol are registered trademarks of Dolby Laboratories.
All other trademarks are the property of their respective owners.