Parasound HALO C-2, Руководство пользователя, Страница: 61 / 68

TECHNICALLY SPEAKING continued
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Boundary Gain Compensation reduces excessive
bass below about 35 Hz, to prevent the boominess
that can occur when speakers with substantial
response down to 20 Hz (including subwoofers
that meet THX Ultra2 standards) are used in typi-
cal-sized home listening rooms. It should be acti-
vated in setup if you have such subwoofers, but
otherwise turned off.
On-Screen Messages
The front-panel display and video on-screen display
may sometimes show these messages while you’re
watching a movie:
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“Dial Norm Offset” (Dialog Normalization Offset):
Once the C 2 is calibrated for your room and sys-
tem, a volume setting of “0” will give you the
same sound levels in your room that you’d hear in
a commercial movie theater – assuming that the
dialog in the movie was recorded at the correct
level. The “Dial Norm Offset” message, which
flashes briefly on the built-in display and OSD at
the beginning of a Dolby Digital DVD, shows you to
what extent the dialog on that DVD deviates from
the standard. For example, if the dialog offset is +4
dB, that DVD’s dialog was recorded 4 dB too “hot.”
Reducing the C 2 Controller’s volume setting by 4
dB will restore normal overall levels.
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“Digital Error”: The digital signal being fed to the
C 2 has errors in it, and the C 2 needs a little time to
analyze and accept it. This may happen very briefly
at the start of a DVD or CD and for longer periods
when surfing channels with a satellite receiver.
While this message appears, you won’t hear any
sound; so a slight delay whenever you tune your
satellite receiver to another station is quite normal.
Autocalibration Distance Measurements
The C 2 calculates and displays the actual required delay
time as equivalent distance.If you are accustomed to
thinking about equivalent distance in terms
of 1ms of delay = 1 foot (or .3 meter) of distance, you
shouldn’t be concerned when the C 2 displays sub-
woofer equivalent distance that is quite different than its
physical distance from the calibration mic location. This
isn’t a shortcoming or fault, but rather it is because the
C 2 autocalibration algorithm is extremely sophisticated
and measures the real “acoustical distance,” not simply
the physical distance from the sub to the calibration
mic. Acoustical distance is the actual amount of time
required for a sound burst to travel from the speaker to
the listening position, which the C 2 then converts to an
equivalent distance in the display.
In the high frequency range with very short wave-
lengths, physical distance and acoustical distance are
nearly equal, so equivalent distance does closely fol-
low 1 ms = 1 foot. But at lower frequencies with
longer wavelengths, the acoustical distance grows
significantly longer than physical distance. Further
contributing to this are delays in the low-pass
crossover circuit, the voice coil mass of the sub-
woofer driver(s), and the fact that longer wave forms
require some time to travel from wall to wall in a
room before they start to resonate.
The C 2 autocalibration is the only correct way to
accurately adjust for the actual acoustical distance,
because it is the only way to insure that a burst of
sound occurring simultaneously in all channels will
also be heard simultaneously at your listening posi-
tion. It is another reason why the C 2 is capable of
recreating a uniquely seamless and vivid envelope
of sound in your home theater.
Helpful Web Addresses
The following are the Web addresses for companies
mentioned in this manual:
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Parasound:
www.parasound.com
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Dolby Laboratories:
www.dolby.com
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DTS (Digital Theater Systems):
www.dtsonline.com
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THX:
www.thx.com