Pioneer SC-LX901 Product Reference Manual page 6

Multi-Channel Stereophonic Philosophy
[waza]
skill/technique/ability
MCACC Auto Room Tuning
LX502
Create the optimum acoustic environment with
Pioneer's MCACC (Multi-Channel Acoustic
Calibration System), developed with the
expertise of professional recording studios. The system—
complete with custom microphone—automatically compensates
for differences in speaker size, level and distance, and equalises
response.
MCACC Pro Auto Room Tuning
LX901 LX801 LX701
MCACC Pro goes a step further by analysing the
phase and group delay characteristics due to
network filtering to precisely control phase
differences between speakers. This correction is
also performed between channels, providing a smooth flow of
sound as if all delivered from the same type of speaker. Other
features include independent correction for dual subwoofers, and
speaker position adjustment in 1-millimeter increments. MCACC
Pro corrects phase differences in all ranges and all channels, from
phase difference in the original audio material to the sound
emitted from the speakers.
Phase Control LX901 LX801 LX701 LX502
When amplifying multi-channel audio signals,
receivers use a Low Pass Filter (LPF) to
process low-frequency signals for subwoofer
output. This causes "phase lag"—a delay of
approximately 5 msec—of the low-frequency
signals compared to the main channel signals. As a result, the
delayed bass makes the sound lack synchronisation. Pioneer's
Phase Control technology effectively eliminates phase lag and
significantly improves the multi-channel sound without any
extra operation.
The "Phase Control" Compensates for the Delay of Low-Frequency Sound
Source AV Receiver
PHASE CONTROL
Speaker distance, sound pressure level, and
frequency response are all uneven.
SET-UP
MIC
Auto Phase Control Plus
During Blu-ray Disc/DVD/multi-channel file
playback, Auto Phase Control Plus makes real-
time analysis of the phase difference between
the LFE (low frequency effect) and the main
signals, and automatically compensates the gap.
Elimination of phase lag enhances strong bass
and clear high-frequency sound—especially effective for audio
content such as live performance and music video clips.
* Effectiveness depends on content
Superior sound provided by compensating the lag in the subwoofer channel on the disc.
Speaker Polarity Check
MCACC Pro will check the speaker polarity for proper
connection. "Reverse Phase" will be displayed on the GUI
Speakers
screen if the speaker's wiring (+ and -) is inverted.
Standing Wave Control
Acoustic standing waves occur when the sound waves from
your speaker resonate with those reflected off the walls.
Depending on the speaker placement, your listening position
or the shape of the room, standing waves have a negative
effect on the overall sound, especially in certain lower
frequencies. Standing Wave Control effectively decreases
resonance and prevents inaccurate EQ-setting calibration.
6
AV RECEIVERS REFERENCE GUIDE
Acoustic Calibration by MCACC
Before Calibration
Speaker distance, sound pressure level, and
frequency response are all equalised.
The sound field is automatically
measured using the supplied mic.
Calibration
Speaker sizes and number of
speakers are automatically detected.
LX901 LX801 LX701
Effect of Auto Phase Control Plus (data comparison)
Original disc playback
Front L
LFE
Delay setting: 0 msec Time
LX901 LX801 LX701
LX901 LX801 LX701
Standing Wave in a Typical Listening Room
= Standing Waves
After Calibration
SET-UP
MIC
Playback with Auto Phase Control Plus
Front L
LFE
Delay setting: 9 msec Time