Reference Guide

Introduction MCACC MCACC ProThe Essence of MCACC Advanced MCACC Feature Comparison Technical Details
MCACC Reference Guide
Technical Details
Speaker Adjustment
MCACC applies the most suited test signal for each item to
make measurements.
Speaker Size Detection
With MCACC, the speaker size is detected by a general method
using frequency characteristics. In addition to the measurement
by MCACC, Advanced MCACC and MCACC Pro check the
linearity, and more precisely measures the ability for low
frequency playback.
Speaker Distance Adjustment
Why does precise adjustment of the speaker distance improve
the balance of the whole sound field in your listening space?
That’s because with a multi-channel speaker system, a single
speaker placed at a different distance from the other speakers
can have an adverse effect to all the other speakers, and distort
the sound field for the whole system, as shown on right. In
reverse, if all the speakers are at an equal distance, the phase
will be aligned. As a result, the sound improves not only at the
listening spot where the microphone is placed, but also in the
whole listening area by optimized balance of the sound field.
Pioneer is one of the few manufacturers providing speaker
distance measurement in 1 cm-increment. What’s more,
Pioneer’s Precision Distance is the only technology allowing
millimeter-level manual adjustment to the speaker distance.
Speaker A
Input Power
Output Power
Speaker B
Low Frequency Linearity Measurement
Power maintained at lower frequency:
detected as Speaker Large
L R
With a 2ch system, all points on
the bisector are at equal distance
On a stereo system, a set of points
with equal distance from the two
speakers becomes a straight line as
shown on left. So it is relatively easy
to gain the point where the sound
waves from all sound sources (two
speakers) intersect in phase.
L R
SL SR
A
With a 3ch system, the intersection of two
bisectors needs to be at an equal distance
With a 3ch system, the intersection of the
bisector between L and R and the bisector
between R and SR, point A, is where the
sound wave from all sound sources
intersects in phase, as shown with a red
triangle. The bisector between L and SR
automatically passes through this point.
With a 4ch system, the additional channel
must precisely match the point fulfilling
the condition for 3ch
With 4 or more channels, the distance for
the additional channel(s) (shown with the
green arrow) must precisely match the
already affixed point A for 3ch. So it
becomes more difficult to achieve the point
where the sound waves from all sound
sources intersect in phase.
The ideal is to have a spot with the same acoustic distance from all speakers
All channels are in phase, with ideal sound field
for all channels
Distorted overall sound field
L R
L R
SL SR
SL
SR
Interference on other
channels distort the sound field
SL ch out of phase
How to interpret reverb graphs (Reverb)
1. Case with different reverb characteristics for high/low frequencies
Time
Time
A B
Level Level
The graphs show changes in microphone input level along a time axis,
beginning from a state of quiet at time 0, when test tones begin to be output,
and continuing while a constant level of sound is output from the speakers. If
there is absolutely no reverberation in your room, the graph will look like
figure A. If there is reverberation, the graph will show a gradual accumulation
of acoustic power, as shown in figure B.
0 80 160
Level
(dB)
Time
Low Frequencies
High Frequencies
Time period point
to be selected
Time period point
to be selected
0 80 160
Level
(dB)
Time (ms)
Front left
Front right
Time period point
to be selected
2. Case with different reverb characteristics by channel
3. Case with similar reverb characteristics for each frequency and channel
0 80 160
Level
(dB)
Time (ms)
Front left low frequencies
Front right low frequencies
Front left high frequencies
Front right high frequencies
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