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Introduction MCACC MCACC ProThe Essence of MCACC Advanced MCACC Feature Comparison Technical Details

MCACC Reference Guide

Full Band Phase Control

While Phase Control’s bass management technology controls

the LFE channel timing and phase within the AV receiver, the Full

Band Phase Control’s technology has further evolved to control

the phase of all the units of the multi-way speaker system. With

a normal multi-way speaker system, the audio signals are

separated with the network filter inside the speaker and routed

to each unit. However, group delay occurs between the units due

to this processing through the network filter. Using a

microphone, Full Band Phase Control automatically measures

and analyzes the group delay that occurs across the whole

frequency range, then compensates only the phase

characteristics without affecting the frequency characteristics,

by adjusting with a FIR filter. As a result, multi-way speakers

sound coherent like full-range speakers, while retaining their

advantage of the wide frequency range—a significant

advancement in sound quality.

When the frequency range is separated via the network filter on

a multi-way speaker, although the total frequency characteristic

is designed to be flat, the phase and group delay characteristics

are not flat. As shown on right, Full Band Phase Control solves

this in three steps by using the MCACC microphone and DSP to

measure, analyze, and make compensations.

The phase and group delay adjustment of Full Band Phase

Control is applied not only to each speaker unit—simultaneous

analysis and compensation is also made between all connected

speakers. So even on a setup consisting of speakers from

various brands or series with completely different

characteristics, you can enjoy a natural and seamless

performance as if delivered all from the same speakers. With

accurate sound reproduction for the full bandwidth in all

channels, Full Band Phase Control creates the ideal sound field

for multi-channel reproduction with unprecedentedly clear audio

localization and a tremendous surrounding sound.

Because of group delay due to the network

filter, the sound output order is: high-range,

mid-range, low-range.

Low-

range

Mid-

range

High-

range

Frequency Characteristic and Impulse Response of a General

3-Way Speaker

Full Band Phase Control Off Full Band Phase Control On

Adjusts group delay for each unit

TWEETER

(+)

MIDRANGE

(+)

WOOFER

(+)

TWEETER

(+)

MIDRANGE

(+)

WOOFER

(+)

Three-Step Processing within the AV Receiver

Apply FIR filter with the calculated

filter factor to each channel

Sound field with matched phase

and group delay characteristics

for all speakers achieved

Impulse response

before compensation

Impulse response

after compensation

Phase and group delay for each

speaker is adjusted to have the ideal

characteristics of a full-range speaker

Measurement Step 3

180

–180

180

–180

Frequency

Less influence from room environment

Avoiding overcompensation allows

adjustment without deteriorating sound

quality

Calculate phase characteristics

from impulse response

Extract the optimal model from

the approx. 5,500 phase models

(99 % of the commercially available speakers)

Allows compensation for only the phase

component by creating an all-pass FIR filter

Calculate the inverse filter factor for

adjusting the selected phase model

Measurement Step 2

Measurement Step 1

Special sweep signal output from

each speaker

Signals measured with dedicated

mic

Digital Signal Processing (DSP)

of measured signals

Impulse response gained from

each speaker

1000

−

1000

−

2000

−

3000

−

4000

−

5000

−

6000

−

7000

−

8000

−

9000

0.004

0.0035

0.003

0.0025

0.002

0.0015

0.001

0.0005

−

0.0005

−

0.001

200

235

276

324

381

448

526

618

726

853

1002

1178

1384

1626

1910

2244

2637

3098

3639

4276

5024

5902

6936

8148

9573

11247

13214

15525

18240

1000

−

1000

−

2000

−

3000

−

4000

−

5000

−

6000

−

7000

−

8000

−

9000

0.004

0.0035

0.003

0.0025

0.002

0.0015

0.001

0.0005

−

0.0005

−

0.001

200

235

276

324

381

448

526

618

726

853

1002

1178

1384

1626

1910

2244

2637

3098

3639

4276

5024

5902

6936

8148

9573

11247

13214

15525

18240

Phase

G delay

Phase

G delay

Input impulse waveform

Speaker impulse response

before compensation

Speaker phase & group delay

characteristics before

compensation

Speaker phase & group delay

characteristics after

compensation

Speaker impulse response

after compensation

Woofer Midrange

High Frequency

(tweeter)

Mid Frequency

(midrange)

Low Frequency

(woofer)

Tw ee te r

Before compensation: simultaneous input for full range is

output in the order of high, mid, then low frequencies

After compensation: simultaneous input for full range

results in simultaneous output for all frequencies

Group Delay Compensation Effect

1 2 ... 10 11 12 13 14 15 16 17

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