The effect of re-running MCACC

Introduction

Measurements taken 2018-09-18

MCACC is the auto calibration feature of Pioneer AV-Receivers. When you connect the calibration microphone delivered with the receiver, the MCACC menu is started and you have options or running it fully or partly automated. When you start MCACC, all speakers will sequentially produce sound which is analysed by the receiver, using the microphone. The idea is that this feature makes the sound reproduction better. I wondered if I could measure the changes done by this feature.

Equipment & Room info

See Game room.

Measurements

Note that the initial measurements were executed with an 'old' MCACC calibration active, generated about a year ago and before I placed acoustic absorption panels.

Front Left Speaker

Green graph: Old outdated MCACC results, set at 'ALL ADJ'.

Red graph: Updated MCACC result, set at 'ALL ADJ'.

Blue graph: Updated MCACC result, set at 'Symmetry'.

Front Right Speaker

Green graph: Old outdated MCACC results, set at 'ALL ADJ'.

Red graph: Updated MCACC result, set at 'ALL ADJ'.

Orange graph: Updated MCACC result, set at 'Symmetry'.

Rear Left Speaker

Green graph: Old outdated MCACC results, set at 'ALL ADJ'.

Purple graph: Updated MCACC result, set at 'ALL ADJ'.

Blue graph: Updated MCACC result, set at 'Symmetry'.

Rear Right Speaker

Pink graph: Old outdated MCACC results, set at 'ALL ADJ'.

Blue graph: Updated MCACC result, set at 'ALL ADJ'.

Turquoise graph: Updated MCACC result, set at 'Symmetry'.

Subwoofer

Red graph: Old outdated MCACC results, set at 'ALL ADJ'.

Blue graph: Updated MCACC result, set at 'ALL ADJ'.

Green graph: Updated MCACC result, set at 'Symmetry'.

Result description

There are definitely differences in the frequency spectrum, due to the re-calibration. Often about 5dB but sometimes up to 10dB.
However, this does not provide a notable improvement in frequency reproduction. Some peaks&dips are smaller, others are larger.
For the sub, it seems to be equalised worse than before since the peak is higher and the drop-off sharper.
The difference between SYMMETRY and ALL ADJ is hardly visible. From a frequency perspective not relevant.
There seems to be more dB output at higher frequencies, this is expected due to the additional wall treatment that was added (absorption removes high freq. reflection and thus dB, MCACC seems to compensate this correct).

Questions / unclear findings

The Jamo S426 Rear Left seems to be severely lacking at about 180 Hz. Defect or nulling?
The Jamo S426 Rear Right seems to be severely lacking at about 100 Hz. Defect or nulling?

Conclusions

MCACC has limited effect on frequency spectrum, probably due to room modes overruling.
MCACC adjustments are hardly visible below 500Hz.
MCACC adjustments do compensate room absorption.
It does not seem necessary to rerun MCACC after each room change. (of course, in case of speaker or listener replacement it should be rerun because MCACC also compensates timing/delay in the audio path to your ears).

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