How Room Correction Works

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Every room changes the sound of your speakers. Room correction measures that change and adjusts the signal to counter it. The brands differ in detail, but the basic process is the same.

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The four steps

Beginner

  1. Measure. A microphone at your seat records test sounds from each speaker.
  2. Compare. The system compares what it measured with a target, the sound it’s aiming for.
  3. Correct. It designs filters to move the measured sound towards the target, and sets each speaker’s level and distance.
  4. Apply. The filters run inside your receiver or processor from then on.

Why measure in more than one place

A measurement is only accurate for the exact spot where the mic was. Move a short distance and the response changes, especially in the bass. That’s why most systems ask for several positions: they aim to improve the whole listening area rather than one point. Dirac says more measurements give better results.

Why the target isn’t flat

A perfectly flat response usually sounds thin in a room. Most systems aim for a little extra bass. Anthem’s ARC, for example, deliberately keeps some of the room’s natural bass lift. See What Is a Target Curve?.

What room correction can’t do

  • Fill deep dips. Where sound cancels itself out, adding more power just adds more cancellation.
  • Remove reflections and echo in the mid and high frequencies. That needs acoustic treatment.
  • Make every seat perfect. Yamaha puts it simply: physics makes it impossible for every location in a room to be perfectly calibrated.

Based on manufacturers’ documentation and REW’s help.

Next step

Which System Do I Have?

Find out which room correction your receiver or processor uses, so you can follow the right guide.

Continue: Which System Do I Have?
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How the systems differ

Advanced

Magnitude only, or timing too

Simpler systems use parametric EQ, which changes how loud each frequency is. Room responses are mixed-phase, and EQ alone can’t fully correct that. Dirac corrects the impulse response with mixed-phase filters, adjusting timing as well as level.

Why boosting dips is a bad idea

Every 3 dB of boost needs twice the amplifier power. A deep dip might need 24 dB or more, which risks clipping, and the dip moves as soon as you change seat. Good systems limit boost and concentrate on cutting peaks.

Bass management and multiple subs

Bass management sends low frequencies from each channel to the speakers best able to play them, usually the subwoofers. Anthem suggests an 80 Hz crossover for most speakers, and 100 to 120 Hz for compact ones. Dirac Bass Control goes further and tunes the timing, level and phase of subwoofers and speakers together around the crossover. Dirac ART uses other speakers to actively cancel bass resonances below about 150 Hz. See Bass Control setup and ART setup.

Where each system corrects

  • Anthem ARC corrects up to 5 kHz by default, with only the target shape applied above.
  • Dirac Live Full Bandwidth corrects 20 Hz to 20 kHz. The Limited Bandwidth licence stops at 500 Hz.
  • Lyngdorf RoomPerfect‘s default target keeps the speaker’s own character rather than forcing a flat line.

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