Technology & Engineering

Acoustic Resonance Control® (ARC)

The second front in the war against performance-robbing resonances.

We’ve discussed how a speaker driver makes sound by moving back and forth. As it does this, half the sound comes out the front of the driver and the other half comes out the back. The part that comes out of the back of the speaker driver, the back sound, is usually trapped inside the box of the speaker enclosure. If the conditions are right, this trapped sound can create a pipe resonance effect at certain frequencies. 

ARC Port This internal cabinet resonance, the frequency of which is usually a function of the depth of the enclosure, can impart a thick character to voices in the midrange of the speaker’s response. 

To overcome this issue, Polk engineers designed and patented their Acoustic Resonance Control (ARC) port technology. The ARC port is usually coupled with a traditional bass port (which helps enhance the low-end response of a speaker). 

In this illustration, the ARC port is the second, smaller port (shown in yellow). Using sophisticated electronic tests, Polk engineers are able to tune the ARC port to suppress the internal cabinet resonances that can interfere with high performance audio. The result is Polk's famous clear and natural midrange response. 

Hear it today in Polk RTiA and LSi Series speakers.

ARC port technology holds *US Patent # 5696357.

This article was last modified on Mar 26, 2013

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