How to Underpower a Subwoofer

Avoid underpowering a subwoofer to prevent potential damage.

Underpowering any speaker creates risk. Whenever a subwoofer is underpowered, the temptation to crank the gain or input knob to compensate for a lack of volume is ever-present. Additionally, distortion-producing processing such as bass-boost knobs or other such controls causes distortion. Ironically, it is typically these compensatory controls that cause damage more than the lack of power.

Things You'll Need

• Subwoofer specifications
• Amplifier specifications

Instructions

1. Examine the RMS (root mean squared, or average) power rating of the amplifier in watts. Make note of this.

2. Look at the power requirements of the subwoofer, expressed in wattage.

3. Determine if the RMS wattage is less than the rated or expected power requirements of the subwoofer. If it is, you are underpowering the driver.

Tips & Warnings

• Listen for audible distortion from the subwoofer, such as clacking or popping. These are indications that you are overdriving the woofer through excessive use of tone or bass boosts.

• Remember that bass boost and tone controls can demand that an amplifier output up to 12 decibels more power at the frequency at which the boost is centered. This will cause excessive distortion, given that the amplifier is already underpowered for the driver.

References

• Electronic Web Matrix of Digital Technology: A Guide to Optimizing Speaker Performance
• Human Speakers: EPI Power Ratings Explained
• ePanorama: Amplifier Power