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Optimal Subwoofer Performance

A frequently asked question that we receive is "How do I improve my subwoofer system's bass response?"

Below are some common issues and methods to correct them:

JL Audio subwoofer

Using multiple subwoofers and have very little bass output

  • Double check the wiring polarity of all subwoofers to make sure they are properly connected. If one subwoofer (or more) in a group is wired with the positive and negative speaker connections wired in reverse with each other, it will result in bass cancellation.
  • Make sure that the subwoofers are in an appropriate enclosure. When using multiple subwoofers, it is necessary to multiply the enclosure volume for a single subwoofer by the number of subwoofers you are using. Placing multiple subwoofers in an enclosure meant for just a single will usually restrict the subwoofers and severely compromise low frequency extension.

Subwoofer(s) lack deep bass extension

  • Check the manufacturer’s recommended enclosure specifications to ensure that the enclosure you are building or purchasing matches to their provided recommendations. As an example, a subwoofer in a sealed enclosure that is smaller than the recommended volume or a ported enclosure that is tuned too high will compromise its low frequency extension.
  • Double check the crossover settings and make sure that the Low Pass filter is being used. If the High Pass filter is being used by mistake it will limit the low frequencies going to the subwoofer. For a subwoofer system, we typically recommended applying a Low Pass filter with a filter frequency set to 80 Hz as a starting point. 


JL Audio subwoofer box

Subwoofer seems muddy or lacking in detail, impact, or output

  • Check the level balance between the subwoofer system and the satellite speakers. If the bass level is too high the midrange can seem low or the bass undefined and muddy.
  • When using a ported enclosure make sure subwoofer enclosure's tuning is not too low. This can compromise upper bass range and the transition with the midrange speakers. Double check with the manufacturer for suggested tuning.
  • Make sure the enclosure is of rigid construction, built to the manufacturer’s recommended size, and secured to the vehicle. If the enclosure is loose, bass energy will be lost since the enclosure will move when the subwoofers play and acoustic energy will be wasted.  Read more on Securing Enclosures.
  • Try facing the subwoofers different directions to see if impact or output improves.

Subwoofer sounds boomy

  • Make sure the sealed enclosure volume is not too small. This will compromise the low bass extension and may emphasize the upper bass range resulting in bass that sounds boomy. Learn more about Sealed Enclosure Characteristics.  
  • When using a ported enclosure, ensure that the enclosure's tuning is not too high. This may compromise low frequency range and emphasize the upper bass range too much.  Learn more about Ported Enclosure Characteristics
  • Check equalizer settings on the amplifier or source unit and make sure they are set to flat. Application of too much boost by way of bass equalizer and/or bass boost settings may compromise the sound system's overall response, leading to boomy system output.

Poor bass output in a convertible vehicle with the top down

JL Audio down fire box

  • In many convertible vehicles, a down-firing subwoofer enclosure works best. This maintains a good loading effect for the bass frequencies, even with the top down. Oftentimes, if the enclosure were to point up, back, or forward in a convertible you would not have the added benefit of the loading effect, leading to a good amount of  bass escaping into the open air while the vehicle is moving.


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