DIY Polyfill Subwoofer

Adding polyfill to a subwoofer will enhance its performance.

Adding polyfill to a subwoofer box is a simple method of enhancing the overall sound of the subwoofer in certain situations. The polyfill has the role to virtually increase the internal volume of the box by delaying the sound waves a bit, creating the impression of a bigger box. This is especially useful when the volume of the box is below the recommended specifications of the speaker manufacturer. Even though a specific type of polyfill was created for this purpose, its characteristics are almost identical to those of regular craft polyfill, so you can use whichever you like.

Things You'll Need

• Polyfill
• Screwdriver
• Universal adhesive

Instructions

1. Remove the screws that keep the speaker in place.

2. Lift up the speaker from the box, carefully not to disconnect the wires from it.

3. Add some polyfill inside the box and place the speaker back in place.

4. Fix the speaker back in screws and play some music to see how your subwoofer performs.

5. Repeat the above steps until you’re satisfied with the sound. There is no precise formula to calculate the amount of polyfill needed, so you’ll just have to try and see what works for you. It mainly depends on the size and performance of your subwoofer.

6. Remove the speaker from the box once you found the right quantity of polyfill needed and remove the polyfill as well.

7. Apply a thin layer of adhesive on the inner walls of the subwoofer box and insert the polyfill, fixing it to the walls.

8. Put the speaker back in place and fix it with screws.

Tips & Warnings

• Build the subwoofer box according to the dimensions specified by the speaker manufacturer if possible. A polyfill-stuffed subwoofer box will not sound as good as a box with the proper dimensions.

• Arrange the polyfill evenly inside the box and avoid having it touch the speaker.

• Don’t use polyfill in bandpass subwoofer boxes, as it will modify its tuning frequency and alter the sound.

• Don’t use polyfill if the box is already larger than specified by the manufacturer, as it will only make it sound worse.

References

• DIY Audio and Video: DIY Audio Speaker Box Building FAQ -- Tutorial
• Klaus Audio: Using Polyfill in a Subwoofer Box

Resources

• The12volt.com: Subwoofer Enclosures
• Crutchfield: Subwoofer Enclosures