I’ve been building subwoofers for years now, and I’ve always used car audio drivers. However, I recently started building speakers using pro-audio drivers, specifically mid-woofers and horn loaded compression drivers. I love how dynamic and clean-sounding these drivers are, so it was only natural that I decided to give pro-audio subwoofers a try.
I did some research on pro-audio subwoofer drivers with relatively low Fs (resonant frequency) and high Xmax (maximum linear cone excursion), and the Lavoce SAF184.03 stood out as a promising candidate. It features a beefy 4" voice coil and 1500W power handling. Some might scoff at the Lavoce’s 30 Hz Fs and 13 mm Xmax, but keep in mind that I plan to build multiple subwoofers in tiny sealed enclosures – at least by 18" subwoofer standards, so deep bass output likely won’t be an issue, and I’ll still be able to keep enclosure sizes in check.
I eventually settled on an enclosure design featuring generous 4" radius rounded corners even though I knew it would be somewhat challenging to make. Using 15 mm kerf-bent Baltic birch plywood not only keeps the enclosure weight in check but also is stronger than MDF, not to mention the wood grain looks very nice when stained a light color. The braces and baffle were made from 18 mm MDF.
I used a biscuit joiner to cut slots in the plywood. The two MDF braces are attached to the plywood using biscuits, essentially serving as the form around which the plywood was bent.
The braces also feature circular openings to support the heavy subwoofer motor, which probably weighs close to 15 kg (~33 lbs) by itself.
The front baffle and rear panel were painted black, and the birch plywood was stained white with a two-component oil. I lined the walls with polyfill sheets.
I placed four pillows filled with polyfill inside to improve deep bass response. In total, I used about 1 lb of polyfill per cubic foot. The gross internal volume, before accounting for driver displacement, is approximately 3 cubic feet (~85 liters), which is about 25% smaller than the typical minimum enclosure size recommended for a standard 18" car/home audio subwoofer.
With the addition of polyfill, the subwoofer’s resonant frequency decreased from about 61 Hz to 56 Hz. The impedance curve reveals that inductance is well-controlled, allowing this subwoofer to be easily crossed over as high as 500 Hz. The nominal impedance is 8 ohms.
The near-field frequency response indicates a roll off that’s less steep than the expected 12 dB/octave for a sealed enclosure, thanks to the driver’s strong motor. When placed along a wall in a typical sized room, the subwoofer should deliver flat frequency response down into the mid-twenties, especially after reducing the ample mid-bass output using EQ or an AVR’s room correction capabilities.
Finally, a complete build video is available below. Please let me know what you think.
I did some research on pro-audio subwoofer drivers with relatively low Fs (resonant frequency) and high Xmax (maximum linear cone excursion), and the Lavoce SAF184.03 stood out as a promising candidate. It features a beefy 4" voice coil and 1500W power handling. Some might scoff at the Lavoce’s 30 Hz Fs and 13 mm Xmax, but keep in mind that I plan to build multiple subwoofers in tiny sealed enclosures – at least by 18" subwoofer standards, so deep bass output likely won’t be an issue, and I’ll still be able to keep enclosure sizes in check.
I eventually settled on an enclosure design featuring generous 4" radius rounded corners even though I knew it would be somewhat challenging to make. Using 15 mm kerf-bent Baltic birch plywood not only keeps the enclosure weight in check but also is stronger than MDF, not to mention the wood grain looks very nice when stained a light color. The braces and baffle were made from 18 mm MDF.
I used a biscuit joiner to cut slots in the plywood. The two MDF braces are attached to the plywood using biscuits, essentially serving as the form around which the plywood was bent.
The braces also feature circular openings to support the heavy subwoofer motor, which probably weighs close to 15 kg (~33 lbs) by itself.
The front baffle and rear panel were painted black, and the birch plywood was stained white with a two-component oil. I lined the walls with polyfill sheets.
I placed four pillows filled with polyfill inside to improve deep bass response. In total, I used about 1 lb of polyfill per cubic foot. The gross internal volume, before accounting for driver displacement, is approximately 3 cubic feet (~85 liters), which is about 25% smaller than the typical minimum enclosure size recommended for a standard 18" car/home audio subwoofer.
With the addition of polyfill, the subwoofer’s resonant frequency decreased from about 61 Hz to 56 Hz. The impedance curve reveals that inductance is well-controlled, allowing this subwoofer to be easily crossed over as high as 500 Hz. The nominal impedance is 8 ohms.
The near-field frequency response indicates a roll off that’s less steep than the expected 12 dB/octave for a sealed enclosure, thanks to the driver’s strong motor. When placed along a wall in a typical sized room, the subwoofer should deliver flat frequency response down into the mid-twenties, especially after reducing the ample mid-bass output using EQ or an AVR’s room correction capabilities.
Finally, a complete build video is available below. Please let me know what you think.
Your DIY turned out really stylish. Even (within the subwoofer category) to be considered beautiful. 
