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DIY Subwoofer Build with Concrete Base

This Subwoofer build with Concrete Base uses the concept of a Linkwitz Transform (LT). It essentially boosts the bass output of a subwoofer driver in a smaller sealed enclosure compared to the typical larger enclosure required by a ported enclosure.

I am using a MiniDSP 2×4 to implement the LT. The subwoofer uses a 300 Watt amplifier that I have built a few years ago. The driver is a JBL GT4-12 inch subwoofer and the enclosure is roughly 35 litres sealed.

You can read more on the LT here, or here.

LT-Sub-01

Measuring the Thiele Small Parameters for the JBL GT4-12 subwoofer driver.

LT-Sub-02

Determining the optimum enclosure size for the driver in a sealed enclosure.

LT-Sub-03

Using the Linkwitz Transform (LT) Excel spreadsheet to optimise the LT circuit and performance.

LT-Sub-04

Having cut all the MDF parts, I start to assemble the enclosure.

LT-Sub-05

The nail gun is such a useful tool for assembly work.

LT-Sub-06

Cutting the bamboo plywood cladding.

LT-Sub-07

Applying glue to the bamboo cladding.

LT-Sub-08

With the cladding in place, I can place something heavy on top to keep it down while the glue sets.

LT-Sub-09

The 16mm white Melamine board is used to construct the mould for the concrete base.

LT-Sub-10

Assembling the cut parts of the mould.

LT-Sub-11

Using silicone sealant to seal all the corners inside the mould.

LT-Sub-12

The concrete is mixed.

LT-Sub-13

Pouring the concrete into the mould.

LT-Sub-14

Tapping the sides of the mould with a rubber mallet to remove all the bubble in the concrete mix.

LT-Sub-15

After having left the concrete to cure for a couple of days, I can remove the mould.

LT-Sub-16

Continuing to clad the enclosure with the bamboo plywood.

LT-Sub-17

I can now router the excess bamboo plywood flush to the edges.

LT-Sub-18

Glueing the baffle to the enclosure.

LT-Sub-19

The jigsaw is used to cut the hole for the plate amplifier.

LT-Sub-20

The enclosure is ready to be finished with a few coats of clear spray lacquer.

LT-Sub-21

Mounting the subwoofer driver.

LT-Sub-22

Installing the plate amplifier.

LT-Sub-23

Inputting the biquads attained from the LT spreadsheet onto the MiniDSP.

LT-Sub-24

The final down-firing enclosure on its concrete base.

 

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