Not too long ago I had a patreon giveaway.  The winner won a custom speaker designed by me.  Once the winner was chosen he wanted a custom subwoofer that would match his already built soundbar.  Since he did an amazing job, I knew I to give him something that would at least match the quality.  So I decided to build a custom Voxel Subwoofer with a Cherry inlay.  Now most people who are familiar with the Voxel Subwoofer that Paul Carmody designed, know it is a passive subwoofer.  That means you need a 2.1 amp to run it.  That wasn’t going to work, so I decided to take on the task of making this a self powered subwoofer with and adjustable crossover.

Parts Used

All the cuts were made out of 1/2 MDF.
Sides (2): 12×9.5
Top and Bottom (2): 5×12
Front and Rear (2): 5×8.5

Build Video

Subwoofer Location and Port

When i built this, I almost forgot about the port.  I was so interested in where to put the electronics that I momentarily forgot about the port location.  I say that because, I put my port off-center in the rear near the bottom.  Although this worked, I had to cut a little bit of the internal flare off.  This was due to the fact the motor of the subwoofer would get in the way otherwise.  So if I were to do it again, I would put the port and the subwoofer in the original locations.  Then I would put the electronics where they best work for you. Here is a picture taken from here which shows the original locations. 
If you notice the subwoofer is center from front to back (6″) and 4″ from the bottom.  The Port is centered on the rear (3″) and 2 1/4″ from the top.  I cut a 5 1/8″ hole for the subwoofer and used a 1/2″ rabbet bit to recess it flush (see video).  For the port, I used a 2 1/2″ hole saw.

Finally, the ports will actually be glued together to make 1 really long port.  With this in mind, make sure you put one inside the box and one outside the box (through the port hole) before you glue it together.  Otherwise, you will never get it in the box. A helpful hint, have some duct tape on hand.  Once you glue it together hold it in place by taping around the two pieces.  This will make sure they don’t come unaligned while the glue is drying.

Wiring the Electronics

I found it easiest to wire the electronics first, then tape around them to paint.  Feel free to do whatever works best for you.  Just make sure to cut the holes before you glue to box together.  Also, watch the video if you are confused.  This may help clarify some things.
Let’s start with wiring the adjustable low pass  This has both an in and an out.  If you notice the input has three wire terminals, a left, a right and a shared ground.  What you will need to do is either use the screw terminals or solder to the bottom of the board a wire to each of these.  Once those are connected to the board, we will wire them to the RCA.  The rca, is a mono plug, so we will need to solder both the right and left wire together.  These will be soldered to the positive of the rca (the tip on the bottom).  You will also want to solder the ground to the special grounding washer that is provided with the rca.  A couple quick tips, make sure to wire the positives through both the nut and the rca ground, as well as the hole in the rear for the power before soldering the positives.  If you don’t you will have some issues trying to put it together.
Next let’s wire the output on the adjustable low pass.  This is a mono output, since it is going to a subwoofer.  Luckily the amp we bought came with a jst cable (grey cable).  This cable just plugs into the amplifier on one end and has a right (red) left (white) and ground (black) on the other end.  You can easily just combine the red and white (right and left) sides and screw them or solder them into the positive out and the black to the negative.  Once that is finished, just plug the jst terminal into the amplifier.
Power is easier than you would think.  You will just run the power from from both screw terminals (of both the amplifier and pre-amplifier) together.  The ground will be soldered directly together and into the power jack.  The positive wires will also be soldered together, but will first be run to one side of the power switch.  Then run a separate wire from the other side of the power switch down to the power jack.  Once these are wired, you only have one step left.
Wire the subwoofer.  This is as easy as taking either the left or the right speaker out and running it to the subwoofer (+ to + and – to -).  It does not matter if you use the right or the left.  If you are wondering the other side is powered, so you could run some banana plugs out the back to power a second Voxel Subwoofer if you want.  This one would just be passive without the need of anything else.  This subwoofer will control the crossover, power and volume of both subwoofers.

If I were to give any last tips on the wiring, I would say to make sure you have secured all your wires.  Most manufacturers just use some type of glue.  So if you have any epoxy or hot glue on hand, glue those wires in place.  The last think you want to hear once you fire up that sub is a bunch of wires vibrating against the mdf. 


I did a 1 1/2″ Inlay out of 1/4″ Cherry wood.  I picked a spot, in this case approximately 1″ over and routed out a 1 1/2″ groove for the cherry inlay to sit perfectly flush in.  After I pained the Subwoofer, I just glued this in and held it in place with painters tape.  In the end, I used some nice polycrylic (does not yellow) over the white paint and the cherry wood.  

Final thoughts

This is a fantastic subwoofer for a small soundbar or even a desktop setup.  I personally would encourage anyone thinking of building one of these to give it a shot.  I have never hear a 5 1/4″ subwoofer that could play that low or that loud before.  In fact, I built one for my DIY Dayton Soundbar just for fun.  I am still impressed with the sound of it.  However, I will be sticking to my DIY Cube Cubed Subwoofer.  ANd I know for a fact that my Patreon winner loves it!

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