10-inch Subwoofer

included in Audio

2018-07-12 1026 words 5 minutes

Goals

Low frequency cut off 30 hertz at -12 dB
High frequency cut off 150 hertz
Dynamic
Acoustic Suspension
Medium size about 1 to 2 cubic feet or 28 to 56 liters
Loud enough to handle bookshelf speakers. Can lower the volume of bookshelf speakers to compensate.

Bunghole of Materials (BOM)

I have to be funny sometimes. Fine, bill of materials.
Dayton Audio Ultimax 10-inch Subwoofer
1.25 cubic feet flat-pack from Denovo
BASH 300 Watt Subwoofer Plate Amplifier
Gorilla Glue
2-inch thick Eggcarton Foam
6-32 Hurricane T-nuts (Qty-8)
6-32 Screws with a square drive bit
6-32 Washers

Extra tools that I had to get are the following.

24-inch long clamps
Power Drill
Drill Bit Set
Jigsaw

Assembling

First, I started putting the box together, by making sure all the sides and bracing were counted. After everything checked out, I started doing a dry fit of all the sides and bracing. The bracing requires some sanding to make it easier when putting them together with glue. The Gorilla glue requires water to activate. I used a spray bottle to spray the areas where I would be putting the glue. The number of clamps that I had was not enough, so I had to glue one edge at a time. It took about a day to finish assembling all the sides. The time for the glue to mostly cure took less time because the arid climate where I live helps with that. When the glue was mostly cured, I was surprised that it was a strong enough bond that just holding one panel still stayed together. During the curing process, I noticed the glue foamed. I did not have a lot of trouble with the glue. The foam helped seal the edges and gave me an indicator of where I should have to add more clamps. Note to self: MORE CLAMPS.

The next step after assembling the box is the placement of the amplifier. All home subwoofers put the amplifier on the back of the box. I wonder if I could do it differently by placing it on the side. I measured the required cut-out dimension on the side where I would like to place the amplifier. I found out that the top or bottom half of the left or right side can be used. I picked the top left side. I could not place the amplifier near the front, so I had to place it towards the back of the left side. By placing it on the side, I could reach the controls from my chair. I could easily put it on the right side, but the switch for turning off will be toward the back which will be hard to access.

The reason why I cut the hole for the amplifier is that it will make a good access point for me to guide the woofer as I mount the woofer. I can lift the woofer and rotate it easily. The Dayton Audio Ultimax 10-inch subwoofer is heavy. The side hole makes this process easier compared to putting the hole for the amplifier on the back.

The third step is drilling holes where screws will be placed to mount Dayton Audio Ultimax 10-inch subwoofer. The CNC process already cuts out the Dayton Audio Ultimax 10-inch subwoofer, so I do not have to do that step. All I need to do is place the woofer in that hole and mark where the screws will go. The side hole makes this process easy.

Next, is putting in the T-nuts and connecting the wire to Dayton Audio Ultimax 10-inch subwoofer from the amplifier. Then screw everything down by starting with the Dayton Audio Ultimax 10-inch subwoofer and finally the amplifier. The screws that I used for the amplifier are a rustic coarse thread with a built-in washer. I had to make some pilot holes for these screws to make them easy to screw in.

Setup

At this time, I stood back and was amazed by the subwoofer that I built. I took a little moment. Well, OK, a long moment. I hook it up to my sound system. It requires some tweaking. This was not the first 2.1 setup that I had. I used Audacity and generated pink noise to start setting the crossover point. Then I set the volume for the subwoofer. I used a MiniDSP 2X4 to help with the setup. I lower the bookshelf speakers down to about -15 dB. This subwoofer is not loud. Oh, well.

Back to the Drawing Board

Over time, the subwoofer sounded grainy and not dynamic. It was not loud. As I did some research. The control label “volume” is not a volume control after all. I think I set this control too high, so I researched more. I require some equipment that is costly like an oscilloscope or SMD DD-1. At low volumes, the subwoofer begins to reproduce other sounds as if something has delaminated. It kept on getting worse and worse.

I started on a venture to either do an RMA for the Dayton Audio Ultimax 10-inch subwoofer or find a replacement. Shipping the Dayton Audio Ultimax 10-inch subwoofer will cost a lot because of the weight and distance. Also, shipping will not be the only problem. Parts Express deciding to replace the woofer could be 50 to 50. It will cost me too much to do the RMA process, so I went on the process to look for a replacement.

For the replacement, I would like a woofer that has high Qms and is louder. My previous subwoofer before the Dayton Audio Ultimax 10-inch subwoofer had a high Qms and I liked how it sounded. I found a replacement for the Peerless model SDF-250F75PR01-06. I modeled the woofer in WinISD. The simulations show it is 4.5 decibels louder than the Dayton Audio Ultimax 10-inch subwoofer. Also, it hit another goal of 30 Hz at -12 dB. Normally, when designing loudspeakers or subwoofers frequency response level is -3 dB. In the room, it is more like -12 dB for frequency response level. Third, it can fit the box and it fits the cut out, so no modifications are required.