Building 8 inch ported sub woofer box – Full size enclosure

Having a good sound system is fun, but what else is fun is making one by own. However, I already have a basic sound system and I needed to improve its quality.

When talking about quality, subwoofer is obviously the main factor because it’s pretty hard to get it right. As humans, we are less sensitive to lower frequencies so it had to be very powerful and to do that, we need precise technology to achieve maximum efficiency. For the any kind of subwoofer, enclosures is must for lots of reasons and it will help to reduce cancelation, distortion and improve ton of other stuff when get it right.

 

There are many types of enclosures, but Sealed, Ported and Bandpass enclosures are the most popular ones. Thus, each one has its own advantages and disadvantages. In short, Sealed enclosures are provided more accuracy output while Ported providing more loud output and Bandpass will focus on the specific frequency range and amplify it’s better than others.

 

So in my project I’m going to make a ported enclosure with 8” subwoofer for the several reasons. First one is my amplifier is based on TPA3116D2 which is capable of a maximum output 100W for subwoofer alone, but my power supply only capability to provide 65 watts max, So I’m not getting very good power output so I’m not going for sealed enclosure because it need more power to get the same loudness comparing to other types. Also, I already have a sealed enclosure box, so I’m not going to make it. And about Band pass, it would require some precise calculations or otherwise it would be sounds bad. Since I’m going to use cheap subwoofers I found on the market, I’m not going to get it right calculations and it’s a lot easier to build ported one without messing with those.

 

There is lot of designs you can use to make something like this. You can always find some good designs and helps, out there on the internet with tons of resources. With days of research I got this plan of enclosure from this site http://ddaudio.com/support/box-plans/. It is very detailed and looks accurate to me according to my research.

You can download PDF file from this link from their website.

First, I have to make cuts plan for MDF board. For the board I’m using 8×4 standard size ¾ inch MDF board. From one board I could have made 3 boxes, so I planned to make 3 of them for more fun.

I convert retard units to metrics, so I’m not getting any confuse. However since I do not have the correct tools for getting the job done, I asked help from professionals for cut the board.

After cutting is done, I used simple plain nails and glue for the keep it together build. At this point you can use screw drives instead nails, but you have to drill the holes half way through. In both cases there is a huge chance to board get cracking, so avoid that possibility much as I can, I used thinnest nails I could find.

Halfway through the building, I started painting work. Because it’s very important to seal MDF board completely, or otherwise toxic that leaking from MDF board might get you a cancer or something. However the painting MDF board could be a hardest part of the whole process. For any kind of finish you have to use some kind of primer base. In my case I used a generic wood sealer to the first coat. Then sand it and apply paint on it. For glossy finish or better looking finish you may have to go for more layer of coatings and sanding. But in my case I don’t need to get nice look, so I end up with just a painting box with minimum effort. you can clearly see how bad is my paint job. 

After painting I attached speaker terminal, connect wires and tape loose wires in to the box or they will make rattling sounds when box works.

When finished the wiring I attached the speaker and seal the box. When you attach speakers to box use sealing material between speaker and enclosure to ensure an airtight seal between it.

After finishing, check for air leaks in box and seal them properly with glue or any other material. You can easily spot the leaks when playing some high base from amp, you can feel the air coming through.

 

For the whole process it cost me at around 9000 LKR to complete 3 subwoofer box with drivers. My expenses as follows.

For MDF board LKR 3750.00

Cutting LKR 800.00

Paints LKR 1000.00

3 Subwoofer Drivers LKR 3000.00

Nails and other costs LKR 500.00

 

Total cost is LKR 9050.00 which is around 56$. For one Subwoofer it cost less than 20$ and that’s so much cheap considering other options in the market.

With this subwoofers I will attempt to make complete surround sound system in a later post.

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