Car Subwoofer Enclosure Build

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Introduction: Car Subwoofer Enclosure Build

Intro: I have been building car audio subwoofer enclosures for over 10 years, with tons of experience in audio engineering and acoustics. If you have any questions feel free to leave me a comment on this instructable and I will try my best to answer you in a timely manner.

Thank you for viewing!

Step 1: Design to Fit Customer Needs

For this build the customer had a 2008 Mercury Milan, he was wanting a very musical enclosure with tons of low-end response with not very much power. In order to achieve this I decided to go with a 4th Order Bandpass with a 2:1 ratio. 4th Order Enclosures are optimal for low power, high output music designs.

I initially wanted to do a "folded horn" design but was limited with the amount of trunk space I had to work with.

The drive I used is a Sundown Audio X 12" on a C2 Audio 1200 watt amplifier.

Step 2: Acquire Raw Materials

For this build because it was going into the trunk of a vehicle I wanted to keep it as light-weight as possible, so I choose to use 3/4" Baltic Birch Plywood. Not only is Birch Ply MUCH lighter than standard MDF board, it is much stronger...and because this customer wanted this box to match his wood grain interior, this was the perfect choice.

To attach the wood panels together I used Titebond 3 "Green" Wood Glue, and pocket hole screws...alone with a few 1-1/2" Decking Screws

Step 3: Cutting Subwoofer Baffle and Box Panels

This step is fairly simple, I cut all of the panels to match my initial blueprints.

For the subwoofer baffle I decided to do a 1.5" thick face, with a 1/8" deep flush mount. This made it much easier to position the subwoofer flat on the baffle, and gave extra insurance that the gasket would make an air tight seal.

Step 4: Attach Side Panels and Port

After cutting all the panels, I began to attach them. For this step I used mostly pocket holes for aesthetic reasons...once the glue joints dry the screws no long serve a purpose anyway.

I made sure to have all of the joints COMPLETELY covered with a good amount of wood glue, I also went back over the joints with extra glue once the joints were initially dry.

Step 5: Add Bracing to Prevent Panel Flex

One of the worse ways to lose sound quality and volume is from panel flex. To prevent this from happening I used a piece of 5/8" threaded rod, along with matching washers, lock washers and nuts.

This box is VERY solid and the panels have absolutely no flex to them.

Step 6: Prepare and Mount Wire Terminal Cup

For this enclosure I decided to use a nice looking gold plated terminal cup. I used some 8 gauge OFC wire for the speaker wire to insure the least amount of wire resistance possible with the most power transfer from the amplifier.

Step 7: Stain and Polyurethane

After the box was finished I decided to use a "Cherry" color stain, and 5 coats of ultra gloss polyurethane to finish and protect the plywood.

Step 8: Wiring the Subwoofer and Sealing the Sealed Chamber

At this point all that was left to do was wire up the subwoofer, and apply some 3/4" foam sealing tape around the edges of the sealed chamber.

I was skeptical of sealing the chamber this way, however after testing I found it to be VERY effective and I will for sure use this method again!

Step 9: Place Enclosure Into the Vehicle

The final step was to put the enclosure into the car, and wire to the amplifier.

Thanks for checking out my instructable! If you have any questions feels free to leave a comment and I will try to answer them the best I can!

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    40 Comments

    0
    Aaronleon
    Aaronleon

    Question 8 months ago

    Hey fellow baseheads. Is there one of you that possesses the appropriate software and would kindly be generous enough to work me up a set of plans for a dual 12-in ported. It would be driving to scar audio 12-in SDR D2 subwoofers. Powered with 2,000 Watts RMS wired down to one ohm. And would be going in the trunk of a 2013 Nissan Maxima SV.

    PREFER TO BE TUNED SOMEWHERE AROUND 35 HZ. I WOULD BE MORE THAN APPRECIATIVE FOR THIS ASSISTANCE AND I WILL FOLLOW THE BLUEPRINTS TO A T AND DOCUMENT THE BUILD. LOOK FORWARD TO HEARING FROM YOU GUYS

    0
    YusufG3
    YusufG3

    Answer 5 months ago

    Hi Aaron, i know your request is from a while back so i hope you've managed to build your sub enclosure and enjoying it already. I would loved to have assisted being a fellow bass junkie but i myself am quite the noob when it comes to these these fancy enclosure design softwares.
    Just thought i would ask you this though, have you tried the online calculators? i've used a few and they're pretty simple-ish.
    https://subbox.pro/en/ and https://www.ajdesigner.com/fl_subwoofer/subwoofer....
    Sub Box Pro alows you to select your exact brand and type of speaker and if it isn't in their list, you can enter the speakers values in manually.
    Once you're done, it'll actually give you a 3D rendering of your design which also includes the specific size of boards to cut, etc.
    Good Luck , Cheers
    PS: I am in NO WAY affiliated to anybody, these are just my personal recommendations.

    0
    haroldhprittjr
    haroldhprittjr

    Question 9 months ago

    I love the look of your box I’ve been on line studying all the different kind of enclosures and it seems most all are ported but I guess I’m kinda old school! I’m use to building sealed enclosures and never messed around with the ported or all these band pass boxes that are so new and the going thing now but during the past year I’ve managed to trade up some equipment well a descent amount but my big main 2 are a sundown x15 and a skar skv 2500 watt amp and from studying and talking to others about them they should pair up real well so I wanted sealed but can’t but they say 4th order is the next best thing so I could have the best of both worlds well I haven’t even purchased my wood yet but birch 3/4 is what I understand is the best and to coat te inside of the box like sealing it in there with rubberized undercoating I’ve seen these guys show results of test with and with out! Looks like it helped but I was needing help with my peremitters of building it with figures ona hard hitting box and a really low side for the 20 hz then I lean that I have to tune the large ported side to the size of the small side that sounded idk to me but I’ve seen two or three say it like that. So I seen your build and right off like I was thinking 1.5 and 4-5 cubic feet for the x15 but I’ve seen the figures on line it’s like most say 2.0-3.0 and 5-7 but sundown says on there site these are ment to be used in smaller than normal they call for a little bit ove 4 cubic feet for just the ported so I guess I’m going to go like I have seen one set up I’ve seen it’s go ahead and use the specs to build a ported box then add a sealed chamber with the end cap we’re you can move it closer and tune that side and the ported one I have a 8 inch pvc pipe to make it out to be my port and I have enough to use the end that has the flange we’re i could take it out and cut some off and if I cut to much I can add another peace buy removing the cut peace out of the flange witch would be on my horn that bolts in but I only know one thing that might be wrong that size port is for a ported box if 6th order needs tuned to small sealed side what size would I need and am I wrong for wanting to be able to tune the sealed side and if so I would have to tune the port or haven it that way would be an advantage because if I couldn’t get enough out of one by haven both I would I need help with this I don’t feel like I’m in over my head but again idk it’s a lot to take in when I was never good at math and never had algebra or trig in school so if you lead me closer to my goal I would highly appreciate it you just don’t know how much thanks for the pics and Info about your build it looks great bet it sounds great!

    0
    kbrules33
    kbrules33

    Question 2 years ago on Introduction

    What demotions do i need for a 10 in sub

    0
    rickdod3
    rickdod3

    Answer 2 years ago

    Hi, unfortunately, I cannot give you that info without knowing what subwoofer you're referring to. Different manufacturers have different requirements.

    0
    lakrymist
    lakrymist

    2 years ago on Step 9

    Hey can you share the dimensions ? I'm building the same box for the same sub in a similar space.

    0
    rickdod3
    rickdod3

    Reply 2 years ago

    Hi, the dimensions are on the diagram on step 1 :)

    0
    Dominic714
    Dominic714

    Reply 2 years ago

    I'm trying the same thing with a smaller trunk lid. Could I just make it 3 inch low and 3 wider. Etc.. as needed to make it fit my trunk?

    0
    Dominic714
    Dominic714

    Reply 2 years ago

    Also do you ship I've got PayPal. And could use your skillz

    0
    rickdod3
    rickdod3

    Reply 2 years ago

    Hello Lakrymist, unfortunately I do not have the dimensions of this enclosure. This was many years ago that I built it. Very sorry

    0
    chrisb06
    chrisb06

    Question 2 years ago on Introduction

    i am trying to fit (4) sundown sa10's in the trunk of a nissan altima 2008 model. i want to do a 4th order. can u give me some numbers i need to target? im not asking u to design the box unless u want to. i just need to know what i need for front side and back side per speaker or all together and port. and thanks. btw i am chris from north carolina

    0
    rickdod3
    rickdod3

    Reply 2 years ago

    Hi Chris, for SA10s I would aim for around 1 cubic ft of space PER woofer for the sealed section. As for the ported section, I would utilize as much space as you can manage. Generally speaking, for a 4th order bandpass to be "worth" while, you need at least a 2:1 ratio. That being 2 parts ports per 1 part sealed (for example, 4 cubes sealed space for 4 SA10s you would want at least 8 cubes of ported area). If you do below a 2:1 ratio, you still increase your playable bandwidth musically, but you're not gaining any output in decibels. Honestly, if you have less than a 2:1 ratio I would look into doing a standard ported box rather than a bandpass. Hope this helps!

    0
    JacobC177
    JacobC177

    Question 3 years ago on Introduction

    i was wonder if you can tell me how to tune a ported box .. im trying to desing a slot port and a 4th order for myself i understand the size of the port is roughly half the cone are i just dont understand tuning fully

    0
    rickdod3
    rickdod3

    Answer 2 years ago

    Hi Jacob, sorry for the slow response. Tuning a ported box will depend on a lot of different parameters. Mainly the specs of the subwoofer, and the environment it is going into. I can't really give any tuning suggestions without knowing details. Also, the same generally goes with port area, there is a ballpark number to aim for, but it will depend on the environment and subwoofer specs.

    0
    rickdod3
    rickdod3

    6 years ago on Introduction

    I have been doing car audio installs for over 10 years. If you read the description under each photo you will answer the majority of your questions.

    1) This is exactly what the customer wanted. They did not care about trunk space, they wanted a loud and low end enclosure. That is exactly what I designed and built.

    2) As far as it being "too big" that is not a small subwoofer, even with a standard ported (or even sealed) enclosure, it would have taken up roughly about the same amount of room. Also, I put a TON of effort and time into the design and planning of this build. Taking everything into account, cabin dimensions, trunk lid sound wave loading etc.

    3) This box was intended to sound good, that was the only goal. He did not care what it looked like. All of the astectics decisions were made by me. Function > Looks.

    0
    zaidjay0
    zaidjay0

    Reply 3 years ago

    thanks for you're input I'm currently searching the web for the proper measurements for a 4th order bandpass for 2 sundown audio sa10?

    0
    zaidjay0
    zaidjay0

    Reply 3 years ago

    can u help me with this?than you

    0
    NickL181
    NickL181

    Question 4 years ago on Introduction

    i have a sub woofer in my car and i am not satisfied with the basic seal box i built, and i want a folded horn box, and I wanted your opinion. the sub is a Rockford Fosgate hx2 its a 10" and im running it at 800 watts
    and 4 ohm stable.