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Discussion Starter · #1 · (Edited)
XtremeRevolution's Subwoofer Boxes

This thread will be dedicated to the design and sale of my custom subwoofer boxes and baffles. I've decided to make my services available to the community at an affordable price, as custom, well-built sub boxes are generally not cheap, and pre-fabricated boxes are generally junk.

If you need a subwoofer box designed and can build your own, if you have a box and want to see how a sub will sound inside it, or if you need a box designed and built by me, you've come to the right place.

Subwoofer Box Design

I offer my services for subwoofer box design free of charge. If you need a subwoofer box designed for a sub you own or will be purchasing to put in your Cruze, please reply to this thread and provide me with the following information:

1. Make/Model of Subwoofer
2. Subwoofer's T/S parameters (Qes, Qms, Fs, Vas, Sd, Xmax, and RMS Power handling)
3. Where in the trunk you plan on placing this sub
4. Make and model of your subwoofer amplifier
5. Types of music you primarily listen to
6. Primary goal for performance (Sound quality, SPL, best use of a box you already own, smallest box possible, etc.)

Based on the above information, I will provide you with a frequency response chart of a simulation for a given sub, in a specific box, with your car's cabin pressurization gain and boundary loading (cabin transfer function) to give you an idea of what it will sound like in your car.

Subwoofer Box Sales
While I'd prefer to teach you how to build a good box, I understand that not everyone has access to the tools or space to build one, so I also offer my services for building a sub box for you should you need one built.

Pricing:
Single 10"-12": $195
Dual 10"-12": $235


The above pricing is for subs that require .75-1.25 cubic feet of internal volume per sub, sealed. I can provide you with a price for boxes that don't meet those dimensions or for 8" or 15" subwoofers on a case by case basis. Ported boxes will also be quoted on a case by case basis.

These boxes will be built with routed bracing and an extra thick front baffle with a recess for the sub. These will be made out of 3/4" MDF, will be precision cut and routed, free of leaks, and will be nearly indestructible. Basically, the MDF material will fail before the joints do. They will be carpeted with your choice of either Black, Charcoal, or Medium Gray carpeting. I can substitute that for a different fabric (such as black shag, faux tiger fur, etc.) for an additional cost. A strip of speaker gasket tape and an adequate length of 12 gauge OFC wire will be included.

Prices include mineral wool as fill. Depending on where you live, expect shipping to be anywhere from $40-$80. Particularly large boxes may be more expensive, while particularly small ones may be less expensive. With double thick baffles and internal bracing, these boxes typically weigh 35-60lbs unloaded. As always, local pick-up is free. I am located in the southwest Chicago suburbs.

I was recently asked why the prices of my boxes was so high. I figured I'd copy my response here so people could get an idea of what's involved.

  • I use quality materials. I use 3/4" MDF instead of 5/8" like some companies do. I use latex backed cabinet fabric so it doesn't shed, I use a gold plated terminal, and 3M Super 77 spray adhesive to hold the cabinet fabric on so it doesn't peel off like I've seen happen on countless prefabbed boxes.
  • I glue my boxes together with Titebond II wood glue. This might sound like a no-brainer, but if you actually take apart a pre-fabbed box, you'll find that they aren't actually glued. They are nailed or screwed together, and they are caulked on the inside. The caulk breaks apart after a little while and the box leaks everywhere. Gluing takes far more time. My boxes don't need caulk because the glue seals it perfectly. In fact, once clamped and dried, the bond is so strong that if you try to break apart two glued pieces of MDF, the MDF breaks before the glue joint does. In other words, short of severe water damage, my boxes are indestructible, and that's a difference you can hear. My sub boxes make subs sound louder and tighter than any cheap prefabbed box you can pull off a shelf (assuming same alignment).
  • Design. I design them for free, but you won't find anyone else making 4-point bracing like this at anywhere near this price. A double thick baffle with a precision flush mount made specifically for the sub you're using? You will have a hard time finding any shop that can do this well, let alone at an affordable rate. My boxes are also designed to fit in the specific car while taking up as small of a footprint as possible.
  • Custom work. Let's face it, I can't work for free, and I charge a heck of a lot less than a good retail shop will. You'll find prices in the $200-$500 range. For a single sub box, here are my rounded costs. $35 on MDF, $15 on cabinet fabric, $5 for the terminal, $10 for the spray adhesive, $5 for the wall damping, and figure in another $5 for things like crown staples, screws, and speaker gasket tape. Total is around $75, and I still have to put miles on my car and spend gas going to Home Depot or Menard's to pick up materials from time to time. I'm sure some of you have seen boxes for sale online, shipped to your door for that much as it costs me to make mine, but my boxes aren't made in China; they're made in my wood shop, which brings me to my next reason:
  • My carbide router bits and saw blades aren't cheap and MDF wears them out much faster than real wood. Shop vac filters aren't free. My circular saw was $200, my router was $300, my shop vac was $100, my router bits were another $200, my sliding miter saw was $350, my air compressor was $250, my crown stapler was $50, my brad nailer was $150, my drill was $200, and the list goes on and on and on. All in all, I have well over $2500 invested in tools, all of which wear down over time, and we aren't even getting into the cost of electricity to power them.
  • It takes me 5-7 hours to make a box, depending on number of subs and complexity, and that doesn't include cleanup time or tool maintenance.
 

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Discussion Starter · #5 ·
Good luck in your entrepreneurship.
Eh, I'm not really doing it to make a business out of it. I use my home theater speaker design for that. This is more something I'm trying to do for the community. A good custom box will run you about $400-$800 from a high end shop, and that's what I build.
 

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This is awesome and will keep this in mind if I ever decide to upgrade more.

Sent from my SCH-I500 using AutoGuide.com App
 

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Discussion Starter · #8 · (Edited)
Can we get together some weekend and build one? I'll supply the stuff and a case of your choice :)
Sounds good to me. Let me know what sub will go in there so I can design one ahead of time and you'll see how a real sub box is built. I'll need 3/4" MDF, carpeting of your choice, 3M spray adhesive, and a terminal cup. I can probably find a terminal cup somewhere in my boxes of home theater speaker parts; they're $5.50 each (for the good ones at least). I usually buy the wood glue by the gallon because I go through it so fast. Any Saturday should work for me, but let me know ahead of time when you want to swing by. It should take about 3 hours to build one.
 

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Alright cool. I'll let you know here soon (a week or two) what I'm thinking of getting as far as stereo stuff goes.

If I don't hear back from Insane Speed Motorsports, I'll dump the money I budgeted for those upgrades into my Electronics budget (Retro Fit / Stereo System) and I'll have more money to play around with.

Saturdays work best for me as well, and 3 hours isn't bad at all. I assumed it'd be most of the day.

I'll pm you when I get more figured out.
 

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Discussion Starter · #10 ·
Alright cool. I'll let you know here soon (a week or two) what I'm thinking of getting as far as stereo stuff goes.

If I don't hear back from Insane Speed Motorsports, I'll dump the money I budgeted for those upgrades into my Electronics budget (Retro Fit / Stereo System) and I'll have more money to play around with.

Saturdays work best for me as well, and 3 hours isn't bad at all. I assumed it'd be most of the day.

I'll pm you when I get more figured out.
Well, there will probably need to be a few breaks in between to let some of the glue dry before we continue onto the next part, but I don't see it taking more than 5 hours. I'll keep an eye out for your PM.
 

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I know I asked you about a box for a JL sub but I forgot I had 2 MB Quartz rwe-204
Qes-.631, Qms-6.5, Fs-37, Vas-30.9, Sd, Xmax, and RMS Power handling-150w. I have a A/D/S P240 and P440 not sure which to use but one will power the door speakers. I was going to try and put them in the left and rt corners of the car and going for sq. I can cut the wood and put together but I am terrible at design lol. I could not find the Sd or Xmax on the subs.
 

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Discussion Starter · #12 · (Edited)
I know I asked you about a box for a JL sub but I forgot I had 2 MB Quartz rwe-204
Qes-.631, Qms-6.5, Fs-37, Vas-30.9, Sd, Xmax, and RMS Power handling-150w. I have a A/D/S P240 and P440 not sure which to use but one will power the door speakers. I was going to try and put them in the left and rt corners of the car and going for sq. I can cut the wood and put together but I am terrible at design lol. I could not find the Sd or Xmax on the subs.
What size sub are they technically? I'm seeing 8", can you confirm?

I can't find any information regarding those amps. What are the power ratings and at what impedance? Do you have the data sheet for them?
 

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Discussion Starter · #15 · (Edited)
I looked them up and confirmed they're 8" subs.

Qts is too high to be used in a sealed box. Realistically, these are designed for ported boxes or free air use in rear decks, although they'll bottom out with anything over 50W in free air.

If you want to use them though, you'll be pleasantly surprised at what they can do in a ported box, if you give them the space...

Put them in a ported box, ~1.15 cubic feet (gross) per sub and two 2" round ports at 12.5" in length for a tuning of around 33hz. You could lengthen the ports a bit, but I very highly recommend you use double flared round ports. These in particular, and you'd need 4 of them if you're building two boxes.

Precision Port 2" Flared Port Tube Kit 268-348

If you're only building one box for both, build it to 2.3 cubic feet and use two 3" ports at 13.45" in length each, or one 4" port at 11" in length.

Precision Port 3" Flared Port Tube Kit 268-350
Precision Port 4" Flared Port Tube Kit 268-352

Line all of the box walls except for the baffle with 2.5-3" of acoustic foam, mineral wool, or fiberglass insulation pad (the fluffy stuff unless you can get Owens-Corning 703 rigid fiberglass board).

Frequency response looks great. Very good extension for an 8" sub.


Excursion control at 75W is good. I think you could safely give them 100-150W each.


Vent velocity is good and low, which is where it should be if you want to prevent port noise, chuffing, or de-tuning.


Personally, I'd build these subs if I were you. They're low powered enough to where you can use 1/2" MDF with some bracing inside and a 3/4" MDF baffle instead of 3/4" MDF all around. It will save you a bit of space and you don't really need 3/4" MDF all around with low powered 8" subs if you're tight on space. The box requirement is a bit big, but they'll put a big smile on your face if you build them, I guarantee it.
 

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Discussion Starter · #20 ·
I also have a infinity 475a amp and a arc audio fd1200.1 amp should I use one of those instead of ads
I would go with the Infinity. You'll have a bit more power out of that and you have some more power to be gained.

Would you suggest building separate boxes or build one box
It all depends on where you want the subs. It would be easier and cheaper to build just one box.
 
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