Enough volume for truck subwoofer? You've been measuring wrong...

How do you measure for an underseat truck subwoofer box? What measurements do you need and how do you calculate the volume for a sealed or ported enclosure? In this video we look at the basics of calculating the approximate air volume available for a truck so that you can better pick subwoofers that will properly fit your space!

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Here at Car Audio Fabrication I teach you how to Master Car Audio in an effort to Design, Build, and Install your ideal car audio system. Whether you are a hardcore basshead or a HiFi focused audiophile I would love to have you subscribe and join our community!

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Car Audio Fabrication – Master Car Audio – Design, Build, Install

[efunkyman]

The best detailed explanation of how to build an under seat box that I've ever seen. Thank you.

[modzbydesign]

When I started building boxes, years ago, we learned to subtract the material thickness 3/4" x 2 = 1 1/2" from each O.D. dimension 8.75" x 5.75" x 13.00"x (55.00") to start getting volume!

[kylehuffman]

Use framing squares to extend the seat line for the bottom of the seat. There's no need to eyeball anything.

[QuadDoc]

Holy Wow Mark! That was brilliant!!
I wish you were around when I was starting in car audio!
All of the newbies now have a Very short learning curve because of professionals like you giving priceless advice for free! Thank you so very much Mark for all you do!!

[ventronicscca]

Easiest way to calculate wedge shaped boxes is to add long side and opposite small side together and divide it by 2. That will give u a value equality if that box was square. Use that number as the height then multiply the width and length as normal. Much easier and faster then figuring out a square and a rectangle. Hope that helps someone. Math can be a killer sometimes.

[travishill]

As an owner of a crewcab F-150 I was excited for this video. I ran into all the issues you pointed out. I used the cardboard cutout method but on the framing for the box skeleton. Ended up fiber glassing the bottom and wrapped that up the curved back and towards the front. Then mounted 4 8" shallow mount subs up firing. They lose output lower than 35-40hz but adequate volume from there up. Great video. Can't wait to see what else you do to this truck.

[LCFTW]

The basic drawing that you're starting with there is essentially what I built for my F150. My box is sealed with 1.1 cu-ft volume, substantial bracing, filleted internal corners, with a single down-firing Rockford Fosgate T1S2-12. And I didn't raise the seats. When you work out the math and geometry, it basically converges on one solution that will maximize vertical clearance (of the driver cone) off the floor. With a 600w JL mono amp driving mine, my truck rocks!

[stevej]

I love Crutchfield, I’ve been buying stuff from them since 1990 👍

[masonjelvin]

wish me luck, my buddy and I are doing his wrangler TJ. we’re getting pretty creative right now because we want to conserve all the space we can since we off road a lot

[crazydon]

hey guys, I have been adding wood thickness to get I.D. measurement for 30+ years. but lets be honest, most ppl that are going to build a box, already have the sub, and are now trying to make a box for it. which sometimes isn't cosmetically pleasing. my fellow Basshead.s will agree that Spl outweighs the looks. and yes, I too was thinking he forgot about wood thickness. but that's not what mark was doing. he starts with O.D. because cosmetics are his arena. it will look amazing. he can pick different subs, and have room to modify the I.D. if needed. smaller subs can surprise you if done correctly. I blow ppl's minds with my partitioned astro, 2 sundown x6.5.s in a center console I built all the time.

[keydaniels]

More and more options are becoming available for pickups finally!

[samueldevaney]

I recently finished a ported under seat box for my F150. I built the port on the back side of the box, external from the mane chamber. It sits on top of the small step in the floor of the truck.

[topnotchcontent]

I've been reading Crutchfield Magazine since the mid 90s

[ericschwacha]

@LAZER MAE, ported boxes will always give you Deeper bass and will need MORE space than a sealed box(Sealed boxes are more for people who want a very punchy and cleaner bass and if you have a good amplified aftermarket speaker system, which I still have with my American Bass 12” HD; 2000 underrated Watts rms in a triple baffled quintuple interior braced cause it is a 55lb Sub). I personally do installs and make custom boxes(always better than a ‘Pre-Fab’ box). All subs have specs on how much space they need for both sealed and ported box(which to dive deeper, you can Tune your box to the proper amount of Hertz, esp, what your sub performs best at, ). I always go with around 33-40 Hertz, anything under 20 hertz is ‘Subsonic and many amps have subsonic filters. So in short, if you want to have rolling thunder, go with ported. Cleaner and punchier bass, then Sealed is for you.

[ChaosAttractor]

I have 4 18’s under my truck seat. The seat is in my garage resting on top of 4x18’s still in the box.

[russsmith]

First of all Mark I'd like to say you do awesome work and you pay a lot of attention to detail and that's what I like .I need to get with you on building a subwoofer enclosure for a 2002 SVT Lightning behind the seat course it's a standard cab or do a blowhole one or the other I need some bass man without my knees being in the dash. I don't think it's possible without doing a blow hole or blow through or cut through or whatever you call it I'm 51 years old and I've been trying to get it some decent bass out this truck since I bought it in 2002. I've got two layers of sound deadening material for the entire vehicle except the roof so I think that's off to a good start. Will you help me brother please?

[mickrambo]

My k10 has a janky lumpy floor under the seat. Used fiberglass bottom to match it. Put some plastic down and fill with water before putting the top on to find the volume. The box is also what holds the seat in the truck since I removed the frame for more space. Not sure of the legality of that but w.e lol.

[sykamuru]

I have a 2020 f250 and I just threw my 4.5³ft 24Hz box on the back seat with 2 kicker comp R 12s on 2 Skar skv2-1500.1Ds strapped to 3, 000 watts @ 1ohm paired with the LC2i Pro

[froshouseable]

There is an easier way than separating out the triangle. Just find that average between the two sides. volume.

[ethanericsson]

Try a seat lift kit. I did one and can fit big subs