Bandpass Designer, Sealed Designer and Vented Designer provide accurate theoretical solutions for subwoofer driver characteristics and attributes (Thiele Small) and box/enclosure parameters with an easy to use interface. It consists, basically, of a box with a hole in it. However, despite its simple design, vented boxes are considerably harder to get good performance from than sealed boxes – although many times the extra effort can be worth it. If you do choose to install it in its own sealed chamber, ensure that there is adequate air space to avoid heat build up. You may choose to ventilate the chamber. Draw the cutout of your sub and port with a protractor or you can use a string by finding the center of the cutout and tracing around. It is good to use around all internal seams will ensure your box is 100% airtight.
At this point of the build only the front of the box has been attached, our next step is to mount the port into the enclosure. Also a calculator can not pick up sounds like the human ear so it is recommend to listen to the Enclosure in your vehicle before finally fully sealing it just in case you want or need to make changes to suit your Bass needs/wants! Start fastening the box together, ensuring that the large sides slightly overlap with the smaller ones for additional strength. When the box is fully wrapped you have the carpet over lapping each other, use a straight edge and cut though both pieces of carpet then remove the free pieces.
The basic difference between our sealed box (Competition) and infinite baffle (Freeair) woofers is the design of the cone suspension. Once you’ve glued it in place, place the box back into the trunk well to make sure you’re happy with the it and double check to make sure it still fits, and that its level and stuff like that. The Parts Express Project Showcase is also a great resource for speaker concepts and plans.
Measure the height, width, and depth of the vehicle space that you are willing to devote to your subwoofer. If you don’t have a lot of room, then sealed is probably a better choice as the enclosures can be smaller than an equivalent ported sub. The low frequency threshold of human hearing is about 20 Hz. So you may wonder why you’d want a subwoofer that produces frequencies you can’t hear.
Typically power-handling is improved though, unless the box is REALLY too small! Built to blend in with the rest of your vehicle, subwoofer boxes for trucks are the easiest and least costly addition you can make with the biggest impact. With the box completely built, but no speakers in it, run a bead of glue or silicone along the insides of all the joints for added sealing. Build several equal enclosures, one for each subwoofer, or design a single structure divided into different boxes. Most of Sunfire’s stuff online is more affordable ($500ish) and not nearly as crazy as the TS-EQ12 that polar linked. It is a good idea to spray the box while on the carpet it helps control over spray.
But in the context of an open boat environment the best sounding subwoofer is the one where its limits and the amplifier limits are not exposed. Because of the low strength level of medium density fiberboard of MDF, they tend to weaken and break apart easily thus rendering any music box built using them a short life span. The first is that I preferred the look of them and the second is that sonosub is probably the easiest type of subwoofer design you can build. It worked very well, but slot ports require more space and are more difficult to build and calculate (especially so if you do 45’s on the corners, round over edges, etc).
Fortunately the workings of a (sub)woofer are extensively documented, both mathematical as well as practical, which gives us plenty of background information to calculate and evaluate performance and frequency range prior to actual construction. The subwoofer box bracing task is needed to illiminate standing waves in the box and also brings strenth to the subwoofer enclosure constraction. Building a box for your subwoofer is one of the best ways to put your peronal touch on a car’s audio system. The links I’ve provided are useful places to get software and hardware that is well regarded by DIY fans.
After the caulk dries, place the subwoofer inside the enclosure and mark out the circles for the mounting screws. When properly integrated, the actual location of the subwoofer will disappear and the bass will seem to be coming from the little bitty speakers on either side. Now it is a good time to start sealing the subwoofer box from the inside to ereas that will be hard to reach afterwords. I actually used a circuit similar to this to build a guitar amplifier into a cigar box (same workhorse LM386 and all).
Since most manufacturers will provide the recommended box volume in cubic feet, you’ll need to convert the internal volume from cubic inches into cubic feet. As the majority of cylinder subwoofers are made in America of cardboard tube with the sonotube brand name, a subwoofer made in this way is commonly known as a sonosub. Our box is 56 inches long, 13.5 inches tall, 2.5 inches deep on the top, and 7.5 inches deep on the bottom. Now, compare the volume of the box you’ve sketched to the manufacturer’s recommendation.
Conventional sealed box subwoofers use the trapped air space inside the box to control speaker cone movement. The effect was to turn an ordinary looking sub into a terrible looking one!…should have stuck with the white. A more accurate version of the above method involves using a resistor in series with the subwoofer system, and connecting the multimeter (set to voltage mode) across the resistor.
Aside from good sound production, this is perhaps one of the most central reasons why people choose fiberglass over other materials when it comes to designing a subwoofer box. If you’ve chosen an 18 inch driver for example and want to build a subwoofer with a Qtc of6 then you’re going to need a bigger box than aiming for the same Qtc level with a 15 or 12 inch driver, so this is why determining the size you have available is important. For a relatively low budget and some time, you can make something that matches or beats the performance of a considerably more expensive commercial subwoofer.
The second reason we put a subwoofer inside an enclosure is to limit the excursion of that subwoofer. We have established that power handling ratings are only relevant within a driver’s actual operating range; sensitivity ratings for a subwoofer only count in the sub-bass region below approximately 125 Hz. A subwoofer could actually have a response that is rising at frequencies that are outside the range that you intend for the sub to be used. Be sure the hole is as perfect as possible to minimize gaps between the box and the tube. The only downside of this is that the box will need to be pretty large, potentially several hundred litres.
Paint or cover to either blend in or contrast with the location the box will sit in your car. But before you build the sub box you need to figure out what kind of wood to build the sub enclosure out of. The key to picking out the perfect building material for your box is to find material that is as non-resonate as possible. Use at least one slanted wall in order to make the enclosure fit the car compartment, solve size problems and decrease the box internal vibrations.
Two ends of a subwoofer box glued together with a simple clamped butt-join with Titebond II will never be cleanly separated. Fourth, you have good reason to be proud of a box that you built, rather than one you paid for. This part is hard, it takes a mallet, someone holding the cylinder and someone forcing the endcap in. It needs to be a tight fit so air doesn’t escape when you’re using the subwoofer. The fundamental Thiele-Small calculations can be performed using a scientific calculator and a little knowledge of algebra.