Woofer Box for sub-woofer

[Wolfy3769]

I understand that the Woofer box had a certain cirteria - like the volume of air, that is link to the size of the sub-woofer. But what about the shape? I understand that there are sealed-type, pot-type and I dont mean that but physical shape. IS a rectangular box better than a trapezium box (something like a rectangular box but with 1 size slanting) or a contour box that fix according to the shape of your boot? Does the shape of the woofer box affect the sound quality? Or I only need to concern abt the volume of air??

 

What other spec should I pay attention to when selecting a woofer box. Frankly, a $80 or a $200 one, I can't tell the difference. It is easier to demo-test component speaker but I think not the case for woofer box and sub-woofer so dont had much of a chance to listen to the difference. What type of wood material is best? what is their respective characteristic (sound). What abt insulation material?

 

Another matter is regarding the bass... what is the correct determining of good bass?? a heart thumping one or one that is not strong (not heart thumping) but still shake the window?? I was previously advise by a tuner that my previous setting had made the bass "too hard" and should adjust it to be "more gentle".. Do "too hard" a bass bad for the setup or this is depending on the type of music one listen too.

[Kermit]

I am no Woofer box expert. But maybe just offer my 1-cent thoughts...

 

Firstly, in determining an ideal woofer box, I would consider (in order of importance and logic):

 

1) Volume of air (should be determined by the speaker specifications stated in the manual, if its a decent and reputed brand.)

2) Shape (I don't think shape will affect the sound much, as long as the shape takes up the desired volume)

3) Sealed or potted? (u're right, this should be determined by what music u listen to and whether you're going for SPL or SQ)

4) Construction material (This makes a difference to the SQ. The heavier, or more dense the material used, the lower the freq can go and more energy felt/heard)

5) Damping material (This will alter the volume of air inside the box, usually to reduce an "over-sized" box...use discreetly only if by no choice, your box design has to be bigger than recommended.)

 

Secondly, you'll need to consider other restrictions such as cost, durability, mobility, boot space, car space etc...

 

Hope this helps...pls also consult other opinions for reference.

[Headshok]

my 1 cent worth:

 

as for ported or sealed, go for sealed.

 

mani shops in sg duno nuts abt ported boxs.all they noe is that got hole in box means ported. even this very 'experienced' shop located somewhere in the west also duno but smoke their way through.just becos got lobang they say "for spl,, good good"

 

I play SPL i also use sealed and i still get my "OHHHMMMMM".if you do not port your box properly, be prepared to not be able to get certain frequencies properly as the port will filter them out.you'll end up with some nice loose and boomy bass. so if u wanna play ported, u better know wat u want.

 

i have this "racist" woofer box, tuned at 40 hz( i tink), u play techno or trance, the bass just wont come out. but when u play hip hop and RnB, the bass comes out super explosive. hope u get the idea.

 

for material, the usual material is 3/4 inch MDF, cant go wrong with that. But some shops will give u nicely wrapped boxes, charge u $100 for it, and when u knock knock, it sounds damm thin..

[Headshok]

remember, chao chao 3/4" mmdf. best is to get it customed made. the shop i noe does it for $80.

 

also, if you want a more solid box, get the installer to coat a layer of fibre glass resin over it to strength the box.

 

as for the last part on "too hard the bass". it depends on YOU and not ur installer. if you are comfortable with the bass, that is all that matters. heck care wat ur installer say. If pple poke fun at ur setup, tell them to fk off and get out of ur car. cos one mans food is another man's poison.

 

have fun man.. heheh..

[Xiaogary]

$80 for 3/4 inch box custom size quite cheap. Material alone cost $20+ already for the wood. Plus carpeting another $5. PLus glue, nails, screws, silicon, grill, wires, adapter for wires...etc.

 

Thread owner: I diyed mine 12 inch sealed box according to the contours of my rear seat and boot for maximum space saving....no regrets. If you want, maybe u can tell me the size u need. I asked mine dad whether he free to help u buy material to do or not...haha. U just need to tell me the dimension of the box, and volume of air needed inside, volume displacement of the cone, diameter of the hole and mounting depth. All can calculate one. The benefit is, u will get a solid box. If u see some ICE shop, they cut the wood crooked one, so the joining part leak air. Mine dad uses machine and with his 40+ years of experience in carpentering, a subwoofer box is nothing compared to those kitchen cabinets with complicated compartments and drawers.

[Kwongwing]

Now you tell us got this lobang

Early early don't say!

[Headshok]

eeh boss, u really gonna change HU ah.. remember our pack ah.. i pay u installment can? just ordered pair of amps from andrew.. heh.. gonna gone case liao.. goin to see wat i can sell off.. heheheh

[Kwongwing]

Not yet lah - bought a D2 but got new home liao for the D2 - will be a while lah

[Headshok]

huh? wait..how come don fix ur D2 in ur car?

 

haha.. aniway. take ur time. gotta raise funds for the new amps.. the audioarts coughin like siao.. not enough power.. heheh

[Kwongwing]

I can still tahan with my current HU - though would have to re-dp wiring again.

Have to re-wire HU connections to power amps and also from amps o x-over, speaker connections from amp to front, etc. Damn jialat

 

D2 going into new car - not mine

[Headshok]

aiyoh.... hahaha..

 

take ur time to change ah.. heheheh.. i settle my amps first.. heheh

[Xiaogary]

Earlier my dad not free mah, now he everyday kiao ka, shake leg at home, so if got $ to earn, can side line a bit...haha.

 

Plus, I really feel those ICE shop's subwoofer box too shabby in constuction le, dont wish fellow forumers to spend money, and get those poorly made box. In the end only those ICE Shop benefit. I will help if I got time lo, but when busy with work or study really no choice cannot help.

 

Also custom made box can fit to the contour of the rear seat, help to save space by maximising the contours. So that the box dont need to be so thick compared to when it is a rectangle or square box. With some mathematics also can calculate the interior volume minus the cone displacement volume to make those solid solid subwoofer sealed box.

[Kwongwing]

I am only joking lah

Anyway good lobang for fellow forummers - Happy CNY!

[Ivan0507]

some articles to share.

 

 

When designing a woofer system for a high-end auto sound installation, you should stick to a very logical and straightforward procedure. The most important factors are size, performance, cost, and ease of fabrication.

 

The first step is to decide how much room you want to dedicate to your woofer system; generally, the bigger the system, the better. This decision will inevitably affect the other parameters of the design process. High-performance systems generally require large woofers and large enclosures. This usually raises the price of the system and lengthens the amount of time required for construction.

 

After you have decided on how much space your woofer system will occupy, you must determine what type of enclosure is right for your particular application. The simplest type of woofer system is the "infinite baffle." The infinite baffle is nothing more than a barrier that separates the front of the speaker from the rear of the speaker; this barrier is called a baffle board. A typical infinite-baffle installation in an auto sound system consists of mounting the woofer(s) on the rear deck of the vehicle or on the back of the rear seat. In any infinite-baffle design, it is very important that no path exists for sound to reach from the rear of the speaker to its front. If this happens, cancellation will occur and bass output will be reduced.

 

An infinite-baffle system is probably the easiest way to install woofers in your vehicle. You can expect good performance from such an installation, and since there are no boxes to design or build, installation time and cost are kept to a minimum. Unfortunately, there are several disadvantages to the infinite baffle. When a speaker is mounted in an enclosure, the air inside the enclosure acts like a spring against the speaker cone, and he resulting buildup in pressure provides mechanical damping and prevents excessive cone movement. But an infinite-baffle installation does not use an enclosure, so the mechanical damping is poor, resulting in "hang-over" and lack of definition. The power handling of the speaker will also be compromised since the infinite baffle provides very little control over cone excursion.

 

The second type of system is the "sealed box," and it is similar to the infinite-baffle design. A sealed box is just that: a completely airtight enclosure. Since the speaker is mounted in one face of the enclosure, there are no paths for sound to travel from the rear of the speaker to its front. Sealed boxes are very easy to design and build, and they generally perform well with almost any driver. Superb damping, good power handling, solid low-frequency response, and simplicity of design and construction make the sealed-box enclosure an ideal choice for many installations.

 

There are some drawbacks to using a sealed box, however. Using a box that's too small can have adverse effects both on your system's output level and on its deep-bass performance. Efficiency is another matter of concern; typically, sealed-box systems are less efficient than vented systems (see below) and require more power and equalization to achieve comparable output levels.

 

The best performance will be obtained by mounting the woofer in a "vented box." Vented systems, also known as ported or bass-reflex systems, use a duct to help fine tune the driver's performance. A good vented design provides essentially flat response to just above a low-frequency 3-dB downpoint, with system output rolling off at some rate below that frequency. As frequency approaches that at which the box is tuned, system output from the vent increases and is driven to full acoustic output by an ever-reducing excursion of the woofer itself. At this frequency, output comes almost exclusively from the vent and woofer excursion is at a minimum. This is quite different from a sealed system, where cone excursion increases four times for every octave of reduction in frequency. Reduced excursion means lower distortion, since the vent is not subject to the mechanical suspension limitations of the speaker. The excursion-controlling aspect of a good vented design is of fundamental importance, particularly in high-performance systems where high acoustic output and low distortion are desirable.

 

The biggest disadvantages of vented enclosures are the increased complexity of their design, poor performance when designed improperly, and unloading of the speaker at frequencies below the tuning frequency. However, note that most speaker manufacturers provide specifications, construction plans, and tuning charts that allow you to construct a vented system rather easily.

 

Once you've selected the type of enclosure, you can begin the process of selecting the driver(s). For an infinite-baffle system, a low-compliance driver is required. This type of speaker usually has a tight (accordion) surround and a large magnet, both of which compensate for the poor damping inherent in typical infinite-baffle systems.

 

Sealed systems, on the other hand, require high-compliance drivers. In order to provide good low-frequency output without excessive damping, these speakers almost invariably have loose, roll-edge suspensions. If a small sealed box is to be used, the cone should be constructed of fairly heavy material and be capable of long excursions. Typical heavy cone materials are plastic, polypropylene, and plasticized (treated) paper.

 

Vented systems, like infinite-baffle systems, work best with low-compliance drivers. The reduced excursion properties of vented systems allow the use of a much tighter cone. This results in less distortion, better transient response, and better cone control. Additionally, these drivers tend to be more efficient because of their lighter paper cones. It should be noted, however, that just about any speaker will work in this type of enclosure