damm... i burned my woofers..

[cacin]

If you want to design enclosure, search for tool in the net. One of them would be winISD. I think from the mathematical calculations you can see how your sub will behave in a given box. therefore, you can play around with box size/type and size to get what you want.

 

[appleyard]

since with one woofer can achieve those number , then could u share how you hit 140db with a single 15"? what type of enclosure you recommend? vented?sealed?cubic feet capacity?

What you want is displacement. Normally more subs means more cone area and more air displacement. No one is chasing numbers with sealed enclosure.

Ported box is preferred because its more efficient. You may wanna look at Hoffman Iron Law as well. SPL is not easy. First you have to find the resonant frequency of your car i.e what freq is the loudest in your car. Then you built a ported box tuned around -3hz from that resonant freq. Built a big box (the biggest your car can afford) and big ports. You need big port area to have lots of air displacement. Build a lot of bracing aroung your box as box flexing will lose SPL. Also Sound proof the whole car as body flexing will lose SPL as well.

Install 2 or 3 fully charged battery's as to provide the power. Get a test tone which is the same as your resonant freq. Then its time for metering.

You think it will be easy? But if you are interested in numbers, its worth the effort.

 

[renxun]

today i just send my box design to be made and d volume that biggest i can put on my car is 2.4cubic feet for my single 15". So far i just tell the guy to let the box be a sealed enclosure. only if i need ports then only think of the size and length needed.... however i read alot of write up about sealed and ported enclosure... and since sealed enclosure wouldnt give advantage on numbers so what does it actually had to offer?

 

[cacin]

sealed enclosure are the easiest to design. No port calculations and stuff.
It allows for minor mistakes in design. Try screwing up your port length in Ported designs.... :)
It also provide an air suspension/cushion in the sealed box. No need infrasonic.
Less susceptible to turn on/off pops.
Sealed enclosure size is also smaller. after a certain size, better use vented/ported. At a small size box, sealed is better that ported.
Sifus, Please correct me if I am wrong.

 

[appleyard]

2.4 cu.ft for a single 15" ported is kinna small. Sealed is ideal for that sub.

Mine was 4.65 cu.ft net after port displacement with port area over 80 sq. in. tuned to 34hz for a single 15".

I'm building a new enclosure approx. 5.0 cu.ft with port area of of 60 sq in. tuned to either 26hz or 28hz. That would make the sub a killer at low freq.

For sealed, it would give you a better transient response and lower group delay. In other words tight bass. But that does not mean a ported enclosure cant do that. Its just harder to design and built a ported enclosure who would do all that i.e excel in SQ but also can do SPL.

WinISD is a good start for box building. I find it very helpful over the years but, its not entirely accurate.

 

[appleyard]

sealed enclosure are the easiest to design. No port calculations and stuff.
It allows for minor mistakes in design. Try screwing up your port length in Ported designs.... :)

Yes but you need to calculate net internal volume to determine the box Qts

Sealed enclosure size is also smaller. after a certain size, better use vented/ported. At a small size box, sealed is better that ported.
Sifus, Please correct me if I am wrong.

It a small size its better to built a sealed box. A small ported box will result in boominess i.e there is a big peak where it play a certain freq. loud and quiet on other freq.

 

[renxun]

my woofer qts is 0.60 and now i shall wait wat is the effect after my box completed.. inside the box im sticking it with dampening sheet as recommended from a few web write ups....

oh ya .. btw apple what car you drive that you could fit a box at that volume to your car?wouldnt it be a lil' bit too big for a single 15"? im only driving a normal sedan with the car booth as my only compartment to place my sub

 

[Kippo]

What you want is displacement. Normally more subs means more cone area and more air displacement. No one is chasing numbers with sealed enclosure.

When burping near port tuning freq., displacement is not important. The subwoofer cone excursion will be minimal. What is important is to be able to harness the resonance of the car 'cabin gain'.

Ported box is preferred because its more efficient. You may wanna look at Hoffman Iron Law as well. SPL is not easy. First you have to find the resonant frequency of your car i.e what freq is the loudest in your car. Then you built a ported box tuned around -3hz from that resonant freq. Built a big box (the biggest your car can afford) and big ports. You need big port area to have lots of air displacement. Build a lot of bracing aroung your box as box flexing will lose SPL. Also Sound proof the whole car as body flexing will lose SPL as well.

As rule of thumb, you play around +/- of the resonance freq. of the car. Sticking with one number i.e. -3hz is not maximising the potential.

Though it is good to have large port area (min. 50 sq.in for 15" & min. 30 sq.in for 12"), there is a limit. Getting port area bigger than Sd is not worth it.

 

[appleyard]

my woofer qts is 0.60 and now i shall wait wat is the effect after my box completed.. inside the box im sticking it with dampening sheet as recommended from a few web write ups....

oh ya .. btw apple what car you drive that you could fit a box at that volume to your car?wouldnt it be a lil' bit too big for a single 15"? im only driving a normal sedan with the car booth as my only compartment to place my sub

What I meant is the box Q allignment. Ideal box allignment is 0.707 which most will go for. A q allignment over 1.0 is boomy and lower than 0.707 will have too much bottom end extension.

I'm driving a kembara that look like this
Fi at Labuan carshow 12/8/07 - SSA:

 

[Kippo]

It also provide an air suspension/cushion in the sealed box. No need infrasonic.
Less susceptible to turn on/off pops.
Sealed enclosure size is also smaller. after a certain size, better use vented/ported. At a small size box, sealed is better that ported.
Sifus, Please correct me if I am wrong.

1. A sub in Sealed box do need infrasonic filter when the enclosure vol. is slightly large.

2. Turn On/Off pops are electrical problem and has nothing to do with the type of sub-box

3. It does not mean if u want a small box, you MUST use sealed box. A ported box is capable of being small while at the same time giving extended output. It is just that ported box is worth the trouble to do once you want a slightly larger box.

 

[Kippo]

2.4 cu.ft for a single 15" ported is kinna small. Sealed is ideal for that sub.

For sealed, it would give you a better transient response and lower group delay. In other words tight bass. But that does not mean a ported enclosure cant do that. Its just harder to design and built a ported enclosure who would do all that i.e excel in SQ but also can do SPL.

1. 2.4 cu.ft for a 15" is not small. The size of the box will depend on the sub design. Most sub-makers prefer to design their sub to need a larger box to have good low freq. extension.
In the case of Adire Audio Brahma, it has been designed to only need small box.


2. Not all subwoofers default box is sealed. It will depend on the sub design. Some companies design their subs to perform better in ported box. Though the subs can be used in sealed box but it will not give its best performance.

3. Question of good transient in sealed box is a generalisation. There are subs which perform similar in terms of transient in ported or sealed box.

 

[Kippo]

my woofer qts is 0.60 and now i shall wait wat is the effect after my box completed.. inside the box im sticking it with dampening sheet as recommended from a few web write ups....

Do not be overly concerned of woofer Qts. You have to look at overall system Q.

Sticking dampening sheet in the sub box is fruitless. You will fare better if you brace the box. The sub-bass freq. wavelength is long to even have a reflection in the box.

 

[renxun]

ok.... this evening took the box home and install in my car... the bass is tight and real good for sentimental songs and R&B but as i switch to boom music such as groove coverage and some clubbing songs its not too satisfying... cant really feel the punch.... the R&B songs really rocks with this sub...

when i push the woofer to work harder.. it seems that it had reach its box limit. (i guess so) because it looks like it was force to suck in and the air inside doesnt let the diaphram go ...ermm .. how to say ... the harder i want to hit the harder it want to rebel from inside of my sealed enclosure...and it produce some sound similar to distortion ...aiks.. headache now.... it doesnt performed as expected.... SQ bass definitely improved however i loose all my boom and punch.i guess my 3 units of mtx RT 12" hit harder last time playing dance music but sucks down to bottom when playing R&B musics due to not having the tight and low deep heavy bass as my 15" now