subwoofer box question
01-29-2005, 01:59 PM
#1
Drives Ice Cold
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subwoofer box question
hey guys, i had goten 2 12 inch alpine R's for christmas this year. I already purchased a 1.2 farad capacitor for them and now i need to buy abox. I was wondering what the differences are between a bandpass box, a sealed box etc. Also i was wondering if anyone builds boxes for a first gen cl because all the boxes that i have seen to fit the speakers are very bulky and take up a ton of room in the trunk. Thanks in advance!
01-29-2005, 02:53 PM
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VP Electricity
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Hm... the cap ain't for the subs, it's for the amp, and you don't seem to have an amp... some amps benefit, some don't.
You'll get different answers to your question. Here's mine.
Sealed boxes are two types. The ones that are so big that the airspace doesn't help are called "infinite baffle". This is what you get when you put your woofer on a board across the seat back, and use your whole trunk for a box - rarely done anymore, especially by people looking for lotsa bass. The ones that are small enough where the air inside acts like an air-spring, and is effectively part of the speaker mechanical suspension, is called "acoustic suspension". You'll be working with the second one.
Acoustic suspension boxes have the highest power handling in absolute terms. However, there are practical considerations that I need to mention or Bass Mechanic will bring them up : ) It can be the smoothest sounding and most accurate in many ways, and is the choice of many for sound quality.
But you're probably not looking for sound quality in the absolute sense.
Sealed boxes roll off at some point, at about 6dB of volume for each octave.
Ported boxes work on the principle that Coke bottles are on when they hum when you blow over the top of them (paging Dr. Helmholtz, line 1). They resonate at a certain note, and below that note they roll off (get quieter) at 12dB/octave. So, in absolute terms,you don't get anything for free, but in practical terms, if it's tuned right, the audible range gets louder and the inaudible range gets quieter, but you don't care, since it's inaudible, and since at the resonating frequency the speaker is almost not moving at all, power handling with correctly-tuned boxes is not a problem (at worst you use a subsonic filter, but that's rarely needed anymore).
Ported boxes give you more output, but are trickier to make, and almost impossible to buy right for your application. You also have to have ports big enough in area of opening that the air doesn't compress as it rushes in and out and create a limit to how loud it can get - and the bigger the area gets, the bigger the volume of the port has to get, and the bigger the box has to get as a whole. Not bad things, but things to know.
Bandpass is like a sealed box firing INTO a ported box. It can make a smaller woofer sound like a bigger woofer, but for two 12", it's pretty much a non-starter IMO. The box size and port sizes would be so great that it would eat your whole trunk, and unless your ports are huge in area, you will get compression when uising larger woofers. I'd recommend agsint that kind of work for Alpine R's... not worth it. BTW, ALL generic off-the-shelf bandpass boxes suck ass, just about. Very complicated to design, and sometimes, even when the computer says they should go off, they STILL suck.
BTW, bp boxes where the ported box fires into a ported box are patented by Dr Bose and no one can sell them or the recipe for them without risking legal action from Dr. Amar''s sharks... and they usually suck, Good for 5-1/4"s, though...
If you want small and you have two 12"s, get a good quality sealed box that meets Alpine's specs, and live with it for a while. It may be fine, or you may get the bug and start changing things every few weeks like us tweaks do.
You'll get different answers to your question. Here's mine.
Sealed boxes are two types. The ones that are so big that the airspace doesn't help are called "infinite baffle". This is what you get when you put your woofer on a board across the seat back, and use your whole trunk for a box - rarely done anymore, especially by people looking for lotsa bass. The ones that are small enough where the air inside acts like an air-spring, and is effectively part of the speaker mechanical suspension, is called "acoustic suspension". You'll be working with the second one.
Acoustic suspension boxes have the highest power handling in absolute terms. However, there are practical considerations that I need to mention or Bass Mechanic will bring them up : ) It can be the smoothest sounding and most accurate in many ways, and is the choice of many for sound quality.
But you're probably not looking for sound quality in the absolute sense.
Sealed boxes roll off at some point, at about 6dB of volume for each octave.
Ported boxes work on the principle that Coke bottles are on when they hum when you blow over the top of them (paging Dr. Helmholtz, line 1). They resonate at a certain note, and below that note they roll off (get quieter) at 12dB/octave. So, in absolute terms,you don't get anything for free, but in practical terms, if it's tuned right, the audible range gets louder and the inaudible range gets quieter, but you don't care, since it's inaudible, and since at the resonating frequency the speaker is almost not moving at all, power handling with correctly-tuned boxes is not a problem (at worst you use a subsonic filter, but that's rarely needed anymore).
Ported boxes give you more output, but are trickier to make, and almost impossible to buy right for your application. You also have to have ports big enough in area of opening that the air doesn't compress as it rushes in and out and create a limit to how loud it can get - and the bigger the area gets, the bigger the volume of the port has to get, and the bigger the box has to get as a whole. Not bad things, but things to know.
Bandpass is like a sealed box firing INTO a ported box. It can make a smaller woofer sound like a bigger woofer, but for two 12", it's pretty much a non-starter IMO. The box size and port sizes would be so great that it would eat your whole trunk, and unless your ports are huge in area, you will get compression when uising larger woofers. I'd recommend agsint that kind of work for Alpine R's... not worth it. BTW, ALL generic off-the-shelf bandpass boxes suck ass, just about. Very complicated to design, and sometimes, even when the computer says they should go off, they STILL suck.
BTW, bp boxes where the ported box fires into a ported box are patented by Dr Bose and no one can sell them or the recipe for them without risking legal action from Dr. Amar''s sharks... and they usually suck, Good for 5-1/4"s, though...
If you want small and you have two 12"s, get a good quality sealed box that meets Alpine's specs, and live with it for a while. It may be fine, or you may get the bug and start changing things every few weeks like us tweaks do.
Last edited by elduderino; 01-29-2005 at 02:56 PM.
01-31-2005, 08:38 AM
#4
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the type r subs have a horrible responce curve, they definitly wont sound good in a ported box. they dont sound good in a sealed box either but a sealed box is easier to build than ported.
since you already have the subs any sealed box close to the size the manufacturer reccommends will be fine.
if you get serious into caraudio consider another sub and a custom box.
since you already have the subs any sealed box close to the size the manufacturer reccommends will be fine.
if you get serious into caraudio consider another sub and a custom box.
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