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Old 4th October 2005, 00:16   #1
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Default types of enclosures for a subwoofer...

for all those who dont know what kind of a enclosure to use for ur subs here is a vague idea on what to keep in mind while deciding on the type of enclosure u need..


Enclosures for Woofers:

Sealed box A sealed box is an airtight enclosure housing your subwoofer. A sealed box is best for any music that demands tight, accurate bass. Expect flat response, deep bass extension, and excellent power handling. Since a sealed enclosure tends to require more power than a ported box, use an amplifier with ample wattage for optimum performance...


Ported box A ported box uses a vent (called a port) which allows movement of air in and out of the enclosure chamber. This additional air movement reinforces low bass response. You get more output from a ported box than you would from a sealed box at any given level of amplifier output. Some people simply prefer the sound of ported boxes for rap, techno, or any hard-driving music because they play louder than comparable sealed boxes...


Bandpass box A bandpass box is a special type of ported box designed for maximum slam. The woofer is mounted inside a dual-chambered box; the woofer fires from the sealed chamber into the ported chamber, and sound waves emerge from the ported side. Because the sound that comes out of the port is extra loud within a narrow frequency range, bandpass boxes are considered super efficient. Their aggressive sound is popular with many hip-hop, techno, and metal fans...


Free-air subwoofers A free-air system consists of woofers mounted to a board attached to the rear deck or placed in the trunk against the rear seat. The trunk acts as the enclosure housing the subwoofer. Free-air systems save space and have flat frequency response. The woofer must be specifically designed for free-air use, and the trunk must be airtight for best results..

Source: Crutchfieldadvisor

Last edited by Aditya : 5th October 2005 at 01:05.
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Old 4th October 2005, 09:55   #2
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mclaren, appreciate the effort but i think this is a cross post. BTW while you covered most common boxes you forgot to include my favourite - Transmission Line. Now dont tell me this box is not practicle in a car. I've built one (using 3 10" woofers). :-)

Last edited by navin : 4th October 2005 at 09:58.
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Old 4th October 2005, 11:50   #3
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I would go with the sealed simply because the box will have to be smaller.

Navin, how about a bandpass subwoofer with the 6x9s with the tweeters disconnected?

Last edited by Vivekphadnis : 4th October 2005 at 11:52.
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Old 4th October 2005, 12:58   #4
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bandpas are notorious for one note bass. i would consider aperiodic for the 6x9s.
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Old 4th October 2005, 14:20   #5
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well here u go navin..ur request is my command sir..

Transmission line enclosure:

In a classic transmission line, the sound wave from the back of the woofer is channeled down a long pathway filled with a fibrous bundle of wool or another synthetic material. In a properly designed line, very low frequencies exit the end of the transmission line that extend the low frequency response one half octave below the fundamental resonance of the driver.

In a transmission line enclosure, the back wave of the woofer does not bounce off an interior wall and radiate back into the room through the thin cone of the woofer as in sealed or ported enclosures. These multiple echoes color the sound and can only be eliminated in a transmission line enclosure.

There is no pressure in a transmission line to excite strong enclosure resonances. In a sealed or ported box, enclosure resonances can usually only be controlled, not eliminated as in a properly designed transmission line enclosure.

Together, the extended low frequency response, the lack of multiple echoes from the inside of the box, and the elimination of wall resonance account for the extremely clean, well controlled and powerful sound of a properly designed transmission line speaker...

PS: yes navin it is a cross post,sorry about that..had posted the same in another thread then decided y not create a new thread to eliminate lesser knows like me from searching hassles..and can u pls add this to the 1st post of this thread..thanks..
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Old 4th October 2005, 16:26   #6
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very nice now we can investigate ML-TL and Aperiodic boxes as well :-)
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Old 4th October 2005, 19:05   #7
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here u go my man !!!!

ML-TL Enclosure:

The difference between a ML- TL design and a simple bass reflex enclosure???

From the outside the two look very similar and performance wise there is not a large difference. The principle difference is the way the air volume in the cabinet is used to provide the spring that interacts with the mass of air in the port to form a resonant system..
The ML TL enclosure can be thought of as a form of transmission line where quarter wavelength standing waves are used to provide the spring for the mass of air in the port.To physically model a straight uniform TL, clamp a yardstick to the edge of a counter or desk and pluck the free end so that it starts to vibrate. The vibration pattern is analogous to the air velocity in a TL. The TL's air velocity is zero at the closed end as is the yardstick's motion at the clamped end. The TL's air velocity is a maximum at the open end as is the yardstick's velocity at the free end...

There are two ways of changing the frequency of vibration for the yardstick. If you shorten the length cantilevered off the counter, the frequency of vibration will increase. Make the length longer and the frequency decreases. This is how straight TL's have traditionally been tuned by adjusting the length. The second way of tuning the frequency of the yardstick is to add a lump of mass to the free end. Put a piece of modeling clay on the free end and watch the frequency decrease.. For a given frequency, one can shorten the TL (make it stiffer) increasing the tuning frequency and then add mass (air in a port) to pull the frequency back down and get a similar tuned result. One other benefit of having a lump of mass at the terminus is a rolled off port output above the first quarter wavelength resonance. This result is similar to a bass reflex port's response..

here is a pic of a ML-TL enclosure for better understanding :

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Old 4th October 2005, 19:14   #8
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Aperiodic Enclosure:

Refers to a type of bass-cabinet loading. An aperiodic enclosure type usually features a very restrictive, (damped), port. The purpose of this restrictive port is not to extend bass response, but to yeild a smoother response pattern by lowering the Q of the system and reducing the impedance peak at resonance. Most restrictive ports are damped with quantities of sound absorbtive material...

here is a pic :



PS: anything else navin ????
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Old 4th October 2005, 20:49   #9
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Transmission line is one the best enclosures but the problem is the size of the enclosure because of the length of the transmission line. The box becomes very big (in length). There is a problem sometimes dealing with the size of ported box in the cars. The transmission line is even bigger.
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Old 4th October 2005, 22:02   #10
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so right JB. when i had my TL in my contessa all there was room for in the trunk was an icebox.
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Old 5th October 2005, 00:32   #11
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Quote:
Originally Posted by navin
so right JB. when i had my TL in my contessa all there was room for in the trunk was an icebox.
Navinji, A contessa, a TL sub, and an icebox... boy u used to have fun back in the day...
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Old 5th October 2005, 10:02   #12
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Yup. We were single. very wild. and completely nuts. ths ice box allowed us to irrigate our throats at regular intervals. Nowadays when my wife complains to my friends that i like to sit at home they laugh and say "Navin partied enough for 3 life times - he's all partied out".

There were weeks when we averaged about 500ml or rum/vodka and other 80proof spirits per day. We slept an average of 3-4 hrs per day. We'd party till 3-4am and get to work at 8:30am and we did this from 1981-1995! 14 years running. Some called it Alchohol fueled Adrenalin. I was once tested with a BAC of .25. 3 times the limit then. I only hope my son does not follow in my footsteps.

Funny thing where in all this I managed to get through regular life (school, work, etc) as well.
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Old 5th October 2005, 12:54   #13
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Now I know why one chap called Navin is so good at audio. I should start drinking more.
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Old 5th October 2005, 14:28   #14
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I used to say "Alchoholics never die. we just get marinated" dont quote me though.
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Old 16th March 2006, 14:05   #15
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Well i have a question to ask.What are Glas b*** tube Few days back in a friends car i saw one.

The top was closed with a gl*** though sides were out of wood only.I didnt notice if there was any place to let air in or not.

I have pioneer306 Dvc Sub and want it in an enclosure.What should i go for the car i have is esteem.

One more question i wanted to ask.Right now my woofer is installed on a wooden tray with the speakers right behind the back seat and as u all know that the rear windshield in car's like esteem is quite tilt so does it affect the b***??and is there any need to put spung kinda material under the wooden tray.I've seen it in my friends car but the guy from whom i got the tray installed says that its useless...What say guys???

Last edited by somebodystopme : 16th March 2006 at 14:06.
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