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Old 20th November 2009, 12:22   #1
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Default Enclosure design for pioneer 12 Subwoofer

Hi,

I am planning to build a subwoofer enclosure for my lancer, the model and the dimensions are..

The subwoofer i am using is pioneer TS-W307D2 and it is a sealed enclosure (36 litter ) .

I am planning to use the fiberfill from pillows for damping ,does it really improve the quality of the sound ??

please help ..
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Old 20th November 2009, 15:21   #2
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Hi Sreejesh, Fiberfill or Polyfill usually helps the subwoofer feel like it is playing in a bigger box than what actually is, so it gives the advantage of using a smaller box (practicality) but getting the bigger-box sound (more SQ). In terms of damping, polyfill is claimed to smoothen the bass, make it more deep- but this is entirely subjective and may prove to be difficult to judge for people like you and me.

If you are adding polyfill say 250 grams (as much as a small pillow),you might want to reduce the volume of the box by 0.10-0.20 cu ft by reducing the sides.

Last edited by greenh0rn : 20th November 2009 at 15:22.
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Old 21st November 2009, 11:27   #3
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Thank you. I am planning to freely fill the entire box with fiberfill then find the differences by removing the fiberfill.
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Old 24th November 2009, 23:50   #4
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There wont be any difference as i have practically checked out. Fibre fills are not impressive when it comes to enclosure applications. Just make sure there is no leakage in your enclosure i mean it swhould be 100% sealed.
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Old 27th November 2009, 09:51   #5
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yes the bass would hit harder with a completely sealed box.i too frankly didnt find any difference with fibre fills.
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Old 27th November 2009, 11:45   #6
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Yes You are right, I tried with filling the enclosure with Fiber fills but it was a bad experience the Bass was not good as I expected then I removed the fiber fill and tightly sealed the walls of the enclosure, the out put really surprised me !!

I will upload the video

Now what happened is my front door started making its on beats..
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Old 27th November 2009, 13:41   #7
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I was in similar assumption, that filling help smooth out the music. Fillings absorb the sound which keeps reflecting inside the box. Making it sound more boxy.

Fillings are also done for deeper bass. We achieve this by principal mentioned above, if you dampen mids and highs created at the back of the speaker by the fillings, we end up with 2 bass (front & back of cone), 1 mid and 1 treble.


Here you have a sub hence things change.

People even have bass reflex holes in their box which gives louder and not very deep bass.


PS: Where did you find fiberfills? How much did it cost you? Im looking for my speaker boxes which hold my JBL 9x6
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Old 30th November 2009, 10:19   #8
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@sreejeshmp: Any updates on your woofer?
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Old 30th November 2009, 13:25   #9
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ok this is my expereicne with damping in sealed boxes.
1. Using some damping helps (about a 1/2 kg per cu. ft.) beyond that it begins to get int eh way.
2. damping does more than just abosrb the back wave. it converts this energy to heat and dissapates it. For this reason it is best that the damoing be loosely installed and even "hand-tossed" so that the fibres are 'seperted'. To protect the loose fibres from entering the voice coil gap it makes some sense to cover the rear of the woofer basket with a thin muslin cloth.

Damping cannot compensate for more than 10% loss in box volume. So do NOT expect to stuff a 12" woofer in a 0.5 cu. ft. box (when it was designed to fit in a 1.5 cu. ft. box) and expect damping to compensate. A 1.25 cu. ft would be as small a box the hypothetical 12" woofer I have mentioned woofer would require.

If you want to stuff the woofer in a box that is say 25% smaller than is designed box you will get a peak in the midbass. This peak can be reduced by going aperidoic. You can fashion a aperiodic vent using a short (2-4") f 3-4" diaPVC pipe filled with poly fill. Again here experimentaion is the key too mcuh stuffing and you loose the advantage.
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Old 30th November 2009, 13:56   #10
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If you want to go ahead with Sealed enclosure , custom make the enclosure as per the company given specification , make sure all the edges and corners internally are well sealed without any leakage. I recommend you to add bracing or stiffners dont worry about the damping part.
enjoy a well defined bass.
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Old 30th November 2009, 20:31   #11
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The company recommendation is a sealed 24~49 litter enclosure, so I took the average of the volume recommended by the company that is 36 litters .
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Old 30th November 2009, 21:20   #12
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yes the min and max volume is subjective to your space availability for the enclosure installation in your car , if you have sufficient space you can stretch volume till 49 liters also, 36 liters is around 1.27 cu ft .
continue your custom enclosure building
cheers !!
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Old 1st December 2009, 02:01   #13
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Quote:
Originally Posted by Ravi Nandrajog View Post
yes the min and max volume is subjective to your space availability for the enclosure installation in your car , if you have sufficient space you can stretch volume till 49 liters also, 36 liters is around 1.27 cu ft .
continue your custom enclosure building
cheers !!
Min and max enclosure size is given as general preference, with bigger box expect better low end extension and smaller box the sub will sound more punchy as you limiting the sub upto a certain frequency, generally above 25hz.

To determine the enclosure there are some parameters that are required, i.e. Fs, Qts, Vas. With the help of these parameters and keeping the QTC of the enclosure of .707 (which is used as most commonly to determine what freq response the sub can deliver), it can be modelled to know what will be it's freq. response with the help of some softwares. Beyond that in car audio there is a something called cabin gain which is considered by manufacturers and a Qtc of .9 to 1.1 is what considered for the enclosure design / spec. To determine one needs to know what freq range can the sub handle. Most subs can handle freq. response down to 25hz and some subs with good strong motors, can even handle freq much below than the specified 25hz limit (though mostly there ain't much music below that level). And In some cases sub with a limit, cannot handle freq. below the level of the specified freq of the sub, as it could result in mechanical noise and on a longer run could damage the sub.

Randomly picking a size for the enclosure is not what I would suggest. That's one of the reason the manufacturers specify the enclosure volume keeping these things in mind. Also, let me add in sealed enclosure the shape of the enclosure doesn't matter it's the amount of internal volume / air available for the sub. In a Small sealed enclosure powered close to the given rated power will have better control over the sub and the frequency will sound good tight with good low end extension.
In your case stick around 33 liters which is around 1.2 cu.ft in case you want more deeper bass you can add polyfill to give you additional 25% volume i.e. you can add upto 700grams with the enclosure size mentioned. Anything more than that will give the sub a feeling of being in smaller enclosure in other words the the effects are reverse. Polyfill does make the enclosure act as a bigger enclosure plus helps to break in the standing waves if there is any.
In some cases with the exact enclosure size as per specification it is yet advisable to add about an inch of polyfill on the inside walls of the enclosure.

By the way what is the power rating on the sub and the RMS output of the amp you will be using on it?
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Old 1st December 2009, 08:37   #14
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Where do I get poly-fill in Bangalore? How much does it cost?

I need to do it for my boxes which have JBL 9x6. I have noticed bass being tight and deep. However vocals and few frequencies sound boxy. I think I get rid of boxy sound by adding poly fill on all walls.
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Old 2nd December 2009, 00:19   #15
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Quote:
Originally Posted by Invinsible View Post
Min and max enclosure size is given as general preference, with bigger box expect better low end extension and smaller box the sub will sound more punchy as you limiting the sub upto a certain frequency, generally above 25hz.

To determine the enclosure there are some parameters that are required, i.e. Fs, Qts, Vas. With the help of these parameters and keeping the QTC of the enclosure of .707 (which is used as most commonly to determine what freq response the sub can deliver), it can be modelled to know what will be it's freq. response with the help of some softwares. Beyond that in car audio there is a something called cabin gain which is considered by manufacturers and a Qtc of .9 to 1.1 is what considered for the enclosure design / spec. To determine one needs to know what freq range can the sub handle. Most subs can handle freq. response down to 25hz and some subs with good strong motors, can even handle freq much below than the specified 25hz limit (though mostly there ain't much music below that level). And In some cases sub with a limit, cannot handle freq. below the level of the specified freq of the sub, as it could result in mechanical noise and on a longer run could damage the sub.

Randomly picking a size for the enclosure is not what I would suggest. That's one of the reason the manufacturers specify the enclosure volume keeping these things in mind. Also, let me add in sealed enclosure the shape of the enclosure doesn't matter it's the amount of internal volume / air available for the sub. In a Small sealed enclosure powered close to the given rated power will have better control over the sub and the frequency will sound good tight with good low end extension.
In your case stick around 33 liters which is around 1.2 cu.ft in case you want more deeper bass you can add polyfill to give you additional 25% volume i.e. you can add upto 700grams with the enclosure size mentioned. Anything more than that will give the sub a feeling of being in smaller enclosure in other words the the effects are reverse. Polyfill does make the enclosure act as a bigger enclosure plus helps to break in the standing waves if there is any.
In some cases with the exact enclosure size as per specification it is yet advisable to add about an inch of polyfill on the inside walls of the enclosure.

By the way what is the power rating on the sub and the RMS output of the amp you will be using on it?
Hi brother, all these details come along in the manual provided with any branded woofer.
Custom build enclosure as per the company specs dont forget your car boot space.
Practically as per what i have experienced the fibre fill and poly fill dont help much.
What matters in a sealed enclosure is volume, sturdiness and sealing .
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