6th Order Bandpass Subwoofer (rear & front chamber size?)

Hello !

I make subwoofer for my home theater system, it's only for low level LOW FREQ BASS presence.

The subwoofer is ¨no name¨ DVC 8 inch (buy on ebay = china stuff)

I want make 6th Order Bandpass box only for hide the subwoofer.

I don't understand why the REAR and the FRONT chamber is not the same volume ? Anybody know why ?

Why don't take the vented box volume on each chamber ?
exemple: for this sub 18L volume vented why don't take this two times. One for FRONT and other for REAR ?

If the sound make 360 degree why the CHAMBER is not the same ?


Thanks in advance or your answer ;) !!!

nicK
 

MaVo

Member
2006-01-07 12:40 pm
you need the Thiele Small parameters of the driver. perhaps you can find them in the package, or on the internet.

http://en.wikipedia.org/wiki/Thiele_small

from there on, you need a subwoofer simulation program to simulate the response of your driver with a box.

just building one without knowing how big it needs to be will not work with a bandpass.

if you dont know the TS parameters, you will have to measure them or simply use a closed box as enclosure, since there the volume doesnt matter as much as with other enclosure designs.
 
I have all information of this little subwoofer but I just don't understand why the REAR and FRONT chamber have not the same volume in 6th Order Bandpass ?

I create bandpass box only because my 7.1 system is hidden.
I don't view any woofer or tweeter in the room.

nicK
 

Attachments

  • oem8dvcspec.jpg
    oem8dvcspec.jpg
    21 KB · Views: 399
One chamber in 6th order box acts just like a classic BR box, so it needs to be BIG for your sub to play low, while the other chamber acts as a lowpass filter and doesn't need to be big because it is tuned fairly high in frequency (as high as you want your sub to play).
You can make the second chamber as big as the first, but there is no purpose doing that because it won't bring you better or deeper bass, you'll just have bigger box and ridiculously short port on that chamber.
 

Ron E

Member
2002-06-27 10:41 pm
USA, MN
nickthevoice said:
I don't understand why the REAR and the FRONT chamber is not the same volume ? Anybody know why ?

Why don't take the vented box volume on each chamber ?
exemple: for this sub 18L volume vented why don't take this two times. One for FRONT and other for REAR ?

If the sound make 360 degree why the CHAMBER is not the same ?

Well, if you put an equal enclosure on each side of the driver, one would produce sound always 180 degrees reversed from the other and you would have little or no sound at frequencies whose wavelength is longer than the distance between the two ports. Try it and see ;)

The chambers of the system are different sizes and different tunings to make the sound blend better and cover a wider range.
 
Hello ;)


The problem with 4th order is...............I HATE :devilr: SEALED BOX

all the sub I had car or home in sealed box have ugly sound, when have big quick loud sound the distortion cone and other bizzard sound.

it's just my feeling !!! :)

I know many people say the best soundQ subwoofer is SEALED but for me NO :whazzat:


Thanks ;)

nicK
 
For my 360 degree history, it's difficult to explain so here's a picture of my brain

For me the BEST AUDIO reproduction is :

* Class-A amplifier to reproduce all the 360 degree of wave.
* Flat cone speaker to reproduce almost the same 2 phase of 180 degree to create best 360 degree (I say almost because the driver don't have 1 motor by side) I understand me I'M NOT CRAZY :smash:

* For this reason I don't undertand why the 6th order bandpass doesn't have the same box in her 2 chamber


:angel: Thanks !!!:angel:


nicK :)
 

Attachments

  • 360degree.jpg
    360degree.jpg
    27.6 KB · Views: 376
* For this reason I don't undertand why the 6th order bandpass doesn't have the same box in her 2 chamber

With a sixth-order bandpass you have one 2nd order bandpass (i.e. tuned box) in front of your woofer and one on the back.

The woofer outputs the same signal on its front and on its back. If these are summed as is then you will have no sound - they will simply cancel out. The same happens if you use any form of waveguides or resonators or whatever in front and on the back of the driver. If these are equal then the output is again nulled out due to the fact that you feed both of these contraptions with the same signal but 180 degrees out of phase.
It is getting interesting as soon as those resonators are tuned differently. Not only do you load the driver over a large bandwitdh (whatever large means) - the difference of the inherent natural phase-shift of these resonators adds another 180 degrees, helping to add the SPLs of the front and back efficiently.

Regards

Charles