box volume

Printed From: the12volt.com
Forum Name: Car Audio
Forum Discription: Car Stereos, Amplifiers, Crossovers, Processors, Speakers, Subwoofers, etc.
URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=126849
Printed Date: April 28, 2024 at 9:41 PM

Topic: box volume

Posted By: 01trublugt
Subject: box volume
Date Posted: April 05, 2011 at 8:26 AM

I am trying to figure out the volume for a sealed enclosure. I used two different online programs are both ar coming out with the same volume - .1784cuft. This is for an 8" sub and if my math is right there is no way for me to even get the speaker into a .1784 cuft enclosure. Here are the speaker specs I used to get to the .1784cuft number. If someone has a better software than I am using and could double check me.

Fs - 28Hz

Qes - .30

Qts - .30

Vas - .81 cuft.

Qtc - nothing was listed on the speakers specs so I used .7

Here is a link to the speakers spec sheet just incase I left something off: https://www.tb-speaker.com/detail/1208_03/w8-740p.htm

Replies:

Posted By: lspker
Date Posted: April 05, 2011 at 9:18 PM

Is that volume plus speaker or including

Posted By: DYohn
Date Posted: April 05, 2011 at 10:15 PM

EBP of that woofer is 93.33 so it is best suited for a vented enclosure. Try about 0.5 cuft ported at 39Hz.

-------------
Support the12volt.com

Posted By: 01trublugt
Date Posted: April 06, 2011 at 7:40 AM

lspker: No that does not include the driver displacement. The displacement is an extra .03cuft that I would need to add bringing the total box volume to .20.

DYohn: If I use the .5cuft, do I need to add the driver displacement to that or just go with the .5cuft? For 39hz I am figuring a 2" port at about 9.6" does that sound right?

I have built a ton of sealed boxes but never a ported one so forgive the ignorance of this question. For the port I plan on cutting a hole in the MDF that is the same 2" diameter as the inside of the port and rounding it over for a clean look on the outside. On the inside I will rout out a bit more so that the port slides into the MDF a bit to give it all a flush look from the outside. Would I cut the port to 9.6" or make it 9.6" in total length which would include whatever portion of the MDF that will be incorporated into the flare part of it. Hope that makes sense.

Posted By: DYohn
Date Posted: April 06, 2011 at 10:32 AM

Actually it models best in a bit less than 0.5cuft, so build for 0.5 cuft net and the space occupied by driver and port should make it come out about right. The length of your port is the total inside length from the outer face of the front baffle to the back of the port. As long as you are within 10% of calculations you are good. 2" diameter (inside diameter) @ 9.66" long results in 39Hz resonance in 0.5 cuft.

-------------
Support the12volt.com