Is all airspace created equal ? ....( shallow v.s deep )....

[SMT]

 I've been into car audio since 1991 when I was a Junior in high school  and for the next four years pretty much read every Auto sound and security, Car audio, and Car stereo review magazine from front to back . Worked at multiple car audio shops in the Mesa Arizona area from 1994 to 2006.

  I have contacted multiple texts at a few of the major car audio manufacturers and yet no one can give me a definite answer.  Today I spoke with Brian at sundown audio and I even told him that I probably will register on this particular forum today if it means I might finally get my answer after all these years.

here it goes .....

 What type of performance ,and speaker reliability differences can one expect from a shallow enclosure  with the identical air space as a deep enclosure .

Example :  we are going to use a single sundown audio U series 12" sub 2 ohm dvc. (1ohm total) ran to a Sundown 2000D.

 Enclosure #1 has 2 cube internal volume 13x13x20" the  woofer is mounted on the 13 x 13 section.

 Enclosure #2 has 2 cube internal volume also but 15" tall 59" long and 4.5deep . Woofer mounted on the right side 10" away from right wall.

 Enclosure #2 is a non bandpass blow through and will have 4 inches of built-up MDF rings that will be mounted through the bed and cab to the rear cab wall ( should look flush when done) there will also be a 32 in.² port 49 inches long inside the box and threw the cab of the truck being that will be on the opposite side of the woofer( 29 hz tuned).

 Brian from sundown said 1 inches between the vent on the end of the magnet to the rear of the enclosure should be okay.

 And by the way I know that I need to come up with more air space  to make up for that internal port but I was just Kind of using a fast example .I will probably add more onto the height of the box to come up with more so we don't saccrafice any more of the length of the truck bed.

 Can somebody explain to me if there is a difference in sound between these 2 examples ? I understand standing waves and a little bit about loading but I have always been stumped on this question . Most through the years I've always been told airspace is airspace and it doesn't matter but I can't help but think that's false. 

 

Thanks for your help.

[Markous]

A sub doesn't care about enclosure shape as long it has the proper volume to do it's thing. Why would think that's false?

[audiofanaticz]

Airspace isn't just airspace, and it changes how the wavelength acts. From what I have experienced is as the depth shrinks the frequency response of the enclosure flattens out some. However this is usually at 100+ hz so its rather useless since most people will have a low pass crossover set at 70-80hz.
Subwoofer placement on the baffle and its location to where the port opening inside the enclosure is something to worry about a little more because you dont want your woofer firing straight into the port opening.

Standing waves are something not to be concerned with on a subwoofer enclosure, it would be completely different if you where talking midrange, or higher frequencies in general.

Granted things change when inside the vehicle, but usually it wont be anything too noticeable by ear from example a to example b, that is if everything spec wise stays the same such as airspace, tuning, port area, etc.
Now if this was something you where doing for strictly SPL you would be building a lot of test boxes and changing things 1 thing at a time and retesting.

As for the pole vent clearance, generally as long as you have the diameter of the vent for space behind the box you are okay. So if its a 3/4 inch pole vent you ideally want the back plate of the woofer 3/4 inches away from the wood. The pole vent is for cooling so its distance shouldn't effect output of the sub/enclosure, but having it in a shallower enclosure can.