facing the port forward you lose some db's
face the sub toward the rear along with the port
this is your port size for a 4cuft box: 4 x 10 x 26.69

28 hz subsonic filter and your box tuned to 29hz
if you build the port to the spec i have listed

 

alright, i'm going to draw it all up on autocad once it's done dling, and then i'm gonna get started. thanks a lot for everyone's help, i'll be sure to take pics when i'm done so this thread will have a deneumont. yes i suck at spelling long french words.

 

ScionRI,
Call Image Dynamics, I'm sure they will help you with your design. Your enclusire sounds way too big (4 cu ft) is almost twice as large as the recommended 2.3 cu. ft. With most drivers the larger the box/enclosure the less power handling. Image Dynamics will help with this also, afterall, they would not recommend an enclosure that would compromise the driver. You may gain a little on the low end but if you're going to use a subsonic filter at 28hz what is the point? Also, check excursion on WINISD at 28hz. 28hz is still very close to the 29hz tuning frequency you are shooting for.

I too will be installing an IDMAX in my Xb. SoundDomain has a great Image Dynamics forum where it is very common to have Eric Stevens (ID Founder) answer email questions.

Mike

 

Go ahead and slap yourself. Subsonic @ 28hz?!!??! for a 29hz tuning!? A subsonic isnt even necessary, let alone @ 28hz... sheesh... keep it 20hz or below on the subsonic,,,

 

well if he rus the subsonic @ 20 there is a good chance that the freqencies will damage that sub of his has a fs of 27hz anything below that will cause damage at high volumes...better safe then sorry

 

Wrong,worng,wrong! It is the tuning frequency of the ported enclosure not the Fs of the speaker. Below the tuning frequency of the enclosure the driver will "unload" or start moving alot. Look again at where the excursion starts to really increase on WINISD. It will start increasing below the tuning frequency not the Fs.

Mike

 

ok that makes sense but if the tuning frequenc is 29 wouldn't you want a filter at 28 to kill the unwanted frequencies?

 

To get all of the benefits from such a large box I would start by using subsonic filter at 20hz. If it is still moving way too much then incrementally adjust it to a higher frequency.

Mike

 

winisd says that the cone excursion peak to peak will be like, 3.5" at max volume at 20 hz, and the idmax manual says that it can take that. but i mean, would i be better off going with a smaller enclosure? the stock winISD says ~3ft tuned at 29.29 hz

what should i do?

 

how does 2.9ft^3 tuned to 28hz sound? then the cone excursion is cut much lower, and it handles power easily past like, 22 hz. . works?

 

bump

 

Honestly, you probably won't need more than 30sq/in of port. The tuning is lower than I usually do, mine are usually tuned to 31-33hz and I've never liked using subsonic filters.

 

ScionRI,
Use WINISD to compare the 2.9cu. ft. enclosure tuned to 30 hz to the 2.3 cu. fy enclosure tuned to 28hz. They are very similar in performance. So close that you would not be able to tell the difference when listening to music. But the cone excursion at 20hz in the smaller enclosure (the enclosure size and tuning frequency that Image Dynamics recommends) is 1/2 an inch less.

Same performance, Smaller box, less excursion, = :D :D in my book.

Mike

 

i made my box, did it 2.5cubes @28hz by reccomendation of the ID techs. juuuust barely fits in my trunk :D
http://img.photobucket.com/albums/v2...k/DSCN0651.jpg

there it is. took about 4 hours to build, used a router for the 11" cut out. the only problem now is getting my entire back hatch from vibrating like a ****![/u]

 

looks good
now all you need is some sound deadening

happy bumping