Can anyone send me a picture graph from a box making program, like Leap. I copied a box design for a vented 12" from Diamond Audio awhile back. I was going to buy a sub from them. Well, I ended up buying a RE sx 12' sub instead. 1000 watts rms... Instead of me making my own ported sub box that was recommended, I thought 'hey this design from Diamond Audio must be better than my design'. Well, I finished a huge install and I am very disappointed. So, I need help. Can anyone send a graph with the 'sound result' for this Diamond designed box and then suggest what I can do to make it better, (leaving the port size as is). I cannot change my completed trunk, and I can only change the air space the sub is working in. I cannot change the port in any way without smashing the inside out and I don't know if I can do it... Well may be half way, but, I don't want to take a chance...

Most likely this Diamond Audio box is designed for SQ and I want some low end boom.
The air space the 12" sub is working in is .911 cf. The port is 2.5" wide, 12.5" tall and about 40" long. I've already taken off the air volume the sub takes up.
Thanks for any help...

 

12" subwoofers require anywhere from 1.8-2.5 cubic feet after port and other displacements. If there is only .9 cubic feet in your existing one, then thats your issue

 

True, I knew about the air size requirements, but, it seems that the small air size of the box was compensated with the huge, lengthy port... from Diamond Audio. So, I was hoping to see my results to see how much more volume to add to the box and keep the port the same size. From what I can see, the port is almost double what it should be normally with a 2 cf box.

 

Build a new box.

 

^^^^ What he said, I don't think there is anyway to fix that problem without building a new box.

 

OK, so, I add 1-1.5 cf to the front of my box for the sub to run in. What is the frequency response with this port in it. Anyone? That's what I am asking. I've spent several thousands of dollars on this install. I can't just make a new box, like I mentioned earlier... Can any one show me what the frequency response is with my original box verses a larger box with the same size port as my original box? Any help would be VERY appreciated.

 

If you keep your port and make the box's internal volume (NOT including port) to 2cubes, you'll be tuned to around 30hz (assuming your port length is 40").

Now what I would do in your case is remove about 8" of port length. This will give you tuning closer to 33hz in the end. Or, remove 12" of port length and go with 36hz tuning. Not sure how your box is designed but if the port is internal then this will help add to the internal volume and mean less you'll have to add later. Then calculate for 2cuft of internal volume. Add whatever you have to make that happen.

Your currently tuned over 45hz. I'm sure some notes are really loud but 45hz tuning isn't really for playing music.

Only problem with this is, it'll take MUCH more power to be the same level of "loud" at 33hz than it takes to be loud at 45hz.

My vote is 2.0cuft @ 36hz.

 

Awesome, that's exactly what I was looking for! I totally believe Diamond Audio goofed up on their specs for their boxes. I believe they meant for the 12" sub to go into their 15" box. That would have made more sense. Funny, they said and I quote "Warning - The use of a 30Hz subsonic filter is highly recommended for use with this enclosure". AND they claim these specs: Fb - 40 Hz, F3 - 33Hz. I see that this is impossible! Hopefully, anyone who bought their subs did not make their recommended box, or they would have been very disappointed with their results... Like me...

Cheers!

 

if you have to keep the port the same size, then a 1.8 cube box will give you a 32 hz tune...which will deliver very good results.