A few questions about a design for 2 DD9918s


LongThrow

My Kickers be swaggin'
May 17, 2014
428
0
Springfield, MO
It's been a long time since I've visited this forum, social media seems to have stolen all attention from the old forums.

I have 2 DD 9918s that I'm wanting to put in the back of my crv. I can't wall it off, as I have to keep the rear seats (I have 2 kids now, life comes at you fast, eh?)
I have a max dimenion of 42W x 24D x 24H. I am using 2 8 Inch ports, 22 inches long. From what I am able to math out, I will have to do subs up port up, with my math I came out to 11cf net, after all displacements, with the ports sticking roughly 4" out of the box, thats give me a tuning of 30-31hz, simulated port velocity of 32m/s @ 30hz. I will be running 2 Synergy 8.1s, 1 per sub, roughly 10kw per sub.

Anyone see an issue with this design? I know I'm kinda short on port area, might end up with some port compression around tuning, but this is the best I can do fitting 2 big *** 18s in a crv.
 

Buck

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If you have that much power, maybe you get 10 cubes. My spidey senses are saying don't do this. I don't have all of the info, but I've been around bass crx's, with 4 12's and stuff like that. I don't see how you're going to fit those in there properly. You might be able to get 10 cubes, I worry about the strength of the box, trying to probably leave out bracing to gain airspace.

I mean each sub is .46 cubes air displacement. So 11.865 - (2 * .46) = 10.945. You're already under 11 cubes before a double baffle and port and bracing displacement.
 
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Rosshimself

CarAudio.com Newbie
Apr 24, 2021
15
3
Florida
I’ve been away for a long time too. From all my playing with win isd back in the day you’d probably be better off with just a single sub especially if you’re going to be squeezing inches to get enough space for the subs.

I typed that last night but I didn’t want to be that guy without any posts.
 
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LongThrow

My Kickers be swaggin'
May 17, 2014
428
0
Springfield, MO
  • Thread Starter Thread Starter
  • #7
You are NOT getting 11 cubes net out of 24 x 24 x 42. Not happening.
The subs call for 5-6 cf per sub. If I can be atleast 5cf per sub net, It may be pretty peaky but as long as it can be do Ill try it. Im mainly concerned about the port area being enough. I'm going to try and see what it does, worst case scenario, I pull the subs and trade/sell them for 15s and rebaffle the box, or just build a new one. I just wanted to get some input and see if this design is still something that is feasible.
 
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LongThrow

My Kickers be swaggin'
May 17, 2014
428
0
Springfield, MO
  • Thread Starter Thread Starter
  • #8
And yeah I did under estimated port displacement, I thought it was .3 per sub. All it should do is change tuning by a couple tenths and .3 cubic foot less internal space. Looks like after port and sub displacement now, Ill be at around 5-5.2 per sub depending on how much bracing is done to the box, I should be fine with that, just gonna be a little peaky. If it doesnt work out Ill just downsize and rebuild.
 
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Rosshimself

CarAudio.com Newbie
Apr 24, 2021
15
3
Florida
I understand wanting to use what you have but unfortunately the measurements you have only give you like 11.3 gross(this is wrong I admit I didn’t get your measurements right, it’s more like 14 gross). You have to consider that you are trying to choke the subs with a small port and small enclosure. The only way I can imagine the space and equipment working is an isobaric arrangement with the amount of bracing required. Without proper bracing I expect the enclosure to flex and fail.
 

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