ported box for 2 12" subs

[BlaineGreen]

I bought 2 subs and an amp and sealed box for like fifty bucks, and I have never heard of the brand (CrossFire) everything is crossfire, the subs, the amp. The subs say 300W rms, and the amp is 300x2 rms. But I don't like the way they sound sealed, and was wondering if someone could help me build a ported box. The problem is, I drive a 97 ford f250 xlt and I have a back seat, that unfolds kind of into a little bed type thing. I have two questions/ problems.. Problem 1 the space is only about 20"x5' so i'm wondering, if there is a type of ported box that can be long and rectangle? my second issue, is will the sound be, bad? because it is such a small cab space i.e the subs being about 7-8" from the people listening>? and also, will these subs work in a ported box? if so, what dimensions would I need? i'm good with carpentry and would much rather build a box than buy one.

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[blazian87 10+ year member]

How much depth do you have? Ported can sound bad if the specs are not right. It can sound pretty good if done right though. I have a feeling your sealed box is too small, which usually is very peaky up top. If you don't have much space, go with the biggest sealed box you can possibly fit. If you can fit 2 10's ported, that would sound way better and be louder as well. What's the max dimensions you are willing to give up? If you want sound quality though, I would spend a little more for something better.

 

[BlaineGreen]

I don't use the back seat, so I can use the full 20" deep, 5' long and about 35" tall. I just don't know, 20" isn't very deep. so like I said it would have to be long. and yeah I know, I was planning on buying a sundown 10" and building a 4th order, but I had to spend almost 600 on some tires so i'm low on dough.. just trying to see if making a new box for 50-100 dollars of wood, can get any better sound

 

[Spooney 10+ year member]

Sounds like you have plenty of space to build an adequate enclosure for those 12's. Might help if you could share the model number of the subs. Would make it much easier to help you design a box. Sounds like you got a great deal on your equipment.

 

[BlaineGreen]

The Subs are Crossfire DB3 12 I can't really find any information on them, the only reason I got them was because I figured for 50 bucks I couldn't really lose anything.. haha

 

[BlaineGreen]

This is the only info I could find

12" Subwoofer

2" 4 Layer voice coil

45oz Magnet

Polypropylene cone

 

[Jeffdachef 5,000+ posts]

where is the sealed box firing lol? might be just running into subwoofer loading issues, it needs solid wall to bounce off of.

 

[blazian87 10+ year member]

This is the only info I could find
12" Subwoofer

2" 4 Layer voice coil

45oz Magnet

Polypropylene cone

Lol this tells us nothing.. But anyway.. I would probably go with 4-5 cubes net tuned to 32 hz.

 

[BlaineGreen]

Yeah, I literally can find nothing on them, like they don't exist..haha but the subs are pointing to the back, I had them pointed towards me but it sounded really weird.

 

[blazian87 10+ year member]

Yeah, I literally can find nothing on them, like they don't exist..haha but the subs are pointing to the back, I had them pointed towards me but it sounded really weird.

Yea the subs need something to reflect or load off of. Thats why most people face their subs to the back.. On all my setups when I tried facing forward, it always sounded weird and lost alot of output. The only time facing forward works really well is when you create a wall and everything behind it is completely sealed.. Always try putting subs in corners and especially if you're running sealed, put it really close to a wall for cabin gain.

 

[ThatChevyGuy 5,000+ posts]

i faced mine up in an extended cab

 

[blazian87 10+ year member]

Yea in an extended cab truck, facing up would be best.. I have a trunk car and I have all my subs facing up only because it was the easiest way to fit 4 10's ported. It worked out great still.

 

[BlaineGreen]

So, after some searching, I found a manual for the subwoofer from the crossfire website! http://www.crossfirecaraudio.com/wp-content/uploads/2014/01/DB312D.pdf but I think I can use this information and a box calculator? turns out, the subs only take 200rms and the amp puts 300. My friend ran these for about two years like this, so I don't know how bad it has been? maybe the amp doesn't put full 300 watts. But in theory, I take all the information, (fs,vas, qms, etc) and use a box calculator? Is this reliable?

*Edit*

So, I found the manual for the amp, and it puts 300x2@2ohms and 150x2@4ohms does this mean, since the subs are dual voice coil, and I don't have them wired parrallel, that they only have 150 watts to each?

 

[blazian87 10+ year member]

So, after some searching, I found a manual for the subwoofer from the crossfire website! http://www.crossfirecaraudio.com/wp-content/uploads/2014/01/DB312D.pdf but I think I can use this information and a box calculator? turns out, the subs only take 200rms and the amp puts 300. My friend ran these for about two years like this, so I don't know how bad it has been? maybe the amp doesn't put full 300 watts. But in theory, I take all the information, (fs,vas, qms, etc) and use a box calculator? Is this reliable?

*Edit*

So, I found the manual for the amp, and it puts 300x2@2ohms and 150x2@4ohms does this mean, since the subs are dual voice coil, and I don't have them wired parrallel, that they only have 150 watts to each?

It will depend on the impedance of the sub. Use a DMM and check the ohms. Then use this website to see the final load. Subwoofer Wiring Diagrams

Overpowering is fine as you can always turn the gain down appropriately. If you're underpowering, then you can make your box bigger for efficiency

 

[Jeffdachef 5,000+ posts]

So, after some searching, I found a manual for the subwoofer from the crossfire website! http://www.crossfirecaraudio.com/wp-content/uploads/2014/01/DB312D.pdf but I think I can use this information and a box calculator? turns out, the subs only take 200rms and the amp puts 300. My friend ran these for about two years like this, so I don't know how bad it has been? maybe the amp doesn't put full 300 watts. But in theory, I take all the information, (fs,vas, qms, etc) and use a box calculator? Is this reliable?

*Edit*

So, I found the manual for the amp, and it puts 300x2@2ohms and 150x2@4ohms does this mean, since the subs are dual voice coil, and I don't have them wired parrallel, that they only have 150 watts to each?

Crossfire puts out excellent products, by no means a garbage company. Your friend could have abused those subs, you never know.

If your subs are dual 4 ohms check to see if you have them wired series or parallel. If you have them wired in series, you are getting FAR less then 150 watts.

Set the gain properly too. Use the DMM method.