12" subs sealed enclosure question...

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I have a 2000 Chevy Silverado xcab. I built a custom fiberglass enclosure under the back seat and am now ready to buy my subs.

A little added information. I have the Memphis Belle to run my system. The subs I am thinking about getting are the Elemental Designs e12k dual 4ohm. That would give me a 1ohm load to get 1000 watts out of the amp. I have exactly 1 cu ft sealed per sub.

My question is - I want a very hard hiting system, and after reading alot of the posts on this site- no one has talked about sealed enclosures hitting hard. Anyone have experience on sealed enclosures hitting hard with this power/sub size? I figured 2 12" subs sealed are better than 1 12" sub ported due to the total speaker surface area. And the XMax of the e12k is pretty high. This should help the sq/spl - i am looking for both.

I am open to options reguarding this setup.

Also - i have a shallow mounting depth of about 6 1/2". I would prefere less so I can flush mount the subs.


You really do not have much choice about what type of box you can build. If you want to keep the back seat in operation you will need to keep a sealed box. You could build a ported enclosure for 1 10' or maybe 1 12'. The problem is you will not have the air space required to tune it right. A lot of subs are designed to work in smaller enclosures. Your 2 12''s will hit real hard and sound real good. You may not be able to hear it down the street, but inside the truck you will be happy I am sure.

You did put the subs in a rear/down fire position right???? If you did it will sound better than putting them up, or facing forward. I know it is harder do build that way, but it does sound a little better. If you built them in an up fire position that sounds real good in the front seat, but the back seat does not sound great. Feels good on your A$$ and if you put your girl back there she will really enjoy it.

But if you do not want to get rid of the back seat you did the right thing.

Well, I didnt build them facing down!! I can still change it I guess. It will be a little work though. How far off the ground do the speakers have to be?

Here is a couple of pics of my box:



It does not have a top because I havent got the subs yet. But they will be flush with the top.


Well the only thing I can see is this. If they are flush with the top, and depending on the sub you may have WAY to much excursion. This means when the speaker is at the top of its throw it will hit the bottom of the seat. How deap is that box where the speakers will be?? You could set it down about 1 inch to allow for a longer excursion. It all depends on the speaker, and the amount of travel it will have. Mine face up also, but I gave them 1 inch of travel, plus when people sit back there I did not want them near the sub. Yes I know they are still near it, but oh well. You have to do what you have to do.

You look like you have a bit more room under your seat than I did, so you might be able to get away with a ported 12, if done right will give you more bass than those 2 10's.

Like I said before the 2 10's will give you a tight bass sound, and good quality. It will not break windows, but it will sound good to you.

I do not know if doing a down/rear fire design will make a difference worth all the work. The sub companies that make box's like this say the rear fire/down design helps front load the speaker which will give you a better bass response (they say) I cannot confirm or deny this. But if you do choose to do this you would put the speaker facing the back of the truck and an angle.

I think your box will do a good job the way it is. I am going to play around with building a new box to fit mine with the rear fire / angle design. But for now mine plays and sounds good.

I assume that the area in the middle of the box is for an amp?? If not and you decide to rebuild a box there is a couple extra inches of Air Space (if you wanted to port it). I know it may sound or not look the best but they make metal grills that will fit over the speaker. I would only do this to protect your speaker from a big A$$ crushing them.

It looks good so far, with a little carpet, or paint it will look good. Is that all fiberglass?? It almost looks like wood with a fiberglass resign put on. It also looks like you used 1/2 inch wook instead of 3/4. Is there a reason for this? The only thing I could think of is more air space.

I assume that the area in the middle of the box is for an amp??

It looks good so far, with a little carpet, or paint it will look good. Is that all fiberglass?? It almost looks like wood with a fiberglass resign put on. It also looks like you used 1/2 inch wook instead of 3/4. Is there a reason for this? The only thing I could think of is more air space.
Yes - the area in the front of the box is for an amp - the Memphis Belle. The box is not finished yet. It still needs the top. It was made out of 5/8" mdf. I did not use 3/4" because I am going to resin the inside and outside of the box to keep from flexing. With me doing that, it would be ok to use 5/8" mdf instead of 3/4". Also by using 5/8" iit allowed a little more air space. The bottom of the box is fiberglass and resin. After the bottom was done and dried - i put a coat of just resin to give it a smooth look - I know knowbody was going to see the inside - but I did.

You mentioned 2-10" subs. I was never interested in 2-10" subs but two Elemental Designs 12" 4ohm DVC subs in a sealed enclosure @ 1 cuft each. Would you still recommend 1 ported 12" rather than 2-12" sealed? I have enough power to run them sealed (i think-see below). Also - when I say flush - I should have said that they will be mounted 5/8" from the top, and the throw of the subs are .61" (5/8"). The mounting depth where the speakers will be mounted is about 7" (top mounting). And yep - I will be making some kind of speaker grills. Not sure out of what yet.

The Memphis Belle is a 5-channel amp that breaks down like this:

4x75 watts@4 ohm or 4x115 wats @ 2ohm

and 1x1100 watts @ 1 ohm (subs).

I feel this is a sufficient amount of power for a couple of 12" subs, even sealed (i hope). Or even 1-12" ported (maybe too much power).

Thanks for taking the time to talk about this.


You mentioned you have 1.0 cu Ft per speaker. Is that enough?? I know it is close, but what does it say for optimal sealed air space for your 12's? This is what I would do. Finish the box the way you designed. (this way you have tunes for awhile) Then play around with building a box for one 12 ported. If you build the box right one ported 12 will beat 2 sealed 12's. Well when I say beat, it is relative to the sound you are trying to achieve. Like I said your truck should hit pretty hard, but will not hit the real low bass, and may not rattle your neighbors windows. But I believe with what you have you will enjoy the music. If you are only looking for sound quality then you have the best setup for that. (my opion). It will give you a crisp tight bass. It fills in nicely with a good set of Components.

that should be plenty of power for your subs. I am pushing half of that in my big truck and it sounds good. My little truck is pushing 2 times that with 2 10's. But that is my loud truck and my big truck is my everyday truck. Keep on doing a good job, and try differnt things. Building a ported and tuned box is not that easy, but can be done. You may have to do it 3 or 4 times to get it right, but it is fun. When you really get good at this you can start changing baffels inside the ported box to create even more resonance. But if you like the way this one sounds keep it.

I ment 12's I was thinking of my truck while I was writing. Sorry.

Thanks for all the input. I do not have the subs yet. This is why I am asking so many questions. I dont want to waste $, I would prefere to get 1 12" if thats what be best. Looking to be loud but still have good SQ.

Thanks again,


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