Well it's time to revisit an old thread on how a sub box is made. Here is the link to my original archived thread: https://www.fiero.nl/forum/A...130314-1-085303.html

I quit working on this box because there was a thread in the mall where a member was trading a sub box with sub for some parts I had laying around. This is the setup I got through the trade:



It is a "ported" 8" sub enclosure with a Pioneer sub installed. I am pretty sure after reading up more about sub's and enclosures that this thing is not even close to being in spec for the sub, and probably is not producing anything near accurate base. It is not a very sturdy enclosure, I can flex the sides with not a lot of force and was pretty rough when it arrived. I had to make a new MDF ring for it because the one that was in it was all stripped out and split, and put the trim around the bottom to give it a more finished look.

So I have decided to continue my progress on my other under the dash sub enclosure that I started so long ago. I considered using the Pioneer sub instead of the kicker, but when I looked up specs for the Pioneer it requires an EVEN larger sealed box then the Kicker did. The minimum sealed spec for the Pioneer is .5 cubic feet while the Kicker is .33 cubic feet. Which I know this box is still going to be shy of that, but hopefully will still provide decent results. This was the only place I could find any specs on the Pioneer that I have, at least judging by picture because I was not going to yank it out just to get some numbers off it. http://carmusic.20m.com/products.htm I was going to update the original thread a week or so ago and noticed that unfortunately it had been archived. This is where I am currently at with it,







I don't think it is turning out bad at all for not having many tools, and being my first experience building a sub enclosure or even really working with wood. Probably has the most hours in it of any sub box constructed. The only tools I had available where a jigsaw and a file. I didn't even have a try square or clamps, and let me tell you there was A LOT of filing.

Well I do not have the top pieces glued on yet because I still need to go buy a speaker terminal cup and install that so I figured it would be easier to seal around it with access from the top.

One question that I do have is whether or not it is necessary to seal all the joints with silicone? And is there any specific kind I need to buy? So far the entire thing has been assembled with regular elmers wood glue, and today I went around all of the seams on the inside with an extra bead of glue to make sure everything is sealed. So is silicone really needed?

Let me know what you think.


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[This message has been edited by zmcdonal (edited 03-22-2013).]

quote Originally posted by zmcdonal:One question that I do have is whether or not it is necessary to seal all the joints with silicone

I would say yes. The glue you're using will probably eventually dry out and not create an airtight seal.

I mean, you probably won't hear a huge difference unless you have a solid ear for sound/music, but it is the proper/right way to construct a sealed box.

[This message has been edited by 1988holleyformula (edited 03-22-2013).]

Yeah I definitely want to do it right, with the amount of work I've put into it so far, there's no sense in doing it halfa** at this point. Is there any specific silicone to use or just any silicone that says it will work with wood? Do I just run the silicone right over the beads of glue?

This is my vote. If you like to make quick progress and dislike wait time.

I just sealed mine with normal silicone BUT I screwed mine together like a brick !@$#house too plus have two 2 inch ports on the bottom BUT I also have two 8 inch 150ish jvc subs in it...Yes its the same box in the linky dink.....

quote Originally posted by zmcdonal: Well I do not have the top pieces glued on yet because I still need to go buy a speaker terminal cup and install that so I figured it would be easier to seal around it with access from the top. One question that I do have is whether or not it is necessary to seal all the joints with silicone?

Not that it matters, but with the woofer out of the enclosure, you should be able to seal around the inside of the speaker terminal you use. Also, most "custom" installs I've seen (meaning non mass produced enclosure) don't really use terminals. They usually drill a hole to pass the speaker wire through and silicone seal the wire in the hole, as you don't put the terminal "on display". The speaker wire usually enters the enclosure somewhere unseen. A terminal is nice if you plan to remove the enclosure frequently but other than that /shrug.

Yes, as others have said you really should use silicone to seal the enclosure. The idea is to isolate the backwave of the woofer from it's front wave as they are generating opposite wave forms. Any "leak" between the 2 "sides" of the wave could have a cancelation effect reducing the DB you hear from the woofer. Also, you might want to consider some screws to hold it together as the pressure to the inside of the enclosure from the woofers backwave might pop simple glued joints apart.

Looks good, by the way. I think once you get it done and installed it will look nice in there . What are you planning to use to cover the enclosure?

[This message has been edited by Khw (edited 03-23-2013).]

You can take a look at my "build" thread about a homemade sealed box for two 10" Rockford Fosgate T1's here: https://www.fiero.nl/forum/A...130314-6-083429.html

While they now reside in the trunk of my 03 WRX, they still sound great!

[This message has been edited by 1988holleyformula (edited 03-23-2013).]

Get you a counter sink bit from Walmart or hardware store, and put course thread drywall screws about every two inched in every joint, will be no way in hell box can come apart. Had a box I put in my S10, years ago I used this method but used liquid nails to glue together. Had a pair of L7 12's in it with a 2000 watt rms 1/2 ohm stable amp pushing them. I tried to blow the box and couldn't! Lol

I've been kind of on the fence as far as screws go because I only used 1/2" MDF, that would make it pretty tedious in my opinion. Any suggestions?

As far as covering the box, I plan to use some dove grey automotive carpet that I have left over from my dads transam project. At some point in the future I am planning to get a new carpet kit for the Fiero and was going to go dove grey as well, so it might look kind of our of place for a while but one thing at a time, right? Planning to have it look like the pic I posted in my original thread which is Alex4mulas old yellow car I believe.

The main reason I am planning to use a terminal cup is because I already have wiring going to the current sub setup. I had looked on some audio forums and read that most people don't use terminal cups, they either just runs wires through a hole with some silicone or they use bolts, which I considered the bolt method, seems clean and simple, but read that it can burn the wood if there is a short somewhere, so that makes me a little hesitant.

[This message has been edited by zmcdonal (edited 03-23-2013).]

www.partsexpress.com

You can find a terminal cup there.

Just went to radio shack, was hoping to pick up a terminal cup there. Was hoping to not have to wait on shipping, anyone use the bolt method? Anyone have a reason that I should not use the bolt method with ring terminals?

With 1/2" MDF, or any MDF/particle board really, you would want to pre-drill the screw holes before putting in the screw. Make sure you go deep enough for the entire screw length, countersink the hole for the screw head and use a large enough diameter drill (equal to or slightly larger than screw shank, the inside diameter of the threads). Any other way and yeah your going to wafer/split the MDF.

I've done the bolt method for a speaker terminal before. I think if I remember right I used #10 or #8 bolts. I didn't have any problem with the wood burning. That might happen on a really high power setup during a SPL contest or showing off to freinds, but I doubt it would happen on normal day to day use assuming no shorting. Even then, depending on how much amperage the amplifier is pulling, I would imagine it would blow it's fuses before the wood would burn.

[This message has been edited by Khw (edited 03-23-2013).]

Well this is how I ended up doing my speaker terminals:





I used brass screws because I read they were more conductive and better choice then regular steel. I used a T-nut on the outside so everything with hold nice and tight on the inside and ring terminals on both sides. Should I use lock nuts on the outside posts to keep them from loosening up with all the vibration? I think it turned out pretty nice.

I am currently in the process of sealing all the inside seams with silicone. How long do I need to let that outgas before putting the sub in the housing? I read that silicone fumes could potentially be harmful to the adhesives used when the sub was made. It says on the tube to let it cure for 24 hours, but I am guessing that I should keep the sub out of it longer then that?

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Looks like it should work out good!

A wouldn't say more than a day or two to let the silicone thuroughly dry. It's going to outgas the most while drying so once it's dry you should be fine.

How do you know if you shoudl seal a box or leave a port?

I made a thin box that sits behind the passenger seat and houses a flushmount 10 inch Blaupunkt sub. I never put a terminal cup on it bacause I figured i'd just leave the opening as a port. Sounds good. But maybe would be better capped? This is made from 3/8 inch plywood.

http://i294.photobucket.com...tcars/fierosub-1.jpg

[This message has been edited by 2.5 (edited 03-26-2013).]

quote Originally posted by 2.5: How do you know if you shoudl seal a box or leave a port? I made a thin box that sits behind the passenger seat and houses a flushmount 10 inch Blaupunkt sub. I never put a terminal cup on it bacause I figured i'd just leave the opening as a port. Sounds good. But maybe would be better capped? This is made from 3/8 inch plywood.

I am by no means an expert, but sealed vs ported depends on the sound you are going for as well as the space you have available. Your sub should have minimum enclosure specs listed somewhere for min sealed and min ported. A novice builder is usually best to start with sealed enclosures as they are the simplest, the ported ones can get pretty tricky, since the port is supposed to be tuned to specific size/frequency.

Sealed boxes
The most common and versatile type of enclosure is sealed. This style enclosure is ideal for any application where space is going to be an issue. In some cases a sealed recommendation for subwoofer box will be half of what the ported recommendation is. They also have the advantage over ported and band pass enclosures in terms of overall sound clarity. A sealed subwoofer box will deliver a tight, clean and accurate bass response and have a flat frequency response curve. In general a sealed box will be for listeners looking for sound quality driven system that is clean across the entire frequency band.

Vented & Ported Subwoofer Boxes
Next up are ported or vented enclosures, “ported” & “vented” are synonymous, it just means the enclosure has a hole in it to let air escape. You know that guy you can hear from 2 blocks away? Well he is likely running ported box. This style enclosure will likely be about twice the size of a similar sealed box since the airspace inside the chamber is much larger. Ported enclosures are tuned to a certain frequency range which is determined by the port length, width and diameter. The port can be in several configurations such as rounded or a slot which is narrower and taller. Each subwoofer will have a specific frequency they are designed to run at for maximum output. Depending on what you plan to use the enclosure for it can be tuned to various frequency ranges by modifying the port.

quote Originally posted by zmcdonal: ...Depending on what you plan to use the enclosure for it can be tuned to various frequency ranges by modifying the port.

Thanks. I'm for sure a novice, thought mine sounded good and its not even a port, just about an inch and a half round hole .
I suppose I could experiment by capping it off, and also using some sort of tubes inserted to see how it changes the sound. Its been a few years but I do remember trying to get a certain amout of cubic inches/feet of space in the box, it does have some pillow stuffing in it, and I would have been aiming for a sealed box since that is what requires the least space.

[This message has been edited by 2.5 (edited 03-26-2013).]

quote Originally posted by 2.5: How do you know if you shoudl seal a box or leave a port? I made a thin box that sits behind the passenger seat and houses a flushmount 10 inch Blaupunkt sub. I never put a terminal cup on it bacause I figured i'd just leave the opening as a port. Sounds good. But maybe would be better capped? This is made from 3/8 inch plywood.

It depends on what you're going for, quality (tone reproduction) vs. quantity (loudness). For the former, you want sealed, and for the latter you want to look at ported, bandpass, or more exotic enclosures. Though, a ported enclosure can still produce plenty good quality bass, and most people won't be able to tell the difference anyway.

Sealed boxes don't always require less air space, it depends upon speaker design. For instance my 1995 Boston Acoustic 10.4LF subs. The
ported enclosure requires 1 cubic foot with a 3" diameter port 6.5" long while the sealed enclosure for the same sub is recommended to be 1.4 cubic feet.

quote Thiele-Small Parameters for Boston Pro 10.4LF: Max.Input Power 500watts. Continious Input Power 250watts. Sensitivity 98db. Re 4 ohms. Fs 33 Hz. Vas 2.34 cubic feet. Qts 0.36. Qes 0.42. Qms 2.53. Sd 56 square inches. Voice coil diameter 2 inches. Le 0.65 mH. Xmax (one way) 7.5 mm. Sealed Enclosure: 1.4 cubic foot. Ported enclosure 1 cubic foot-port 3" Dia. x 6.5"Length. (all specs. include basket and port displacement so there is no need to build the box larger to compensate).

[This message has been edited by Khw (edited 03-26-2013).]

Got it all sealed up today and started working on carpet for it. I am getting really anxious to see how this is going to sound after all this work.

I think my next audio endeavor will be switching out my pioneer 4x10's for some 5 1/4" components with separate tweets. That should be pretty straight forward with the template available from Fierosound, and the fact that I have a spare dash in my basement should make it really easy to work out any fitment issues.

[This message has been edited by zmcdonal (edited 03-26-2013).]

One thing that I am slightly concerned about is securing the trim ring that I made so that the sub fits in the box to the face of the box. My concern is that if I ever decide to switch out the square kicker for a different sub in the future, I don't want it to be a huge pain (since some people in my original thread suggested I use a different sub). The way I have it set up right now, there are 4 t-nuts on the trim ring, and 4 on the face of the box. I was planning to put them all in the face of the box, and sandwich the ring between the sub and the box, but the edges around the speaker opening got kind of thin since that was the first piece I cut with my amateur jigsaw skills

I have been tossing around the idea of using strip caulk around the inside of the ring to seal it up but was not sure if that would hold up to the pressure in the box. I was also considering using 3m molding tape around the trim ring to keep it nice and tight. Any suggestions? it does have 4 screws going straight from the front of the sub to the box face but i was concerned with air leaks on the 2 sides that the sub is only secured to the ring. I really wanted to avoid glueing the spacer piece due to the fact that if I decide to try a different sub all I need to do is make a new spacer piece and most round 8's share a mounting pattern so it wouldn't be a huge deal. Just trying to avoid a headache if I ever want to change it in the future.

Well I had the day off today so I finished up my sub box. Got it all fitted and figured out the mounting, finished up the carpeting. It sounds awesome!! 100 times better then the other "sub box" I had installed. Clearly my old 8" ported tube was no where near in spec. I think my old setup was working more like a boomy mid bass speaker then a sub. This new box hits HARD. I am really impressed with how it sounds. I still need to tweak one of the cables I used to mount it, and dial in the gains on the amp but I am VERY happy with how it turned out. I will post up some pictures later with the end results. And let me just add it is a SNUG fit up under the dash.

[This message has been edited by zmcdonal (edited 03-30-2013).]

Well here are the finished installed pics.







I am really impressed with the bass this box provides. I thought it would be intrusive and take up passenger leg room but it really doesn't, the pictures are kind of deceiving. I am just shy of 6 foot and tested out the leg room and I can still stretch my legs all the way out and be comfortable. The only thing that is a little compromised would be the dead pedal area on the wheel well.

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