Knertified

I wanted to start up this thread because of a couple of recent threads where people have sealed up the subwoofer box on the rear deck and installed an aftermarket 8" subwoofer. We have not been able to get any pictures or tutorials yet because the installers did them, not the members.

I hoping that someone else has done this and can offer two answers.

1. How did you seal the rear deck where the subwoofer sits?
2. Which 8" sub did you use?

I would rather not install a JL W3 as the person in the other thread did. I feel the W3's are not very accurate and sloppy in comparison to other subwoofers I have heard.

I am going to look up the depth of the W3 to see if we can start with that at least. Then many we can start a list of subwoofers that *should* fit.

stangd1909

Subscribing.....I would like to know as well.

csmeance

would like to know as well.

ewwwitstofu

I'd also like to know. I need my trunk space!

Knertified

I looked up the W3 along with some other subwoofers. The W3 depth is 4.31 inches and the max diameter is 8.54 inches. I looked on crutchfield and every subwoofer I checked was less. I checked the JL W7 and it is 6.83 inches in depth! I believe in a previous thread an installer didn't think a W7 would fit and that the W3 was pretty close. The W3's depth is probabally a good depth to go by.

raoacura

I will tell you about my experience but please don't ask for any pictures because I did not take any. I will try to explain things the best I can. All dimensions that I list are a best guess from what I can remember. Also, you should know that I do not consider my problem solved yet.

For the sub, I bought an Elemental Designs dual voice coil 4 ohm sub. I chose this sub because 1) when wired in parallel you get a 2 ohm load so it “can” be used with the stock amp (although there really is not enough power); 2) it can run either free-air or sealed; and 3) in a sealed box, ideal size is .35 cu ft but the specs say you can go as small as .2 cu ft.

The stock rear deck basically is made of 4 panels: the top (where the sub is mounted), the bottom (about 3” below the top), the front (toward the inside of the car), and the rear (toward the trunk). Inside the deck is basically about a 3” by 11” rectangle that runs the width of the rear deck. Theoretically, if you could seal off the center section and have a “box” large enough you should be good to go. This is a difficult for several reasons:
- none of the panels are flat – they sort of have a non-uniform ribbing
- the panels are not sealed where they meet except for some spot welds here and there
- all of the panels have holes in them. The top has holes where the “fabric” part of the deck fastens (plus a few other misc ones). The front has holes where the trunk lining attaches (figured this one out after the fact). The bottom has about a 5” cutout exactly below the sub and another 3” x 4” cutout a few inches away.

Here is what I did:
- I cut a plug out of 3/4 MDF for the left side (as viewed from the back of the car looking forward). This was trial and error process to get something that fit well. The plug looks more like a parallelogram than a rectangle because the front and back panels are both angled. The plug is screwed in from the top and bottom. It is mounted very close to the left speaker to give as much room for the sub as possible. (afterthought: maybe I could go a bit farther)
- I could not do this for the right side because there is not enough room to the right of the sub (the seatbelt stuff gets in the way). For the right side I used ¼” material. I had a tight fit without any screws.
- Next step was fun with fiberglass. I used fiberglass to seal both plugs, ensure the right side plug was there to stay, reinforce the top, seal the seam where the top and bottom meet front and rear, and seal other misc. holes. This was a big pain that I would like to avoid in the future. Note: my car smelled like a boat factory for 2 weeks. I was beginning to wonder if it would ever go away.
- I built a plug for the 3” x 5” hole. I put the connectors for the woofer into this plug.
- I built a plug for the round hole below the woofer. The ED sub extends below the bottom deck about 1/4” (through the hole). The good news is that the sub is tapered on the bottom so there is about 1/4” of clearance from the sub to the bottom rear deck all around.

After sealing everything up it was time to try things out. I was very disappointed when I heard basically nothing out of the sub. I didn’t think it was on. I pulled everything apart and tested and it worked so I put it all back together. The next morning on the ride into work I again heard nothing out of the sub. I started to think that perhaps the inputs for the sub were too low and maybe they were shorting out against the bottom panel. I removed the plug below the sub and that was not the problem. However, the sub now seemed to be working. Although now it is running free-air. It does sound decent but not nearly what I was looking for. My guess is not enough power.

Next step – I purchased a JL 300/4 amp along with Polk SR6500 speakers. My thought is to run the front Polks with 2 channels and the sub with the other 2 channels. I have already replaced the rear speakers with Infinity Kappas (2 Ohm) and they are just fill so the factory amp is fine for those. After getting the amp and speakers mounted (BTW – the SR6500 are NOT plug and play but they do sound fantastic), it was time to seal up the sub and try again. This time I was in more of a hurry so I decided that since I only had a 1/4 inch gap to fill around the magnet that Dynamat would do the trick. I put some tape on the bottom of the sub so the Dynamat would not stick to it and I placed some Dynamat to seal up the hole. I think it did a pretty good job of sealing. I was adjusting the amp from inside the trunk and you could feel the sub hitting on the kick drum. Once again, however, I noticed that the sub was not putting in much audible bass. It was putting in a lot of pressure but not much sound. I decided that removing the seal worked before so I would try again (but this time it was easier because I only have to cut Dynamat). Instantly I now have some bass in the car but I am again running somewhat free-air. I have to give the sub a lot of power before I can hear it and I think it is putting in way too much pressure. It hurts my ears, but I still cannot really hear the bass well. I have a theory that that perhaps the “box” is too small to run sealed. Maybe a different sub would work better.

Note that I am looking for SQ – not SPL. I am past the days of having a lot of boom in my car and I have the hearing damage to prove it. All I want is to be able to hear all of the music without having to turn it way up.

One thought:
- instead of fiberglass, I probably could have sealed the plugs and everything else with Dynamat. Anyone have any comments on that?

A potential plan B: Build a better box that is the right size
- build a hollow box with 3/4 MDF (no top or bottom – only sides) that is large enough to get .35 cu ft but sized so that it will fit in the rear deck area.
- cut the bottom and back panels of the rear deck so the box will fit in.
- screw the box into the top deck
- (no, I am not really saying this am I?) fiberglass the top of the box to the top panel for a good seal and structure (is there a better way?).
- fasten a bottom to the box made of 3/4 MDF.
- to get the size you need, I believe the box will stick down below the current top trunk lining. This would require cutting of that lining but I don’t think it would take much trunk space – certainly less than a separate box would take. There will also be an issue with what to do with the safety pull that allows you to open the trunk from the inside.

Perhaps someone can help me on a different problem with the 300/4 and the SR6500s. I am running speaker level from the Acura amp into the JL. I have input set to high and I have the level turned ALL the way down. With this setup, the SR6500s are quite a bit louder than stock at a given volume setting (I used to listen around 6-8 and now I listen around 4-5). They also seem to be somewhat intense (sound great if you crank them but I want to save my ears). As an experiment I tried running the SR6500s off the factory amp and they acutally sound pretty good. I have to fade the level toward the front in order to make the rear be just fill. I also run the volume about 8 – 10 with this setting. When listing to XM (rare) or FM (rare), I do have to go to about 16 or so on the volume but I don’t normally listen to them because they do not sound very good. At this point I am thinking of using the SR6500s without an amp. Am I crazy?

Knertified

raoacura: What are the chances of just sealing up the sides with mdf and then covering the rest of it with dyanamat extreme (thin) to seal the rest? Is that feasible?

csmeance

won't the dynamat flex due to the air pressure? Also is it nessary to use fiberglass?

raoacura

I wish I had a good answer for you. I think it will work on the areas where you are only sealing around a 1/4 inch gap (which is everything except for the 3 x 4 in hole). We need an "expert" to chime in here. I do not think that dynamat would do the trick on the large 3x4 inch hole - you would need some sort of plug. Also, I'm not sure you could get a pices of 3/4 MDF on the right side.

Also, I'm not sure how big the final box is when you do this. We will need to find a sub that does a great job with a small box. Note that putting some polyfil (stuff you make pillows out of) is supposed to help when you have a small enclosure but I have not tried it.

raoacura

That is the question of the day. I don't think that it would flex much if you used it only in the cracks and the small holes but I really don't have any data.

I used fiberglass because I knew it would work. After doing it, I would prefer to avoid it in the future. I had done some boat repair work in the past and that was easy so I thought this would be easy. It turns out to be pretty tough getting things into place when you can't really see everything. It took me quite some time. I am open for alternative suggestions (hence the thought of using dynamat).

A SiQ TL

popeye deno did it.
Here is the link to his thread (with pics)
https://acurazine.com/forums/showthr...woofer+project

Knertified

Yeah i saw that thread but he actually plasma cut and tig welded a new box LOL. This thread was started to see if we could put our heads together and come up with an easy way to make use of the factory space without cutting into our cars.

bh1906

SubscribingSubscribing

popeyedeno

Hey guys,
Good discussion...I first tried to problem solve a "sealed" (no pinhole leaks, today or out in time due to stress) enclosure without any cutting, that would withstand the pressure. One issue was a decent sub that would fit within the stock mental enclosure (magnet size, depth were issues) without cutting...but I ran into the issues discussed here...and as raoacura mentioned, there are too many "details" that need to be taken into account, aside from the depth and mangnet size issue. I concluded that it would not be any easier then cutting (and cutting gave me an extra desgree of flaxibilty in terms of access from below)

Here is my input if I were to do it again, without cutting

1) I think by the time you work around the issues to get a sealed encloure without cutting, you will have expanded just as much, or more energy and the resulting enclosure will not be as rigid (unless you line the interior with fiberglass, at the expense of volume..and raoacura can appreciate the fiberglassing issues here) and the sound pressure will flex the enclosure (for some, this may be a no care..but purists/audiophiles may have an issue)

2) The main issue is that there doesn't appear to be any 8" ( but some have said the W3 will fit) that will both fit in the stock hole on top AND have a magnet size that clears the hole on the underside (a small amount of cutting can take care of this..but we are not looking at cutting options, right)...Assuming there is a sub that meets the above this is what I would try:

a. Sacrifice a gift box for it cardboard to use as template for side plugs..insert the cardboard into the enclosure from the top, remove the seat belt assembly on one side and then fit the cardboard to get a rough outline for a side plug. Repeat for other side, minus the seat belt assembly..cut the plugs out of 1/2" mdf (easier to fit than 3/4) and cut/adustt until it can fit in snugly (don't worry about the holes..just use kitty hair or resin to seal the edges from inside and outside)...and then silicon from from both sides for insurance
b. Use fiberglass resin to seal all the seams that are tac welded. find something like a blistick/chapstick cap to cover the anchors for the top deck cover, and use the resin to glue it to the deck, without messing up the anchors..you now have sealed these pinholes. Also, apply the resin from the inside on the child seat metal anchor area and use indoor/outdoor DAP flexible slicon from the top..
c. Either make plugs, then seal the rectangle hole or just fiberglass and seal
d. Optional: I would line the interir with a couple layers of fiberglass to prevent the metal enclosure from flexing..give it strength and rigidity
d. Build a ring as a spacer around the bottom hole (1/2 or 3/4 depending how much space you need..use two if needed)...this will give clearance to the magnet if if protudes from the bottom hole (needed for vented speakers, like the Elelmental design Raoacura and I have use (raoacura, could this be part of the reason you don't hear the base well when you sealed the bottom? Do you have at least 1/4 space?) . Then lay fiberglass accross the bottom area and nicely curve the area around the ring..this will give a bulge at the bottom...glue some matching carpet in this area..you can later cut a hole in the liner and this bulge should blend and give your TL an extra curve
e. Test for pinholes..use a frequency sweep CD and stick your and your buddy's ears close to the box to identify pinhole leaks..use the DAP silicon liberally to seal them. (I cut a hole in the side plug for the speaker wire and siliconed it)
f. remove the manual trunk cable, seal the holes and reroute it
g. You can also line interior of the box wiht dyanmat etc if you didn''t glass it..this will hopefilly address pinholes the resin lining missed.

I can personally attest that this will be very time consuming, especially since gavity will be your enemy (working upside down, resin dripping etc) and you'll get to know your trunk well. Wrote this from memory, so hopefully I did not miss anything...but the trick is finding the right sub and willingness to put in the time (or pay someone)...
The other problem I had was mounting issue..the aftermarket sub took more area on tip, but the uneven surface casue sealing issue..I built my custom spacer/sealing solution, but I think it'd be just easier to take an 8" ring, sand it down to 1/4 or 1/8 inch thick, put on top of current hole (get a ring for your sub)and then build up the surrounding area with fiberglass/kitty hair..sand and install the sub.

Well, hope this gives some perspective...so who's going to bite?

A SiQ TL

Hey Deno,
long time no talk,
Did you get your amp put in yet, how about the 2nd sub? I want to hear how it sounds.

popeyedeno

Hey toby,..no, lack of time; I PM'd you..I keep changing my mind on equipment layout etc to keep it stealth

soontoownTL

there are a few products yu guys might want to look into if you need the trunk space, first is the pioneer premier subs, very shallow design 3 " tall!

http://www.crutchfield.com/S-OMyUPi2...0&I=130TSS2541

@nd which is what i am going for is a product from alpine which is very compact and sounds like 2 12" in the trunk, plus very good sound quality

http://www.crutchfield.com/S-OMyUPi2...1000&I=500PLV7

lembowski

iTrader: (1)

Looks like it also costs as much as 2 12's and a amp. I really wanted to do the stock box thing you guys are planning, but becasue of time issues and just plain not wanting to put the effort into it I slacked a put the Infinity Basslink in. Don't get me wrong the Basslink sounds awesome, but I would love the setup to look like this

raoacura

When I first put the sub in and was using the stock amp, I did have about 1/4 inch of clearance. I did as you said and made a ring out of MDF with an MDF bottom. I then fiberglassed the inside of the ring before installing it. I did not, however, try this once I added more power from an outboard amp. Good idea.

I like all of your thoughts above. I too considered the "cap" to fill the holes but still allow you to plug in what is supposed to go there. You would need to get something deep enough for the plugs to fit.

Not having done it I can't say for sure but my gut tells me that it would take less time in the end to cut and build a proper size box from the beginning. Of course, every bit of work I have done my my TL has taken about 5 times as long as I predicted.