Any recommendations on how to mount an enclosure for a sub by the passenger wheelwell in the back? It's a 10" JL Audio. I've got the box all fabbed up to meet halfway between the room I've got with the tops in the back and the manufacturer's recommended size. I plan on covering it in OEM carpet, but I'm just not sure on how to mount it in the car. I don't want to make a quick stop and get nailed in the head by a 20lb box!

Also, I was talking with my dad about it, and he asked if I was going to put insulation in the box. Is he crazy or is it something I've never heard of doing?

 

Insulation, by means of poly fill, will only help if the box is too small for the sub. If the air space it tight then the poly fill will help fool the sub into thinking it has more room.

Other than the adding poly is a bit moot.

As far as mounting, I always liked straps or studs.

You can mount a stud to the wheel well using a jam nut, and pushing the bolt through from the outside. That gives you a nice stud. Then, drill an exact hole in the box where it would sit on the well and meet the stud. From the inside of the box secure it down to the stud with a washer and nut, and then install the sub. Not going anywhere.

For a strap, just mount the strap to the wheel well, and like it sounds, when the sub box in is position wrap the strap around it and use a low profile buckle like what you find on backpacks and luggage.

 

Im thinking about screwing mine to the back wall with a strap. Next to my amp. And im filling my sub with poly-fil. 3.00 at a craft store. Makes the sub think its in a bigger box. Another forum member suggested it. I should have my system done this weekend.

 

What dimentions on the box? thought about a piece of Velcro on the bottom? Or a piece of that rubber foam fishnet looking stuff tool box drawer liner

 

I have seen first hand that Velcro does not hold a sub and box in the event of a 'fast' stop or an accident. It just makes a cool ripping sound before it lets go and hits whatever is in front of it.

 

It's a 10" sub that's 4.34" deep. The box is 16.25" wide x 13.25" high x 7.25" deep.

JL Audio's suggested box was a 1/4" bigger in width and hight, and a 1/2" deeper, but I'm limited in space because I still want to put my t-tops in the back.

Velcro sounds kinda bubba-ish. The sub is gonna be right behind the passenger seat, and I don't want my girlfriend getting nailed in the head.

 

That's somewhere along the lines I was thinking. Is there any way to mount it from the bottom side of the box from under the car? I'm thinking I would probably have to pull the spare tire and the gas tank, but I really don't want to do the latter of the two, so if I do have to, your wheelwell idea sounds pretty good.

 

When I bought my car, the PO had a plywood board glued with construction glue, to the roof of the rear compartment. He mounted all of the stereo stuff on it. I removed all of it and I'll tell you it was a BIT(H to get it off! Just an idea.

 

That must have been....... interesting. Do you have any pictures? I'm not considering doing it, I just need a good laugh

 

Sorry, I don't. It was in the middle of August out in the sun, and my body was stuffed under the black rear deck cursing like all-get-out. I was not in the mood for snapping pictures. Maybe next time.

 

I've read a lot of threads with stereo & speaker updates, where and how they' mounted.
I did a sketch that positions the sub back just below the courtesy light on an angled plywood platform cut to wrap around the wheel wells and would be a tight force fit. This would also give you the air volume you want for the sub and room for t-top storage. Personally I don't like the way a box looks just plopped in a corner back there. This would integrate well into the storage area, and give you a place to hide the amp. Obviously you'de put matching carpet on it. What do you guys think?
Glenn

 

Great sketch and good concept. A few guys have done something similar.

You will encounter a HUGE problem with vibration and normal sound deadener will not solve it. You would have to construct the entire structure out of MDF and just fit it to slide in the back there.

The sub, especially if it's good enough to need all that ai space, it going to push air in and out very fast. Think of the static woofer cone. When it hits it pops out and then back in. This is called excursion. When the cone goes back in it's compressing the air in that enclosure which in turn gives it a boost on the other end giving max excursion when it's really hitting.

There is a reason good sub boxes are made with 3/4" or even 1" MDF or hard board and that's because it won't move or flex when the sub is really kicking.

Enclosing the front there and using the back end as an enclosure means the other five sides of that enclosure are just thin fiberglass. All sides of that new enclosure will flex in and out and vibrate easily. It will stress the GLUED joints and sound just like a ghetto sub in an uninsulated trunk.

I have watched an SUV from the outside where a single sub was pushing a sealed enclosure and it was pushing the windows and rear quarter panels by 1/4". That's metal and glass. Imagine thin fiberglass.

If you boxed the whole thing and then slid it in you could avoid all that flex but that makes the project a lot more complicated.

The other issue, and this is secondary to that one, is firing direction. Yes, bass is direction less, but you get the best results when those low frequencies can 'hit' something or a surface 3'-5' in front of the sub's cone. If it's firing into open air you don't even hear the 'thump' until it hits something. This makes sound quality go down considerably.

If you can design that box so the sub fires down or even sideways giving it something to fire on then it'll sound a lot better too.

Hope this helps.

 

Hey Db,
Interesting. This isn't my area of expertise, this was for a basic concept. If this had a complete sealed structure with vents, which would then eliminate fiberglass vibration, then a lot of vibration issues would be solved, correct? Also the angle could be higher to face the sub more towards the front. Another thought would be to use two smaller 8 inch subs to give more room so that the angle could face more forward.
I haven't seen the other guys install like this, that's why I thought it could integrate nicely into the storage space with t-top storage room.
Glenn

 

Venting could help a little but depending on the sub this will diminish a lot of the tight hard hitting bass that sealed enclosures are good for.

Also, in that same respect, one good 10" would till be a lot better than a pair of 8" subs. They usually just don't have the excursion for producing good low frequencies.

Finally, aiming the subs at the front is the worst place to aim the subs with them being in the back. By picking the furthest point you will be causing the greatest loss of sound quality and performance. If the sub is in the back you will want to find a way to aim it at any of the closer surfaces. The front is the furthest. Catch my drift?

 

Gotcha.

 

I wish I had pics of the box I had in my 77. It had 2 8" kickers, 2 horn tweeterd and a big Kenwood amp on the front. It took the width of the rear compartment, went from the back nearly to the seat backs and had enough room under it to slide the TTops in the bags under it. And it rocked, HARD.
Was mounted on legs on both sides under the bottom

 

I have to disagree with this statement. In my experiences, facing the sub forward produces a cleaner sound, in exchange for the heavy bass and overall loudness of the low end. Reflecting the sub off of anything exchanges crispness for the heavy, sloppy sounding bass.

I had 4 DVC 8's firing forward that could reproduce a very fast double kick drum in a way that few others could. It was very tight and crisp, you could hear each time the kick drum was hit. People with rear firing subs would get a "muddy" sound out of the same music. It was loud bone shaking bass, but it wasn't the individual hits of the drum. All the sound kind of ran together.

 

Key words. 8" subs. 8" subs are on the line between subs and speakers. They generally have very low Xmax values meaning the coil travel from full excursion to full retract is far less than 10" and obviously 12" subs. Because they are so much more like a speaker it's perfectly fine to aim them forward as mids and highs are definitely directional.

Subs, and their low frequencies are not. If you put a pair of 8" speakers in the rear and face them forward it will sound fine but even a good set of 6.5" speakers will give you the same mid bass frequencies.

If the installer is after bass, low frequencies, something that hits and resonates, stick with 10" or higher. For C3s, a 10" sub is perfect. If the installer likes the sound of mostly mid frequencies and high frequencies then 6.5" speakers are in order. If there is a call for a nice blend of mid-bass and higher then adding an 8" sub or more will help.

That being said, there is no reason to mount an 8" speaker like a sub if it's purpose is quick snappy responses like a drum beat. It can and should be mounted as a speaker, not a sub.