Sub woofer(s) behind headrest

['95MSM]

This took on life in the what did you do today thread. I'll get it started.

Perhaps the first bit to cover is that the windblocker has to go. I did this to an NA, so I didn't have to make this "sacrifice". I love having some sort of blocker - we have an Oris Windstop - but I could understand someone not wanting to go without a windblocker. They extend the top-down season a couple of weeks on each side of spring/summer/fall.

For those that have not had the deck carpet out to see just what is beneath it, the center area is part of the unibody chassis - i.e. it is an integral part of the car and houses the fuel tank. There are twin tunnels on either side of this center section. The righthand side is accessible from the trunk. The lefthand tunnel is blocked by the shield that protects the filler and vent tubes for the fuel tank. There is a shallow cross tunnel at the front edge of the deck, but it isn't large enough to do much more than store a couple of umbrellas or a skinny spotting scope (we've made many trips to Yellowstone in our Miata). The tunnels are closed in on the top and forward side by some flimsy sheet metal that unbolts. I call this the parcel shelf, since all you can do with that area is stow small stuff.

Sidebar: I cut the forward wall behind the passenger seat off, reinforced the remaining sheet metal and fabricated a new, heavier "door". The new door is held in place by a single 6mm (10mm hex) bolt. Peel back the "backrest" carpet, undo the bolt and you have access to the open portions of the tunnels. Very useful for emergency supplies, or if you are taking a long trip and are desperate for space, just about anything you don't need on a daily basis.

The side tunnels have lots of length, but not so much width. The tunnel has a large radiused corner where it blends to the 'cross tunnel', so the width narrows to about 7" (from memory, don't hold me to it) toward the back. I'm just enough of a tech snob to not use oval speakers, so I went about fitting an 8" into the sheetmetal over the lefthand tunnel, preserving the storage space behind the passenger seat. I also thought a Miata is so small I didn't think it warranted dual subs.

The magnet on the Pioneer sub I selected is typically large for a high power speaker. I found that the magnet or speaker frame would hit the inboard side of the tunnel. I have resources the average guy does not, so I grabbed a block of aluminum at Boeing Surplus (now closed, sadly), chucked it into my lathe and made a 3/4" thick ring that bolted to the parcel shelf sheet metal. The sub mounts to the top of the ring along with the grill. I brought the aluminum to a mirror finish, so I got some bling along with my improved sound system.

The fact that most serious sub speakers need a raised mounting ring kept me from writing it up with pictures. It certainly doesn't have to be aluminum (or any metal), but not too many people are going to have tools to make the required riser.

As I mentioned in the WDYDTYMT thread, the coup de grace was finding a class T amp that fit into the bottom of the tunnel. This was 12 - 14 years ago and IIRC class t amps were fairly new. Some criticized the full-spectrum sound quality, but they run really cool (compared to standard amps) and made good sub woofer amps. Configured for 1 channel operation (taking two inputs and merging them), my amp was rated at about 300 watts max and has a remote gain switch that I mounted in the slot at the front top of the glove box.

I also closed in the back of the tunnel in a very in-elegant manner: a cardboard wall covered with and sealed to the chassis with more strips of Fat Mat.

I would be happy to answer any additional questions, but my install was done so long ago the speaker and amp probably have not been available for 10 years. I did quickly google T class amps and there are lots out there.

Since we are talking amps, my mounting place for the midrange and headrest (remember, this is an NA) speaker amp is pretty unique. I squeezed a normal sized Alpine 4 channel amp in between the fuel filler tubes. It sits at a 45o angle with the forward end down, and the right rear corner sticks out through the top of the shield that protects the fuel filler tubes. I lost all of ~ 6 cubic inches of trunk space, but it does make swapping shocks (or adjusting any shock with a top adjuster) a little more complex.

[dpdptp]

You should be able to do dual subs if you went with a set of Kicker Comp RT's they have a mounting depth of only 3.75in  800rms and 1600max 1ohm or 4ohm

I'm currently running one 12" in the trunk at 4ohm, in a cheap vented box and the sound is ridicules.

I'm planning on building a custom box for two 10" on the back shelf which should allow the top to still go down, that's if the design in my head works as it should.

I know not everyone is in to the thump thump boom boom, but I just love it when my 17yr old and her friends call me the coolest old dude..!

Growing old is mandatory but growing up is optional..! and I'm a Toys R Us kid..!

['95MSM]

The problem isn't depth, it is how wide the frame and magnet are just below the mounting surface. Without measuring, I'd say you could install a speaker with a depth of 7 or 8", if it was T shaped instead of V shaped.

So when your Kicker ridicules you, does it call you a wuss for driving a girlie-car? That must be embarassing in front of your buddies.

[dpdptp]

If my life depended on spelling/grammar I would be so dead.!
It would be embarrassing around my friends if they could out drive my girlie-car. 

[HELLIONMX5]

Are there any measurements of where to cut?

['95MSM]

For speaker placement? Once you have stripped it down to reveal the parcel shelf filler panel it will be very clear.

[HELLIONMX5]

For speaker placement? Once you have stripped it down to reveal the parcel shelf filler panel it will be very clear.

Gotcha.  Never stripped it down before.