Double Bee Garage

I am admittedly a self-proclaimed [hobbyist] audiophile.  I am not talking the full blown ICE audiophile spending thousands more than the worth of the car it is being installed in audiophile but I very much like a well-balanced, user tune-able, clean, and sometimes loud audio system.  We can all agree the original HK system is not that and understandably so as these cars are marketed for the “ultimate driving machine” not the “ultimate listening machine”

Fast forward to selling that car and filling the void with my Mcoupe there was much there left to be desired.  I had come across Bimmerforum’s member Moonvan’s subwoofer box build to stuff a pair of JL 6W3’s into the factory hump cover in place of the original HK box said I would do that one day.

Roughly 2300 days later, I did it.  In a combined complete overhaul of my Coupe’s interior to include retrofitting the extended leather parts, from Kelvin’s Z3 roady that met its unfortunately demise thanks to some mountain twisties and pile of wet leaves in the road, I decided now is the time to make this happen. 

I molded the shell, build the box, volume tested the enclosure and successfully installed a pair of 6W3 woofers under the factory covers in a very similar manner to Moonvan’s original, but with less MDF.

I also made a mold before I reinstalled my own box and have since produced 6 replicas.

With my recent acquisition of a 3D printer, I want to attempt to reduce my production time and “hand laid fiberglass” enclosure to be more repeatable.  I also have since found a friend’s acquaintance that is very savvy in vacuum bag molding that I plan to learn from.  But until then, these are hand made by me, with a lot of itching, sanding, and grafting together to make the ultimate stealth box for our Coupes.

I can still make one if you like. 

The Basics:
3M Fiberglass resin, multilayer 1.5oz fiberglass cloth, with a 1/2″ MDF face

The installation details:
This will require removal of the carpet/padding beneath the box
This will require removal of the rear most driver side OEM mount from the car
This will require trimming of the factory covers that are not seen when installed
This will require an aftermarket amplifier (300watt 2-ohm output capable)

The Idea:
Build a dual JL Audio 6W3v3-4 fiberglass box that fits under the Z3 Coupe factory panels using OEM mounting locations

What you’ll get:
1 drop-in, prewired (12ga), UNLOADED fiberglass box painted flat black.

What this means is the box will be shipped to you without any sort fabric/carpet/covering, with two holes/wires/spades/screws ready to install the JL subs and be mounted in your car with the factory hardware. As seen below

Pricing
$900 SHIPPED (Cont US)

$150 non-refundable deposit on the start of your box, the balance due after completion and before shipping.

Add-on options (subject to material availability):
Subwoofer grill badge $45 (available separately for $50 shipped Cont US, Custom prints available for extra)
Black carpet face $40
Black Suede face $60
Custom amp rack – Starting at $75- contact me
Rivnuts (& loaner tool)* – $10 ($30 tool deposit(refundable) +return tool shipping) to replace factory plastic expanding nuts on divider bulkhead (m5x0.8 bolts will be required, not provided)

Butyl mat & Felt tape* – $10 ~4sqft of mat. & 2″x 3′ felt tape used to ensure no rattling from the covers (buytl is the silver stuff, felt tape is mared in red arrows)

FAQs

Why Unloaded?
To save YOU money. Me buying the subs retail and installing them is just going to make shipping a bear and more risky. You can get the subs shipped to your door with FREE shipping through most online retails or from your favorite local ICE shop.

Why JL Audio 6W3’s?
Because I like JL as a brand, and I stole the idea from Moonvan’s build from years past so I knew it could be done.

Will you make a box to fix X/Y/Z sub?
No, I have no desire to ever go through the “prototype” phase again.

How big is the box?
It’s an odd shape so that’s hard to answer. The box is sized to JL Specs to meet the design internal space requirements and fit under the OEM plastics.

That seems expensive?
Fiberglassing sucks. These are going to have to be hand laid one at a time. Material and shipping isnt cheap either. JL sells dual stealth boxes in the $900-1300 range for comparison. You’re welcome to make your own, I’ll answer any questions you have.

How much are the subs?
I ordered mine through Crutchfield for $210/ea.

Photos: