# Car Audio Subwoofer-Custom Installation



## tulowd (Jan 24, 2019)

Hey All;

Since I have actually been getting a little dusty with MDF the last week or two, I thought I would share some of the wood portions of the car restoration project I've been immersed in.

Essentially, I am resto modding a convertible 1987 Mustang with a full race suspension, a 525hp carbureted small block and a pile of modifications, including a monster sound system.

It's a street car/cruiser that will also see the race track and drag strip, as well as the cars and coffee meets and some local car shows once completed.


I was involved in various positions within the car audio industry from the early 80s until the late 90s, basically the peak of this very popular car after market category. Since last summer, I have had a resurgence in interest and have bought up a pile of old equipment and performed a few decent installations in some friends cars and one tricked out Harley.

My car is losing the rear seat, which will be turned into a parcel/storage shelf with a pair of 15" Dr. Crankenstein subwoofers, and something for midbass in the side panels. Working with 30 year old plastic that was ****ty to begin with will be a separate adventure in fibreglassing or chemical bonding, please stay tuned. 

My plan here is to build something that follows the interior curves and body lines as well as looks like something that may have been installed at the factory as an option. Plain, with appropriate materials, shapes and access. The car has a 12 pt roll bar in it, so that is both a pain and a boon as you will see.

Decided to build an enclosure that bolts into the re-enforced areas of the chassis ( lots of extra metal has been welded into the car for chassis stiffness and suspension attachment point strengthening). Two main panels are the front and rear, from which all the other measurements and reference points will be taken. Lots of initial cardboard templates. Stripped one of the side panels all apart to get just the basic plastic frame in place. Then contour cut the bottom out, to allow the panel to come in and out, independent of the roll bar and the sub cabinet, once that is permanently installed. Also made up a set of hybrid bolt/studs that thread into the seatbelt anchor points and offer a stud for the panels to attach.

Will be Dynamatting and Dynalinering the areas under the panels, then continue the design for the bracing and dual panel baffles, as well as the trim and beauty panels. All told, this will likely have well over 100 hours in it by the time everything is finished, wired and leather/vinyl and carpet wrapped. The panels have been in and out of the car at least 100 times already, but it's getting there.


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## tulowd (Jan 24, 2019)

And the front panel construction; this is as far as I got. Hopefully get some more done over the weekend, after it stops pouring rain here.


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## kp91 (Sep 10, 2004)

Love to see someone else using cardboard as templates! It's amazing what you can mock up with cardboard, hot glue and duct tape


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## Stick486 (Jan 4, 2013)

nice detail work...
why not use a coupling nut, nutsert, E-Z Lok or a coil instead of welding two bolts together..
https://www.ezlok.com/threaded-inserts-for-metal


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## JOAT (Apr 9, 2010)

I like to use cardboard to tape together to give me an idea of what my project would look like finished, before I start using up wood. 

Nice work. But as soon as I saw it I was immediately reminded of the guys at stoplights with their sound cranked up so loud, even several cars away, and their windows up, that I can't hear my own radio.


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## tulowd (Jan 24, 2019)

Stick486 said:


> nice detail work...
> why not use a coupling nut, nutsert, E-Z Lok or a coil instead of welding two bolts together..
> https://www.ezlok.com/threaded-inserts-for-metal


Because the seat belt anchors are already threaded 7/16-20 and I have dozens of seat belt bolts and a mig welder. The other end is now 1/2-13 which is way more common, and I have all the appropriate nuts and washers etc. Also, metal insert are not very strong, we use them at work on light fixtures and they fail way too easily in my experience. Usually I weld Gr 8 bolts in to use as studs, or I cut Gr8 threaded rod to size, but these things are a goofy size.

This took less time to make than driving to the hardware store......plus I like using my welder whenever I can lol.

If you look closely at the upper bolts and some of the engine pictures, my fasteners of choice are polished ARP 12 pt stainless steel fasteners that exceed Gr 8 status. I believe there are a couple of hundred in the engine and throughout the whole car.

2019 ARP Catalog


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## tulowd (Jan 24, 2019)

Some progress in terms of design and rough in/mock up after spending the week in Austin and San Antonio. Made a mistake in the layout/measuring of the angle of the back board support, so had to cut a new angle (twice!) to get the baffle to sit just right. These boards have been in and out of the car at least 100x. Would be even less fun, if it wasn't a convertible.

Caught a masked culprit that resembled the Hamburgler in the garage after locking up for the night. Heard noises, then the door started banging and moving........then a little paw stuck out from between the frame and the door. Handsome young fella......and apparently not in too much of hurry to get outta there, lol. No damage, and hopefully he doesn't like Judas Priest or Black Sabbath which will be blaring from the audio system in the back from now on. 

Got to use my 30 year old B+D plunge router and a modified MilesCraft circle template to cut the two 14-5/8" dia holes into the 1" MDF. Quite the duststorm, even outside with the shop vac going with a hood. Motivation to connect the Dust collector and make an outdoor hose available asap lol.

The Dynamat and Dynaliner are starting to go in; as the 3 main boards take shape and become the correct size, the rest of the assembly and parts fitment begins to make itself apparent.

Originally was going to try to wrap the boards in material before assembly, but I'm rethinking that plan, along with making a second layer of trim panels that will wrap against the inner quarter panels and old seat back frame. Blind fastening is going to be the desired method. Stay tuned.

The centre spine/support on the speaker baffle and two outside cabinet ends (all yet to be built) will be glued and screwed to the baffle and bolted into the floor via some brackets (also yet to be built) and welded to the floor pan and suspension pickup points.

The OEM carpet is getting the factory backing removed, pressure washed and then laid on top of the fully Dynamatted floor and 1/2 thick Dynaliner, which will also be used throughout the rest of the rear seat floor and old seat frame as well as inside the speaker cabinet.


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## RainMan 2.0 (May 6, 2014)

It’s coning along Paul , looking good . Subwoofers abs car audio used to be my favourite subject . 
Unfortunately I got tinnitus from a visit to our local theatre . I have never subjected myself to that many dB before in my life . 
The tinnitus increases the worst when I go into an enclosed vehicle , so car audio is out .
I sure miss it though , as you bring back memories of the days when I was fabricating my own systems .
The best compliments I ever received were people telling me that it was factory , and there’s no way I built that lol .
I guess I’ll use my linear actuators for a computer desk or something.


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## tulowd (Jan 24, 2019)

RainMan 2.0 said:


> It’s coning along Paul , looking good . Subwoofers abs car audio used to be my favourite subject .
> Unfortunately I got tinnitus from a visit to our local theatre . I have never subjected myself to that many dB before in my life .
> The tinnitus increases the worst when I go into an enclosed vehicle , so car audio is out .
> I sure miss it though , as you bring back memories of the days when I was fabricating my own systems .
> ...


Thx and sorry to hear about your scenario.

If you used linear actuators, then you are ok in my books. I screwed around with pneumatic powered drawers and slides when everyone else was doing the electrics. Lots of fun and frustration getting this all to work smoothly and quietly.

What actuators do you have - presumably 12V 6" or longer stroke? 

Once I get into the trunk build I may end up motorizing some of the panels/reveals/storage compartments.

Bracket made up and welded into position. The Threaded portion of the 1/2" bolt will have a nut on the top and bottom, along with lockwashers to keep the baffle inert and supported in both directions. The outer enclosure ends will be attached in a similar manner.

And yes, the bolt was positioned thru the bracket, then welded onto a nut and large washer below to stiffen the mounting plate.....and because I didn't have the correct length bolt in hand, duh!! Looks bubble gummy but most of the mass is the nut and washer, so it's not entirely a Ray Charles weld up scenario. Only blew one hole thru the 18g floor pan too, so I'm getting better at this. Mount is way stronger than the floor now, so it should serve it's purpose. If it was all visible, I would grind and dress the welds, these are straight from the gun, cleaned up with wire brush before primered. Moving ahead.....slowly.


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## tulowd (Jan 24, 2019)

Been a while, had a few little work trips away to MN, MA and NH and also updated the Fox coupe setup I did last year; finally swapped out the little MTX amp for an Orion HCCA225 high current amp running 1 Ohm mono, making 400 watts rms into the 4 ten inch speakers. Sounds awesome and tight, one woofer needs reconing, as it rattles the voice coil or spider. Disconnected and still rocks.

Got both side panels templated and then built out of 1" MDF; also welded in support studs into the floor and made structural L brackets to pull them down into the floor. Everything got Dynamatted and then Dynalinered prior to the second to final mockup fitting.

Screwed up the initial vinyl upholstery job on the back panel, thankfully that turned out to be a blessing. Took 2 hours to remove 250 staples by hand, then had to sand, grind and fill the mess I left behind. Duh!!

Ended up buying a new Harbor Freight wide crown 22 g gage air stapler with super short staples and redesigned the entire upper panel and trim. Figured on using the bolster and material design of the Recaro seats that are going in the front would make sense - from a distance it will look like there is actually a back seat. Will all be covered in Alcantera and Napa leather, stitched to match.

Made a rear trim panel that will be mounted from behind using blind stainless ARP 12 pt bolts into the reverse installed threaded inserts.


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## tulowd (Jan 24, 2019)

So after final mockup, turns out the upper trim panel fits perfectly on each side.....but 3/8" too far apart! Had to cut it in half, take out 3/8" and then dowel it back together......my first ever such attempt. Harbor Freight to the rescue, using Woodcraft supplied longer dowels. Pretty happy with the results, one skim coat of two stage spot putty and the seam disappeared.

The rollbar downtubes run at an angle, so I had to play with the drill press and a 2" holesaw. Ended up starting the hole and then finishing free hand before cutting the lower trim pieces off. They will be fastened to a baffle trim panel I have yet to design; want to wait until everything else is put together to see how it all looks before proceeding.


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## tulowd (Jan 24, 2019)

And picked up several yards of foam, matching Ford carpet and real Alcantera (aka Ultra Suede) for the upholstery to begin. This is a very satisfying part of the project, not sending it out, but rather doing myself. Takes long and is hard on the fingers, but I am pleased with the results. The trim panel is getting stitched up in leather; that I cannot do myself.....yet.....some kind of sewing machine is in my future, after the car is on the road.

The upper panel is upholstered around the back top edge and down to just where the baffle will attach. Usually, these panels would all be fully upholstered, but because they need to interconnect structurally and airtight, this was a hybrid assembly and finishing process......aka a real PITA!!


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## tulowd (Jan 24, 2019)

The lower front panel received a dado style groove from my circular saw in order to allow stapling the bottom carpet and top Alcantera in one space, the transition is hidden behind the horizontal lower rollbar. 

Keep in mind, every layer of material represents app 1/8" of thickness when fully compressed. This meant having to cut 1/4" off the front of the angled baffle on both front and rear vertical faces, at the appropriate angles. Measure 10x, cut twice. Worked out and fit like a glove, I'm happy to report.

Then finished Dynamatting the inside of the enclosure, and finally permanently install the baffle; followed by upholstering it inside the vehicle. Hardest install and finishing project in my 40 yrs of car audio.


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## tulowd (Jan 24, 2019)

And the final part; over 2 hrs of careful stretching, stapling, cutting and tucking until it was all done. The gaps are perfect, the material is tight and the blind speaker plug receivers are invisible under the foam and Alcantera. They may be used for the final trim piece, yet to be designed and built.

Apologies about the post and picture rampage, but I thought it made sense to detail all these steps, since this is a very unusual project, even in the car audio world. About 90% completed; the last trim piece(s) and speaker install is only going to take a day or two. May decide to build a speaker flush trim / beauty panel; that will have to wait until the car is actually back together and driving.

Next step is to make up and install the two large L+R wiring harnesses, finish the insulation and start the carpet installation. Hoping that, along with the completed upper trim panel will be done by the end of this coming weekend, after I return from Cleveland. Took my son to the Syracuse Nationals this past weekend, simply breathtaking workmanship and ideas galore. Will do a separate post on that.


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## tulowd (Jan 24, 2019)

Weekend was productive, altho it was over 100*F/40*C here, so a bit sweaty lol. Sure glad I didn't have to cut or router any mdf.

Subwoofers now installed and wired, temporary grilles refinished and installed, rear trim panel back from upholstery shop installed. Wired it all up to my test bench 50 ft away and it rocked Dire Straits "Money For Nothing" in 2 Ohm mono from a little Fosgate Punch 45. That would be about 80 Watts rms per woofer, the final setup will be around 325 Watts rms per speaker using some Orion HCCA high current power.

Have to build two more small outer trim panels, and re-upholster the factory inner side panels, but that will have to wait. Rest of the floor pan, firewall and front kick panel areas are now 90% Dynamatted and Dynalinered. Also started making the 3 new wiring harnesses; once those are run the carpet is getting the backing removed, pressure washed and installed. Big progress, at least visually speaking - car doesn't look like a total wreck anymore lol.

:grin:


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## harrysin (Jan 15, 2007)

Such an installation will produce fuel economy because the air pressure from those woofers will assist the forward motion. The downside is that such a system will upset many motorists especially those sat next to it at intersections.


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## RainMan 2.0 (May 6, 2014)

Nice outcome , looking really good


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## tulowd (Jan 24, 2019)

Hey Everyone: Been swamped with non wood and non audio work and travel the last few months - completed some more wiring and prep on the car - actually fired it up about a month ago, so my electrical work and engine prep was all as it should be. Travelled every week in Aug and Oct, so zero got done. Got home from Atlanta last night to see we have received our first dusting of the white stuff. Did pickup another PC690 plunge router and a 10 year old made in Taiwan 14" King Bandsaw with Kreg fence, 6" riser and 6 blades last week. Time to finish winterizing everything and cranking up the heat; then clean up the garage and prep for winter projects. Grabbed another bunch of car audio equipment and traded off 4 of my Orion SX amps for some Focal component speakers as well as another pair of Orion HCCA250s. Should open a store lol. Some pics and videos coming up here and I'll start (or add to an existing) thread on the bandsaw.


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## andycraig (Mar 6, 2021)

You've really done great work. Appreciated!! 
I'm trying to add a little bump to the system. I was thinking about adding a 10-inch shallow mount subwoofer that way I can retain some storage in the cab. Not entirely sure what subwoofer to get or what amp to pair with it. I can build the box myself.


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## old55 (Aug 11, 2013)

Welcome to the forum @andycraig


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## andrewjordan (Mar 10, 2021)

Its amazing that you have use cardboard


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## old55 (Aug 11, 2013)

Welcome to the forum @andrewjordan


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## RainMan 2.0 (May 6, 2014)

andrewjordan said:


> Its amazing that you have use cardboard


I think the cardboard was used as a template . Then mdf is cut from the card template


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