Date:         Tue, 11 Aug 1998 18:20:54 EDT
Reply-To:     FrankGRUN@AOL.COM
Sender:       Vanagon Mailing List <Vanagon@vanagon.com>
From:         Frank Grunthaner <FrankGRUN@AOL.COM>
Subject:      Subwoofer/Stereo Details in '82 Westfalia
Comments: To: Vanagon@VANAGON.COM
Content-type: text/plain; charset=ISO-8859-1

My Westfalia restoration/reengineering excersize is nearly complete with the
successful
installation of the subwoofer for the stereo system. I contemplated many
possible locations
including a fourth order bandpass install in the unused part of the Westfalia
storage cabinet
next to the water storage tank. That didn’t work because of wall rigidity
problems. The
final solution has worked very well, so I thought I would post the details to
the list.

The final solution: I mounted the subwoofer in a custom cabinet I fabricated
beneath the
driver’s side swivel seat. Got the idea some time ago from someone’s question
on the list.
To begin, I cut a 9 inch diameter hole through the tiedown plate and through
the swivel
mounting steel. Trusty sabre saw and five blades. I then bent up the rearward
facing lip on
the small storage area, so that it was parallel to the bottom of the well. I
rerouted the relay
(refrigerator) and the seat belt switch lines to lie in grooves I cut in the
top of the speaker
box woth a router. I then cut (carefully) the front thin sheet metal that
closes off the
underside of the seat base. Later, I elastically glued the carpet to the front
wood box
surface, so the final installation is indistinguishable from stock.

The box was fabricated out of 0.75 inch medium density particle board (MDPB).
I first
built a box into the storage well. For the bottom, I filled the well with a
single piece of
MDPB. For the rearward side, I put a single piece with enough clearance to
slide in the top
cover and screw it in place. The front of the well uses a piece of MDPB which
comes to the
floor level of the under seat well. The sides use pieces which come o.75
inches above the
seat well base. A larger sheet then forms the base of the under seat well part
of the
enclosure, going from the front edge to the front-of-well piece noted above.
Two long and
thin MDPB parts form the long cabinet side walls, going from the front to the
rear MDPB
piece. A front end wall is fabricated of the same thickness. These two boxes
are assembled
(screw and wood glue) separately and then inserted into the cavities. I
predrilled the upper
and lower assemblies so that they could be caulked and screwed together in the
well (but
could be disassembled at a later date if necessary). The upper box screwed to
the front
storage well board, the two sides, and laterally into the rear part. I also
clearanced the lower
seat well board with a router (0.375 inches deep) in the size of the speaker
magnet in order
to fit the proper speaker height and depth. At this stage, I caulked all
interior seams, routed
the speaker wires through the cabinet, and filled the assembly with fiberfill.

 A full top cover is made from a single sheet and slid into place just
clearing the upper side
of the metal seat well. This top with aligned hole for the speaker is then
screwed in place
with a series of countersunk number 12 screws. The rear was easy, but the
sides and front
required a set of guide access holes, which I drilled through the sheet metal
of the seat
base. I then made a spacing collar of two disks of 0.75 inch thick MDPB. This
spacing
collar was caulked and screwed into the top cover sheet. The 8 inch Pioneer
subwoofer
was then screwed in place and a grill safety guard added. I modified the
swivel locking
spring with a leaf spring mounted to the top of the box. Finally, I bonded the
front carpet
back in place.

Some more details: I mounted the subwoofer amplifier (300 watts bridged) under
the
passenger seat well, saving the storage well area. A plastic guard frame
protects the amp
wiring from the tools, etc in the passenger storage well. To mount the amp, I
again cut
access holes in the seat well base metal, then brought up stainless steel
socket cap screws
from the tire area. Plenty of air ventilation.

The Stereo consists of a Sony cassette deck and changer controller (ESP line)
without
amplifier section, but with four low level outputs. I use a four channel
amplifier (300 watts
RMS) to drive four 5.25 inch Boston Acoustics coaxial speakers. One in each
door in
more-or-less the stock speaker location, and two in the rear Westfalia
cabinet. For the rear,
I cut and modified the stock Blaupunkt grills the mount flush internally, then
added the
BA’s with appropriate cone clearancing. The four channel primary amp is
mounted on the
internal shelf under the dash, behind the glove box. Same area holds the
crossovers and
subwoofer logic. A 10 disk Sony CD changer is mounted vertically in the
Westfalia
stove/storage cabinet against the back wall touching the drivers seat back.
Some cabinetry
mods, but nothing serious, except for a rubber water guard. Also use power
antenna.

Performance: Good clean sound more than adequate for classical and oldies.
Subwoofer
cutoff starts around 35 Hz. Upper bandpass starts to cutoff around 175 HZ.
Similar low
frequency blockers for the Bostons.

Sorry for the length. Hope this helps someone.

Frank Grunthaner