Most
speaker boxes are
either fiberglass mat, or MDF construction. MDF while easy to
work
with
and achieve good results, lacks the custom touch. Fiberglass
allows you more freedom to do what you want. In this guide we
are
are building a simple box to show the process of working with speaker
rings and glass mat. Many of the same steps apply
for a
built in sub woofer box.
Start by
cutting out a
MDF base for your new enclosure. If you are building a built
in
box, this does not apply to you. Once you have your base, you
need
to figure out how you want to aim your speaker. How you aim
them
depends on the type of speaker and personal preference. Once
you
know how you want to aim the speaker you can start cutting and gluing
dowels to hold the speaker rings in the correct orientation.
These dowels only need to be strong enough to hold the rings
until
your first resin application dries. Make your enclosure the
correct size to meet the volume needs provided by the speaker
manufacturer.
Next
using hot glue or
stables wrap your form in either fleece or cotton. While
fleece
is the preferred fabric, I like to use cotton. Cotton will
soak up
less resin which makes a stronger lighter box.
With the
fabric
stretched tight you can apply the first layer of resin. In
this
step you do not use glass mat. You are just trying to get the
fabric
to retain a shape you can work with. For resin, I recommend a
cheap poly based resin. There is no need for more exotic
epoxy
resins as the resin will not see high stresses or UV. In any
case, you should follow the resin manufactures instructions for mixing
and working in only a well ventilated area. If you have
experience with fiberglass you can add up to 50% more hardner to speed
cure times. Any more than 50% compromises strength and
creates too much heat.
Now that
you have a
rigid form you can
begin building your mat layers. I suggest the heavy weight
mat
used by marinas for boat hulls. The heavy weight mat is both
inexpensive and strong. Mix enough resin to lay down 3-4
pieces of
mat
that are 12"x12". You can cut down a large paint brush to
apply
resin and stab out air pocket. Another method is to use a
fiberglass roller. No matter what method you use keep you
tools
in paint thinner between coats to prevent them from becoming un-usable.
Keep applying mat and resin until the enclosure is complete
and
sturdy. A good gauge of when the box is strong enough is when
it
can support your full weight.
Once the
subwoofer box is strong enough to support your weight, completely sand
it with 80grit sand paper to provide a good base for the auto-body
filler you will apply.
The key
to applying auto-body filler, is use thin coats and more coats
than you think you need. You will need to sand between coats
to prevent delamination. Whenever sanding use a quality dust
mask.
Keep
applying and sanding off the filler until all major holes and dimples
are filled. Now is the time to install any speaker
terminals or brackets you need to complete your install. I
also take
this time to remove any dowels that have become loose. For
any I canno remove, I simply mud them in place to prevent them
from coming loose later.
If you
plan to carpet your enclosure you can stop at this point. If
you are going to paint it you need to apply a glaze coat to fill any
pin holes and minor dimples left. After the finish is defect
free sand from 120 to 600 grit sandpaper in preparation for primer and
paint. From here you have a wide variety of choices from
lacquer paint to Rhino-Liner.
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