Types of drivers |
Drivers
can be classified into several types depending on the configuration of their
diaphragms. Drivers have progressed with the strength intrinsic to each type
best suited for respective user's purposes, rather than any particular types
of drivers having been made do for all purposes. Let's spend some time going
over typical types of drivers. |
|
|
Interpretation of catalog specifications |
Catalogs
carry many figures as "specifications". Let's try to grasp the
meaning of these figures. |
|
Enclosures |
Drivers produce sound by their diaphragms moving
back and forth to create compressional waves. The sound radiated from the
front and back of diaphragms is identical except that their phases are
opposite. What will happen if drivers are driven unbaffled, or mounted to
nothing? As illustrated, sounds radiated from the front and back of
diaphragms cancel out each other, silencing bass sound. The purpose of a
baffle is to isolate the front sound from the back sound, which allows for
bass sound to be audible. There are many types of enclosures available where
a variety of baffles are incorporated. Next, we will discuss representative
enclosures. |
|
|
Enclosure materials |
Among the
many types of materials available even for general consumers, plywood will be
the best choice in terms of price, processability and acoustic
characteristics. Typical easy-to-obtain plywood types are presented below
while many more are available. |
(1) LAUAN
PLYWOOD |
This
plywood is one of the most widely available plywood. Plywood of lauan, which
is a tropical wood, is commercially available in various thicknesses. Its
appropriate level of rigidity makes this material one of acoustically
excellent candidates. Only solid plywood should be chosen for enclosure
production purposes. |
(2)
LINDEN PLYWOOD |
Linden
plywood is generally lauan plywood laminated with a linden veneer. With a
surface smoother than that of lauan, and with very acceptable appearance,
this type of plywood is a good choice for aesthetic acoustic applications.
Plywood made only of linden is too soft for acoustic applications. |
(3)
OREGON PINE PLYWOOD |
This soft
plywood made from North American trees is characterized by reproduction
capability of high quality sound. No materials other than this may be
appropriate for enclosures where advantages of enclosure vibration is
positively intended to be taken. |
(4)
LUMBER CORE MATERIALS |
This
material is composed of glued-up square-cut wood, and used as the base
material, with a surface material sandwiching the base material. Often
laminated with linden material, this plywood is rather soft and,
occasionally, has a hollow structure. This structure makes these materials
acoustically unsuitable. If its use is still chosen, candidate materials
should be closely inspected whether to have a suitably high density
structure. |
(5) PARTICLEBOARD |
This product is made of glued and pressed wood chips
to form sheets. Bonded chips using adhesive are extremely hard and heavy. The
use of large sized chips makes these boards unfit for screwing or nailing. Also,
an attempt to glue these boards together will result in difficulties. In this
respect, it is not very adequate for the general public to process, compared
to most other materials. |
(6) MDF
(Medium density fiberboard) |
Like
particleboard, these products are also glued and compressed under heat. What
makes this material differ from particleboard is that this MDF is made from
very fine wood powder. This construction permits use of wood screws for ease
of processing. |
(7)
LAMINATED WOOD BOARD |
These are
boards made up of glued square-cut pieces of wood. Nowadays, use of many
types of choice woods is possible, and subsequently, excellent sound, thanks
to the availability of such choice natural woods, can be enjoyed. However,
the physical property inherent in such natural woods, such as its likelihood
to warp, remains present even after they have been made to form enclosure
components, resulting in occasional distortion or cracks in enclosures. |
Assembly of enclosures |
No more
than mere cutting materials to predetermined dimensions is necessary before
assembly of enclosures. However, bonding options are abundant. The most often used bonding means is the use of the
‘plain joint’ method. In addition to means using ‘tenons or grooves’ prepared
prior to assembly work, this ‘plain joint’ is another very effective method.
For assembly, wood work adhesive is used. Unlike bookshelves or chairs where
nails or wood screws are a main bonding means, wood work adhesive is the key
component in assembling enclosures. Wood work adhesive is an effective means
for maintaining tight seals between bonded surfaces. Application of a more
than sufficient amount of adhesive, followed by immediate wiping of extra
adhesive, squeezed out from member meeting surfaces, will permit neat and
tidy finish. The temporary use of nails, wood screws or sash clamps for
glued portions before the adhesive sets will ensure formation of strong and
solid bonding. Should the structure provide removability of the back board,
or some similar ideas are incorporated, used of packing (e.g. gap filing
tape) is highly recommended. |