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. |
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Interpretation of catalog
specifications |
Catalogs carry many figures as "specifications".
Let's try to grasp the meaning of these figures. |
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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. |
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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. |