Toyota
Sound Pressure Level Competition
Hatchback
Sound Pressure Level (S.P.L.) competition became a large event
for many car stereo enthusiasts. Plethora
of people desired vehicles that would create a hefty pressure level for
a small amount of equipment and install labor cost.
One of these driven customers contacted me for an install of four
subwoofers and two 750 watt amplifiers with requirements of 150db
results. I accepted this
challenge and provided a ported enclosure for the customer.
The install would be located into a small
Toyota
hatchback with many rust holes and a lack of being able to be a
completely sealed interior air space without a large amount of extra
labor. A single large
enclosure design was chosen for a higher possibility of S.P.L. creation
with a low amount of subs. The
stereo install was quoted for a two day custom install.
This time period would only allow for a labor and mind intensive
experience.
Fabrication of the enclosure initiated at the measurement of the
back seat and trunk space, which will provide the mounting position for
the enclosure. The choice of
using a sideways “U” with two subs mounted stacked perpendicular
from the floor of the car on each arm of the “U” facing towards the
inner portion of the automobile. This
configuration will allow for the reflection of pressure from the front
of the sub off the first rear of the enclosure towards the front of the
car. The subwoofers were
mounted only one deep to reduce pressure cancellation.
The actual rear of the enclosure was fabricated so that it could
be adjusted for accurate distance from the microphone.
Fiberglass and medium density fiberboard provided unsurpassed
versatility to the fabrication of the enclosure around the inner body
panels of the car.
Following the initial fabrication of the front portion of the
enclosure, the tuning needed to be complete.
The rear of the enclosure allowed for wall movement for frequency
tuning. 80 Hz range was
chosen due to the size of the vehicle and the resonance of fiberglass.
The distance was chosen to be around 72 inches, similar to other
personaly designed S.P.L. vehicles.
The
response of the stereo system surpassed the 150db.
The high pressure was acceptable to me and the customer.
The Installation was carpeted with black trunk liner.
Amplifier, batteries, capacitors, and connections inhabited the
rear of the car behind the rear portion of the enclosure.
The install was complete in two days.
Over a period of time the car started to deter ate due to
vibration. Sadly the
possible pressure results decreased.
If the owner sealed the interior of the vehicle, it may surpass
the 150 db mark with positive results.
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