HINTS & TIPS FOR ”DO IT YOURSELF” ENCLOSURE BUILDERS
ABOUT THE RECOMMENDED
ENCLOSURES
The performance of these recommended enclosures will vay
from vehicle to vehicle. It is more difficult to get a tight and well
defined bass in a SEDAN vehicle because of the tightness
between trunk and interior of the vehicle. In this case a band-
pass box could be a better choise.
- All volumes are inside measures.
- Volumes occupied by speaker and ports have already been
added to the given enclosure volumes.
- Use conical bass ports for best result. (DLS BP-75 or BP-
110). If the ports are too long for the box you can use a bend.
Either cut the tube and glue it together in angle, or use factory
made tube bends. It´s easier to use the factory made ones. The
total length must be the same as for a straight tube. Make the
measure in the center of the tube.
The port opening inside the enclosure must not be closer to an
interior wall than 3” (75 mm), otherwise it will have negative
effects on the airflow.
- The enclosure must be very steady and completely air-tight.
Use 22 mm particle board or 19 mm MDF-board. The particle
board has a self resonant frequency of 14 Hz while the MDF
has a resonant frequency of approx. 400 Hz. It´s important to
do some type of bracing inside the enclosure to avoid vibrations.
Volume taken up by bracing should be added to the enclosure
volumes.
ENCLOSURE DAMPING
Most enclosures should be damped inside with syntetic
(acoustic) wool or damping mat (line). Attach the damping ma-
terial on the wall opposite from the speaker and port. A sealed
enclosure should be filled up to 70-100% with acoustic wool.
In a vented enclosure the speaker and port should be on the
same side, otherwise a fade-out of some frequencies can occour.
In most vehicles, except for SEDAN cars, the speaker and port
should be directed backwards for best result.
ENCLOSURE PLACING IN DIFFERENT
TYPES OF VEHICLES
In
small vehicles
like VW Golf, Peugeot 306 and similar the
bass box should be installed with both speaker and port directed
backwards. Alternatively booth speaker and port can be directed
upwards. This way of mounting is valid for all types of vehicles
where the trunk is incorporated with the inner compartment.
In
sedan vehicles
with the passenger compartment separated
from the trunk, the enclosure should be installed with booth
speaker and port directed towards the rear seat. Some cars
have an opening in the middle of the rear seat for loading skis
etc. You can install the enclosure behind this opening and direct
speaker or port through this opening. There must be some free
space in front of the port, (between the rear seat and the port
opening).
In
large vehicles
like station wagons the best sound is achieved
with the enclosure installed behind the rear seat with booth spea-
ker and port directed backwards. Alternatively you can install
the enclosure on one side of the luggage compartment.
CALCULATE YOUR ENCLOSURE
Box volumes:
When caculating the volume of an enclosure you simply multiply
the width (W) x heigth (H) x depth (D).
Use measures in dm and you will get the answer in liters.
A trapezoid box is calulated as below:
Vol=width (W) x heigth (H) x upper depth (UD) + lower depth (LD)
2
Be sure to measure the
inside dimensions.
W
H
UD
LD
VENTED ENCLOSURES FOR SP121 & SP15
VENTED ENCLOSURE
Subwoofer
Volume (liters/ft3)
Port
Damping
F3
Fb
SP12 single VC
vol: 41,9 / 1,48
4” x 35 cm/13,8”
Line inside
38,1 Hz
38,6 Hz
SP12 par. VC
vol: 36,9 / 1,30
3” x 25 cm/9,84”
Line inside
30 Hz
32 Hz
SP12 ser. VC
vol: 40,4 / 1,43
4” x 17 cm/6,7”
Line inside
50 Hz
50 Hz
SP15 single VC
vol: 60 / 2,12
2x4” x 35 cm/13,8”
Line inside
53 Hz
45,0 Hz
SP15 ser. VC
vol: 60,55 / 2,14
2x4” x 37 cm/14,5”
Line inside
44,7 Hz
44,0 Hz
F3
= approximative lower frequency for vented
boxes in Hz. Often called F-3 dB point = the point
where the power is 50% lower.
Fb
= Box resonant frequency
SEALED ENCLOSURE
SP15
: 54,5 liters, F3: 67,5 Hz
1,92 ft
3
(Use only one voice coil)
SEALED ENCLOSURE FOR SP15
SPL ENCLOSURES FOR SP12, 15, 15S, 18S
The enclosure examples can be used only for the reproduction
of normal music. If you want to use these subwoofers for SPL
competition, which they are designed for, the design of an
enclosure is more complicated.The vehicle must be modified
in many ways and the enclosure must be individually designed
for each vehicle type and also for the different competition
classes.
On our website www.dls.se you will find some helpful hints
(PDF document) regarding the build of SPL competition
vehicles.
RUNNING-IN PERIOD
Allow the speaker to play for at least 15-
20 hours. After this time the
performance is correct.
