Elenco Electronics AM/FM-108CK Assembly And Instruction Manual page 54

AM/FM-108T RADIO BAFFLE
NOTICE: Keep the box the kit came in. After you have completed the radio and it operates satisfactorily, you may want to install a baffle
to improve the sound.
The final step in the radio kit will be to assemble and attach a baffle to the speaker. You will need to remove the baffle located in the
bottom of the box. If it does not want to come out easily, use a knife to cut the holding tabs.
When a speaker is not enclosed, sound waves can travel in all directions. As a speaker moves outward, it creates positive pressure on
the air in front of it and negative pressure on the rear. At low frequencies, out of phase front and rear waves mix causing partial or total
cancellation of the sound wave. The end result is a speaker less efficient and distorted.
To eliminate the low frequency cancellation, a speaker is placed inside an enclosure. Now the front sound waves are prevented from
traveling to the back. The speaker will now compress and decompress air inside, increasing its resonant frequency and Q relative to the
free air values. This type of effectively air-tight box is called an Acoustic Suspension.
Screw
M1.8 x 7.5mm
Nut M1.8
Baffle
1. Start at one edge and carefully remove the baffle from
the bottom of the kit box.
3. Bend the top side upward as shown.
6.
M1.8 Nut
Back View
Insert the baffle as shown in Step 6 . Secure into place with the M1.8 x 7.5mm" screw and a M1.8 nut as shown in Step 6. Secure the
side of the baffle with a piece of tape as shown in Step 7.
Optional: To make an air tight seal, place a bead of seal between the PC board and the baffle.
AM/FM-108T Kit Carton
4. Bend the two sides upward. Attach the
three sides using scotch tape or glue
(Elmer's, Duco Cement, or other).
M1.8 x 7.5mm Screw
Cut Off
2. Cut off two pieces of the flap as shown
and bend the four flaps upward as
shown.
7.
Tape
-53-
brown
side
5. Bend the bottom side upward and
attach it to the other sides using scotch
tape or glue. Bend one mounting flap
down as shown in the figure.
Back View