I used a Pyramid PB-251 car stereo Amplifier for
my sound system. One channel for the sound effects and one channel
for the robot's voice. A CD player or laptop computer are the audio
source. It is mounted to the back inside of my torso with four flat-head
machine screws attached with epoxy putty.
Because my robot is a costume, I really thought long and hard about
what type of speakers to use and where to mount them. My solution
required custom making some special brackets out of 1/16"
The 6x9 speaker is for the robot's voice, and the two 4" speakers
from Radio Shack are for the robot's background clicking sound effects.
The 4" speakers are mounted to the two side vent openings and
the 6x9 voice speaker is mounted behind the neon using screws attached
to the arm sockets.
By mounting the lazy susan with the side that has 8 screws attached
to the torso (the other side has 6 screws), I was able to straddle
each vent opening with two bolts. This paid many dividends and provided
the lower mounting bolts for the two side speaker brackets. One
more screw epoxy puttied above the vent openings provides the third
point of attachment. The vents, aluminum mesh, and black cloth,
are simply sandwiched in between the bracket and the torso, very
exactly launch plus eight hours..." It sounds awesome!
Here are templates
for the brackets.