Introduction: T-Rex PA Speaker
Second Prize in the
DIY Audio and Music Contest
T-Rex PA speaker is a project I made in January 2015.
It is by far the biggest custom speaker I made. the whole piece measure 86" tall X 105" long X 68" wide.
I was standing with it in the second image ( i am 5'9) to show the scale of it.
the main driver is a 15" PRV 1000W PA woofer. with two 3 1/2" tweeters.
Step 1: Design Phase
The concept for this dinosaur is to make a meaner version of the one from the movie Toy Story.
The woofer will be mounted in the mouth and two tweeters on both side will be mounted on the connecting tissues near the jaw.
the model is made with 3ds Max.
because the scale of this sculpture. I had to separate it into several pieces. I did around the knees, the thighs, the tail, and neck.
However, look back at it I would have separate it into more parts. like the toes, the front arms. and maybe make the head to 2 pieces. the smaller the parts the easier later on for me to rotational fill it will resin.
I included the STL file of the dinosaur because I would also want to try print a much smaller version of it with 3d printer. perhaps a desktop sculpture with a 3inch full range speaker. I will update on the process later on in a different post.
The upper teeth is made as a whole piece to exaggerate the features of T-rex. In fact, the real Tyrannosaurus's tooth could grow to 9 inches tall. The lower teeth is designed smaller and they are one by one separated.
Step 2: Construction Phase
I separate the model into manageable parts.
Tail, thighs , Feet, head, torso , upper teeth, lower teeth ( 9 pieces)
I convert them to patterns in Pepakura. then comes the time consuming tedious process. Cut , score, glue. the wooden plate is cut with jigsaw to support the whole structure. wood beam is insert to ensure there is no wrap.
I brushed on thin layers of epoxy resin with calcium carbonate and chopped strains fiber on the inside. then rotational poured more urethane resin inside to reinforce.
for the head part to reduce the weight . i filled the inside with a good amount of urethane foam.
Step 3: Sand, Prime, Paint
Once the polymer is cured and the desire strength is achieved. I measure the strength by standing on the parts. each parts should be able to hold my weight with ease (160 lb)
lightly sand the seams on the paper to make sure the surface is unified without obvious seam lines on where patterns are glued together. then Prime it with 2K automotive primer. I have tried with house paint primer , latex primer, oil base primer and other medium. I found that automotive primer really soak into the paper and bond it to a hard surface that is much harder than plastic it also resist moderate scratch.
The primer I use is EVERCOAT super build 4:1.
lastly, I painted with satin racing red top coat.
Step 4: Assembly
The size of the dinosaur made it impossible to pre assemble. I had to assemble it on site.
each piece is tightened with 3" x 1/4 Carriage bolts with wing nuts. assembly goes Torso -> tail -> left knee -> left foot -> right knee - > right foot - > lift it stand -> wire the crossover -> mount the head -> mount the speakiers -> hot glue the teeth.
Step 5: Completion
Since the completion, this T-rex speaker has been displayed at various places in San Francisco. It is very loud if hooked up to a powerful amp. I have it hooked up to a band and DJ for events and they were very satisfied with the sound. though, what I made may not reproduce the sound as accurate as possible. it does draw a lot attention no matter what it was playing. I still think of it as a sculpture with functions after all.
Practice and Enjoy
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