DIY: Mini Piezo Tweeter
For this construction I found some 5/8 inch thick Particle Board that I had left over from other projects. You can adapt this design to use material that is a different thickness or type. The goal was to keep it very simple. Dimensions on the drawing is given in Inches, however metric sizes for the same design are given below. I don't know the thicknesses of material available outside the U.S.A., so you may need to adapt a few dimensions to accommodate what you have.
Metric Dimensions are:
|A = 6 cm||B = 4 cm||C = 9 cm||D = 14.5 cm||E = 1.5 cm|
|F = 18 cm||G = 21 cm||H = 2.5 cm||J = 1.75 cm||Holes in Front / Rear panels centered at 4.5 cm|
If using thicker or thinner material, you will adapt the dimensions listed in E and G to compensate.
Construction is simple. If you do not plan to router the edges (ie. leave the cut edges square), you can use small finishing nails and glue. I routered the outside edges on mine after assembly - I used 1/4 inch wooden dowels to attach the sides to the top (using finishing nails and glue to hold the front and back panels to the sides and top). The glue used is common white glue (Elmers) or yellow carpenters wood glue. Please pre-drill all the holes where you plan to use nails - this will prevent the particle board from splitting. I used a drill bit that was approximately 1/2 the diameter of the nails (1/16 inch - approx 1.5 mm). Make sure that you don't allow the nails to enter any opening in the front or back panels. I used the same small drill bit to make the holes for the tweeters and aluminum jack plate.
Note: Router blades cut wood and particle board just fine,
but they cannot cut nails - if you plan to router the edges. you have 2 assembly options:
The Front and Back panels are not flush with the outside edges - they are offset (indented) 5/8 inch (1.5 cm) - the width of the material used to make the box. Doing this protects the Piezo's and the connector when these are in transit.
Once assembled, dry fit the Piezo's and line them up - marking the holes where you will put the screws to hold the Piezo's in with. You must pre-drill particle board - it will split when you put in screws if you don't. I used small sheet metal screws.
I cut a 2 1/2 inch by 3 inch (62 mm by 75 mm) aluminum plate for the rear panel and drilled a 5/16 inch (10 mm) diameter hole in the center for the 1/4 inch phone jack. I used 2 other sheet metal screws to fasten this plate on with.
Once you are finished with the cabinet, its time to get some wood filler and fill in any holes that you have created. Wait a day to allow everything to set, then sand the surfaces. Get out a can of flat or gloss black spray paint (you can use another kind of finish if you want), and give it a good coat. Wait an hour, and give it a second coat. I hung mine on a wire when I painted it so that I could get all surfaces evenly. Wait 6 hours for the paint to set, then wire all components using the following Schematic.
I used small screw on rubber feet on each corner on the bottom surface. You will need a non-slip surface here, otherwise the tweeters will be vibrated off the top of any speaker cabinet that you place these on. Stick on rubber feet fall off too easily to be of any use in this project. As you can see by the 3 photos at the top of this Web Page, this cabinet was regularly touched up with spray paint - it was dropped and scratched up frequently over a period of 10 years of at least once a week giging. They don't weigh much and can take quite a bit of abuse.
Placement of these tweeters should be at, or above ear level of your audience. High frequency signals are highly directional - you need to specifically aim them at your listeners.
The piezo tweeter drivers are available from Radio Shack (in the U.S.A.) for around $5.00 US each. They are also stocked by Parts Express. You could easily upgrade these to different piezo tweeter drivers, just make sure that you alter any dimensions that might be needed to allow the different tweeter drivers to fit properly.
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