Ultrasonics are defined as anything above 20,000 Hz. Most tweeters cannot reproduce ultrasonic frequencies because their moving mass and resulting high inertial resistance prevent significant response to a signal above 20 KHz. A few designs can do it, some esoteric and expensive and some cheap and ubiquitous. Plasma tweeters are massless but require high voltage and gas cooling. Some planar and ribbon tweeters can go up to 30, even 40 Khz but they're pricey. Piezoceramic tweeters fit the bill for this project due to low price, high sensitivity and ready availability.
Building a CTS High-power Ultrasonic Array Speaker
Use a saber saw to cut two side-by-side rectangles to fit the inside dimensions of the tweeters' mounting flanges.
Sink the tweeters into their rectangles. Use the cordless screwdriver to sink screws into the plywood through the tweeter mounting holes.
Drill holes in a corner of the plywood to fit binding post shafts, and securely mount the binding posts with the wire loops on the same side as the tweeter backs.
Cut two lengths of speaker wire to reach between tweeter terminals and binding posts. Split the ends, strip 1/2-inch of insulation off the ends.
Insert copper or positive wire sides through the tweeter positive terminals and wind them around for good contact. Repeat the action with the tinned or negative wire sides and the tweeter negative terminals. At the binding post end, twist both copper wires together, and insert through the red-marked post tab. Repeat with both tinned wire ends and the black-marked post tab.
Solder all connections.
Building a Pyramid High-power Ultrasonic Array Speaker
Perform Steps 1 through 3 of Section 1, but instead cut four side-by-side rectangles.
Cut four lengths of speaker wire to reach between tweeter terminals and binding posts. Split the ends, strip 1/2-inch of insulation off the ends.
Insert copper or positive wire sides through the tweeter positive terminals and wind them around for good contact. Repeat the action with the tinned or negative wire sides and the tweeter negative terminals. At the binding post end, twist both copper wires of two tweeters together. Repeat with their tinned wires. Repeat both actions with the second pair of tweeters.
Twist the positive pair of wires for the first pair of tweeters together with the negative pair of wires of the second pair of tweeters. Solder this connection together and insulate with tape. Attach the remaining negative, tinned wires to the black binding post tab and solder. Attach the remaining positive, copper wires to the red binding post tab and solder.
Things You'll Need
4 Pyramid TW125 piezo horn tweeters or:
2 CTS KSN-1141 piezo horn tweeters
8-inch-by-15-inch piece of plywood
16 pan-head sheet metal scews
Cordless drill and bit assortment
2 speaker binding posts
To solder, heat up the iron until it melts solder. Lay the tip of the iron and the solder on the connection and let solder flow into the connection. Remove iron and solder.