This is ultrasonic directive speaker kit. already assembled
You can experiment directive sound beam.
sound reach about 5m in silent room.
This kit is based on article of Elector magazine in March 2011.
Please read this article for details of kit.

• 48pcs 10mm,ultrasonic transducers
  
• PWM driver PCB

DC power jack is most popular 5.5mm(internal 2.1mm) type using laptop.
about 15V to 19V center pin is +(plus) if 24V, you need larger heat sink.
audio input 3.5mm phone jack.
read more details.

D class driver and transducers on one board

previous version of parametric speaker is here.

youtube demo

This kit produce strong pulse. radio, smartphone are effected by ECM noise.
There is distortion from principle of ultrasound.
I DO NOT ACCEPT RETURN FOR YOUR TECHNICAL PROBLEM.