Directional Speaker Parametric Speaker

I bought this for 12,000 yen on an auction, but I found it difficult to adjust myself and couldn't achieve the results I expected, so I'm selling it. I think this is for those who are knowledgeable about electronics. Tested with a 15V adapter and MP3 player. The following is the description from the auction:

This is a speaker that uses ultrasonic waves, allowing you to enjoy a very sharp directivity.
The sound quality is about that of a pocket radio, but it's quite good for a parametric speaker.
It uses 48 40kHz transducers.
It has higher output than conventional parametric speakers due to a special driver circuit.
It reaches about 10m to 20m in a quiet room.
We recommend using a power supply of around 19V for extended use. You can use up to 24V, but the heatsink will get hot, so please replace it with a larger one.

It will be sent assembled and with basic adjustments. The specifications of the circuit board may change.

What's included in the completed kit:
Ultrasonic speaker unit and driver board shown in the image
What you will need:
A DC power supply of about 15V-19V and 2A. The DC plug is a standard 5.5mm with a positive center pin.
Laptop DC adapters can be used.
An audio source with a 3.5mm audio jack input that can produce enough sound to drive the speaker, such as the speaker output of a PC or laptop.
Outputs from smartphones like iPhones are too weak to be used.