Soul Singer: The Black Onyx Keyboard

Relax, I'm going to. My father has been willing to show it to you after your outstanding performance at the comp.
Alright, man, a deal's a deal. You need to let me see the artifact.
Your father is the only person in Cadence I actually care about.
It plays like a dream, every chord produces 4 overtones, creating amazing soundwaves which can never be replicated.
Voila. The Black Onyx Keyboard, our prized artifact of music.
Seems pretty regular to me.
Eddie was just showing me your keyboard.
Howdy, Mr. Lennon.
The Node?
Oh hey father.
Hello boys.
It's a fine treasure, the artifacts of music.
You played well at your performance, Jack. Maybe you could even win the Node.
♫♫♬♪♩
♫♫♪♬♪
I've told you all I know. The rest is up to you to discover the truth behind the instruments.
That harmony was abnormal. How can that be a real instrument?
Where can I find them?
Mr. Lennon, you have to tell me more about the artifacts.
They're scattered, I can't tell you where they all are.
Enter competitions, fly across continents, it will take you quite some time.
You'll have to seek out the best musicians in the industry.
These things can make me the world's greatest musician. I have to have them.
How can I find them?
I'm willing to do it.
And?