Class diagram for electric guitar and bass

Hi I was recently asked this in an interview to represent a 6 string guitar and a 4 string bass in class structure. I am still new to software design and analysis so was not able to complete the answer. Moreover my lack of knowledge about the musical instrument played a big role in my failure. But I tried the same at home and below is what I could create after some online references.

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I have never seen a electric guitar except on google while I was working on this problem. So I tried to create the uml diagram as per the information I could find online. In-fact I didn’t even knew what a bass was before I worked on this problem.

I created the main Instrument class which would basically refer to guitar or bass or any similar instrument. For InstrumentSpec, I created another class that has guitar or bass common specs. Now since guitar specs would also include Pickups, Strings, Toggle Switch and Control Knobs, I moved them into separate classes.

The interviewer also asked me to design the class diagram in a way so that he could identify if note from one is equal to note from other based on fret positions and string played. So I added Frets class to include the information about position, distance, location and pressure applied and added a field stringName in instrument class to determine what string is being played in the instrument.

I am still new to software class diagrams and thus seeking help in understanding improvements in my class structure.

All comments are appreciated.