Extracting Angular code to separate JavaScript file
Simplifying
Namespacin'
Removing unused variable
Allowing notes to calculate their own frequency
Removing unnecessary method
Removing unused directive
Removing unnecessary fields from instrument config
Combining start/stop into one button
Re-arranging code
Replacing separate start/stop methods with toggle method
Making method private
Highlighting play button while synth is playing
Adding some basic responsiveness
Removing duplicate extra notes

Not sure what that was all about...