At the first beat of the waltz... sits this flagship of the Dr. Beat metronome series, the DB-90, with tones and drum patterns that will help you keep time without feeling like a convict music. In the second beat of the waltz... comes the Rhythm Coach function with built-in microphone, a pitch generator to tune your instrument, an input for an instrument, a MIDI input and many other functions intended to sweeten the pill of musical exercise .