Improvising over a Drone or Pedal has been something I’ve always enjoyed. Not only is it relaxing and simple, it really helps me hear scales, modes and melodies. When a single note instrument is your main axe, you need a little “crutch” to help you hear harmonic context. Of course piano is great for this, but sometimes you want to work on your instrument and not have to put on an Aebersold… ;(
At Berklee, in the 80’s, I would balance a cassette tape with my wallet on it to hold down a string pad on my battery powered Casio so I could practice over a drone. Now, my friend Aaron Shragge (who plays trumpet, shakuhachi, and sings), introduced me to this electronic tambura which I’ve been using almost every day for the last few years. Here I’ve posted similar sounding mp3s of the tambura drones for your use. There are an infinite number of things you can practice over these drones. I enjoy playing a odd mode, say the 3rd mode of harmonic minor or harmonic major and just improvising with that for a few hours. Another great exercise is to sing 3 notes and play those notes on your instrument. There’s also a link to an online metronome which works nicely with a drone.