I’ve posted a bit before on practicing with drones. I recently came across this online tuning fork that can be used to set up drones in your practice. There are some features you can customize with it, including changing the tone from a pure sine wave to a sawtooth wave. I’ve found electronically generated tones like those are quite challenging to tune to, which is what I’m looking for when practicing for intonation. Something about the organic sounds of acoustic instruments makes them more forgiving, so I like the added challenge of playing perfectly in tune with the sine wave. Try setting up the root of a scale and playing your scales very slowly over the drone, making sure to lock into each interval as perfectly as possible. It really helps sharpen your ears for intonation.
