One of my students, Candido, recently asked about playing rootless voicings in the LH, in the context of playing with a bass player. This is a great question, and one of the most important skills to develop for playing jazz piano.
There are 2 aspects to this, as it relates to playing with a bass player:
1. You generally want to keep your left hand in the range from around middle C to an octave or so lower. If you play any lower than that on the the keyboard, you'll be getting into the bass player's range and the music will start to sound 'muddy.' So learn your chord inversions so you don't have to play so low. My Intro to Jazz series starts you off in this direction.
2. Rootless voicing: Since the bass player will generally cover the chord roots within their bass lines, you can leave out the roots, playing the 9th of each chord instead. This gives a very colorful sound that is characteristic of jazz. You can also include the 13th, and sometimes the 11th. My Intro to Jazz series starts off with these characteristic voicings.
Important note: If you're just beginning to learn jazz, I strongly suggest that you play basic 7th chords for a while, until they become effortless. Then you can start working in 9ths, 13th, etc., while leaving out the roots. Or learn both styles at the same time. If you only learn the more advanced voicings from the beginning, you'll be too locked into using them in every situation. A lot of jazz-influenced music uses basic 7th chords (such as jazzy pop music) so you'll want to have a solid foundation with those chords. This will also help you to be flexible in improvising voicings as you play, so you're not totally reliant on only a few pre-learned voicings.
Here's a video in which I demonstrate some differences in playing with a bass player vs. playing solo. Let me know if you have any questions.
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