I am also a guitar player and not all that proficient at keyboards. I have found that using a keyboard helps with the timing however. Most if not all recent keyboards let you set the key. If playing in D for example set the keyboard up a couple of semitones this takes some of the complication out. Then record the part if you hit a bum note no worries lift it or drop it in the Editor. I find typing in notes and trying to adjust the timing far more difficult. If I am typing in notes I tend to use a score editor.

Midi keyboards are not expensive and extremely handy IMHO.

Tony

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