WysiwyG is right about the bars of the 21 chord harp getting in the way. If you play it above the strings, like most players do nowadays the short treble strings are almost useless on a 21 chord 'harp. Many players modify their 'harps by moving the chord bar holders towards the base of the 'harp to give more picking room. I have a few 2 key 'harps that use ten bars and, because many of the strings have been doubled, they sound very rich and full. I have bought another 'harp which I intend to convert to a circle of fifths harp, probably in one key.