TANGULAR ARC The bars here are rectangular aluminum tubes played by percussion. In the lower-pitched bars the resonance of the air column within the tubes is tuned to agree with the bar pitch, providing a fuller tone quality. All the bars are tuned so that the side-stuck mode and the front-struck mode are an octave apart, and the bars are mounted at a slight angle to help bring out the effect. This is a simpler version of the approach used in my North-South/East-West Chimes described here and here. The instrument provides two complementary scales, which can be used separately or with borrowings from one to the other. For those familiar with tuning theory, the scales can be described as follows: One consists of harmonics 8 through 16, repeating at the octave. The other is subharmonics 8-16. For a full discussion of this scale pair and why it interests me, see here.

In the audio clip, I’m using the subharmonic scale in a mode based on subharmonic 12 as the tonal center.

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