extending the elektor piano

Although the compass of the Elektor piano which was published in September of this year (.Elektor No. 41) originally covered only five octaves, it was stated then that thanks to its modular design, it could be easily extended to span 6, 7 or even 8 octaves. Judging by the reaction from our readers, it does in fact appear that there is a considerable interest in an electronic piano with a full 8-octave compass, i.e. ninety-six keys and a fundamental frequency range extending from 17.4 to 4148 Hz. For this reason the following short article provides readers with details of the changes in component values and of the additions to the filter circuits which will be required to extend the compass of the Elektor piano.