The larger positive organ was not intended to be moved. The biggest difference between medieval and modern organs is that the positive organ’s pipes were all of the same diameter; the pitch was defined by the length. This caused variation in tone quality across the range, making it ‘flutier’ as the pipes became shorter. Gradually organ-builders introduced ‘reed’ pipes, which concealed a vibrating reed and had an oboe-like sound. Some flue pipes were open tubes like a recorder, while others were stopped – they had their ends plugged, which dropped their pitch by an octave, widening the compass of the instrument.

All organs require air to be pumped through pipes; the journey of the air and the choice of the pipe (and thus the note), is made by playing a keyboard. Graded by size, the pipes of the positive organ sat inside a series of matching openings in a windchest, where the pressure built up as air was fed in from manually operated bellows. The entrance to each pipe from the windchest was concealed by a pallet, which was a kind of hinged doorway or valve. It could be deliberately opened or closed by a mechanism of rods which were directed by the keyboard or ‘manual’.

Styles & Forms | Medieval Era | Classical
Instruments | Hurdy-Gurdy, Organistrum, Sinfonye & Geigenwerk | Medieval Era | Classical