Matthaeus Pipelare was a southern Netherlandish composer who flourished in the late fifteenth and early sixteenth centuries. I can tell you almost nothing about his life because the only thing about him that is known for certain is that he was active in Antwerp but left there in the spring of 1498 until about 1 May 1500 to take up the prestigious and well-paid post of Master of the Choristers for the Confraternity of Our Lady at the Cathedral of St. John in 's-Hertogenbosch. Not much of his work survives but that which does survive is widespread being found in no less than sixty sources located in libraries from Russia to Spain to Italy. It's of such superb quality and so engaging for performer and listener alike that it's easy to see why his contemporaries ranked him alongside Josquin, la Rue, Brumel, and Isaac.
The Missa ‘L'homme armé’ which you can hear below is in some ways quite typical of Flemish musical writing of the time in its complexity, sonority, and extensive use of lower voices including what we now call basso profundo. It's scored for Altus (high tenor), baritone, bass, and basso profundo and makes extensive use of its cantus firmus "L'homme Armé"which Pipelar makes use of throughout the Mass starting in the Kyrie where it appears in all the voices. It's a technically very demanding work clearly intended for performance by a top-class professional choir in which syncopation, faux-bourdon, canonical writing, imitation, homophony, and polyphony all make their appearance. Notwithstanding its musical variety Pipelare's Missa "L'homme Armé" has a tightly integrated feel and a considerable sense of forward motion I'm not surprised it wound up as part of the Sistine Chapel's repertoire. Enjoy :-)