Gemma Coebergh Guus Janssen: Pruledium and Momba
Het ORGEL 98 (2002), nr. 6, 5-6 [summary]

Pruledium and Momba, a piece for organ and string orchestra, was published early this year. It was composed by Guus Janssen, who is not only known in the organ scene, but is also active as a jazz musician. To Janssen, the organ is not only a church instrument. Jan Raas agrees with him; Raas played the organ part of Janssen's piece at its premiere, the orchestra was the Nieuw Sinfonietta Amsterdam, which commissioned the work.
Janssen plays around with norms: he often uses the old-fashioned triad. In Pruledium and Momba, a sixth is often added; which appears to refer to Messiaen, or even Debussy and Fauré, to those who admire classical music; but to Erroll Garner to jazz-lovers. Furthermore, repeated notes are an important trait, as is the opening interval, a fourth.
Janssen called his piece Pruledium and Momba because it is not really either a Preludium or a Mambo.