Donemus Webshop — Weerstra, Erwin Rommert

Erwin Rommert Weerstra studied piano, organ and composition at the Royal Conservatory of The Hague.

After completing his Master's degree in piano at the Royal Conservatory of The Hague, Erwin continued his studies under Andrzej Jasinski. His composition professors were Daan Manneke, Roderik de Man, and Yannis Kyriakides.

Erwin is a prizewinner in several international competitions, both as a performer and as a composer.

He has a strong interest in Peter Schat's Tone Clock. For him, Peter Schat's theory is a very musical way of using set theory: the same chromatic relations, heard as hours, fields, and steerings. Jenny McLeod later extended the theory. Erwin finds it a pity that the Tone Clock is still so little known and so misunderstood, and has made a suite of practical browser tools to make the Tone Clock more accessible and easier to understand and implement. These tools are an all-in-one calculator and visual aid that lets you build fields, place groups, and read complements, welds, and bindings. It would be great if these tools helped more people learn about the Tone Clock!

2025 - Absolute First Prize - Beethoven International Music Competition - “Il Vicolo Verde”
2025 - Second Prize - Concorso Internazionale di Composizione “Orazio Michi dell’Arpa” - “Cari Lumi Che Pietosi”
2026 - Third Prize - 2nd Franco Margola International Composition Competition - “Malochomorphose”