LOOSE STRING FOR VIOLIN Prelude J811, Mi (E), carbon steel, 4/4 medium tension. Prelude strings are strings made with a solid steel core, unaffected by changes in temperature or humidity, and offer incredible bow response. Prelude strings give us the warmest sound available on solid steel core strings at the best price. Prelude is the teachers' preferred choice for their student's strings due to its unique blend of warm tone, economy, and durability.