Zyex by D'Addario Zyex Composite Synthetic Core Violin Strings produce an extremely warm, rich sound. Zyex uses a new generation of synthetic material, creating strings that are extremely stable under drastic climatic conditions. Zyex strings settle in on the instrument very fast, within a matter of hours. Zyex has a warmer sound than most other synthetic core strings and they have excellent projection making them exceptional for soloistic use as well as symphonic. The E-string is plain steel and the A, D,& G strings are composite synthetic core with the windings listed below.