ACOUSTIC GUITAR STRING KIT Acoustic guitar string sets EJ13 EJBronze 80/20 Series Custom Light (011 - 015 - 022 - 032 - 042 - 052). 80/20 Bronze, commonly known as brass, is the original acoustic string alloy selected by John D'Addario Sr. and John D'Angelico in the 1930s. 80/20 Bronze strings are very popular for Recording due to its crisp, deep, projected tone, and appealing to many traditionalists and vintage enthusiasts for its historical significance.