In the 1930’s, most of the wound strings produced for musical instruments used large diameter core wires in relationship to the wrap wire diameter primarily because it was easy to make a string this way. This was the beginning of a key breakthrough that D’Angelico and D’Addario explored.

For example, the most popular steel string of the time, the Black Diamond brand, would have a low E string composed of a core with a diameter of .022” and wrap wire of .017”. D’Angelico intuitively instructed D’Addario to try to make a .056 string with as small a core and as large a diameter wrap wire as possible. The challenge was to get that core as small as they could without the string prematurely breaking. D’Addario and D’Angelico would land upon an .018” core and a .020” diameter wrap wire which was a significant departure from standard string design. The resulting difference in tone and feel was astonishing. The thinner core enabled the string to vibrate more freely, providing a louder, deeper fundamental tone, without sacrificing the bright crisp overtones of a string properly wound on a hexagonally shaped core wire. And the bond the hex core provided insured that each string would be consistent and longer lasting than other competitive offerings. The specifications for the steel core acoustic and electric guitar strings of the future had just been redefined by D’Angelico and D’Addario!

John, Sr. always enjoyed approaching artists and trying to find out what they were looking for in a string. He had close relationships with some of the most influential players of the time, often making special string sets for them and always learning from each experience. They were also willing beta testers and tested many of the work-in-progress experiments he would work on. The most famous jazz virtuosos of the era knew Dad as a friend and a valued resource. These professionals provided continuous feedback to John, Sr. and he passed that intel on to D’Angelico and other luthiers throughout his career.