In "A Life on the Road" I believe he mentioned he was using Augustines but carried additional sets with him due to his frustration with G string manufacturing tolerances/issues. This was in the early eighties.
2017 Benito Huipe "Bouchet" Spruce 655mm
2015 Francisco Navarro Concert Cedar 630mm
1976 Masaru Matano 600 Cedar 658mm
1972 Yamaha GC-6D Ezo Spruce 662mm
Word on the street is that if you start using these strings you'll play just as good as Bream did.
Eric from GuitarLoot
Renaissance and Baroque freak; classical guitars by Paul Fischer (1995) and Lester Backshall (2008)
Yamaha SLG 130NW silent classical guitar (2014), Ramirez Guitarra del Tiempo (2017)
ISTR that in the movie "My Life In Music" he didn't mention any particular label, but did say that he carried a micometer with him to check the diameter of strings. I don't think that strings alone give him his extraordinary tone, but also the Hauser model guitars, fingernail density and so on. Pretty sure he could pick up a cheap guitar and make it sound great.