▁Compos er ▁of ▁ 1 5 ▁string ▁quart ets . ▁P elle ▁G ud mund sen - Hol m green ▁( 1 9 3 2 – 2 0 1 6 ): ▁Four teen ▁quart ets ; ▁the ▁t enth ▁and ▁ele vent h ▁also ▁have ▁optional ▁vocal ▁ensemble ▁parts ; ▁the ▁tw elf th , ▁th ir teenth ▁and ▁four teenth ▁quart ets ▁were ▁designed ▁to ▁be ▁played ▁individually , ▁or ▁any ▁two ▁or ▁all ▁three ▁simultaneously ; ▁also ▁the ▁Con cer to ▁Gros so ▁for ▁string ▁quart et ▁and ▁instrument ▁ensemble ▁( 1 9 9 0 / 2 0 0 6 ). ▁Per ▁N ør g år d ▁( born ▁ 1 9 3 2 ): ▁Ten ▁string ▁quart ets . ▁Alexander ▁Go e hr ▁( born ▁ 1 9 3 2 ): ▁Four ▁string ▁quart ets ▁( Op . ▁ 5 ▁( 1 9 5 7 ), ▁Op . ▁ 2 3 ▁( 1 9 6 7 ), ▁Op . ▁ 3 7 ▁( 1 9 7 6 ), ▁Op . ▁ 5 2 ▁( 1 9 9 0 )). ▁John ▁K ins ella ▁( born ▁ 1 9 3 2 ): ▁Five ▁number ed ▁string ▁quart ets ▁( 1 9 6 0 , ▁ 1 9 6 8 , ▁ 1 9 7 7 , ▁ 1 9 9 3 , ▁ 2 0 1 3 ), ▁and ▁On ▁H ear ing ▁Pur cell ▁and ▁Sh ost akov itch ▁at ▁B antry ▁House : ▁June ▁ 2 0 0 8