Altec 515B 1973 Data 

ALTEC 515B is a 15-inch low-frequency loudspeak•er with a frequency r.esponsetrom 20 Hz to 1000 Hz. When used in conjunction with ALTEC 288C or 291-16A drivers, N-500C or N-500F dividing network and multicellular horn of the desired size and coverage angle, the 515B becomes an integral part of ·the identical AL TEC ‘Voice of the Theatre’® loudspeaker system. These systems are currently installed in a majority of the largest and finest theatres, auditoriums and concert areas.

Link for PDF: Altec 515B 1973 Data