AMPLIFIER No. 143A FOR AMPLIFYING WEAK VOICES AMP & LS No. 4 - SPEAKERSET 1 - WAITING AMPLIFIER AMP & LS No. 5 - SPEAKERSET 2 - WAITING AMPLIFIER AMP & LS No. 6A - SPEAKERSET 3 AMP & LS No. 11A - DORIC AMP & LS No. 12A - HARMONY AMP & LS No. 13A - USED WITH HERALD FEATUREPHONES AMP & LS No. 14A - USED WITH SL-1 FEATUREPHONES AMP & LS No. 16A - MELODY
