Sensor & Mic External 139B Polarity Tester
Loudspeaker Polarity Tester 139B
Even in a very noisy environment, Model-139B still can determine quickly and precisely the positive and negative polarity of a loudspeaker、headphone、receiver, and every single unit in a loudspeaker system. Model-139B also includes 3 sets of external input terminals and selectors which can be used to combine with other instruments, to measure the other features of a loudspeaker simultaneously. It is quite suitable for 100% Q.C. testing for loudspeakers in the production line.