... Internal voltage-controlled oscillator, Three working modes MCH-2893A Speaker Tester, impedance test ModelMCH2893ATest parameterImpedance /Z/ ZZero clearing ... Test frequency Fixed frequency: 400Hz, 1kHz 400Hz-1kHzManual adjusting: 20Hz-4kHz 20Hz-4kHzSweep range: 50Hz-3999Hz 50Hz- ... notice. MCH Speaker Impedance Tester,MCH-2893A Speak tester,400Hz,1KHz fixed freq,20Hz-4Khz manual adjusting, 50Hz-3999Hz ...