Features Introduction ※ fast automatic test speaker FO value ※ FO (resonance frequency) in four sections, the option to test, high precision and easy ※ upper and lower value is set ※ digital display is divided into ordinary display and test display, intuitive and accurate ※ LED Display judgment function, fast and accurate for the main purpose QA QC testing and production line testing, rapid determination FO value of the product is qualified. Technical Data Frequency Range 16 Hz ~ 3 kHz, 4-speed: a 16 Hz ~ 80 Hz b 54 Hz ~ 270 Hz c 180 Hz ~ 900 Hz d 600 Hz ~ 3 kHz Fo measurement error ≦ ±........ 1% or ± 1 Hz, the lower limit set error is less than 1% test voltage 1 Vrms ± 10% (According to EIA Std) speaker impedance range 3Ω ~ 100Ω, sub-2 files a:. 3-18 b: 19-100