Two speaker (SPK) polarity testing is not anti-, two beep error ≤ 3dB sensitivity, impedance error is ± 20%, specific reference to the official booklet.
A pair of two friends (SPK) polarity test can not be reversed, two friends pair sensitivity error ≤3dB, impedance error of ± 20%, with particular reference to Shi kind of book.
Two Bala (SPK) polarity test do not reverse, two Bala sense error is less than or equal to 3dB, impedance error is + 20%, with specific reference to booklets.