Check the listing for details. 1PCS Constant Loudness Volume Adjustment Board PH2702 Potentiometer. Color: Black, Condition: New. Listed at 13.71 USD. package：1PCS Constant loudness Volume Adjustment Board PH2702 Potentiometer Technical parameters:Step potentiometer.Product model: RH2702.Product resistance value: A100K X 2.Product size: 38*38MM, height 27.5MM.All buyers who buy potentiometers will give the potentiometer PCB board free of charge. What is equal loudness?The relationship between the actual loudness of the sound and the actual loudness of the human ear is not completely linear. When the volume is low, the hearing of the middle and high frequency will have physiological attenuation. The smaller the volume, the more obvious the attenuation. The function of equal loudness control is to increase the volume of high-frequency and low-frequency components at low volume, so that the loudness ratio of low, middle and high parts is the same as that at high volume. Equal loudness control meets this requirement, and equal loudness control is generally 8dB or 10dB. In order to maintain the equal loudness effect of human hearing in high and low frequency bands when the human hearing is relatively high, some preamplifiers insert equal loudness effect circuits. the principle is to appropriately increase the amplification ratio of middle and high frequency bands when the volume is low. To achieve the consistency of human hearing.•电位器尺寸：