The baffle is also called an open baffle (OB), which means that a speaker is installed on a flat wooden board, and the back is not closed into a box. The advantage is that there is no cabinet, the low frequency sound quality is pure, the sound field is good, the sound is loose, the disadvantage is that the low frequency needs to be output, the baffle needs to be bigger, the better, and theoretically infinite. Therefore, the small baffle will not dive deep at low frequencies, and the large baffle is not easy to place at home. The sense of volume is less than other types of low frequency.