how should the subwoofer be placed to solve the problem of positive and negative phase of sound waves formed between it and the adjacent wall?

To solve the problem of positive phase and reverse phase of sound waves, the best way is to keep the sound waves reflected by the adjacent wall and the sound waves regenerated by the woofer in the same phase, that is, they are in phase with each other. To be more precise, if you want to keep the four sound waves of the woofer, the floor, the side wall, and the back wall in a positive phase, the safest way is to keep the reflected sound waves and the woofer sound waves within 90 degrees. If the 90 degree phase is converted to a wavelength, it is within a quarter wavelength. However, since the sound wave will be reflected back from the wall and then reflected back, the route of travel is already twice, so we divide the quarter wavelength by two, which is the actual calculation, take one eighth. The wavelength is ok. Perhaps this is a lot of people don't understand, let me give an example: If the subwoofer's selected crossover point is 100Hz, then we take the highest 100Hz wavelength to calculate (other lower frequencies are already covered). The 100 Hz wavelength is 340 meters (sound wave speed per second) divided by 100 Hz, equal to .3.4 meters, and the one-eighth wavelength of 3.4 meters is 42.5 cm. Therefore, we should place the subwoofer at a distance of less than 42.5 cm from the side wall, the back wall, and the floor, so that the sound waves reflected from the back wall, side wall and floor of the subwoofer can It maintains a positive relationship with the main sound wave emitted by the woofer. When all the reflected waves are in positive phase relationship with the main wave, it is the time when the low frequency sense is the most abundant. That's why the subwoofer is placed in the corner to get the most abundant low-frequency feel. Seeing this, you may think of a problem: Since the subwoofer can be placed in the corner to get the most abundant low-frequency sense, then the left and right channel speakers are not in the same corner to get the most abundant low-frequency sense? That's right! The same can get the most abundant low-frequency sense, but don't forget, the left and right channel speakers are not only the bass, but also the midrange and tweeter. These monomers have a much higher frequency range than the bass. If you calculate according to the above formula, you will find that the distance required for each monomer is different, so it is easy to generate complex sound waves that mutually enhance or offset each other, which is harmful. Therefore, in addition to the subwoofer, the general speaker is not suitable for being placed in the corner. Another advantage of placing the subwoofer in the corner is that the low volume feels so you can turn the volume knob down. When the volume knob is turned low, it means that the amplifier does not have to output such a large amount of power, and the woofer does not have to move so violently, both of which contribute to the reduction of distortion.