КАК ИЗМЕНЯЕТСЯ ГРАФИК АЧХ ПРИ ЗВУКОПОГЛОЩЕНИИ КОРПУСА САБВУФЕРА

Subwoofer enclosure design. If the enclosure walls are 24mm or thicker, leave them as is. When tapped with your knuckles, the walls should produce a dull sound. If the thickness is 18-20mm or less, the enclosure needs to be reinforced. When tapped, the enclosure will produce a more or less clear sound at the walls' natural resonance frequency of 200-500 Hz and introduce additional tones into the music. To strengthen the enclosure, you can firmly glue stiffeners (wooden blocks no thinner than 3x3cm) from the inside (diagonally) to the ringing walls. You can tightly insert or glue spacers made of the same blocks between the centers of the walls. Just don't hammer the spacers in, as this will break the walls. ATTENTION. With rattling walls and other background noise, the subwoofer's location in the room will be determined by ear, which shouldn't be the case. Subwoofer damping with a sound absorber: three main options. Damping is determined by personal sound preference. (The method described below yields the same results in subwoofers and speakers without a bass reflex port, such as a closed box). With solid, solid walls, if the sound is satisfactory, damping may be omitted altogether. You'll get punch, drive, and hard, defined bass. BUT! In this case, chaotic internal sound reflections from the walls will roam inside the box, and all this muck will be released into the room through the thin diffuser! The sound cone is 🔹️TRANSPARENT🔹️, something even acoustic designers often forget. The sound pressure inside the subwoofer is dozens of times greater than in the room, and all this dirt will be blown out through the cone. But, as I said, if it suits you, then so be it. Soft, partial damping. The inner walls (or at least most of their surface) are covered with 3-4 layers of cotton batting (3 cm). Don't brush the walls; spot gluing is better, just to prevent the batting from falling off and to keep it fluffy. Alternatively, you can place a gauze bag filled with fluffy cotton wool, approximately 1/4 to 1/3 of the subwoofer's internal volume, in the center of the subwoofer. See below for calculations. The cotton wool dampens chaotic internal sound reflections from the walls. The drive (Q factor) will decrease slightly, and the bass will soften.   Full damping. Fill almost the entire subwoofer volume (60-80%) with a volumetric sound absorber such as cotton wool, at a rate of 20-25 grams per 1 liter of the subwoofer's internal (filled) volume (synthetic batting is significantly worse, as cotton batting is too dense). Fluff the cotton wool/synthetic batting well and loosely place (sew) it into homemade gauze stockings measuring 10 x 80 cm to prevent it from spreading and to maintain its shape. Laying the cotton wool (stockings). Lay the cotton wool away from the speaker, wrapping it tightly. The cotton wool should rest against the stamped diffuser holder and partially dampen its vibrations, but not touch the diffuser at its maximum amplitude. Next, lay the cotton wool according to the subwoofer's volume. If something doesn't fit, don't force it in; it's better to reduce it. Attach the pads to the subwoofer enclosure at several points with a hot glue gun or any suitable adhesive. Filling the subwoofer with volume reduces the speaker's resonant frequency by 15-25%, lowering its Q factor. The subwoofer's frequency response is also evened out, reducing hum and roar. ☝🏻 Result: drive is lost, the bass becomes very soft, sometimes even excessively so (overdamping). However, double bass and other live instruments sound great. When overdamping, the density of the cotton can be reduced (further fluffed or even replaced with synthetic padding), but it's essential to fill the subwoofer with volume, not just stuff everything in one corner. We need resonance reduction, not just reflection absorption. As the speaker's resonant frequency is lowered, the resonant frequency of the bass reflex port is proportionally reduced. A well-forgotten old story: an example of the complete damping of a ZYa-type subwoofer. ☝🏻Too little wattage results in booming and bass-like sounds; too much wattage results in a soft but muted bass. You can easily do without any equipment: use as much wattage as you like.