Hi, I'm new to building speakers and recently decided to make a new box for the subwoofer for the existing 2.1 speakers(JBL creature III). The old subwoofer driver had torn its surrounds and therefore decided to make new one.I am not making something very loud but rather flat sounding. I went for dayton ND140 5.25" 4 ohm driver (https://www.daytonaudio.com/product/57/nd140-4-5-1-4-aluminum-cone-midbass-driver-4-ohm) in a vented box. The driver is rated for 40watts (although my amp can do max of 15 watts), 4mm Xmax, 20mm peak to peak. The manufacturer recommends 1cu ft box with F3 of 34hz (parts express says 0.75cu ft with F3 41hz) but when I was designing the enclosure in winisd , it showed that the speaker was already hitting Xmax at 15 watt in a 0.75cu ft box. Increasing box size only makes it worse. I came across several reviews where the driver was put into 1cu ft boxes and worked flawlessly but i couldn't figure out how was it working for them if its already way beyond its xmax limit. Could someone please help me with this.
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Note the asterisk there - the "optimal" box size is based on a simple formula aiming for a flat response, regardless all other parameters. The reason why the calculated volume is so big is because of the high Qts. Do not pay attention to it. Build a reasonable size enclosure for this size of a transducer.
Anyway, even though you lower the volume, it will still be sort of a boombox.
Anyway, even though you lower the volume, it will still be sort of a boombox.