Originally Posted by tima94930
By "jackhammer-like sound that precedes the loud clack at the end", I'm asking about the several instances of seconds-long, fluttering, sputtering, motorboating, jackhammer sounds that comprise the first 16 seconds or so of the video, that are completely different than the loud clack at the end of the video, after which, there is silence. The clack occurs at about 0:17. The fluttering noise is what I get if I play (say) a 25 Hz test tone above a certain loudness. In contrast, if I play (say) a 40 Hz test tone, it sounds like a continuous pure tone. Is there an explanation for it?
Two reasons, the sub is in free air, bass is canceled out and much of the asymmetrical distortion does not, But that's about 10% of what you hear, the other 90% is because the vent is resting on the counter (top of the box in this case) and you hear the air squeezing out of the vent between the t-yoke and flat surface, the air pressure is very high and is lifting the sub woofer off the table and making it rattle.. you can see the driver moving in the video, its 35 pounds and the moving mass is only about 250 grams... its trying really hard to vent!
here is another free air video with 18's. Below 10Hz, it sounds exactly like a motorcyclehttp://www.youtube.com/watch?v=8yZjSYdtBck