I brought home a Yamaha YST-FSW150 powered sub from Goodwill for 20 bucks the other day. It runs well at low volume levels, but there's some very obvious distortion at normal listening levels and above, about 25% on the volume dial. With a sine generator, the resonant frequency is about 65Hz, and it tails off about 10Hz in either direction. The unit is from 2011—barely 10 years old. I'd like to get it working so I don't have to shell out for a new sub 😉
I don't hear anything rattling around inside when I carry it around, and sure enough, I found nothing loose inside the chassis when I took off the rear/bottom panels and driver. The distortion is the same in both the down- and side-firing orientations, or even if I lift the sub off the floor. The noise is definitely coming from inside the box, not from some piece of furniture. Pressing on different spots on the outside of the box (and down the inside of the port as far as I could reach), I couldn't find anything vibrating.
Taking any one panel off the box instantly fixes the buzzing, but also makes it not much of a subwoofer anymore. This means I can't just reach around inside and feel for the vibrating part, or even look inside while it's running. I think this at least rules out the electronics; it must be an acoustic/mechanical issue. However, all parts on the inside of the chassis feel 100% solid, so I have no clue what could be making this noise
The driver cone looks visually fine, and as mentioned, the buzzing completely stops if I break the resonant chamber by removing a panel, so I don't think it's blown out.
I've taken a few blind swings in the dark, to no avail:
What else could even be the source? I can only take the panels on and off so many times before the screw holes strip out, so any tips are appreciated.
I don't hear anything rattling around inside when I carry it around, and sure enough, I found nothing loose inside the chassis when I took off the rear/bottom panels and driver. The distortion is the same in both the down- and side-firing orientations, or even if I lift the sub off the floor. The noise is definitely coming from inside the box, not from some piece of furniture. Pressing on different spots on the outside of the box (and down the inside of the port as far as I could reach), I couldn't find anything vibrating.
Taking any one panel off the box instantly fixes the buzzing, but also makes it not much of a subwoofer anymore. This means I can't just reach around inside and feel for the vibrating part, or even look inside while it's running. I think this at least rules out the electronics; it must be an acoustic/mechanical issue. However, all parts on the inside of the chassis feel 100% solid, so I have no clue what could be making this noise
The driver cone looks visually fine, and as mentioned, the buzzing completely stops if I break the resonant chamber by removing a panel, so I don't think it's blown out.
I've taken a few blind swings in the dark, to no avail:
- I ziptied some wires together to prevent them from touching the chassis walls
- The magnetic-shielding plate looked loose at the corners so I pried it off. (The glue was still completely fine in the middle, as I found out.)
What else could even be the source? I can only take the panels on and off so many times before the screw holes strip out, so any tips are appreciated.
Perhaps the speaker itself is defective. Some days ago here in the forum, a guy found lots of magnetic particles in the magnet inside the voice coil.