Originally Posted by Jermaine Davis
Picked up 2 pb 3000's a few weeks ago and felt like the house was going to fall with all the rattling so I picked up these isolation feet: SVS SoundPath Subwoofer Isolation System, 4-Pack https://www.amazon.com/dp/B00NCSQ5GK..._vPdRCb1MJ1WMH
Adding those stopped all the rattling except with the glass/metal on the gas fireplace. I was thinking about adding an isolation pad to go with the isolation feet, but I can't find any big enough to fit the dimensions of the pb 3000. I'm not sure if it will even help honestly. Does anyone have any suggestions for me and my dilemma? I'm racking my brain trying to figure something out. Every thing is almost perfect except for that freaking glass on the fireplace!
Random rattles can be very annoying, but they aren't always coming from the subwoofers' contact with the floor. Subwoofers, and especially ported subwoofers, produce both sound pressure (SPL) and particle velocity (literally air moving, as opposed to sound waves traveling through
the air). So, using feet or pads under subs can help somewhat with vibrations transferred via direct contact with the subwoofer cabinet and a suspended wood floor, but they may not eliminate airborne vibrations caused by SPL and particle velocity.
One thing you can try to do is to isolate the vibration at the source of the rattle, by using little felt pads where the glass contacts the fireplace. Remember the little round felt pads made to go under lamps or whatever, to protect furniture? Something like this might work, and they would be available in different sizes at stores like Home Depot:
If you were determined to try an acoustic pad, there are larger ones like the one shown below, but they can get expensive. They don't need to be exactly the same size as the subwoofer, as long as they decouple the subwoofer from the floor. That decoupling usually works best with a suspended wood floor, which resonates in sympathy with certain frequencies. That's what your glass screen is doing. You can also make something yourself, using several thicknesses of carpet pad or foam rubber. You just want something that will reduce transferred vibrations from the cabinet to the wood floor.
It's hard to know what will work until you try something, but I would definitely consider the possibility that you need to isolate the rattling glass at the source of the rattle, rather than at the subwoofer cabinets' contact with the floor.
Edit: Since other people read these threads, including Guests who can't post, I decided to add some detail to my post, for general interest. Good subwoofers, such as the PB3000, have fairly thick walls made of relatively inert MDF. The purpose of that is to prevent unwanted resonances within the cabinet itself. But, they are never completely inert. For instance, at high volumes, a subwoofer can slide a little bit on a polished surface such as marble, tile, or wood.
Meanwhile, suspended wood floors--floors which are elevated above a crawl space or on an upper floor--can resonate (vibrate like the head of a drum) at certain low-frequencies. The specific resonant frequency would probably be below 25Hz, and could be well below 20Hz, depending on the density of the construction. So, direct contact with a subwoofer cabinet can create some degree of sympathetic resonance with a suspended wood floor. And, decoupling the cabinet from the floor, with some type of acoustic material, may help with that.
But, that is not the only way that wood floors can be made to resonate sympathetically, and it is not the only way that vibrations may be transmitted to other parts of the room, or even to adjoining rooms. As noted in this and other posts, both sound waves and particle velocity (PV) can create tactile energy which makes the air-filled cavities of our chests resonate briefly (chest punch) from abrupt percussive mid-bass sounds, and which can make wood floors and adjoining structures resonate from low-bass sounds at high sound pressure levels.
So, decoupling a subwoofer from a suspended wood floor, may help a little or a lot, depending on the overall density of construction. Using my friend @darthray
as an example, he gets a lot of sympathetic vibrations in walls, AC ducts, etc, in his HT, even on a concrete slab. So, in his case, he has to be careful about having too much SPL and PV under about 18Hz, and he has to treat vibrations at the source of the rattle. That is because airborne SPL and particle velocity are affecting his room, and not transferred vibrations from the subwoofer cabinets themselves. (Concrete laid on top of soil is not a very good conductor of direct vibration.)
I believe that this issue isn't as well understood as it might be, so I thought that some additional explanation could be helpful.