Originally Posted by ronny31
Page 15, 8 inch concrete block with standard wall on both sides. About twice as good at stopping bass than all the non-concrete stuff in IR-761 (the best bass transmission design in IR-761 is 25db I think, spent 20 minutes scrolling through to see if I found out what was best in that regard but got bored).
When DB drag car builders make panels to stop bass transmission they hammer on it with something, then if they hear something they reinforce it. Then they repeat until they no longer manage to transmit any bass through it. And what they always end up with is a concrete panel. You need concrete to stop bass. To stop bass without concrete you'll need half spacing studs and double 22mm high density variable particle size particle board akin to the stuff Scandinavians use for floors. And even then concrete is much better. Even just thin fiber reinforced poured concrete and then a normal wall at both sides (with some rockwool or something to stop high frequencies). Am I the first on this forum to advocate the use of concrete to stop bass transmission or something? With the amount of resistance and general lack of response to my points in favor to responding to the next guy who mentions drywall, I'd certainly think so.
EDIT: Come to think of it, why should I argue otherwise? Maybe I'll just let you be happy with drywall combos in respect to bass transmission. Then I won't come across as an a-hole in my effort to argue otherwise.
Any resistance you are getting is mostly because your responses are a curious mix of being very helpful; somewhat misleading; or outright wrong. You clearly think you know a lot about soundproofing, but it seems like a lot of your background info is either wrong or is right but in ways that you don't understand.
This response is an example of where you start off 100% right and but then start subtly veering off.
First, you are 100% correct that concrete is a fantastic way to stop bass! I've never heard anybody say otherwise. As I mentioned earlier, stopping bass means tons of mass, plus ideally damping and space. Concrete works so well with bass because it is very dense and so has a ton of mass for the amount of space it occupies. There are elements that are even better (lead and sand, for two quick examples) but all other alternatives are either prohibitively expensive or are difficult to work with in a construction capacity. So concrete is king when it comes to bass.
So why isn't it concrete block recommended more often around here? Because this is a primarily US-central forum and concrete block is relatively uncommon in homes here. Most homes in the US are "stick" homes, made with 2x construction. Drywall is recommended so pervasively because it gives a reasonable amount of mass for relatively low cost.
Yes, it certainly sounds like the sponplat (high density panels) would be even better. I'd love to try the stuff myself. As far as I know, it doesn't exist in the US. Until it does, drywall is the best compromise
(performance for price + availability + workability).
Now, there is arguably an even better solution than drywall for bass that is still doable and that's concrete backer board. I suggested that in a previous post. The problem with concrete backer board is that it's notably harder to work with than drywall and is about double the cost.
But I want to quibble with your response, nonetheless, because you are pointing to a bunch of wall assemblies that do work well with bass and are implying that their STC rating has something to do with that. It doesn't. Even with those examples (several of which are IR-761 assemblies, btw), you can clearly see that the STC value has little to no relation to the wall's performance under 125Hz. Also, you mention "half spacing studs"... I'm not 100% certain what you mean by that. If you mean just spacing them closer together (8" spacing, perhaps) then no, that won't help from a soundproofing perspective. If anything, that would make things worse, since you are now doubling the amount of transmission paths for the sound waves to travel on. Halving the number of studs (going to 24" O.C., if code allows) does work, since it reduces the number of pathways.