noble100
I don’t really understand what is meant by pressurizing the room. Can anyone please explain this physical process and its benefits?
I do, however, understand many of the terms and concepts involved related to achieving very good bass response in a given room.
Yes Tim its clear from what you wrote that you do indeed have a good grasp on the situation. Having read everything here its apparent a lot of others would do well to read through your comments carefully, and more than once. And then go and read the referenced work as well.
This is something I’ve been studying for quite a long time, going back to when I built my first transmission line (Roger Sanders, published in Speaker Builder) back in 1980. Like most things I don’t work on it consistently but in fits and starts, which I just happened to be doing recently, and so was really good timing coming across your Swarm experience here. One sold last October and if another one comes up I am on it, otherwise will probably be ordering new some time later on this year.
Pressurizing the room is kind of descriptive but ultimately misleading. The only way the room could truly be pressurized is a closed room with speakers mounted in the walls. Even then it would only be pressurized when the drivers were moving into the room, depressurized when they move the other way. And even then there would still be the time it takes for the waves to propagate. There would still be nodes and anti-nodes.
A lot of what we read about acoustics is like that, descriptive in a way that makes sense, sort of. Actual experience though, like you have with your Swarm, there is nothing like it for turning abstract idea into concrete reality.
Like, we all talk about this stuff with regard to bass, when in reality its not only bass but all frequencies. With bass its in your face obvious. But its across the board.
My listening room is a standard rectangle- 17x24x9. No odd shapes and when first built nothing in it, no furniture, no carpet, no nothing. At one point in fact it didn’t even have sheetrock! I had the unique experience of hearing this space go from framed up to fully treated, and everything in between.
At one point the only "room treatment" was the carpet. Playing a CD with test tones you could clearly hear the distance between the nodes! As the frequency increases the node spacing decreases, some of them down to a few inches, something you can easily hear if you’re ever in a plain room like this. Clap your hands, you could hear it echo back and forth real fast- and even hear the difference between the fast echo lengthwise and the really fast echo crosswise!
Same thing with bass of course, only as you know the wavelengths are so much longer. So one wave doesn’t even have time to generate a full cycle before it could start getting canceled by its own reflection.
Another thing, almost always the talk is about the speaker location. As if that’s all that matters. When in reality (and as you so clearly understand) listener location matters just as much. Anyone who has ever had the experience I have had, of being able to stand where you cannot hear anything at all, then move your head just a very small amount and its loud, would know this. Its not abstract. Its reality.
This is why the Swarm concept is so patently obviously correct to me. Any one speaker/listener setup can never get us where we want to be. It has to be a combination. Its simply physically impossible to eliminate the nodes. So don’t even try. Instead, make enough small ones to seem smooth.
Brilliant.
