Today I want to talk about drywall and green glue. It’s prevalent throughout the literature, I hear about it every day in my discussions with customers. I really want to define it and talk a little bit about it and also tell you why we don’t use it so you can get some idea on why this whole drywall, green glue thing became so accepted. We have to remember that everything we put in our room contributes to the sound quality.
Some materials in our rooms have more impact on our highs. Glass for one thing is a big one. So we have to be very careful with the materials that we put in our room because sound does take on some of those characteristic. And if we remember that good quality sound is a combination of doing a lot of little things in the right order correctly.
So why drywall?
It’s cheap, it’s economical. All the literature is full of it, people just use it without question and I think that gets us in trouble. It’s a compound of natural materials but it has a particular tonal quality especially in the vocal ranges. It’s cheap, it’s economical and it’s prevalent in most regions of the country but there’s a reason we don’t use it in any of our builds and we’ll talk about that later.
Green glue, what is green glue?
It’s just a product name, manufacturer’s name for what’s called viscoelastic damping compound. It’s just a compound of materials that isolates without hardening. It stays pretty flexible in its composition over time. So it is able to isolate the two layers of drywall that its usually between. That’s good because that’s part of a process called constrained layer mass damping. So constrained layer mass damping is when you take a series of materials, layered materials, you separate them with dampening compounds between them. That further attributes to the vibrational isolation of the structure.
What materials to use? What densities to use? How thick to make those materials? Depends on frequency and amplitude. So it’s complicated. You can’t just use drywall and green glue for everything and a lot of people think that. It’s just not the way to go. It’s very frequency-dependent, it’s very cost-effective but it only works in certain situations and it has a particular sound quality that we don’t care for especially in the vocal range.
So it’s a process. Green glue is a compound used in a process. The process is constrained layer mass damping. You can use different materials to achieve different goals and green glue is just one of those. Our goal with this structure is vibration isolation. We’re taking airborne energy striking a surface, a wall, a barrier and then we’re dealing with vibrational techniques after that.
There are better materials available
So constrained layer mass damping, dry wall and green glue are just products and combinations that we use. The reason why we don’t use drywall in our builds is that we found better materials. Now we still use constrained layer mass damping as a technique but we found better materials that work for tonal qualities in our vocals. So I hope that helps a little bit with the explanation. And remember that this is all about vibration. Not necessarily airborne sound energy, it’s the result of that airborne sound energy striking a surface.
So in the following graphic you see the difference. We’re taking airborne energy striking a surface and then getting a smaller signature, sonic signature, airborne signature on the other side.
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