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Acoustic Fields Inbox #4

Dennis Foley June 4, 2016 No Comments
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Today we are going to talk a little bit about some of the questions and comments I get in my Inbox. I think this is number 4 in our series. So let’s talk a little bit about some of the questions that we get.

1 – This one comes in all the time: „I have built a room and I have used Drywall“. Well, you all know my feelings on that, we don’t use it in our builds. And most of your top studio designers do not either, and there is a reason for that. You’ve got to get away from this thinking that there is not anything better than cheap. I get this all the time, especially the double drywall with green glue thing. Anyway, there is much better materials to use inside your room than drywall.

Get away from that thinking. Drywall has a particular sonic quality to us, and we are going to do some videos on that. We are going to actually do some measurements, we are going to fire some speakers into some Drywalls, we are going to fire some speakers and into some other different materials and we will go to measure the response. But stay away from drywall in your rooms, it’s economical, it’s cheap, but there are other things out there that don’t cost much more or even less that work better. We will talk about some of those, but stay away from Drywall in your rooms. I can walk in your room right now and tell you that it was made of drywall, I can just hear it. And you can, too, if you really concentrate on it.

What are some better materials to use? Simple Plywood, veneered Plywood is a good one. MDF is another good one, there’s numerous other materials. And the other materials align themselves to other applications that you may not be aware of, vibrational control and things like that. So, please, stay away from drywall when you are building new rooms! If you have drywall in an existing room but you are really serious about the sound quality of the room we are going to cover it.

2 – Here is another question we get all the time: open versus closed cell foam. Open cell foam is the acoustical foam that we use, open meaning that it has cells for energy to go in, bounce around within the cell structure, create friction, produce heat, cause loss in energy. So closed cell foam is the foam that you use in your pillows, your cushions on your couch, the seats of your car, things like that. It is not really designed for acoustics, it is not designed for molecular velocities, not designed to change energy and the heat through friction because there is no way for the energy to get inside of it, because, as the name implies, it is closed. Now there are some ways you can get closed cell foam to work for low frequency absorption, it’s a little bit beyond this discussion here, so always when you are dealing with absorption and you want to use foam, foam is a great product. It has a light weight, you can control the frequency responses. The unique thing about our foam is that the cell structure is very consistent, that is why you get that nice curve, cause the cell structure is very linear very uniform and it is very consistent. So always in acoustics you want to stay with the open cell foams for absorption.

3 – A low ceiling, I see a lot of seven foot ceilings. You have to realize that in your room when you are sitting in your chair listening the first reflection from your speakers is the floor, not the sidewalls. The next one is the ceiling, cause those are the two surfaces you are sitting close to. If you think about it that you are sitting on the floor and you’re underneath the ceiling, so those are the two areas that you have to deal with, those are two surfaces that have to be treated correctly. The side walls are responsible for image, definition, separation, a central image focus and issues like that. But these issues of the floor and the ceiling can confuse all those issues that the sidewall treatment is trying to correct. Everything has to work together, so watch your low ceiling situations, if you have low ceilings you better have a low and small speaker, because you want to increase that distances. Don’t put a six foot speaker in a seven foot room, you can’t do that. You cannot deal with this kind of energy in that kind of volume and size.

4 – I get a lot of questions about „I have a suspended ceiling, what do I use for the calculation of the ceiling height when it comes to low frequency energy?“ Well, I guarantee you that low frequency energy 30, 40, 50, 60, 70, 80, 90 cycles could care less about your suspended ceiling, it is going to go right through your suspended ceiling and it’s going to go against the shell of the building. So when you do your calculations, you do your measurements forget about the suspended ceiling, it doesn’t mean anything when it comes to low frequency technology and management.

5 – Floating floor, I see a lot of this, people spend a lot of money on floating floors. What is a floating floor? It is a barrier, it is designed to keep energy and keep unwanted energy from the outside from coming in. Do you really need it? Floating floors are expensive. Did you do some measurements? What is the noise level? What is the monitoring pressure levels in the room, it is going to be 80, 83, 84, 85? Are you out in the country by your self? If yes, then you don’t need a floating floor. Are you in a two story building where the people below you are very sensitive to noise? Then you are going to need a floating floor. So floating floor is a barrier, it is not a sound absorption technology. A lot of people get those mixed up, „I will build floating floors, so therefore I have my low end under control“. Nothing could be further from the truth. Floating floor is a barrier technology. Just keep that in mind and make sure you need it, because they are expensive to build.

This is an unedited transcript from our video series from Acoustic Fields. There will be some errors in grammar and sentence structure that occur during this translation process.

For complete understanding and comprehension, please view the video which is included in this text. For any additional information regarding this topic or others relating to room acoustics, please contact us directly at:

P: 520 – 392 – 9486

info@acousticfields.com

Dennis Foley

I am an acoustic engineer with over 30 years’ experience in the business. My technology has been used in Electric Lady Land Studios, Sony Music of New York, Cello Music and Films founded by Mark Levinson, and Saltmines Studios in Mesa, Arizona, along with hundreds of others. Connect with me on Google+

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