Media room over a garage - will sound insulation help?

fluke242 · « **on:** 7 Jul 2009, 08:26 pm »

I am working on my first dedicated media room and have a question on room acoutics. My media room is above a garage and seems to lose a lot energy (mostly low end) into the garage.

Would installing sound insulation below my carpet help contain the energy? Or any best practices?

Thanks!
John

MaxCast · « **Reply #1 on:** 7 Jul 2009, 08:39 pm »

Since you are above a garage you can't really support you floor so the next is to give your speakers a good foundation. You could try some patio blocks under your speakers. If that helps you could seek a more decore friendly piece like granite.

Norman Tracy · « **Reply #2 on:** 8 Jul 2009, 04:21 am »

Acoustics Sciences Corp. Iso-Damp system is VERY effective if you have the luxury of starting at the studs.
http://www.asc-hifi.com/iso-wall.htm
http://www.asc-home-theater.com/soundproofing.htm
http://www.asc-soundproof.com/newpages/isodamp-hometheater.htm

We used this system in the last HT I designed and the results made me a 100% true believer.

fluke242 · « **Reply #3 on:** 8 Jul 2009, 05:52 am »

Be nice to start over, but can't complain with a dedicated media room... my 1st!

Here is a rendering minus equipment and lounge. My room is in progress mode and none of the acoustic tiles are mounted yet. Still planning and playing...

fluke242 · « **Reply #4 on:** 8 Jul 2009, 05:55 am »

Quote from: MaxCast on 7 Jul 2009, 08:39 pm

Since you are above a garage you can't really support you floor so the next is to give your speakers a good foundation. You could try some patio blocks under your speakers. If that helps you could seek a more decore friendly piece like granite.

Good idea. I want to raise my speakers a bit regardless and could put my new hobby to work - lapidary. A couple nice slabs of marble, jasper, or petrified wood would be nice.

MaxCast · « **Reply #5 on:** 8 Jul 2009, 11:35 am »

What stage is the floor in now? Could you add another layer of flooring before the pad and carpet?

fluke242 · « **Reply #6 on:** 8 Jul 2009, 03:03 pm »

It is currently 95% carpet with a normal carpet pad under that, then plywood it looks like. I can pull carpet and pad but would not feel comfortable taking out more. I even step down into my media room (~3-4"), so I could build up a bit. Just rather low ceiling already and need to weigh the good/bad.

What would you purpose building up with on top of plywood?

Thanks again for your help!

John

MaxCast · « **Reply #7 on:** 8 Jul 2009, 03:25 pm »

I was thinking of another layer of 3/4" flooring then pad then carpet. I don't know how much it would help but you would be doubling the mass of the floor which should lower the resonance???
Is there a way to support the floor from the garage or would the poles be in the way?

Big Red Machine · « **Reply #8 on:** 8 Jul 2009, 04:02 pm »

What if you "floated" another layer of 3/4 plywood with some isolation pads to try and keep the bass energy in the room and inhibit its transmission through the floor. A layer of rubber or some rubber pads?

If you add mass it will still transmit, whether the new frequency is "better" is something I am not sure of.

MaxCast · « **Reply #9 on:** 8 Jul 2009, 04:12 pm »

I like the rubber pad (not pads) idea or green glue

My thoughts are based on a thicker floor like thicker walls in a speaker.

Big Red Machine · « **Reply #10 on:** 8 Jul 2009, 04:26 pm »

If I understand this correctly, lots of mass is good but it has to be isolated from the structure so the whole system works. Like I did my 2 channel room; double greeglued drywall with rubber isolators to the wall studs. So the mass of the room is heavy and hard to shake AND it does not just simply transmit out to the rest of the structure and you fall short of the goal. Does that sound right?

As crazy as I am, I'd put down some commercially available suspension and double plywood with greenglue inbetween and you'd eat up that 3-4" in a hurry. But it should be "better" except you have neglected the sidewalls and that nasty flanking noise comes into play. Bugger!

fluke242 · « **Reply #11 on:** 8 Jul 2009, 04:32 pm »

Isolation does seem key, or at least for the biggest bang-for-buck. I should look at pricing first before I get too ahead of myself. But losing 1.5" would be OK. Perhaps an isolation first then my mass, a heavy vinyl or related, then carpet. Maybe I will sketchup my ideas! fun!

Thank you both for your help!

John

MaxCast · « **Reply #12 on:** 8 Jul 2009, 04:42 pm »

I am picturing a room over a double garage. My friend has one and it is a bit springy. I figured that was the biggest difference between this room and a typical first floor room that may be braced underneath.
I also am assuming the sound in the garage is not a problem it is the loss of bass in the listening room.

Where are the experts anyway?

Big Red Machine · « **Reply #13 on:** 8 Jul 2009, 04:57 pm »

Quote from: MaxCast on 8 Jul 2009, 04:42 pm

Where are the experts anyway?

Good point.

I guess I was coming from the leakage of bass energy is bad from the listeners perspective in that the bass energy may escape and not add to the listening session. Agree, who really cares about the garage.

Springy would be made worse with added weight on that structure.

JackD201 · « **Reply #14 on:** 8 Jul 2009, 05:54 pm »

Quote from: MaxCast on 7 Jul 2009, 08:39 pm

Since you are above a garage you can't really support you floor so the next is to give your speakers a good foundation. You could try some patio blocks under your speakers. If that helps you could seek a more decore friendly piece like granite.

This seems very logical to me. Tip up the energy going through the spikes by having it pass through an interface with a higher resonant frequency to lessen sympathetic vibration. This should work well for keeping your bass intact.

fluke242 · « **Reply #15 on:** 8 Jul 2009, 06:09 pm »

Yes - above a double garage and the floor seems fairly solid. I am not worried about disturbing the cars in the garage with music, just more worried about the loss of energy. It is very loud in the garage compared to a room on-angle, like the bedroom next door it is virtually silent when I close my door.

Insolating the speakers will help a bit, but I would imagine the bass energy will still excite and resonate the floor.

I will keep reading on options for flooring. Seems like I can't get away from isolation to do it right.

John

*Scotty* · « **Reply #16 on:** 8 Jul 2009, 06:40 pm »

John, you basically cannot stop bass energy from escaping your listening room no matter what you do. Your situation is very little different from what you would encounter in the average above ground living-room with frame construction and a basement below it.
The fact that bass energy escapes your listening room is a good thing. When you apply absorptive treatments to the walls of your listening room they are progressively less effective at frequencies below 500Hz. . The loss of bass energy by the room helps even out the frequency response when added to the effect of the room treatments at higher frequencies. You are less likely to wind up with a bass heavy sound after you absorb some of the HF energy. The standing waves created in your room in the bass region will probably be lower in magnitude and potentially easier to deal with. You can always add more bass energy with a subwoofer if you feel the need for it.
Scotty

fluke242 · « **Reply #17 on:** 8 Jul 2009, 08:18 pm »

Hi Scotty,

OK - that sounds logical. Would my money and time be better invested on acoustics (broadband and diffusion) than sound isolation? My next step was to install GIK broadband traps, keep what ATS I have, and add GIK diffusers. I will draft out my plan in Sketchup later with the purposed GIK additions.

Thanks,
John

*Scotty* · « **Reply #18 on:** 8 Jul 2009, 08:41 pm »

In a word, yes. Diffusion is probably the most under-invested component in the audiophiles dedicated listening room because of cost.
When you place a sound system in a typical living room full of furniture,a couple of bookcases and a few lamps and usually wall to wall carpeting,some diffusion and absorption come with the territory. The first thing I have noticed about most posted images of dedicated listening rooms is a complete lack of furnishings beyond a chair in the sweet spot and an equipment rack and these people wonder why their stereo doesn't sound so good and they have a slap echo problem. If you go the minimalist route without much in the way furnishings in the room, investing in enough diffusion to be effective becomes mandatory to achieving your goal.
Scotty

John Casler · « **Reply #19 on:** 9 Jul 2009, 07:29 pm »

Quote from: *Scotty* on 8 Jul 2009, 06:40 pm

John, you basically cannot stop bass energy from escaping your listening room no matter what you do.

Scotty

I might suggest that all the suggestions (IMO) are reasonable but you need to look at WHAT your actual goal is.

If you want BASS ENERGY perception to increase then you need to apply methods to DIRECT that energy to that purpose.

The suggestion to add 3/4" Plywood to the floor "could be" a good one if it is implemented in a way that will then direct the bass energy to you. That can be accomplished most effectively by "stiffening" (making more rigid) the floor (or ANY boundary) and or adding mass to those boundaries. However, doing so also adds to their "responsive, reflective and directive" properties, which can add more problems in the form of greater mode/node responses due to higher directive/reflective capabilities.

If you do go with the plywood, I would NOT suggest floating it unless you are looking to make the floor a "damping" boundary, rather than directive. Floating will increase the absorption of the energy, and reduce the directivity.

If you want directivity (reduced damping and absorption of energy) to facilitate the bass energy reaching your listening chair with less dissipation, then SCREW and GLUE the plywood to the existing floor adding mass, strength, rigidity and resistance to the bass energy which will direct it more towards you (actually in all directions) but at the risk of adding other psychoacoustic energy considerations.

Hope that didn't complicate things, but as in all things, when you change "ONE" thing, it affects everything it interacts with depending on the way it is changed.