Ultra Low Frequency and how to stop it? Modifying floors - AVS Forum
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post #1 of 12 Old 12-22-2012, 06:29 AM - Thread Starter
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Hi,

I have a tremendous amount of bass in my HT Room and need help to stop the most ULF I can from traveling through my walls.
I have a dedicated HT Room with Hat channel, DD, GG and all already installed.
This picture shows my setup:



What especially drives me nuts is how much bass travels through my floor upstairs. The ULF has no respect for my soundproofing I did.

My question is:
Since i will be redoing all my floors upstairs, what would be the best option to help kill the transmission of Low bass.
How should I redo my flooring to help kill some transmission through the floor?
Can anyone help please?

Thanks

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Equipment Speakers:
3x 1099's for LCR duty
4x Fusion 8's for surround duty
8x subs: 4x FTW21's and 4x SI18's
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post #2 of 12 Old 12-22-2012, 09:19 AM
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Quote:
Originally Posted by Fatshaft View Post

Hi,
I have a tremendous amount of bass in my HT Room and need help to stop the most ULF I can from traveling through my walls.
I have a dedicated HT Room with Hat channel, DD, GG and all already installed.
This picture shows my setup:

What especially drives me nuts is how much bass travels through my floor upstairs. The ULF has no respect for my soundproofing I did.
My question is:
Since i will be redoing all my floors upstairs, what would be the best option to help kill the transmission of Low bass.
How should I redo my flooring to help kill some transmission through the floor?
Can anyone help please?
Thanks
do you really need all that ULF ..to enjoy ur HT? its seems like overkill to me!!!!!!!!!!!!!!

loves...home theather/music/football:)
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post #3 of 12 Old 12-22-2012, 09:37 AM
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Sure he does, that's not the point. It takes some serious capability to experience low distortion, full LFE bandwith (3-120hz) listening at reference level.

I've got 4x18's, and 4x15's myself, in addition to some highly capable mains.

Can you enjoy it with less, sure.

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post #4 of 12 Old 12-22-2012, 02:55 PM - Thread Starter
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Quote:
Originally Posted by pioneertop View Post

do you really need all that ULF ..to enjoy ur HT? its seems like overkill to me!!!!!!!!!!!!!!

I really, really, really feel sorry for you.

14 exclamation marks? Really?

Anyways, many thanks for your help with my situation and the help I`m seeking.
Truly nice of you to go out of your way in trying to help someone who seeks some friendly advice.

Merry XMas to you and have a great year next year!
Hope things turn around for you and wish you nothing but success and happiness.

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Equipment Speakers:
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4x Fusion 8's for surround duty
8x subs: 4x FTW21's and 4x SI18's
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post #5 of 12 Old 12-22-2012, 04:32 PM
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check out the last build bigmouthinva did http://www.avsforum.com/t/1437336/fall-frenzy-bigmouthindc-hits-the-road-again-destination-columbus-indiana

there is huge sub in that one and from if i remember correctly it is a room in room design with four layers drywall and GG to contain the sound.
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post #6 of 12 Old 12-22-2012, 05:01 PM
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Hi Fatshaft,

Unfortunately you've discovered first hand how difficult it is to contain low frequencies.

It is my understanding that the best way to stop sound transmission that low is to create a decoupled system and load it with damped mass. You've already got the decoupling, so adding a third (or even fourth) layer of drywall with Green Glue to the system would help to lessen the escaping energy. One thing to pay attention to if you decide to do this is your clip spacing and whether it can accommodate more mass.

I know that there are some products that go down on the subfloor, or you could add another layer of plywood with Green Glue to the subfloor, but I believe these methods are designed more to stop impact noises from getting into the theater than preventing low frequencies from escaping. You'd get better results from loading your decoupled system with more mass.

You might want to give Ted a call and see if he has any other ideas for you.

The room looks great by the way! You've got a wonderful space.

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post #7 of 12 Old 12-22-2012, 08:44 PM
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The bad news is, because your HT in your house, you will have to rip down everything and redo.

It isn't decoupled enough, nor has enough mass to stop the quad 21's with 8400watts behind it.
Is it a room-in-room design? Probably not I'm assuming...

What you need to do is make the walls out of ciderblock (not touching anything but the foundation) for all 4 walls, and then either make the ceiling out of cement too or at least out of solid GG'ed 2x4's with a layer of cement stepping stones on top.
You'd have to check with an architect to ensure the wood could support such weight.
The top 2 materials for adding mass is: cement or multiple sheets of aluminium; because it's 170-200lbs per cubic foot!
Sand, glass or roofing-shingles may also work, if your in a pinch.
Or in a real pinch, solid GG'ed 2x8's might also work.

You want it a solid 8 inches of pure-mass, with a 1 or 2 inch air gap for decoupling.

Ensuring that none of this is coupled to the 2nd floor, at all.

Long story short, you'll have to sacrifice about 10 inches of ceiling height to get enough mass in there.

You need a wall Fs of ~3hz or lower to damp out the ULF, whatever that works out to be mass-wise...

That's about all you CAN do, short of going with an external structure.
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post #8 of 12 Old 12-23-2012, 06:17 AM - Thread Starter
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Austin,

thanks for replying...
Unfortunately, I will not be doing any more work from the inside of my HT Room.
If I would've known, I would've put 3 or 4 layers of DW instead of 2. Lessen learned.

My only option is now from upstairs once I rip all the floor apart. I need to see what I can do from there to at least improve my situation.

thanks again


BassThatHz,
You're so lucky to do what you are doing now. To have a HT Room outside of your home is the best.
I know exactly what you are saying and have already asked an friend who's an architect to come to my home to see if I can
pour cement on the floor...he said no way.

I have an I bean running almost in the middle of my room and it would be too much weight!
He said I could only improve slightly by decoupling the floor...I need Ted's help!

My only option is again working from upstairs OR my REAL options are either I move and restart from scratch or build an extension from my house but would make
it a bunker type extension with 10" of solid cement on all walls floor including a 10" thick ceiling.

So I guess...I'll be calling Ted to see what I can do from upstairs the help kill ULF...I'll take any amount of DB kill right now.

Many thanks to you both for your help and suggestions.

Regards,

My Build Thread
Equipment Speakers:
3x 1099's for LCR duty
4x Fusion 8's for surround duty
8x subs: 4x FTW21's and 4x SI18's
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post #9 of 12 Old 12-23-2012, 03:21 PM - Thread Starter
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OK now more confused than ever before....
Let me explain:

I'm having some fun today trying some stuff and am completely baffled on the results.
The picture below shows what I`m talking about.
I placed 4x 15" subs in the back and brought 2 of the 21's in the front corners.

1st of all it's insane the amount of bass I have now and upstairs there's WAY LESS BASS!
This is what is mind boggling to me. Why is that???

Why would adding more subs = less bass upstairs? eek.gif

Anyways here's the setup now.


thanks

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Equipment Speakers:
3x 1099's for LCR duty
4x Fusion 8's for surround duty
8x subs: 4x FTW21's and 4x SI18's
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post #10 of 12 Old 12-23-2012, 05:13 PM
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If you're really dealing with ULF - which you probably are - the amount of mass required to damp those waves is entirely impractical. This came up back in November when a thread starter said basically, "No holds barred, what does it take?" He got good technical and realistic responses from folks who know. Check out the conversation here.
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post #11 of 12 Old 12-26-2012, 04:44 PM
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Because they are cancelling out some of the bass in the vertical direction.
In theory, you could buy a DCX and 4 low-profile subs, mounting them directly to the ceiling in the 4 corners above your regular subs, and then use the DCX to add the 4 discrete vertical time-delays and invert the signal 180 degrees out of phase, and that should cancel out a tonne of the bass from the above floor.

Say 4 of these:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=297-292
with 4 of these:
http://www.parts-express.com/pe/showdetl.cfm?partnumber=300-802

You could jam them in four 12x12x4 inch boxes.

All total it would be probably around $1000.
I've heard of people doing something similar in other scenarios, but never tried it myself...
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post #12 of 12 Old 12-29-2012, 06:58 AM - Thread Starter
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BTH,

Thanks for the suggestions...I don't think I want to do any of that as a solution.

I have asked my architect friend to give me some suggestions and he basically said to add a sonobase then plywood followed by roofing paper and finally my flooring.

It'll help very little but I guess that's my only option.
thanks again for helping guys...I appreciate the help.

My Build Thread
Equipment Speakers:
3x 1099's for LCR duty
4x Fusion 8's for surround duty
8x subs: 4x FTW21's and 4x SI18's
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