sandbags/ faux floated floors

[shaneoconnor]

so what if.....

i wanted to do something to the cheap for my live room floor.

say, build an 8" subfloor, but i cant do some concrete kind of floating floor ($$/ building will probably fall over)

would a layer of sandbags be conprable? with some subflooring over it.

my main issue is bleed for the studio next door (owned by mission of burma... so low end travels...)

thoughts?

[staudio]

You don't need to pour a floating slab to build an isolated floor. Rubber isolation mounts are the typical thing for floating a wood sub floor. Place one every foot or two depending on the weight load, lay the floor joists vertically on the pads, secure with crosspieces and you have a floating sub floor.

[shaneoconnor]

with just floated subfloor, would i get rejection from like 150hz?

i have low end rumble issues. so thats why i was suggesting having a mass in there.... like sand bags.

[Weasel9992]

Originally Posted by shaneoconnor

with just floated subfloor, would i get rejection from like 150hz?

i have low end rumble issues. so thats why i was suggesting having a mass in there.... like sand bags.

It really depends on the specific nature of the problem. If it's traffic noise, then just isolation mounts will help a lot. If it's train or something right outside your back yard then it might be so effective. The really intense, really low stuff is *very* difficult to eliminate entirely...better to just avoid the problem altogether.

Frank

[nosebleedaudio]

The rubber U bolts work very well, used them many times with very good results.
Will still need everything to be sealed up..
It all depends on what, where, how...

[jwl]

For a floated floor to be effective at lower frequencies, it needs 2 things: first, mass; and second, correct decoupling from the sub-floor below.

Generally, it's difficult to get wood floors to be massive enough to provide isolation at very low frequencies. And, once you get the mass high enough (filling a deck with sand is about as close as you can get), then you have to make sure it is correctly decoupled by using the right number of neoprene (or whatever material you choose) pucks. One of the problems with the Auralex U-boat is that they don't provide specs for the material, so there is no way to tell how much mass you need to get them compressed enough (but not too much) so that they actually do provide isolation.

I recommend this thread on the Sayers forum for more detail on this.

[Weasel9992]

It all depends on the specific nature of the problem. If it's extremely low end stuff (like that train I mentioned a couple posts back), then what you're proposing won't be the total solution. The total solution would require a much more extensive construction effort which might be much more trouble than the space is really worth. Better to find a new space in that case, which is what I meant by "avoid the problem to begin with".

If the problem really is 150Hz kind of stuff, then you probably will get good enough results to make the room useable for your purposes. It still won't be perfect, but you have to ask yourself if "perfect" is what you're really shooting for. "Usable" might be exactly what you want.

Frank

[avare]

I hope you have read the link JWL provided. With everything I have gathered from your posts, if you need an effective floating floor, it is out of your budget range.

Warning, techy talk! The big problem with most wood floating floors on pucks or boats is that the MAM frequency is still in the range where isolation is required. IOW words it makes no difference what the top is isolated with, because the floor will still resonate at the frequency determined by small gap and light weight of the floor.

Resonantly,
Andre

[Weasel9992]

Originally Posted by avare

I hope you have read the link JWL provided. With everything I have gathered from your posts, if you need an effective floating floor, it is out of your budget range.

That's kinda what I was getting at too.

Originally Posted by avare

Warning, techy talk! The big problem with most wood floating floors on pucks or boats is that the MAM frequency is still in the range where isolation is required. IOW words it makes no difference what the top is isolated with, because the floor will still resonate at the frequency determined by small gap and light weight of the floor.

Resonantly,
Andre

"Resonantly"...that's awesome Andre.

Frank

[nosebleedaudio]

Originally Posted by avare

I hope you have read the link JWL provided. With everything I have gathered from your posts, if you need an effective floating floor, it is out of your budget range.

Warning, techy talk! The big problem with most wood floating floors on pucks or boats is that the MAM frequency is still in the range where isolation is required. IOW words it makes no difference what the top is isolated with, because the floor will still resonate at the frequency determined by small gap and light weight of the floor.

Resonantly,
Andre

Would disagree with the space part, your decoupling the vibrations, I use Sorbothane on speaker stands all the time, same thing, very little vibrations are coupled.
And you still need the mass thing as well.

[avare]

Originally Posted by nosebleedaudio

Would disagree with the space part

If acoustics was intuitive, we would not have so many well meaning disasters made. To show the effect of gap the attached jpg is from IR 586.

It shows the transmission loss (TL) of three walls. All three walls have in common 190 mm (8") concrete block. The lowest line is for the concrete block bare. The middle line has gyproc attached with 50 mm (2") z bars and the cavity filled with glass fiber insulation. The top line has the same layer added on both sides of the block. So far it looks like anyone would assume. That is the more material and layers, the greater the TL. The low frequency range shows the opposite. The more layers, the less TL at the (you guessed it) MAM resonance. At 80 Hz the TL is reduced by 12 dB!

You may be thinking that the dip is due to the z bars. The second jpg is from IR 761. The construction is double stud with 16 mm gyproc, one layer on one and two on the other, and insulation in the cavity. The dip at 63 Hz is the MAM resonance.

I use Sorbothane on speaker stands all the time, same thing, very little vibrations are coupled.

There is no doubt that you are getting an improvement of sorts. The big difference in the applications here is that what you writing abut is with correlated noise (meaning unwanted sound) that is pleasant as in more of the wanted sound, whereas with the floor the noise is unrelated. Imagine recording a ballad with a different rhythm coming from the floor!

I don't recall which studio it was, but there was a famous studio complex built in Hollywood, where the walls had to torn down and rebuilt because the bass from one studio would leak into the adjacent studios and musicians had difficulty maintaining the rhythm of their music.

Quietly,
Andre

[nosebleedaudio]

This is not what I was referring to, example: a studio I designed a while back had a very large compressor outside the building, the low frequency vibrations on the motor/compressor was getting thru via the bedrock.
I simply put rubber pads under the compressor frame and the low frequency went away.
This was Not the sound of the conpressor but the vibrations if produced.

[avare]

Originally Posted by nosebleedaudio

This is not what I was referring to, example: a studio I designed a while back had a very large compressor outside the building, the low frequency vibrations on the motor/compressor was getting thru via the bedrock.
I simply put rubber pads under the compressor frame and the low frequency went away.
This was Not the sound of the conpressor but the vibrations if produced.

Thanks for the clear statement about what you are referring to.

Originally Posted by SHANEOCONNOR in the first post in this thread

my main issue is bleed for the studio next door

This thread is not about mechanically coupled vibration or point sources.

Acoustics is arcane enough without the vagaries of impromptu posts.

Andre