newbie design

[vair327]

Hello

I thought I would share a design I was think of building.
The black walls are ext and the green would be int with a 6 in air space. The int walls will be double faced with sheet rock. I have not decided on the ext walls cinder block would be cheaper, then say 2x6 wood frame, and from all the data I have seen pretty good a stopping sound. The live room and the control room would both float on a concret slab.

Any thought would be welcome,

Don't shoot I am still learning.

[knightfly]

No shooting, the use of blunt objects releases more frustration...

Welcome; I'm assuming you've read the topmost announcement in this forum and followed the recommendations;

The other thing is, not everyone here (myself included) uses SmartDraw; so it would work better if you could ALSO post a .jpg of your drawing directly to the board. Just make sure it's under 150k, and you should be good to go... Steve

[vair327]

Sorry, here is a jpeg of the layout. Note that this drawing does not have any sound treatments in any of the rooms.

The wall next to the garage will most likely be don away with.

[knightfly]

Layout looks OK, you may want to build a movable "gobo" of thick fiberglass, no back, to put behind the mix position during mixdowns so that irregular rear area won't unbalance things.

If your concrete block is not filled with either mortar or sand, then adding more air space and gypsum will make 3-leaf walls - slightly better for mids, but WORSE for low frequency isolation. You want to optimise the Lows, then the mids/highs will already be isolated enough.

Those are the main things I see... Steve

[vair327]

So should I not go with two seperate walls ( room in a room) and go with a heavy mass single wall. Like 2x6 sill, staggered 2x4 studs, 3 layer ext (3/4 mdf an two lyers of 5/8 sheet rock), and 3 layer int (2 layers of 5/8 and 1 of 1/2 sheet rock with insulation in the cavity. What about the floor? Should I still float it, and how do you isolate it from the walls?

[knightfly]

"Welcome; I'm assuming you've read the topmost announcement in this forum and followed the recommendations" - from my previous post; the first 2 or 3 threads in the REFERENCE section, which that top post guides you to, should answer most if not all your current questions and probably generate a few dozen more... Steve

[vair327]

My wall design.


Any thoughts?




Sorry for the repost but I thought I was in this message when I posted.

[sharward]

(Reposted from other thread)

Greetings, fellow Sacramentan!

Hey, you're definitely onto something... Hopefully my own garage conversion project has inspired you in some ways.

I'm not the math whiz here (Steve doesn't think he is either, but trust me -- he's better than that for which he takes credit!), but given the similarities between your specs and mine, I'd say you're probably looking at an STC range of somehwere in the 70s -- a tough nut to crack indeed!

However, you may have learned here already that STC, while a useful yardstick for many soundproofing applications, is arguably of limited value in terms of studio construction, where in most cases, low frequency transmission loss (a.k.a. "low TL") is the deciding factor: address the need to contain boomy bass, and the high end will generally obey.

A couple of things that I learned here as my plans matured: with mass-air-mass (aka "M-A-M"), you get better results when you increase the size of the air pocket between the leaves. Steve told me that you get the most bang for your square footage buck at about 12" -- more is better, but the benefit is less pronounced with the additional inches. In other words, if you can afford to sacrifice about a foot between your leaves, you'll be paid back in spades for the loss. Note that "between your leaves" does not mean "between your frames -- if you're using 2x4 double-wall construction, you only need 5" between frames to achieve a foot of separation, since each frame is 3 1/2" thick.

I'm impressed with your 4" of floated concrete. DAMN! I was a little freaked out about floating concrete, hence my decision to use clay bricks instead: virtually the same amount of mass, plus the added benefits of having the "luxury" of doing the work myself, having some level of flexibility later in case I need to break through it, and finally, what I believe will be a really cool looking finished surface -- not to mention the money I save by not having to lay laminate or carpeting. Plus, if I hate it, I can always put a REAL floor on top of it.

I mentioned it in a private message earlier, and I'll renew the offer here -- I'm more than happy to sit down with you in person to go over my plans and review yours. While I'm not an expert by any means, I may be able to point out trouble spots or areas that you may wish to explore more on your own. However, fair warning -- if you decide to visit during any of my construction efforts, you just might be wearing a tool belt before too long!

Finally, you may wish to move your post to the thread you already started in this forum (entitled "newbie design"), just to keep everything in one place. It helps everyone here follow your project from concept to completion.

--Keith

[vair327]

The floor as per Kinetics web site will yield a TL of 70 which is good I have heavy feet and two bass drums.

I figure that the concrete will be easier for me, I can do the form work and the pouring and I have someone finish it for me. I was not looking forward to all that cutting for all the feet and the joists and the blah blah....yuck to much like work for me.

The R.I.M setup is expensive, but you just role it out, put a 1/2 inch sheet of ply over it an tie the sheets together with the supplied ties, lay down a 6 mil plasit sheet over the ply, set in some reinforcement, make your form and pour.

[knightfly]

Sorry, just caught your comment about all layers of sheet rock glue together - No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No No -

Just in case I didn't make that clear; I don't think that's a very good idea...

OK, now an actual REASON

When you place multiple layers of mass against each other but do NOT glue them, they retain their individual characteristics for the most part; one of those is their "coincidence" frequency. This is, for all practical purposes, that material's RESONANT frequency, and at that frequency the material will be WEAKEST in its ability to stop sound (Transmission loss, or TL) - If you instead GLUE the multiple layers together, you get closer to the resonant frequency of one, THICKER, piece of that material.

In the case of gypsum, 5/8", or 15mm, gypsum has a coincidence of around 2500 hZ - 15/8", (3 layers) or 45mm, has a coincidence of around 800 hZ - both "dips" (this phenom is called the "coincidence dip") cause a drop in TL of about 7-8 dB at coincidence.

The lower in frequency this "dip" occurs, the closer it gets to the harder-to-stop bass frequencies, and so the more audible its effect on wall performance.

There is also some speculation that three individual layers of the same material, since each would be slightly different in flexibility, may spread this coincidence dip a bit in frequency; no proof here, just speculation on the part of some very experienced friends of mine...

Brian Ravnaas, a prolific poster on several acoustics related sites, is involved with a company making "green glue", a very highly damped inter-layer adhesive that is said to improve wall performance when gluing multiple layers together; however, if this is done at all it should (IMO) ONLY be done to ONE side of a wall (one leaf, not both) and possibly, in the case of 3-layer construction, ONLY between 2 of the 3 layers.

The UP side of gluing is that it will increase stiffness, which arguably can help LF performance - the DOWN side is, you're putting all your eggs into ONE basket (only ONE coincidence frequency for that leaf) AND, because of the increased mass, you're also LOWERING that frequency closer to the bass range.

Bottom line is, if you're trying for best bass containment you should use multiple layers NOT glued, heavy mass, wide air gaps, tight caulking, full insulation fill for best damping of surfaces.

BTW, I'm short of time for this but you might check the kinetics site to see if that 70 dB figure is STC; I have a feeling it is. If so, your LOW end isolation using the RIM system won't be as good as if you set your slab on 2x6's over EPDM with fiberglass or rockwool fill - the increased air gap will do wonders for the lower range isolation, in combination with the weight of 4" concrete (approx. 48 PSF excluding the plywood)

Remember, STC is a VOICE isolation system, centered on 500 hZ; for drums/bass, the TL at 50 hZ or so is 'WAY more important, so you need to calculate individual TL values instead, and bias your choices toward LF performance... Steve

[bert Stoltenborg]

Hey Steve,

Just a thought about vair's very promising control room:

I cannot read the dimensions in the drawing, but isn't his back wall a bit far from the mixing position? I guess it shouldn't be to far to prevent from delayed reflections.

Bert

[knightfly]

Hey Bert; if it's to scale, looks like the mix position's about 33% back from the front wall; that would put ears in neither a peak or null AFA Axial modes go; and for the others, there's no way in hell I'm gonna calculate for a splayed room and try to lie my way out of it Steve

(Also, looks like that CR might need a couple Gobo's on the sides for Early reflections as it's laid out.)

[bert Stoltenborg]

What I mean is that you shouldn't be away more than 20 msec from the back wall, = 3-3.5 meters.

I can see his dimensions

Must be my eyesight, I'm not the youngest anymore, heheheh...

[knightfly]

20 milliseconds is the approximate point where the brain can detect a distinct echo, as opposed to just "mixing it" with the rest of the crap; "Mixing it with the rest of the crap" will cause phase cancellations/comb filtering, so any path between speaker and ear that isn't AT LEAST 20 milliseconds LONGER than the DIRECT path (between speaker and ear), needs to be absorbed (like Sidewall early reflections, and any rear wall reflections if the path is too SHORT -

With that much depth, though, I'd think about some diffusion on that "office" wall, if it's not heavily absorbed... Steve

[vair327]

So if I understand you reply right you really don't what me to glue the sheets together.

I have removed the office, and added treatments I think .