advice on acoustics needed

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guitarman09

guitarman09

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Soon I will be framing a room inside my basement, which has cement floors and walls. I plan on framing the 2x4s about 16" away from the walls; to the next ceiling joist. I have a bunch of polystyrene sheathing boards, and i figure it would do the room good acoustically if i line the walls with these insulation boards. The cement walls will be a factor because i am not drywalling the room yet(lack of finances, time,...) and will most likely only insulate between the wall studs for now.

I was wondering if anyone knew anything about the sound absorbing qualities of the insulation boards i have, and if they will make a difference in room acoustics if they're covering the cement walls.

Also, what is a good but cheap way to build the floor? I was thinking of laying the 2x4s, insulating with whatever R-value fluffy fiberglass insulation fits, laying plywood, and then a carpet. Will this be fine or will i have problems with sound reflections off the floor?

any suggestions are valued.
Thanks.
 
First of all why are you framing so far from the concrete wall? Storage/access area?

Second, styrene board is a great thermal insulator but will do basically zip, zero, nada in terms of acoustical benefit. It's a closed cell foam that has no acoustical value. In addition, anything that DOES provide a benefit is going to be way overkill if you're doing all the walls in it and leaving them exposed. It will be so dead it's not even funny.

As for the floor, if you want a reasonable and easy to do solution that will cause you no issues, look for a product called Dri-Cor. Put it down first and build your walls on top of it. Good feel, no cavity resonance issues, keeps the room dry, etc.

Bryan
 
Thanks Bryan, and the reason I was planning on framing the room away from the cement walls was that i figured it would help prevent the cement walls from ruining the rooms acoustics, because the studs and insulation won't be in contact with the cement wall. The other reason was that it would also make the room more soundproofed when I end up drywalling the room.

I'm new to all of this, so please let me know if what i am saying is inaccurate.

Thanks again.
 
styrene = fire hazard
rigid fiberglass is the best thing to absorb sound, if not that then mineral wool either of which are far less flammable than styrene.
I've built a room within a room pocket studio - 6 months of research, 3 months of construction and there are still things I did not quite get right (hvac for example).If you have concrete walls, then you may not need to worry about building a room within a room ( not much gets through concrete).
Your styrene is useless, as the first responder mentioned. Great thermal properties, but useless for acoustics.
Read up at Ethan Winers website and John Sayers website. Spend a lot more time here, get some plans and good advice before you spend a dime or labor for even one hour.
Briefly:
low frequency soundproofing (people outside can't hear your drums/bass, people in your studio don't hear car stereos and airplanes) needs lots of mass (multiple layers of sheetrock, or concrete walls).
High frequency soundproofing (guitars, vocals etc) means airtight.
Airtight means lots of planning for HVAC (no holes in the walls, isolated vent systems, corked up electrical conduits, etc). Airtight also means double door systems or very heavy/well made single door systems.

Acoustic treatment inside the room means sound absorption and diffraction, using rigid fiberglass either built into the structure of the room (prettier casue it does not stick out) or panels that you will construct and place (better because you can move them around as you figure out what you need.

Sheetrock & concrete have the same acoustic properties as far as reflection - they are both hard surfaces and will reflect everything. You should get out teh elbow grease and study up.
best of luck!
Chris
 
Yup. Frame the wall 2-4" from the concrete, insulate it with standard insulation, and drywall over the top. That gives you the isolation part. Then you worry about putting the right amount of the right kind of absorbtion and diffusion in the room - 2 very different things.

Bryan
 
If you really felt you needed the extra isolation of a second wall I would consider building it inside out to save on shrinking the room in too much.

Build the wall sections with the sheetrock to the out side, stand them up insulate between the studs with mineral wool and then cover the studs with a breathable sturdy fabric (or slats) for acoustic absorption.
Otherwise you will STILL need to add acoustic panels and all that THAT involves for mounting them.

My thoughts anyway.

Tom
 
IMO that will result in a room that's WAY too dead. Having 100% of the wall surface covered in 3.5" thick 1lb fiberglass is going to completely suck the life out of the room. Not to mention how tough it is going to be to stand up already drywalled and mudded walls...

Now, if you want to do that for maybe just the corners or just up around the perimeter, that would be a good balance if isolation isn't critical (which I think it is personally)

Bryan
 
Bryan,
I agree with you for the most part.
That is why I also suggested slats.
Yes it is a pain to stand up pre sheetrocked walls unless they are sections that are not really big. At this point it is all hypothesizing because we have no Idea how he is going to want to break up the room or even how big it is. If the room is big I'd build the walls sheetrock inside, if the room is tiny you would WANT it to be dead, a small room has a horrible "live " sound.
 
Difference of opinion. I don't want any mixing room sounding like a vocal booth. Yes - small rooms require proportionately more control than larger ones - especially in the bottom end.

A friend of mine once described the effect as 'body sized headphones' which seems appropriate.

Bryan
 
Bryan,
You know, I was a bit short sighted in my answer.
I was thinking mainly of the the tracking aspect, and not the mixing.

It would be of benefit to know more before more advise is given not knowing the full picture.
If there is enough room to set up a mix area I would definitely set it up different than the tracking area. Mixing areas being symmetrical and more controlled as to reflection, but not totally dead, tracking areas non symmetrical and treated appropriately for the room size.
 
Agreed. My assumption (maybe wrongly) was that with a small space, it was either dual use or just mixing.

Bryan
 
for reference, the room is about 24'x14'x8', and i plan on using it both for recording and mixing.

Also i was thinking that since drywalling is not an option at this time, in order to prevent the room from being TOO dead, i could maybe lean some reflective materials such as plywood against the wall temporarily to liven the room up a bit

And for the floor, i was thinking of making one half pine boards (recording), and the other half something like dri-core flooring(mixing). I have read that a reflective floor such as wood sounds great for acoustic instruments, and i also like wood floors.

i appreciate all the feedback
 
Hard floor, soft ceiling works well for a variety of things. If you can't drywall right now, then I'd just make up some absorbtion panels and place them behind the monitors, beside the monitors, and at the side wall reflection points. Leave the rest relatively live for now except for the ceiling.

Bryan
 
Exactly what I would suggest.

If sound from the outside world is not really an issue right now I would kill off the entire ceiling with absorptive clouds or panels and then set up movable panels on stands or even freestanding small walls to break up the room a little. You could make a symmetrical mix area, a vocal area and a nook for hiding junk and maybe an iso box of some sort for noisy computers or amps.

Really, unless you are going to track numerous live instruments at once one big room will sound heaps better.
 
For panels, I was wondering if I could make anything out of these office cubicle partitions I just obtained for free. I have 8 of them right now, and I could possibly get many more if I wished. I'm not too sure if these could be of any use, but I figure that because they are used to absorb sound in offices, and have a very steep price tag, they're definitely worth taking for free instead of being sent to the dump.

The pieces vary from about 5x5' to 6x4'. Are these worth making panels out of? Or should I stick with 703 or 705?
 
Most office dividers are designed to work for the vocal range and higher frequencies only. You might make use of a couple of them for making a temp 'booth' but they likely have absorbtion on the outside that's 1/2" or less with a hard core.

Bryan
 
I'd definitely try them for breaking up the room. Heck you could always build 702 panels and mount them to the dividers!
 
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