Concrete walls

Hello all. My parents are finally taking the washer and dryer out of the basement and letting me put a studio down there (I live in an apartment). Dimensions are a bit rough because there is still a ton of stuff down there, but I think: Walls are 14 x 16’ with a roughly 7’ ceiling (floor’s not really even). There’s a bare-bones stairwell running down the side of one of the walls about halfway into the room. Floor and three of the walls are concrete and one of the walls is concrete on the lower half and wood paneling on the upper leading into a crawl-space under the front of the house. The ceiling is exposed studs and wiring and whatnot, it’s not finished. I do not want to do much in terms of actual construction because my parents may choose to sell the house at some point in the near future. Also, I’m quite busy and on a somewhat limited budget (of course). For the record, I will be recording acoustic guitar, hopefully sometimes drums, mandolin, and vocals (other instruments will be direct into the board). Also I’ll be mixing and mastering at fairly quiet levels. Right now I’m just curious about the walls, and my question is really just should I: Put up sheets of the cheapest plywood I can find with some kind of absorption between them and the wall BEFORE putting in acoustic treatment Or Just plan on spending more money and/or time on actual diffusers and absorbers and leave the actual walls the way they are. Thank you for any responses.

Avalanche Explosion wrote:

and my question is really just should I: Put up sheets of the cheapest plywood I can find with some kind of absorption between them and the wall BEFORE putting in acoustic treatment Or Just plan on spending more money and/or time on actual diffusers and absorbers and leave the actual walls the way they are. Thank you for any responses.

You should spend time finding out why you shouldn't use plywood for whatever reason you think you need to. Tell us what you are trying to do, for what reason, and what goals, realistic with real money values, you plan to implement this. Everyone is busy here too my friend, we all have day jobs ;)

Well, basically I just wanted to know if I should cover up those concrete walls before I even begin the absorbing/diffusing aspect of things, but from what you say it sounds like maybe it wouldn't even be that much better than just leaving the concrete walls. I know I didn't give enough detail, I'm just at such a preliminary/research stage that I wanted to keep it to the basic "is it ever okay to record and mix in a room with concrete walls" question. I have looked for a discussion on this but so far haven't found a thorough one, other than that there are people (obviously) who work in concrete basements. Thanks, AvEx

Avalanche Explosion wrote:

basically I just wanted to know if I should cover up those concrete walls before I even begin the absorbing/diffusing aspect of things

Not necessary. Wood, concrete, dry wall, etc - they all reflect more or less the same. --Ethan

Yes, but do they reflect EXACTLY the same? There are *so* many factors to consider. :horse:

Thank you Ethan. As long as they're close it's okay with me. That really surprises me, but it saves me a bunch of trouble!

Just me here, but I was really motivated to understand the concept behind this statement, where it comes from and what does it mean? "Put up sheets of the cheapest plywood I can find with some kind of absorption between them and the wall BEFORE putting in acoustic treatment" My curiosity is what is to be expected once this type of configuration is installed? Why "the cheapest plywood"? Why plywood? Is it for the reflectiveness of this material or something beyond that? Is it a weak attempt at mass air mass? Maybe an absorber? So many directions someone could take this...but to which your mind was on, that is my wondering.

"My curiosity is what is to be expected once this type of configuration is installed?" xSpace, this idea was largely based on just a plain old gut-instinct telling me that concrete walls--just because they're so hard, I guess--are the last thing a person wants in their studio (from an acoustic perspective). The "cheapest plywood I can find" statement was simply because I didn't want to blow my entire acoustic-treatment budget on plywood (or sheetrock or anything else like that). That said, I did also have in the back of my mind that it could be a big help in terms of low frequencies if I put something absorptive between the plywood and the concrete. I will admit, though, that this was mostly just me thinking a concrete studio is inherently bad. I can see now that I would basically just be losing space with little or no improvement to the actual room acoustics... I'm now just gonna wait until the space is all cleaned out, save my money, research acoustics, and when the time comes spend as much time and/or money as I can on absorption and diffusion. I'm guessing I'll be back for more opinions when that time comes. AvEx

Avalanche Explosion wrote:

"this idea was largely based on just a plain old gut-instinct telling me that concrete walls--just because they're so hard, I guess--are the last thing a person wants in their studio (from an acoustic perspective).

So what? A plywood panel attached on a concrete wall won't make that wall acoustically disappear! As a matter of fact, it will have insignificant effect on the reflection of that wall. You need absorbent materials like rockwool or fiberglass to absorb efficiently. Concrete wall reflects sound back in the room (and absorbs a little I guess). You have to make the wall absorb much more. And you do that with acoustic treatment like bass traps or slot resonators. For such a small room, you don't need diffusion. Cheers, John

yup, it's all hard surface and will reflect as hell (does hell reflect?) There's some good info on this site as well as on Ethan's site(s). Check that, then make up your plan. To understand is half the solution!

Ro wrote:

yup, it's all hard surface and will reflect as hell (does hell reflect?) There's some good info on this site as well as on Ethan's site(s).

Yes, hell reflects. :mrgreen: Here's the relevant article: Surface Reflectivity --Ethan

Yes, hell reflects.

Absolutely! But only from the inside. It's a one-way acoustic barrier. Anyone (and any sound) can get in, but once you're in there, you can't get out again! Outbound isolation is perfect! :) - Stuart -

Thanks for all the input, guys. I had done some research, but I can see that I've got more to do. I am curious, though, John, that you say the room's too small to benefit from diffusion. I play acoustic guitar and mandolin, and was really looking forward to a room that complimented the instruments. They sound terrible in carpeted living rooms and the like, so I was hoping to have a fairly bright room down there, but it's pretty tinny down there now and it's hard to imagine it sounding good with much absorption. I can see that this may involve some experimenting... AvEx

but it's pretty tinny down there now and it's hard to imagine it sounding good with much absorption.

It sounds that way precisely because you DON'T have any absorption down there. Your guitar is probably exciting many modes that give the room it's tiny sound right now, and you'll have dips and peaks in the room response all across the low to mid end of the spectrum. Unless you smooth those out, it is going to continue to sound "tinny", and probably "clangy" and "cavey", and maybe even "boomy" too. Among other things. In order to get the room response to be more even, you need to put in absorption, but not so much that it "kills" the room entirely. And you will probably also need other treatment, such as maybe broadband slot resonators, to keep the highs in the room. I'd start out by taking a careful look at Ethan's web site, where he has a wealth of information on treating rooms, and also use the search button on this forum, to search for things about treating live rooms. I'd also suggest that you actually measure the response of your room as it is right now, so that you can actually see where your problems are, then figure out what to do about them. Just saying that it is "tinny" can't help you very much in that area! You need to know exactly which areas of the spectrum are causing that "tinny" sound, then you can decide what you need to do about them, in order to even out the response. It might even be that what you call "tinny" is really flutter echo, which is a different type of problem that is also usually treated with absorption in small rooms, or diffusion in large rooms. But you'll never know by guessing! Ethan describes an easy way of measuring your room, on his web site, and there are several threads about that here to. Once again, the "search" feature will help you find them.

... it's hard to imagine it sounding good with much absorption.

If you ask me, it's hard to imagine it sounding good WITHOUT absorption!!!! :)

I can see that this may involve some experimenting...

Probably not! Others have already done the experimenting for you: Once you know where you problems are, there are already known treatments for them. Identify your problems, treat them, and the room will sound much better. You can experiment if you want, but why waste your time and money when the information is already available! :) - Stuart -

Avalanche Explosion wrote:

I was hoping to have a fairly bright room down there, but it's pretty tinny down there now and it's hard to imagine it sounding good with much absorption.

The conventional wisdom is that diffusors need to be far away from instruments and microphones, but I'm not so sure about that after trying some up-close experiments. Maybe this video will shed some light: All About Diffusion --Ethan

Thanks guys. I promise I'm doing my homework.