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making a all concrete room........

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  • making a all concrete room........

    I'm attempting to make an all concrete room into a studio. I need some basic info on CHEAP ways to deaden the walls. I have little experience in this area and totally appreciate any and all suggestions. A guy I once knew used empty egg crates to deaded a sound stage--is sounds wacky but it worked! Thanks
    LOVE stinks!

  • #2
    I have all concrete rooms - purpose built with non-parallel walls and sloped ceiling. With no treatment, the reverb was scary - especially the low end. You are definately going to need bass trapping - and if you are unfortunate to have parallel walls and less=than-ideal dimensions (e.g. square room or 1:2 ratio), it will have to be good. There are several methods of killing bass frequencies (the muddy room sound that is hard to kill). Absorbtion: foam or fibreglass needs to be positioned close to the 1/4 wavelength of the frequency. Bass frequencies have long wavelengths, so the foam needs to be several feet away from the wall to work. The least effective place is directly on the wall, as this is where the wavelength is zero velocity/maximum pressure. Diffusion: you can help disperse bass by reflecting it back in all different directions. The dimensions need to be in feet, not inches, so egg carton-type patterns aren't useful. Large convex surfaces are good for bass diffusion. Panel absorbers work well - think of thin panels acting like a kick drum. I use a combination of all methods that is very cheap and effective: thin panels, bent into a convex, and mount in the corners (where all 3 room nodes meet). I mounted mine with verticle aluminium right angle channel, screwed to some 2"x4" timber on the walls. I used rubber along the length of the panels, and fitted the panel into the channels so the panel can flex easily. Behind the panel, I mounted 4" foam, which sits behind the 2"x4" so it doesn't touch the panel, but is held firmly away from the wall, also bent into a convex. I put handles on the panels for easy access (these things also cover up my cabling between rooms). Painted purple, they look really funky, and they suck all the problem low end away like nothing else. I also use 4" foam strategically stuck to walls to control the highs & mids. For your experiments - try bringing some foam mattresses into the room, and try placing them in different areas. I think you will find that - apart from in the very middle of the room where they are most effective, you get the best results in the corners.


    • #3
      If you don't know what you're doing, don't build your own concrete forms...

      Well, I've been to one world fair, a picnic, and a rodeo, and that's the stupidest thing I ever heard come over a set of earphones.


      • #4
        Since I'm just in the planning stage your feedback is greatly educational and appreciated. The room I have is approx. 10x16..its previous purpose was a cistern for collecting water,sooo... I'm trying to use the space to build a studio. The echo is incredible....the ideas about the 4" foam will be used as I have a good cheap source for foam.I'm cosidering using some carpet on some of the walls as well. Back to the drawing board
        LOVE stinks!


        • #5
          Carpet might be ok on the floor for convenience, and to kill flutter echo if you have parallel ceiling. However - carpet is an acoustic nightmare and best avoided. Ever seen a picture of a pro studio with carpet on the floor? The reason is that carpet (or any thin absorbant material) will kill the high frequencies, and do nothing to stop the mids and lows. If you have messed with a digital reverb, you will know that the nicest reverbs are not muddy - in other words the lows and mids are nicely controlled, and the highs linger a little longer. If you have a bare concrete room, you will have a full range, bass heavy reverb that will suck. Carpet on the walls will kill the highs, which are probably the only part of the reverb tail that don't suck. You will be left with just the mud. This is why I would build some bass traps first, and then any absorbant on the wall will need to be as broadband as you can afford (I find 4" foam to be the minimum acceptable - 12" would be good).