seeking advice from my rotel friends.

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  • basementjack
    Senior Member
    • Dec 2004
    • 191

    seeking advice from my rotel friends.

    This is a bit off topic, but I posted it in spaced out and didn't get much response, and I really feel like Club Rotel is my home, I think of all of you as family.

    I'm looking for any and all advice/resources/referals on Acoustic treatments for my listening room - DIY, Materials, theory, etc.. Especially guidelines on where in the room to place absorption for best 2 channel imaging vs home theater. Finally one more bit I'm looking for is the best thing to do to naturally smooth out the bass response in the room, I'll add an EQ only as a last measure.

    So that's what I need.

    Again it's off topic, but maybe not so much, I was convinced for two years the room needed treatment, but after I brought home my new Rotel gear, it sounds so good, I'm now worried I'm going to mess up the sound if I add treatment!

    - Jack
  • 77engineer
    Member
    • Mar 2003
    • 30

    #2
    I have not ordered anything yet but sent a room sketch to Echo Busters and they sent a sketch back with there recommendations. I don't know how good there product is but at some point I am going to give them a try.

    My 2 cents

    Adam

    Comment

    • PiDD
      Senior Member
      • Aug 2003
      • 240

      #3
      I am also interested in room treatments. I have talked to a couple places. One did an off the cuff quote of about $5000 and the other said $1200.

      First off I really believe that room treatment is one of the more important compenents for good sound... and isnt that what we are all after!

      Now the DIYer in me had to look at what can be done on the low. I also have a buddy interested in the same so the research was easier.

      Here comes the disclaimer!! I am in no way an expert.. I try to research all I can and when my comfort level out weighs my cheapness threashold something happens.

      What happened was .. I purchased acoustic ceiling tiles. The Home Depot 5/8 yellow insulation white plastic on one side type. Two boxes (16 tiles x 2), $70 ea box.

      I figured out my first reflection points using the mirror meathod and backed up with math. I put 5 tiles centered on the tweeter at the first reflection points and 8 tiles at a 45 in the corners. I just propped them up for now.

      The sound diff is not drastic but the base is more controlled and the soundstage is higher and has more depth. Thank god I didnt spend $5000!!!

      I have to take some before and after measurements to really test what im hearing... I dont want all the effort to make me hear things!

      This weekend I will make the frames and finish them and take some measurements.

      Comment

      • OakIris
        Member
        • Dec 2003
        • 80

        #4
        I don't even have a listening room, and no where to build one. I envy you folks that have a house big enough and/or partners who are understanding enough to dedicate a room to audio/HT. My problem is that my house is just too small and I have no spare room. I would love to be able to do some sort of room treatments, too, but in my combination kitchen/living room with wood floors, cathedral ceilings and windows all along 1 1/2 sides, where my audio system is located, I think I am out of luck.

        I'll keep an eye on this thread, though - and check out the Spaced Out forum - to see if there is anything that I can try. I'd have to do it "on the cheap" too.

        I do hope the rest of you find a solution for your situations. Audio nirvana, after all, is a goal we all share!

        Comment

        • greggz
          Senior Member
          • Jun 2002
          • 317

          #5
          Basement Jack,

          This is a good place to start. http://www.ethanwiner.com/acoustics.html


          Especially guidelines on where in the room to place absorption for best 2 channel imaging vs home theater.
          Optimizing a room for 2 channel AND multichannel isn’t really possible. 2-channel uses the room reflections to create the ambient envelope. With multichannel you want to deaden the room more so that the rear speakers create the ambient envelope. You'll need to pick one, and understand that the other will suffer to some degree.

          The only way to do room acoustic treatments properly is to hire a pro, which I am most certainly not. But I have been doing a lot a reading in advance of defying my own advice (I just can’t afford to hire a pro AND buy treatments). Here are some general ideas I have picked up on.

          Owens Corning 703 or 705 rigid insulation, in either 1" or 2" thicknesses is one of the most common materials used to make absorbing room treatments. (703 absorbs higher frequencies just slightly better than 705, but it is crushes easier, so if your treatments might get bumped, leaned on, or poked by curious kids, go with 705). It can be obtained from a local insulation supplier (a more specialized place than just Home Depot). Expect to pay anywhere from $0.75 to $1.75 a square foot depending on which thickness and density you choose.

          From what I have read, fiberglass is as good as or even better than foam panels. And it’s safer. Fiberglass wont burn. You’ll want to cover the fiberglass panels with an acoustically transparent fabric. Most people use Guilford of Maine FR701 fabric. Not only is it acoustically transparent, it’s also fire retardant. It’s kind of $$$. You will probably pay more for the fabric than you do for the all the fiberglass. If you want to use a less expensive fabric from your local JoAnn’s, you want a fabric that you can see light thru when you hold it up. Burlap is a good choice, but it is flammable and stinks for a good long while.

          You always want to kill the primary reflection point for your front speakers. Stick a post-it note on the front of each speaker labeled “L” “C” and “R” respectively. Then sit in your primary seat and have an assistant slide a hand-mirror along both side walls. When you can see a post-it note in the mirror, mark that spot on the wall with another post-it note. That spot is the primary reflection point for THAT speaker. You will have 3 spots on each wall you will need to mark (6 spots total). Put an absorbing panel (at least 24”w x 48”h) at each of those spots. There are also 3 primary reflection spots on the ceiling for each speaker too, but pretty low WAF when you start sticking things on the ceiling, so your call.

          If you choose to optimize for multichannel, then you will want to be more aggressive than above. You will probably want to cover the whole front wall and 1/3 of the way along each side wall with insulation (going for a live end/dead end approach for the room). One inch thick should suffice. If you are just making a few panels to hang on the wall, 2” is good, but using massive amount of 2” insulation all over the walls will over deaden the room.

          On the sidewalls adjacent to the listening position you will want some form of diffusion, or perhaps absorption and diffusion depending on your room. How much absorption vs. diffusion? Beats me, only a pro would know. On the back wall you want just diffusion. Bookshelves make good diffusers, or using wood or closed cell foam board you could try and mimic one of the diffusers designs that RPG makes. There are DIY plans on the web that people have posted.

          It may seem counter-intuitive, but the more absorption you have at low frequencies, the MORE bass you will have. Under-absorbed and you get cancellation. To absorb bass, you treat corners (note, not only wall/wall makes a corner, but wall/ceiling makes a corner too). You can use tube shaped bass traps placed in the corners, or you can make “prism-shaped wedges” by stacking strips of Owens Corning 705 insulation, cutting it, and attaching it to the walls. Different diameter tubes will treat different frequencies. For “wedges” you probably want the face be about 24” wide and 48” long. The wedge should be solid insulation, not hollow.

          Rather than go for a finished product right off the bat, I am going to buy about 150 to 200 sq ft of the rigid insulation and start putting it up on the walls in stages using T-bar pins. Put some up, take some measurements, do some listening, put some more up, repeat… Once I have figured out which placements give me the best results, I will then fabric cover the fiberglass and attach it to the wall more securely.
          Gregg

          Our Home Theater

          Comment

          • OakIris
            Member
            • Dec 2003
            • 80

            #6
            Good information, greggz. One thing I have going for me, then, is that almost the entire back wall of my "combo-room" is covered with books, floor to ceiling. The rest of my room is hopeless - can't put insulation over the kitchen cabinets or the windows, I have a wood stove in one corner so that area is out, too. Oh well - somehow the music still sounds good, so I tell myself that since I don't know how much better my system could sound in a properly set up listening room, it doesn't matter. :roll:

            It would appear that you have a good start on fixing the acoustics in your room, greggz. Hope you let us know how it turns out once everything is finished.

            basementjack - please let us know what you decide to do, too.

            Comment

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