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Placement of the speakers in the room

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  • Placement of the speakers in the room

    Hello Everyone!

    Could some one please elaborate on Roy F Allison's law of speakers placement? Does it really work?

    I don't have permission as yet to post attachments. Whenever I do, I would wish to post some PDF files on this topic, for members to throw a little more light on his theories.

    Thanks

    Olivia

  • #2
    Re: Allison's Law

    Welcome. You should be able to post if - as must be the case - you have replied to the Welcome email to open your membership account here. There is a maximum file size size for attachments.

    I don't know much about the "law" of speaker placement but from my own experience of the real world of audio in the home, I think that it would be surprising if a generalised rule would work-out precisely and in all and every room. In addition, it is quite remarkable what the ear will tolerate. Maybe it wasn't really a law, but has been taken as such?

    Certainly we should understand the basis of his concept. I wonder if it applies to stand mounted speakers and/or tower speakers?
    Alan A. Shaw
    Designer, owner
    Harbeth Audio UK

    Comment


    • #3
      Re: Allison's Law

      I believe the "rule" goes something like this.

      From the center of the woofer, measure 3 distances:

      1. The distance to the floor;

      2. The distance to the wall behind; and

      3. The distance to the side wall.

      The goal is to multiply the shortest and the longest distances and have that equal the other distance squared.

      If this is possible for you to do logistically in your room, it's a good place to start to see if the bass response is indeed relatively smooth. (Obviously, if possible, don't be afraid to experiment with speaker placement.)

      Comment


      • #4
        Re: Allison's Law

        Here are some technical notes behind the Allison's law.
        Attached Files

        Comment


        • #5
          Re: Allison's Law

          Hello Everyone,

          Has any one had any experience with speaker placement using this "Law"

          If so, could someone please share their experiences?

          Thanks!

          Olivia.

          Comment


          • #6
            Re: Allison's Law

            Hello Folks,

            I am trying to come up with a logical start point as to the most optimum speaker placement, assuming that:
            • The rear wall is properly treated ( with a book case filled with books facing outwards perhaps....I believe that was Alan's recommendation)
            • The speakers are 2 meters apart
            • The tweeter, is positioned just below the middle of the ear.

            If we apply the "Golden Room Formula", which states that if "X" is the smallest dimension (length or breath or height), the second-largest room dimension may be "1.25 X", and the largest dimension may than be "1.6 X.". So if we assume the Ceiling height as 3.00 meters, the width of the room as 3.75 meters & the length is 4.8 meters.

            If we than go by the "Third Part Rule" we have could place the speakers 2 meters apart, with a slight toe-in, at the point which is the third of the room, along the length.

            Hence at 1.60 meters, if we place the speakers 2 meters apart and than apply S.A.B.'s advice on Allison's Law, we have:
            • The distance from floor to speaker (middle of woofer) as 0.48 meters.
            • The distance of the speaker to wall behind is 1.60 meters
            • The distance of the speaker to the side wall is 0.88 meters.

            This is based on the fact of multiplying the shortest and longest lengths(0.48 times 1.6) and having it equal to 0.88 squared.

            Am I right with these calculations as a good starting point ?

            Any advice would be greatly appreciated!

            Thanks,

            Olivia.

            Comment


            • #7
              Re: Allison's Law

              You mention distances ...
              • The distance from floor to speaker (middle of woofer) as 0.48 meters.
              • The distance of the speaker to wall behind is 1.60 meters
              • The distance of the speaker to the side wall is 0.88 meters.

              In reality, 2 x 0.88m is almost 1.6m (give or take a little). Also, 3 x 0.48m is approximately 1.6m.

              Is there not a danger of trying to be too precise about mm perfect positioning of the speakers when in reality, even these scientific rules result in path lengths that are near multiples of each other, which common sense says should be avoided?

              I've always believed that optimising a speaker in a room needs nothing more than a willingness to experiment and to listen......
              Alan A. Shaw
              Designer, owner
              Harbeth Audio UK

              Comment


              • #8
                Placement ideas for a 7.5 x 5 meter room

                Hello:

                I just recieved the 40.1s today and before I start experimenting, I thought I'd see what you have used that works and get a suggestion or two.

                My room is 7.5 x 5 meters, with the speakers on the long wall. All gear is off to the right side of the room against the wall. The only thing between the monitor 40.1's on Skyland stands is a CJ Premier 350 amplifier on a finite elemente platform.

                Right now I have the speakers about 2.5 meters apart, about 1.5 meters from the rear wall and my listening position is about 3.5 meters from the speakers. Honestly, I unboxed them and just threw them out in the room so they could get some hours playing.

                Definitely open to your thoughts.

                The room is treated with GIK panels and GIK TriTraps in all four corners.

                Even just at this point, the 40.1s are sounding quite good!

                Comment


                • #9
                  Re: Placement ideas for a 7.5 x 5 meter room

                  Congrats on your new M40.1's! I have the M40.1's as well, but in a room much smaller than yours (11' x 17'). Placement of the speakers on the long wall versus the short wall will likely give very different results.

                  For a great description of the general differences, see member Keith's posting at:

                  http://www.harbeth.co.uk/usergroup/showthread.php?t=505

                  Your room is wide enough that you can place the speakers on the short (5 meter) wall, thereby getting the great 3D imaging that setup provides while still having enough space from the 40.1's to the sidewalls.

                  However, every room is different (they're like snowflakes!) and there is no substitute for experimenting with both setups.

                  If you can do this, you should try sitting much closer to the speakers (5-6 feet). The 40.1's really come alive in a nearfield listening setup! You'll also hear more of the direct sound of the speakers and less of the room sound.

                  Good luck and keep us posted!

                  Eric

                  Comment


                  • #10
                    Re: Placement ideas for a 7.5 x 5 meter room

                    Hello Eric,

                    Now you have M40.1? Congratulation! Still use Quad Combo to drive M40.1?

                    Happy listening!

                    Hu

                    Comment


                    • #11
                      Re: Placement ideas for a 7.5 x 5 meter room

                      Took your advice and moved the speakers in a bit closer and moved the couch up about a meter.

                      Much better!

                      I am really enjoying these speakers!

                      Comment


                      • #12
                        Re: Placement ideas for a 7.5 x 5 meter room

                        Hi Eric,

                        I have a room that is 11' x 16' , so very simalar to yours. Would you be willing to share how you have yours set up with the 40.1? Are you using any room treatments? What kind of amplification are you using?

                        Thank you,
                        Don

                        Comment


                        • #13
                          Re: Placement ideas for a 7.5 x 5 meter room

                          Originally posted by tonepub View Post
                          Hello:

                          I just recieved the 40.1s today and before I start experimenting, I thought I'd see what you have used that works and get a suggestion or two.

                          My room is 7.5 x 5 meters, with the speakers on the long wall. All gear is off to the right side of the room against the wall. The only thing between the monitor 40.1's on Skyland stands is a CJ Premier 350 amplifier on a finite elemente platform.

                          Right now I have the speakers about 2.5 meters apart, about 1.5 meters from the rear wall and my listening position is about 3.5 meters from the speakers. Honestly, I unboxed them and just threw them out in the room so they could get some hours playing.

                          Definitely open to your thoughts.

                          The room is treated with GIK panels and GIK TriTraps in all four corners.

                          Even just at this point, the 40.1s are sounding quite good!
                          Hi,

                          Congratulation for the new M40.1. Pls post some pictures of your set-up.

                          Happy listening

                          Comment


                          • #14
                            Re: Placement ideas for a 7.5 x 5 meter room

                            Yes Eric I'd also very much like to see pics of your 40.1s on the foundation stands? Do you still have the M30s? I'm also hoping that Tonepub is Jeff, creator of the brilliant Tone audio, and If so we can all hopefully soon enjoy ( for free!) what will definitely be the best review so far on these great speakers.

                            Comment


                            • #15
                              Re: Placement ideas for a 7.5 x 5 meter room

                              I promise to send pics of my setup in the near future, but I may be changing my setup soon to the long wall. Unfortunately, a challenging new job and my elderly mother's move have cut drastically into my music/audio time lately.

                              I still do have the M30's. I should sell them, I suppose, but just haven't got around to doing that either. Then there's thoughts of using them in a surround sound setup...

                              Comment

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