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Speaker directivity in home sized rooms (Earl Geddes)

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  • #16
    Perhaps, but symmetry is the enemy of good sound. The only thing I see that gives me pause is the tile floor, but as most of it has a rug it's probably not that bad.

    www.billfitzmaurice.com
    www.billfitzmaurice.info/forum

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    • #17
      Originally posted by billfitzmaurice View Post
      Perhaps, but symmetry is the enemy of good sound. The only thing I see that gives me pause is the tile floor, but as most of it has a rug it's probably not that bad.
      Could you elaborate on why symmetry is the enemy of good sound? It seems counter intuitive to me. I think I think that way because of seeing things like theaters, mixing rooms, home theatre setups that seem to be symmetrical and from reading in literature/papers that always seem to use a symmetrical layouts and rectangular rooms..

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      • #18
        When a room consisting of flat surfaces is symmetrical response peaks and valleys from boundary effects are exacerbated. The presence of parallel surfaces is the main reason why treatments are required. Rooms are made the shape that they are for architectural reasons, not acoustical reasons. One notable exception is Carnegie Hall. The building is rectangular on the outside, to best fit within the space available for it. Inside the elliptical shape gives the best possible acoustics.
        www.billfitzmaurice.com
        www.billfitzmaurice.info/forum

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        • #19
          If anyone is curious, Toole has those speakers upside down because they are too tall the right way up. It is really the only flaw in that design I heard when I got my ears on them a few years back. I’m in Toole’s camp in many regards, but have possibly an even higher personal preference for high levels of untreated reflections.

          My rules of thumbs are as follows:

          If you want to recreate an environment(live recordings) go narrow dispersion and over damped reflections.

          If you want the performance to be in your room(good studio mix) wider dispersion with lots of reflected information is better.

          If you prefer audio abomination of performers moving around in your skull, just about any pair of headphones will work.

          Smooth even response with less energy as you go higher in frequency (normal power response tilt) are the only hard requirements which most people can agree.

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          • #20
            In this video Toole mentions $1,800 speakers that have great off-axis curves. He has $30K of speakers in his house less a discount from Harmon.

            https://www.youtube.com/watch?v=zrpUDuUtxPM

            Do the CBT24K line arrays pull off the directivity for $1K?

            https://www.parts-express.com/pedocs...y-response.pdf

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            • #21
              Originally posted by noaudiophile View Post
              If anyone is curious, Toole has those speakers upside down because they are too tall the right way up. It is really the only flaw in that design I heard when I got my ears on them a few years back. I’m in Toole’s camp in many regards, but have possibly an even higher personal preference for high levels of untreated reflections.

              My rules of thumbs are as follows:

              If you want to recreate an environment(live recordings) go narrow dispersion and over damped reflections.

              If you want the performance to be in your room(good studio mix) wider dispersion with lots of reflected information is better.

              If you prefer audio abomination of performers moving around in your skull, just about any pair of headphones will work.

              Smooth even response with less energy as you go higher in frequency (normal power response tilt) are the only hard requirements which most people can agree.
              What I am curious about is why are FLOOR standing speakers doing on a shelf? Shouldn't they be on the floor?

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              • #22
                I tried to find Toole's opinion on CBTs. Here's a quote from Don Keele's page:

                "Inspired by this, Figure 18.21 shows a family of contours taken from the same paper (Keele and Button, 2005) but inverted, placing the loudspeaker at the ceiling interface."

                https://www.xlrtechs.com/dbkeele.com/CBT.php

                Toole also flipped the CBT upside down in his illustrations. Maybe he explains why earlier in his book.

                https://www.xlrtechs.com/dbkeele.com...%20407-409.pdf

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                • #23
                  Originally posted by Unbiasedsound View Post
                  What I am curious about is why are FLOOR standing speakers doing on a shelf? Shouldn't they be on the floor?
                  I’m guessing that the rear port is plugged, and he is using EQ to adjust the baffle step, all in an effort to eliminate SBIR issues. The shelf in the right on axis with the tweeter is really the only thing about this setup that drives me nuts.

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                  • #24
                    Originally posted by Unbiasedsound View Post
                    What I am curious about is why are FLOOR standing speakers doing on a shelf? Shouldn't they be on the floor?
                    Just because they're tall doesn't mean they have to be on the floor, so long as the tweeter is placed close to on-axis at the LP.
                    www.billfitzmaurice.com
                    www.billfitzmaurice.info/forum

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                    • #25
                      Originally posted by noaudiophile View Post

                      I’m guessing that the rear port is plugged, and he is using EQ to adjust the baffle step, all in an effort to eliminate SBIR issues. The shelf in the right on axis with the tweeter is really the only thing about this setup that drives me nuts.
                      I believe the Salon2 s have a bottom port, so in this case it's facing up.
                      Francis

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                      • #26
                        Originally posted by billfitzmaurice View Post

                        Just because they're tall doesn't mean they have to be on the floor, so long as the tweeter is placed close to on-axis at the LP.
                        So are you implying that the sound quality will be the same regardless if its on the floor or not just as long as the tweeter is placed close to on-axis at the LP? If not your whole point is moot.

                        I wonder what Revel manufacturer would say about there Salon 2 FLOORSTANDING speakers being upside down on a shelf. I guess when advertised as FLOORSTANDING most would assume its meant to sound its best when on the floor but hey I am no expert here. LMAO

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                        • #27
                          If someone has Toole's book they can see if he has an explanation for placing speakers on the ceiling. I don't have his book.

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                          • #28
                            I have his book, but didn’t see any reference to his personal system in there. As long as they didn’t do any weird lobe steering the speaker should sound the same, outside of boundary interactions, like floor bounce and SBIR.

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                            • #29
                              Originally posted by bradley.s View Post
                              If someone has Toole's book they can see if he has an explanation for placing speakers on the ceiling. I don't have his book.
                              Yeah, it says right here that when your wife is tired of all your speaker crap all over the floor, that it's ok to put it on a shelf.

                              That room is not what I'd call an ideal acoustic setup, even industry big wigs have to make compromises to work with the space they have.
                              "I just use off the shelf textbook filters designed for a resistor of 8 ohms with
                              exactly a Fc 3K for both drivers, anybody can do it." -Xmax

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                              • #30
                                I posted this earlier in the thread but I'll repost for clarity. Toole took Keele's/JBL's CBTs and placed them on the ceiling. See page 408. Toole doesn't say this is application specific to the CBT. Keele's CBTs didn't have tweeters in the JBL test design. So I don't think Toole placed the CBTs on the ceiling for the sake of tweeter placement. (Maybe Toole did for his personal home with the Salon2s, but I doubt that's his reasoning with Keele's CBTs.)

                                It's weird that he'd put the CBTs on the ceiling without explanation. That's why I think he must have talked about this type of placement elsewhere in the book.

                                https://www.xlrtechs.com/dbkeele.com...%20407-409.pdf

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