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Interview with David Smith on loudspeakers

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  • Interview with David Smith on loudspeakers

    David Smith is, IMO, one of the smartest loudspeaker designers around today. While he's worked at JBL, KEF, McIntosh, Meridian, and PSB, he also ran Snell for a time. His magnum opus there was the fantastic XA Reference.

    Recently (or at least I recently became aware of it) he did an interview TNT Audio where he covered topics ranging from measurements to axial response and directivity to cabinet design to line arrays and dipoles. He's always been quite supportive of DIYers (he posts on DIYA) so his comments about DIY speaker-building should surprise nobody.

    It's the best audio-related thing I've read in 2013.
    --
    "Based on my library and laboratory research, I have concluded, as have others, that the best measures of speaker quality are frequency response and dispersion pattern. I have not found any credible research showing that most of the differences we hear among loudspeakers cannot be explained by examining these two variables." -Alvin Foster, 22 BAS Speaker 2 (May, 1999)

  • #2
    Re: Interview with David Smith on loudspeakers

    Originally posted by Pallas View Post
    David Smith is, IMO, one of the smartest loudspeaker designers around today. While he's worked at JBL, KEF, McIntosh, Meridian, and PSB, he also ran Snell for a time. His magnum opus there was the fantastic XA Reference.
    Man, it looks like he ripped off my design!
    http://techtalk.parts-express.com/sh...12#post1733912
    :D
    well, mine has a rear firing horizontally located ribbon to fill the vertical response deviation a front firing one and add ambient spice to the reproduction. It's adjustable of course.
    http://www.diy-ny.com/

    Comment


    • #3
      Re: Interview with David Smith on loudspeakers

      Now my legacy can never be innovating speaker design by attaching a giant set of asscheeks to the front of it.

      This guy is my mortal enemy.
      I am trolling you.

      Comment


      • #4
        Re: Interview with David Smith on loudspeakers

        Originally posted by r-carpenter View Post
        Man, it looks like he ripped off my design!
        http://techtalk.parts-express.com/sh...12#post1733912
        Look at the date of the review, and the date of your thread. ;)

        Cool design, though. I bet with the dome mids the horizontal coverage is very wide and even. That Paperstone stuff looks interesting, too. Is it so expensive as to entirely mitigate the labor savings from not having to finish it?

        Hearing some of his Snells made me realize the value of vertically-separated bass drivers for upper-bass performance in rooms. Same principle as multisubs, but higher up.

        PS: Not sure if Smith or Don Keele (Mr. CBT) is responsible for the buttcheeks.
        --
        "Based on my library and laboratory research, I have concluded, as have others, that the best measures of speaker quality are frequency response and dispersion pattern. I have not found any credible research showing that most of the differences we hear among loudspeakers cannot be explained by examining these two variables." -Alvin Foster, 22 BAS Speaker 2 (May, 1999)

        Comment


        • #5
          Re: Interview with David Smith on loudspeakers

          Originally posted by Pallas View Post
          Look at the date of the review, and the date of your thread. ;)

          Cool design, though. I bet with the dome mids the horizontal coverage is very wide and even. That Paperstone stuff looks interesting, too. Is it so expensive as to entirely mitigate the labor savings from not having to finish it?
          Thanks, I know I am too late for the party
          After these I realized that aside from line arrays, my general preference would be a large symmetrical loudspeaker. It fakes the virtual size of the image quite a bit nicer then a conventional point source.
          BTW I am not sure if these

          were his design but I got to rebuild/re-veneer them sometime ago and they sounded magnificent.
          http://www.diy-ny.com/

          Comment


          • #6
            Re: Interview with David Smith on loudspeakers

            Very nice interview, thanks for sharing. I love reading these interviews of professional designers.. and what's amazing to me is how similar their approach is with the diy gurus we have here

            Comment


            • #7
              Re: Interview with David Smith on loudspeakers

              I know I have spent to much time reading about vintage drivers when I know what a JBL D130 AND a Hartley boffle are......

              Comment


              • #8
                Re: Interview with David Smith on loudspeakers

                That was a really interesting read, thank you-

                This paragraph really caught my attention:

                "Cabinet construction frequently gets to the heart of audiophile beliefs and common misunderstandings. In audiophile circles, if a little wall thickness is good then a lot is always better. The physics are actually at odds with that. We need to lower the Q of cabinet resonances and higher mass or higher rigidity diminish the effect of any damping we apply. Damping is the key and we want a high ratio of damping material to wall mass or rigidity. The upshot is that thicker cabinet walls will always raise the Q of resonances and make their damping harder to achieve. Raising the resonance frequencies with more rigid walls will seldom get them above audibility, more likely they will just move into a range where they are more audible. This is at odds with many audiophiles understanding so it tends to lead to spirited arguments on the forums, but the physics is clear. "

                I may start a separate thread on it, but now I'm curious what the best method is for measuring and reducing audible wall vibrations. Around here people tend to assume that thicker, heavier, and more bracing is better. But, if it's just pushing up the natural frequency of the panel then that may not be the best way to handle it.
                Does anyone use accelerometers on panels or has quantified this phenomenon?

                Comment


                • #9
                  Re: Interview with David Smith on loudspeakers

                  Go back to the Harwood papers, which are online. Smith himself used CLD panels at Snell, first with neoprene sheet between the walls and later with a vicsoelastic damping material.

                  Also, look at the Black Box thread here. IMO, Dave Pellegrene is really onto something with his thin-wall cablnets.
                  --
                  "Based on my library and laboratory research, I have concluded, as have others, that the best measures of speaker quality are frequency response and dispersion pattern. I have not found any credible research showing that most of the differences we hear among loudspeakers cannot be explained by examining these two variables." -Alvin Foster, 22 BAS Speaker 2 (May, 1999)

                  Comment


                  • #10
                    Re: Interview with David Smith on loudspeakers

                    Great link!....thanks for a very inciteful read!

                    Comment


                    • #11
                      Re: Interview with David Smith on loudspeakers

                      Dave is known as 'speakerdave' over at diyaudio and classicspeakerpages.net.
                      Live in Southern N.E.? check out the CT Audio Society web site.

                      Comment


                      • #12
                        Re: Interview with David Smith on loudspeakers

                        Originally posted by F-Train View Post
                        That was a really interesting read, thank you-

                        This paragraph really caught my attention:

                        "Cabinet construction frequently gets to the heart of audiophile beliefs and common misunderstandings. In audiophile circles, if a little wall thickness is good then a lot is always better. The physics are actually at odds with that. We need to lower the Q of cabinet resonances and higher mass or higher rigidity diminish the effect of any damping we apply. Damping is the key and we want a high ratio of damping material to wall mass or rigidity. The upshot is that thicker cabinet walls will always raise the Q of resonances and make their damping harder to achieve. Raising the resonance frequencies with more rigid walls will seldom get them above audibility, more likely they will just move into a range where they are more audible. This is at odds with many audiophiles understanding so it tends to lead to spirited arguments on the forums, but the physics is clear. "

                        I may start a separate thread on it, but now I'm curious what the best method is for measuring and reducing audible wall vibrations. Around here people tend to assume that thicker, heavier, and more bracing is better. But, if it's just pushing up the natural frequency of the panel then that may not be the best way to handle it.
                        Does anyone use accelerometers on panels or has quantified this phenomenon?
                        I agree, that making the cabinet more dense and thicker walled will raise the resonance frequency, but what forces will cause the cabinets to ring at those higher level frequencies? Take for instance a cement wall that I hit with my fist. Will that wall ring? Yes, it will definitely ring. Will I be able to hear that wall ring with my naked ears? No, definitely not. What about if I hit that wall with a 15 pound hammer? Would the wall ring and could I hear it? Certainly the wall will ring, and some could probably hear it, but I believe most of the audible ringing would be coming from the hammer itself. Is this not like the relationship between a driver and cabinet?

                        Comment


                        • #13
                          Re: Interview with David Smith on loudspeakers

                          Great read. Thanks!
                          1: Sony DVP-S7000 | Denon DVD-2900 | Laptop > Parasound Zdac > Denon AVR-5700 > Focal 826V | Def Tech BP2000 | (2) DIY 15" Subs powered by Crown XLS2500
                          2: Computer > Schiit ‹bered Bifrost > Emotiva RCA Control Freak > Crown XLS 1500 > Focal 706V | Def Tech SM450 | Velodyne F-1000B Sub

                          Comment


                          • #14
                            Re: Interview with David Smith on loudspeakers

                            Originally posted by F-Train View Post
                            TI may start a separate thread on it, but now I'm curious what the best method is for measuring and reducing audible wall vibrations. Around here people tend to assume that thicker, heavier, and more bracing is better. But, if it's just pushing up the natural frequency of the panel then that may not be the best way to handle it.
                            Does anyone use accelerometers on panels or has quantified this phenomenon?
                            I made some tests with an accelerometer some years back. The problem is that there isn't a way to calibrate one for DIY use AFAIK. The simple act of removing and replacing it changes the response significantly. The only way I can see to use them effectively would be to attach it (it has to be stuck to the object somehow, not easily repeatable), then make before/after measurements once in place. Move it to a slightly different place and the response changes dramatically again, a combination of location and attachment. It's difficult to get any meaningful comparisons due to this.

                            dlr
                            WinPCD - Windows .NET Passive Crossover Designer

                            Dave's Speaker Pages

                            Comment


                            • #15
                              Re: Interview with David Smith on loudspeakers

                              Dave, I have used the ATB PC SW and the simple mic Meniscus offers to do cabinet resonance tests while playing a special ATB test signal similar to pink noise. Typically found blips in the 100-500 hz range. Post #18 at this link http://www.classicspeakerpages.net/I...nce#entry81067
                              shows some examples of those measurements.
                              Live in Southern N.E.? check out the CT Audio Society web site.

                              Comment

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