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Home/Pro 8" 2-way: RS28A and B&C 8BG51

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  • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

    Originally posted by davepellegrene View Post
    I had to cancel last minute. My new boat was being delivered to my house Friday evening just before the ice/ snow storm so I had to be there to shoehorn it through my garage door when it arrived. Being 5 hours away in good weather there was no way I was going to be able to make it.

    I'd really like to hear your method. Do you think you will have a right up soon? I don't want to bother you because I'm sure you have more emails to answer then you want to already.

    Dave
    I DO get a lot of emails ;) But it's more the holidays and the family coming from out of town that will keep me from working on it right away. Hopefully, after the first of the year things will settle down and I will be able to pull the paper together. (Stereophile could learn a lot from this too, their method of presenting spliced data always give an incorrect response curve. JA admits that, but doesn't do anything to fix it. )
    Jeff
    Click here for Jeff Bagby's Loudspeaker Design Software

    Comment


    • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

      Originally posted by [email protected] View Post
      Curious if you ever got close to exceeding xmax during your jam session? 6.5mm. Like the idea of a Tapered TL
      Is there enough inductance in the crossover to wire two of these in parallel with a RE of 5.1?
      There are a few tracks where I have no doubt crested the Xmax limit, but it does so very gracefully. I've not heard any signs of overt distress. "Nevermind" from Infected Mushroom's Army of Mushrooms has prodigious bass levels and causes a lot of movement on that woofer. Another CD that digs really deep repeatedly is Yello's "Touch." The bass performance of this woofer is really excellent.

      As they stand right now, I've probably got about .4 Ohm series resistance (I removed the second inductor on the woofer). Using an air core inductor with a pair in parallel would keep the total impedance at right around 4 Ohm according to sims I've done in PCD. Currently, there are a total of 7 components in the crossover.

      The dip Dave mentioned in the response seems room related. I took a measurement from .5m and only saw a slight indication that a dip was forming.
      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

      95% of Climate Models Agree: The Observations Must be Wrong
      "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

      Comment


      • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

        OK, here's the latest update with the current crossover and a set of distortion plots showing the lousy noise floor in my room.

        blue is 2nd harmonic, green is 3rd.

        Click image for larger version

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        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

        95% of Climate Models Agree: The Observations Must be Wrong
        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

        Comment


        • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

          I wonder which would fill a big room or be heard outside from inside. This or the Tempest build.
          " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

          Quote Originally Posted by hongrn. Oct 2014
          Do you realize that being an American is like winning the biggest jackpot ever??

          http://www.midwestaudioclub.com/spot...owell-simpson/
          http://s413.photobucket.com/albums/pp216/arlis/

          Comment


          • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

            Originally posted by [email protected] View Post
            I wonder which would fill a big room or be heard outside from inside. This or the Tempest build.
            The Tempest has a 12" pro-woofer and 98 dB sensitivity. It can play REALLY loud.
            Click here for Jeff Bagby's Loudspeaker Design Software

            Comment


            • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

              Originally posted by [email protected] View Post
              I wonder which would fill a big room or be heard outside from inside. This or the Tempest build.
              A little anecdotal evidence . . . I had that Infinite Mushroom song going the other day for my daughter's boyfriend. The 120W amp was self limiting, meaning it was probably clipping often enough to cause it to shut off momentarily. There was no hint of strain on the speakers, and they were shaking the floor quite a bit. No doubt these can be heard outside when playing inside. And they'd have no problem filling a large room with clean sound and a proper power amp to deliver the peaks. In my 18' x 15' living room, they'll crest 105dB average levels at the listening position with this 120W amp, louder than I would normally listen for extended periods for sure.
              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

              95% of Climate Models Agree: The Observations Must be Wrong
              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

              Comment


              • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                OK, here's the latest update with the current crossover and a set of distortion plots showing the lousy noise floor in my room.

                blue is 2nd harmonic, green is 3rd.

                [ATTACH=CONFIG]43415[/ATTACH][ATTACH=CONFIG]43416[/ATTACH]

                [ATTACH=CONFIG]43417[/ATTACH]
                What distance and SPL do you take you distortion measurements? I guess what I'm asking at roughly what SPL do you see it start to rise?

                I use to take distortion measurements at lower volume with a close mic distance. I've changed to about one meter and I run the volume up higher. I think it gives more realistic measurements.

                Dave
                http://www.pellegreneacoustics.com/

                Trench Seam Method for MDF
                https://picasaweb.google.com/101632266659473725850

                Comment


                • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                  Originally posted by Jeff B. View Post
                  The Tempest has a 12" pro-woofer and 98 dB sensitivity. It can play REALLY loud.
                  How do they do full range? Ok without a sub?

                  Dave
                  http://www.pellegreneacoustics.com/

                  Trench Seam Method for MDF
                  https://picasaweb.google.com/101632266659473725850

                  Comment


                  • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                    Originally posted by [email protected] View Post
                    I wonder which would fill a big room or be heard outside from inside. This or the Tempest build.
                    I'm sure both could handle that and sound great doing it. But the 2 models are quite different. 8" pro woofers get loud. 12" pro woofers get really.....really loud.

                    Comment


                    • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                      Originally posted by Erich H View Post
                      I'm sure both could handle that and sound great doing it. But the 2 models are quite different. 8" pro woofers get loud. 12" pro woofers get really.....really loud.
                      The biggest difference between the two builds would be that the 12" version would play as loud as the 8" version using only 1/10th the power.

                      This one does reach below 40Hz in-room, so a sub would be optional for most music.
                      R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                      Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                      95% of Climate Models Agree: The Observations Must be Wrong
                      "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                      Comment


                      • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                        Originally posted by davepellegrene View Post
                        What distance and SPL do you take you distortion measurements? I guess what I'm asking at roughly what SPL do you see it start to rise?

                        I use to take distortion measurements at lower volume with a close mic distance. I've changed to about one meter and I run the volume up higher. I think it gives more realistic measurements.

                        Dave
                        That's a 90dB reading at 1m. It rises with more power in a fairly linear fashion. I posted that earlier with a series of plots at 5dB increments.

                        Distortion only started hitting 1% when I was hitting it with approximately 20W input levels.

                        All of this will be revisited after everything is finished. Ryan's got a room that has a 30dB noise floor, so I'll be able to get some very nice distortion readings at 1m and not have to do them close mic. These plots should only look better in the quieter environment.
                        R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                        Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                        95% of Climate Models Agree: The Observations Must be Wrong
                        "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                        Comment


                        • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                          Originally posted by davepellegrene View Post
                          How do they do full range? Ok without a sub?

                          Dave
                          That was one of my requirements - that they could be used full-range. The Tempests reach to the mid 40's, I believe the port is tuned to 42 Hz. In room they are good to about 40Hz before falling-off quickly. If you want that last octave then you will still need a sub. The Tempest is an over-achiever. It is a very good speaker, better than I was expecting. I could live with a pair as my mains for a long time.
                          Click here for Jeff Bagby's Loudspeaker Design Software

                          Comment


                          • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                            Pete, on the above graphs, the woofer appears to roll off substantially by around 100. Am I looking at it correctly? Should I withhold judgment until after your visit to Ryan's?
                            " To me, the soundstage presentation is more about phase and distortion and less about size. However, when you talk about bass extension, there's no replacement for displacement". Tyger23. 4.2015

                            Quote Originally Posted by hongrn. Oct 2014
                            Do you realize that being an American is like winning the biggest jackpot ever??

                            http://www.midwestaudioclub.com/spot...owell-simpson/
                            http://s413.photobucket.com/albums/pp216/arlis/

                            Comment


                            • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                              Originally posted by [email protected] View Post
                              Pete, on the above graphs, the woofer appears to roll off substantially by around 100. Am I looking at it correctly? Should I withhold judgment until after your visit to Ryan's?
                              That low end response is very position dependent. Have a look at an earlier measurement.

                              R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                              Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                              95% of Climate Models Agree: The Observations Must be Wrong
                              "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                              Comment


                              • Re: Home/Pro 8" 2-way: RS28A and B&C 8BG51

                                So I've been playing around with the 2D CNC program and spent a while calculating a series of concentric circles at regular cut depths to arrive at this. Instead of adding another section to the back of the baffle to make the guide deep, I just kept it at 1".

                                Why? I want to see what a 1" deep guide will do! I know it won't have the boost down low that the deeper guide does but the shallower guide should offer a little better top end and enough "gain" down low to continue to enable the 1100Hz crossover point. I may cut these next week and begin some testing. And being 1" thick, it will be a lot easier to make and finish these things. No seam in the guide throat is a benefit for sure. These are also designed to bolt right on to the PE 10x17 .75cf TM cabinet. At least if anyone is interested in doing this I'll be able to make them the baffles!



                                Click image for larger version

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                                Last edited by Pete Schumacher; 02-14-2015, 10:32 PM.
                                R = h/(2*pi*m*c) and don't you forget it! || Periodic Table as redrawn by Marshall Freerks and Ignatius Schumacher || King Crimson Radio
                                Byzantium Project & Build Thread || MiniByzy Build Thread || 3 x Peerless 850439 HDS 3-way || 8" 2-way - RS28A/B&C8BG51

                                95% of Climate Models Agree: The Observations Must be Wrong
                                "Gravitational systems are the ashes of prior electrical systems.". - Hannes Alfven, Nobel Laureate, Plasma physicist.

                                Comment

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