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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 300Z View Post
    Good point, the the natural low end response on the RS28 in indeed lower than the TBFC.

    Me personally I would go with the elliptical waveguide, they measure very similar but with the elliptical the woofer could be mounted closer and I like the looks of the elliptical better... :p
    I would like to pair them with the FaitalPRO 6FE100 woofers tho because I'm not changing my current B&C/JBL current system but I really want to build this for another smaller room that will see much less use so it wouldn't be worth the investment for the B&C woofers.

    Any ideas on how much a set of baffles would cost with the ellipticals?
    How big would the baffles be? Same as these? I'd have to redraw the cut files for your particular woofer. PM me for a quote.

    Originally posted by aarond View Post
    By baffles are you talking about the WG/baffle combo? Are you still using the 10"x17" PE dimensioned baffle for this?
    Yes, they fit the PE .75cf TM cabinet using the hardware provided with the cabinet kit. They do need to have a rabbet cut around the back edge in order for the hardware to grab the inserts though. I forgot about that step. Easy fix on the table saw or router table.

    I'm thinking that this particular baffle with the 8BG51 form factor for the woofer would be about $55 for either WG profile. Does that seem reasonable? You'd be responsible for final sanding and the back rabbet. It only took me 10 minutes with 80 grit to eliminate the tool marks. Can't imagine putting the rabbet on the back will take any longer than that.
    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

      Erich over at DIY Sound Group sent me a very interesting new item he just got in.

      Click image for larger version

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      With the RS28A mounted to the guide (flange and all), and with it just sitting on top of a speaker, here's what I got on-axis at 1m.

      Click image for larger version

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      This little guide looks really good with the RS28A! The only modification I made to the guide was to slide the back side of the guide back and forth on some 80 grit sandpaper for a couple of minutes to make sure the surface was smooth enough to get an air tight fit on the flange.

      More on this to come as well. He sent me a little knockdown enclosure that puts the 8BG51 and this pairing together. I'll get the two drivers mounted up and come up with a first attempt XO. Can't do any voicing yet since he only sent me the one cabinet, but he's got a tower underway too!
      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

        Here's a set of plots of the TBFC in Erich's SEOS8 guide. It certainly responds differently to the guide than the RS28.

        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

          So we have a new SEOS-8 based kit coming up at DIYSG soon ( using RS28A and 8BG51 ) ?

          Comment


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

            I would like to see this new kit with a woofer that uses a round frame and rubber surround like the Beyma or 18 Sound ! Is there a benefit using the B&C over these other two other than cost ? Any comparisons ?
            donc

            Comment


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

              The B&C does have a rubber surround.

              Comment


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

                The B&C is the only "pro" 8" woofer I've seen that will provide the bass performance I'm after. All the others cut off around 60Hz or higher. The 8BG51 reaches well into the 40s. If you can find one that models up well, gives us at least 50Hz F3, I'd be happy to use it. Just remember that the sensitivity after baffle step needs to be around 91dB.

                I did just find a possible Beyma candidate . . . http://www.usspeaker.com/beyma%208BR40-1.htm

                It's a smallish 8" at only 200mm diameter, but it does look like it could easily work.





                And then there's a 10" that looks promising too! http://www.usspeaker.com/beyma%2010BR60-1.htm



                Last edited by Pete Schumacher; 03-13-2015, 05:04 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


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

                  Beyma # 8P300Fe and the 18Sound # 8BM500 are the two that I would like to see in a two way , especially with a dome not a CD .
                  donc

                  Comment


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

                    Originally posted by donc View Post
                    Beyma # 8P300Fe and the 18Sound # 8BM500 are the two that I would like to see in a two way , especially with a dome not a CD .
                    donc
                    Neither of them off any bass below about 70Hz or so. But if you'd like to see them in a kit I'm sure we could work one up.

                    The 8MB500 in .75cf tuned to 75Hz has an F3 at 70Hz.

                    The 8P300Fe also has a similar F3 in .5 cubic feet.

                    They're both at about the sensitivity limit to mate up with the RS28 in the guide.
                    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

                      Wow, Pete I love the look of that round guide baffle! Great symmetry.

                      David

                      Comment


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

                        Hi Pete,

                        I for one, am very thankful for all of the information that you have provided over the years. Please keep it up and help us rookies learn. I troll the boards and basically never add since I believe that I have not reached a level of audio knowledge that will allow me to contribute. I have made my own speakers of my own design based in inspiration from you and others. So thank you and keep on Pete!!

                        Kind regards,
                        Eric

                        Comment


                        • Another update. I revisited the baffle/guide and changed it to a 1" deep, 8" wide circular guide with circular profile to the guide walls. I'm much more pleased with the result of the shallower guide's rendition of the high frequency end of the spectrum. They image like crazy and have all the authority you'd expect from an 8" monitor. In-room, usable bass to the mid 30s.

                          Someone in California expressed an interest in buying them from me, but if that doesn't happen, I'll bring them to Iowa.

                          Final response and pics of the monitor.

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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


                          • Pete if those are the same as I heard they are very good. That B & C was surprisingly detailed.
                            John H

                            Synergy Horn, SLS-85, BMR-3L, Mini-TL, BR-2, Titan OB, B452, Udique, Vultus, Latus1, Seriatim, Aperivox,Pencil Tower

                            Comment


                            • If you remember John, we talked about the tweeter being a little bit "hot" and since then I changed the crossover and brought the tweeter down maybe 1.5dB from where it was. I didn't just pad it but changed all the values so that no padding resistor was required. It actually smoothed the tweeter response even further than before.

                              And I must agree with your impression of the woofer. It is as detailed as one could want. I'm very impressed with it. I'll make sure it gets to Iowa for everyone to see how good these B&C drivers really are.
                              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


                              • Here's the final details on the build, crossover and guide specs for anyone who wants to replicate this beast of a bookshelf. Each dimension listed is at a depth of an additional 1/32" except the topmost cut which is 1/64" from baffle flush. The cut below it is at 1/32" and each subsequent cut is an additional 1/32"

                                And if you don't want to replicate the baffle yourself, just PM me and we can arrange to get a set made for you.

                                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

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