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  • #31
    Re: Looking for x-over schematic and parts list

    Well I've got these things built in a couple test boxes. With a couple mods they're sounding pretty nice. The 8 ohm resistor was killing the tweeter. I ended up settling on a 2 ohm. I have A/B-ing them with my Mission 707 8" 2-ways. With the 2 ohm resistor the highs sound pretty similar. As for the lows, they definitely go much lower than the Missions but I could use a little more of the upper lows [ maybe around 400 hz] to bring out the notes of a bass guitar. Any suggestions on how to achieve that. Maybe adjusting the length of the port? I'm gonna keep trying things. If anyone has any suggestions I'd love to hear them. Thanks, Scott

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    • #32
      Re: Looking for x-over schematic and parts list

      Originally posted by Limelight View Post
      Well I've got these things built in a couple test boxes. With a couple mods they're sounding pretty nice. The 8 ohm resistor was killing the tweeter. I ended up settling on a 2 ohm. I have A/B-ing them with my Mission 707 8" 2-ways. With the 2 ohm resistor the highs sound pretty similar. As for the lows, they definitely go much lower than the Missions but I could use a little more of the upper lows [ maybe around 400 hz] to bring out the notes of a bass guitar. Any suggestions on how to achieve that. Maybe adjusting the length of the port? I'm gonna keep trying things. If anyone has any suggestions I'd love to hear them. Thanks, Scott
      So what have you changed, exactly?

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      • #33
        Re: Looking for x-over schematic and parts list

        Hey Chris!
        I changed the resistor in line on the tweeter from an 8 ohm to a 2 ohm and I shortened the port tube to 10 1/4 inches.

        I've also messed with the stuffing. I've been using 1" thick batting from the fabric store, it's the same thing that the Missions are stuffed with. I can tell this is something that really has to be right. Currently I have a piece covering both sides. Nothing on the top, bottom or back. Scott

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        • #34
          Re: Looking for x-over schematic and parts list

          Originally posted by Limelight View Post
          Hey Chris!
          I changed the resistor in line on the tweeter from an 8 ohm to a 2 ohm and I shortened the port tube to 10 1/4 inches.

          I've also messed with the stuffing. I've been using 1" thick batting from the fabric store, it's the same thing that the Missions are stuffed with. I can tell this is something that really has to be right. Currently I have a piece covering both sides. Nothing on the top, bottom or back. Scott
          The FIRST place I'd put lining (stuffing) is on the back. High bass and low mids will reflect right off the back to the woofer cone, and it will transmit it through.

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          • #35
            Re: Looking for x-over schematic and parts list

            Originally posted by Chris Roemer View Post
            The FIRST place I'd put lining (stuffing) is on the back. High bass and low mids will reflect right off the back to the woofer cone, and it will transmit it through.

            OK, I'll give that a try. I'll also post some pics later.

            Can you help me understand how the lining helps transmit the said frequencies? My first thought is that the lining would just deaden them.

            Just really trying to understand what's going on. Thanks for all your help, Scott

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            • #36
              Re: Looking for x-over schematic and parts list

              They aint pretty but they are solid! when I get it right I'll rebuild them with something other than scrap wood.

              Chris, what are the crossover points on this design? Is it possible to cross the woofer a little higher? Thanks, Scott
              Attached Files

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              • #37
                Re: Looking for x-over schematic and parts list

                Originally posted by Limelight View Post
                They aint pretty but they are solid! when I get it right I'll rebuild them with something other than scrap wood.

                Chris, what are the crossover points on this design? Is it possible to cross the woofer a little higher? Thanks, Scott
                2k. All the woofer has on it is a Zobel and a notch filter. It's pretty much running its full available range, minus the horrid peak near 2.5k. You can make the woofer sound a bit louder by making the tweeter a tad quieter.

                Chris

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                • #38
                  purpose of zobel in this design?

                  What's the purpose of the zobel in this particular network? Is it for the notch filter?

                  If I want to lower the crossover frequency to 1500Hz (I'm thinking about using it with the Selenium D220Ti mounted to a Pyle PH715 horn), should a lowpass filter be applied to the DC200-8?

                  Originally posted by Chris Roemer View Post
                  2k. All the woofer has on it is a Zobel and a notch filter. It's pretty much running its full available range, minus the horrid peak near 2.5k. You can make the woofer sound a bit louder by making the tweeter a tad quieter.

                  Chris

                  Comment


                  • #39
                    Re: purpose of zobel in this design?

                    This is the url I had for the d8: http://web.archive.org/web/200712071...ayton_8MTM.htm

                    The XO looks a little different.

                    I have always wanted to build a pair of these guys since I found them. I have shied away from it because of the XO uncertainties. Perhaps Paul can redesign this bad boy!

                    There is just something about a pair of huge skull crushing speakers like these guys. My inner young adult is surfacing!

                    Kevin
                    Shaken, not stirred...

                    Classix II
                    OS MTM's
                    Digger 8 sub
                    Overnight Sensations Center Channel
                    Sprite Build
                    Wolf's PC Speakers
                    Minions III with Voxel Sub

                    Comment


                    • #40
                      Re: purpose of zobel in this design?

                      This thread evolved into a discussion of another speaker with just one 8" woofer. That is what the hand drawn diagrams are about. Chris Roemer has a simpler xover for the Dayton 8, I believe. I built the original version with a cab as specified by the original designer, half the size of Dave Tenney's, using the original xover. I would go with Chris', if you can get it. It is much more modern.

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                      • #41
                        Re: purpose of zobel in this design?

                        The Zobel helps the notch hit its target freq.

                        W/out a filter, it plays up to around 2.5-3kHz, with an ugly breakup near 2.2k.

                        To force it to rolloff near 1500Hz, I'd go 2nd order using that same Zobel, with a 2mH series coil (parallelled by a small 2.0uF cap - for the notch), and a 6uF shunt cap.

                        This will give you about an 83dB woofer (before any baffle step). Not sure why you'd want to pair that with a 109dB tweeter. You'd have to cook the tweeter down by 25-30 dB just to keep your ears from bleeding. Why not look for a 10" or 12" pro woofer for your app?

                        Comment


                        • #42
                          Re: purpose of zobel in this design?

                          Kevin, Chris Roemer has worked up a different XO with fewer parts. I have the original write-up from Dave Tenney, for the D8 MTM and the D8 single-woofer version. The original XO was done with XO Pro. It had an unusually high parts count, which is typical of XO Pro. XO Pro doesn't use measured data, just the fixed-number T/S parameters. I built a few of the original D8 MTM's, a couple were done with the persons name-brand cabinets. Dave said they could work in a smaller enclosure and a friend had some crap-sounding OEM MTM's that were the right size. The single-woofer D8 worked well in many store-bought speaker boxes. I used the original D8 2-way in my sister's "Baby" Advents. She let me put in the newer XO and we enjoyed the improved SQ. She loved it and I thought it was a noticeable improvement in overall SQ. The D8 MTM is an impressive speaker for the cost of the components. Big, floor-standing, tremendous bass capabilities. Even the smaller-size MTM cabinet version has better bass performance than some popular-brand subwoofers I've heard. IIRC, a more current, less-parts-count XO is available for the D8 MTM. I think I have the diagram somewhere if you'd like it.


                          John A.
                          "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
                          Emotiva UPA-2, USP-1, ERC-1 CD
                          Yamaha KX-390 HX-Pro
                          Pioneer TX-9500 II
                          Yamaha YP-211 w/Grado GF3E+
                          Statement Monitors
                          Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
                          Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
                          Blogs: http://techtalk.parts-express.com/blog.php?u=2003

                          Comment


                          • #43
                            Re: purpose of zobel in this design?

                            Originally posted by johnastockman View Post
                            Kevin, Chris Roemer has worked up a different XO with fewer parts. I have the original write-up from Dave Tenney, for the D8 MTM and the D8 single-woofer version. The original XO was done with XO Pro. It had an unusually high parts count, which is typical of XO Pro. XO Pro doesn't use measured data, just the fixed-number T/S parameters. I built a few of the original D8 MTM's, a couple were done with the persons name-brand cabinets. Dave said they could work in a smaller enclosure and a friend had some crap-sounding OEM MTM's that were the right size. The single-woofer D8 worked well in many store-bought speaker boxes. I used the original D8 2-way in my sister's "Baby" Advents. She let me put in the newer XO and we enjoyed the improved SQ. She loved it and I thought it was a noticeable improvement in overall SQ. The D8 MTM is an impressive speaker for the cost of the components. Big, floor-standing, tremendous bass capabilities. Even the smaller-size MTM cabinet version has better bass performance than some popular-brand subwoofers I've heard. IIRC, a more current, less-parts-count XO is available for the D8 MTM. I think I have the diagram somewhere if you'd like it.


                            John A.
                            Ya that would be great. My oldest son would die for a pair of the full size D8's. And if there is a simpler XO then all the better.

                            Kevin
                            Shaken, not stirred...

                            Classix II
                            OS MTM's
                            Digger 8 sub
                            Overnight Sensations Center Channel
                            Sprite Build
                            Wolf's PC Speakers
                            Minions III with Voxel Sub

                            Comment


                            • #44
                              Re: purpose of zobel in this design?

                              Let me find it and put it up here. I want to make sure with Chris that it's the correct diagram for the MTM.






                              I'm pretty sure this is the one, but confirm with Chris it's the one he did. I forget to label some of the XO diagrams. Good luck and if you need any help, don't hesitate to ask. Simpler lay-out, less parts AND improved SQ!



                              John A.
                              Last edited by johnastockman; 10-22-2013, 04:10 PM. Reason: Added XO diagram...
                              "Children play with b-a-l-l-s and sticks, men race, and real men race motorcycles"-John Surtees
                              Emotiva UPA-2, USP-1, ERC-1 CD
                              Yamaha KX-390 HX-Pro
                              Pioneer TX-9500 II
                              Yamaha YP-211 w/Grado GF3E+
                              Statement Monitors
                              Vintage system: Yamaha CR-420, Technics SL-PG100, Pioneer CT-F8282, Akai X-1800, Morel(T)/Vifa(W) DIY 2-way in .5 ft3
                              Photos: http://custom.smugmug.com/Electronic...#4114714_cGTBx
                              Blogs: http://techtalk.parts-express.com/blog.php?u=2003

                              Comment


                              • #45
                                Re: purpose of zobel in this design?

                                Hey John.

                                That looks EXACTLY like the last pair of "Dayton 8s" that I worked on. Thanks.

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