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Dayton CX150-8 Coaxial Project

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  • #16
    Bill, my comment was with respect to creating a Open Baffle midrange. I ran the sim with a narrow open baffle and it looks like a tweeter to mid xo of 2K Hz and a woofer to mid xo of 500 Hz. You could do a thick flat baffle plus a woofer enclosure to simplify construction. Here's a drawing.

    John H

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

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    • #17
      I think it needs a rounded top, not the same radius as the driver, something more like twice the radius. Another cool feature would be to angle the top of the woofer box like your "90.08" line in the frontal view of that dimensional pic.
      A mains
      The Ventures
      Open Invit8tions
      RSR
      Sound Troopers
      Acorns
      442
      DGBG's
      The Monuments

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      • #18
        You can make a removable back cap/box for the mid, that will be within the rules for InDIYana, and remove the box and a XO change for the OB.

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        • #19
          John, how does the directivity work with regards to baffle width?

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          • #20
            Originally posted by jhollander View Post
            Bill, my comment was with respect to creating a Open Baffle midrange. I ran the sim with a narrow open baffle and it looks like a tweeter to mid xo of 2K Hz and a woofer to mid xo of 500 Hz. You could do a thick flat baffle plus a woofer enclosure to simplify construction. Here's a drawing.
            John, the tweeter on this Coax has an Fs of 1940hz. You think it would be ok to cross at 2K?
            My "No-Name" CC Speaker
            Kerry's "Silverbacks"
            Ben's Synchaeta's for Mom
            The Archers
            Rick's "db" Desktop CBT Arrays
            The Gandalf's

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            • #21
              I broke the drivers in for 3 hours with a 25Hz sine wave, about 1/4" peak to peak. Then I let them sit for a couple days. I warmed them back up a little by playing some low level music through the 5.25 inch drivers for about 10 minutes to simulate actual use. For the larger 10 inch woofers, I applied a 25Hz sine wave at a low level for 5 minutes to simulate actual use. To calculate VAS, I used the DATS V2 added mass method, using 40.4 grams for the 5.25 inch drivers and 78.3 grams for the 10 inch drivers. The tweeters were measured cold with no break-in or added mass.


              CX150-8 Tweeters:
              A B
              Re 5.772 6.108 ohms
              Fs 1884Hz 1884Hz
              Qts 1.875 2.757
              Qes 6.338 9.126
              Qms 2.662 3.951
              Le 0.02859mH 0.03001mH

              CX150-8 mid/woofers:
              A B
              Re 6.206 ohms 6.178 ohms
              Fs 62.58Hz 61.24Hz
              Qts 0.4474 0.4138
              Qes 0.4952 0.4542
              Qms 4.638 4.653
              Le 0.4444mH 0.4572mH
              Mms 12.35 grams 12.33 grams
              VAS 0.2176 cu ft 0.2277 cu ft
              SPL 86.74 1w/1m 87.03 1w/1m

              RS270P-8 woofers:
              A B
              Re 7.367 ohms 7.603 ohms
              Fs 21.53Hz 22.88Hz
              Qts 0.3097 0.3183
              Qes 0.421 0.4269
              Qms 1.171 1.252
              Le 0.2979 0.3242
              Mms 70.18 grams 66.06 grams
              VAS 4.06 cu ft 3.821 cu ft
              SPL 86.25 1w/1m 86.72 1w/1m

              Alignments:

              In WinISD, the RS270P-8 woofer produces a flat vented alignment with an F3/6/10 of 32/27/23Hz using a 3 inch ID vent, 12 inches long, in a 1.69 cu ft box. This tunes the 10" woofer to 28Hz.

              In a sealed 0.25 cu ft box, the CX150-8 has an F3/6/10 of 110/76/55 and a Qtc of 0.603, which should be just fine using a 400Hz or so xover. SPL simulations at various power levels in WinISD indicate that both drivers should be able to play at up to 100dB or more before exceeding Xmax.

              My plan is to line the inside of the 1.69 cu ft box with 1 inch of fiberglass on all walls. And I am going to install a large removable panel on the back so that I can remove the entire bass reflex port assembly. This way I can install and adjust a short 6 inch long trap stub on the port. The 1st port resonance of 558Hz is probably inaudible, but one thing that I discovered when working on the Plumbers Delight speakers is that, regardless of tuning, the trap also acts as a general low pass filter, which helps to reduce the amount of internal box midrange energy from leaking out of the port.

              Bill
              Last edited by 4thtry; 07-30-2017, 04:59 PM. Reason: spelling
              SideTowers: http://techtalk.parts-express.com/fo...corundum-build
              Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
              Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
              Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

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              • #22
                Originally posted by tomzarbo View Post
                Bill,
                ​that's going to look pretty cool I think. How do you print out something like that full size? Staples, or go to a surveyor or something like that? Good idea. I end up transferring my computer drawings to full size newspaper print, but it's not as accurate as a full-size printout.

                I usually do a full-scale mock-up in cardboard for more curvy cabinets or those with lots of angles to make sure it looks right full size. I've had my sketches look good as sketches but not so good in the flesh until I adjusted a few dimensions. Man, you're not letting the dust settle are you?

                Also, I'm pretty sure I landed 4 or 6 of those same terminal cups for like a buck or so each at the tent sale? Yeah, I had to buy them too!

                ​TomZ
                Thanks Tom,

                I just printed two full scale drawings this afternoon at my local Fed Ex. Used a wide body 36" HP inkjet in black & white draft mode. Color is expensive, but black & white draft mode is very cheap. Less than 10 bucks for two full scale prints. I intend to tape these prints to the top of a 3/4" 24x48 handy panel and then very slowly (and carefully) cut along the curved line with my hand held jig saw. Should work. I created the drawings full scale in photoshop and then saved them out to a full scale PDF drawing. I have yet to double check the dimensions on the prints, but they should be exact.
                Last edited by 4thtry; 07-30-2017, 05:39 PM.
                SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

                Comment


                • #23
                  Originally posted by jhollander View Post
                  Bill, my comment was with respect to creating a Open Baffle midrange. I ran the sim with a narrow open baffle and it looks like a tweeter to mid xo of 2K Hz and a woofer to mid xo of 500 Hz. You could do a thick flat baffle plus a woofer enclosure to simplify construction. Here's a drawing.
                  Thanks for the clarification, John. So you are talking about the directivity pattern with respect to frequency set up by the open baffle dimensions. But as Kevin pointed out, the 2k crossover is too low. I am looking at a minimum of 3.5K at 12dB/octave.
                  SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                  Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                  Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                  Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

                  Comment


                  • #24
                    Originally posted by 6thplanet View Post
                    I think it needs a rounded top, not the same radius as the driver, something more like twice the radius. Another cool feature would be to angle the top of the woofer box like your "90.08" line in the frontal view of that dimensional pic.
                    On my first draft, I was going to round the top, just as you suggest. But then I stopped, and 2nd guessed myself. The asymmetry of the odd shaped top creates tension and causes the viewer to look twice. It also helps to spread out the baffle step a little (but this could also be achieved by offsetting the driver within a rounded top).

                    Not sure I understand your 2nd suggestion about the 90.08 line
                    SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                    Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                    Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                    Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

                    Comment


                    • #25
                      Originally posted by ani_101 View Post
                      You can make a removable back cap/box for the mid, that will be within the rules for InDIYana, and remove the box and a XO change for the OB.
                      Thanks Ani. I will keep this in mind should I go in the OB direction. Right now I am leaning toward a simple sealed box for the mid.
                      SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                      Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                      Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                      Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

                      Comment


                      • #26
                        Hey Bill just a thought, it may be a lot easier to wrap the curves with 1/8" mdf, I know its more layer which equals more work, but it's an option should the 1/4" hdf give you grief, and you may find that it doesn't have to be as thick as you might think, because of the tension in the curves.

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                        • #27
                          Originally posted by ugly woofer View Post
                          Hey Bill just a thought, it may be a lot easier to wrap the curves with 1/8" mdf, I know its more layer which equals more work, but it's an option should the 1/4" hdf give you grief, and you may find that it doesn't have to be as thick as you might think, because of the tension in the curves.
                          Thanks for the tip. I'll keep this in mind when I head out to my local lumber yards. In my area, I have seen 1/4" HDF and 3/16" HDF. And one place has 3/16" HDF finished smooth on one side and rough on the other. Can't remember seeing 1/8" MDF in my area, but will check around.
                          SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                          Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                          Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                          Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

                          Comment


                          • #28
                            Originally posted by JavadS View Post
                            Looking like a fun build Bill! Javad
                            Lots of fun! And now it is time to search for lumber!
                            SideTowers: http://techtalk.parts-express.com/fo...corundum-build
                            Totally Flat: http://techtalk.parts-express.com/fo...5-totally-flat
                            Plumber's Delight: http://techtalk.parts-express.com/fo...notech-winners
                            Linehopper: http://techtalk.parts-express.com/sh...Esoteric-build

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                            • #29
                              Menards has 1/8 mdf if you have one nearby.

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                              • #30
                                Originally posted by ani_101 View Post
                                John, how does the directivity work with regards to baffle width?
                                Ani above the first dipole null the summation of the front and back waves creates a petal shaped horizontal polar response. In other words dips off axis. It would be a design goal to cross the tweeter at or below the first dipole null so the off axis response is not as lumpy.
                                John H

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

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