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  • #31
    I will excuse your ignorance--I was only talking about the "woofer" part of this coax and its use, and I specifically described incorporating it into a small-scale, 3-way floorstander with a 7" woofer in a TL in my first post (#22).
    Paul

    Originally posted by filmslayer View Post
    please excuse my ignorance Paul , but if you use it strictly for a mid , why not just get something that is a mid ?

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    • #32
      Perhaps a vented enclosure would minimize the likelihood of extra noise?

      Comment


      • #33
        Pressures are higher in a vented box.
        Wolf
        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

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        My blog/writeups/thoughts here at PE:
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        • #34
          Interesting!
          Given it's a small cone with 5mm Xmax, is the pressure differential likely to be high enough to equalize via the holes in question as well as the port at a reasonable listening volume?

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          • #35
            The more I'm thinking about it I'm willing to bet even without those former holes there will still be leakage in the open basket under the coil and up out between the former and pole under high excursion and box pressure. Seems like Paul's 3-way idea is the best use of these; Isn't it best to have minimal cone movement in a coax when the cone is a waveguide for the tweeter anyway?
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            • #36
              Originally posted by Paul K. View Post
              I will excuse your ignorance--I was only talking about the "woofer" part of this coax and its use, and I specifically described incorporating it into a small-scale, 3-way floorstander with a 7" woofer in a TL in my first post (#22).
              Paul


              Hey Paul

              I will take up on your offer (not sure if you were offering, but I am assuming so!). I too received the 5" coax as door prize and have a have a 8" dayton classic that I want to pair with (in a TL with your help of course). How high were you thinking of crossing the mid to the woofer (the coax to be used as tweeter/woofer). Though the DC200 has been used in two ways, I don't want to cross too high. this also would let me place it closer to the floor and have a coax at ear height. What's your thought on a mid TL as we discussed during MWAF, would a mid TL help reduce the pressure as it absorbs the backwave?

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              • #37
                I wasn't making an offer, Ani, but I did just make a quick model of a 16:1 tapered TL for the DC200 in a 60" long line with a line volume of ~2 ft3 using the published T/S values. The results were very good (the line would be folded, of course). I was surmising that the corner between a woofer and the CX120 would be at least 200 Hz, more likely 300-500 Hz in what I was pondering. Honestly, I think using a sealed box volume of ~0.2 ft3 for the CX120 would be plenty large enough to not be concerned about leaking air noises that have been discussed for this driver. However, one could use a tapered TL for it with the whole line stuffed and that should completely eliminate all concerns. This tapered line would probably need to be 20" long, perhaps longer, and tapered at least 10:1, with a 1/4-wavelength resonant frequency around 80 Hz in order to have a reasonably flat overall response. Of course, the crossover would be cutting everything off, so to speak, below the corner.
                Paul

                Originally posted by ani_101 View Post
                Hey Paul
                I will take up on your offer (not sure if you were offering, but I am assuming so!). I too received the 5" coax as door prize and have a have a 8" dayton classic that I want to pair with (in a TL with your help of course). How high were you thinking of crossing the mid to the woofer (the coax to be used as tweeter/woofer). Though the DC200 has been used in two ways, I don't want to cross too high. this also would let me place it closer to the floor and have a coax at ear height. What's your thought on a mid TL as we discussed during MWAF, would a mid TL help reduce the pressure as it absorbs the backwave?

                Comment


                • #38
                  "However, one could use a tapered TL for it with the whole line stuffed and that should completely eliminate all concerns. This tapered line would probably need to be 20" long, perhaps longer, and tapered at least 10:1, with a 1/4-wavelength resonant frequency around 80 Hz in order to have a reasonably flat overall response."

                  Paul,

                  Perhaps I'm misreading this, but are you suggesting these drivers might be used alone in the enclosure you describe above? It's an interesting idea.



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                  • #39
                    Perhaps, but I was only addressing Ani's question as it regards minimizing the chance of audible air leakage noise.
                    Paul

                    Originally posted by TN Allen View Post
                    "However, one could use a tapered TL for it with the whole line stuffed and that should completely eliminate all concerns. This tapered line would probably need to be 20" long, perhaps longer, and tapered at least 10:1, with a 1/4-wavelength resonant frequency around 80 Hz in order to have a reasonably flat overall response."

                    Paul,

                    Perhaps I'm misreading this, but are you suggesting these drivers might be used alone in the enclosure you describe above? It's an interesting idea.


                    Comment


                    • #40
                      FWIW there are other companies designing coincident drivers that vent the former as well.

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                      • #41
                        Something occurred to me-
                        The video places the coax into a tube. Is it possible that the mounting holes are buzzing with air and not the former/gap?

                        I know I've had that noise and this was the culprit before.
                        Later,
                        Wolf
                        "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                        "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                        "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                        "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                        *InDIYana event website*

                        Photobucket pages:
                        http://photobucket.com/Wolf-Speakers_and_more

                        My blog/writeups/thoughts here at PE:
                        http://techtalk.parts-express.com/blog.php?u=4102

                        Comment


                        • #42
                          It's not the mounting holes as they get sealed up pretty good on that tube as it's small enough to reach the gasket material towards the inside.

                          Originally posted by rickcraig View Post
                          FWIW there are other companies designing coincident drivers that vent the former as well.
                          The question is why? A vented former helps relieve the pressure from under a solid dust cap, there is no dust cap and pressure to relive on a coaxial so I don't see the use for those holes.

                          Originally posted by dynamo View Post
                          The more I'm thinking about it I'm willing to bet even without those former holes there will still be leakage in the open basket under the coil and up out between the former and pole under high excursion and box pressure. Seems like Paul's 3-way idea is the best use of these; Isn't it best to have minimal cone movement in a coax when the cone is a waveguide for the tweeter anyway?
                          With other coaxials I have used before there is still some leakage of air going down through the gap around the coil and back out however it's much less then this. I am going to try and seal up the holes and see what kind of difference that makes.

                          I posted more on a different forum that I thought I would copy here:
                          I was doing more testing and while the noise from the former vents mostly occurs below 200hz you can still hear some up to 400hz if the level is high enough, though how noticeable it would be with music content is questionable especially if high passed at 400hz. But another issue came about while doing those tests and that's that the cone on one of mine broke away from the former at the glue joint. You can see in the photo below and how small the bead of glue is. I wasn't pushing crazing power into it 10-20w at 400hz listening for noise from those vents and all of the sudden it started buzzing loudly. Could just be a QC issue on that one as my other driver looks more like the photos of it on the product page with the glue joint being a good bit wider and it was fine with when I played the same signal through that one at even higher levels. So I guess that's just something else to look out for on these.



                          Photo's of the other driver with better glue joint and showing vented former from above:




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                          • #43
                            Any real-time measurements available, especially distortion?
                            Kenny

                            http://www.diy-ny.com/
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                            • #44
                              I've been following this thread because I picked up a pair of the CX150, but haven't had a chance to play with them yet. One thing I'm curious about is if you hear the noise at all frequencies, or only at certain intervals of frequencies. You're sticking the speaker on the end of a pipe, which will produce a standing pressure wave at those low frequencies. Is it possible that you're just getting excessively high pressure at those frequencies, but in a non-pipe enclosure you won't see this problem?

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                              • #45
                                Dayton Audio has taken notice of your concerns regarding air rushing noise on our Dayton Audio CX120-8 4 and CX150-8 5-1/4" Coaxial Drivers. We were able to duplicate the noise in our own listening evaluations under certain conditions. Due to manufacturing mistakes, we are pulling these speakers from inventory. We are working with our factory to fast track replacements as soon as possible.
                                Your results may vary.

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