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Coaxial driver for center channel use

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  • #16
    Check out the latest update. Not sure what sizes he is doing, but this might be up your alley

    https://www.avsforum.com/forum/155-d...roject-49.html

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    • #17
      Originally posted by technodanvan View Post
      Unfortunately the FaitalPro has a similar problem as the SB Acoustics - the frame isn't round! I'm sure they're all fine drivers, but I am not confident in my ability to get those recessed. I suppose I should give it a shot someday, but not for this project!
      It's really not that hard. I've been experimenting with asymmetrical baffles so I've made a few. Surface mount the driver on the face of your enclosure. Then use a removable baffle that mounts to the enclosure. On the back side of the baffle trace the outline of the speaker. Use a drill to make the radius on the corners. Then cut to the inside of the line. Clean up the cuts with a file and some sandpaper so the driver fits tightly. Flip the baffle over and on the front side use a roundover bit with a follower to radius from the front of the speaker frame to the face of the baffle.

      Hope this made sense I'm still working on my morning coffee. I'll post some pics if anyone is interested.

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      • #18
        Originally posted by nater View Post
        Check out the latest update. Not sure what sizes he is doing, but this might be up your alley

        https://www.avsforum.com/forum/155-d...roject-49.html
        I think someone alluded to some new pro-style coaxials coming out. They look interesting, but I'm not really sure I need the efficiency they're going for. Something to keep an eye on though.

        Originally posted by devnull View Post

        It's really not that hard. I've been experimenting with asymmetrical baffles so I've made a few. Surface mount the driver on the face of your enclosure. Then use a removable baffle that mounts to the enclosure. On the back side of the baffle trace the outline of the speaker. Use a drill to make the radius on the corners. Then cut to the inside of the line. Clean up the cuts with a file and some sandpaper so the driver fits tightly. Flip the baffle over and on the front side use a roundover bit with a follower to radius from the front of the speaker frame to the face of the baffle.

        Hope this made sense I'm still working on my morning coffee. I'll post some pics if anyone is interested.
        dev - that makes perfect sense. I hadn't considered using a second baffle, that would make things a bit easier to line up. I had always assumed I'd try using one of the tracing router bits to make a template, then countersink it into a single baffle.

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        • #19
          [QUOTE=technodanvan;n1389615]Unfortunately the FaitalPro has a similar problem as the SB Acoustics - the frame isn't round! I'm sure they're all fine drivers, but I am not confident in my ability to get those recessed. I suppose I should give it a shot someday, but not for this project.

          Javad Shadzi has several times presented a technique for recessing non-round drivers in his detailed build threads for the Pretty Persuasions and Stratfi builds. Here's a link: http://techtalk.parts-express.com/fo...x-build-thread
          See post #28.

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          • #20
            Kieth Etheredge had a great design using (I think?) a Faital Pro coax driver. It was one of my favorite entries at MWAF 2018 (entry # SP20) I think the design was called 7-6-2.
            KEtheredge87
            Ah. Here's a link. http://techtalk.parts-express.com/fo...27#post1382227

            Again, it is pincushion. That or the SB mentioned before I'm sure would be worth the effort. Javad has put some good tutorial videos out there for tracing and making a pattern for non-circular drivers. For a couple pieces of scrap lumber and probably a $20 pattern bit kit, I think it's well worth to try a good driver...
            SEC DIY 2014 Speaker Show is on! *November 8th*
            Wanna win a set of Newform Research R30 ribbons?!?!
            SEC DIY 2014 Thread

            SEC DIY 2012 Speaker Show
            SEC DIY 2011 Speaker Show

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            • #21
              I just read through Javad's thread - such good work. Really need to review threads like that on a daily basis to keep the ideas (and ambition) flowing. He (and plenty of others here) make it look so easy.

              Out of curiosity, who would I contact at PE to find out if they're going to handle some newer drivers? In particular, I found that Tang Band has a whole lineup of new coaxials up to 8" that could be interesting. Haven't seen any dealers in the states though.

              http://www.tb-speaker.com/products/w8-2314

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              • #22
                PE mentioned a month or two back (on Reddit) that they would be getting those coax models. Sent from my moto g(6) using Tapatalk

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                • #23
                  Well, Tang Band offered to ship me a pair of their new coaxials direct from the warehouse since they don't currently have a supplier in the US. Coupled with the cost of freight though, they're approaching the cost of the Seas C18EN002 - which has outstanding off-axis response, as measured by Troels. I can't really see being the guinea pig for something that pricey, not when viable alternatives are available at similar price points. Also, the Seas coaxials (among others) seem designed for midrange use, whereas I get the impression Tang Band is shooting for a more full-range solution, which I don't think I really need.

                  Has anyone seen off-axis measurements for the MR18REX? If they approach that of its more expensive sibling I think it'll be the way to go.

                  Also, I keep calling it "Mr. Rex" in my head.

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                  • #24
                    Given the relatively small numbers of coaxials I think I'm going to stick with the Seas C18EN002, mostly because a number of third parties have actually measured it, and it measures well. It's expensive, but considering the cost of the two mids + tweeter used in other large center channel designs, not exorbitantly so. I'll probably grab three of them around New Year's to "lock me in" to the project - one for the center, plus two more for matching mains someday.

                    Given the stated 87 dB sensitivity for the mid and 90dB sensitivity for the tweeter, and the likelihood of shooting for an Fc somewhere around 250-300 Hz between the mid/low arrangement, does anyone have suitable suggestions for the woofers? I'd like to stick around a similar sized frame at the C18EN002, so the RS180 or RS180P could be contenders. Going low-ish in cost here seems like a good way to offset the cost of the Seas itself, but I also want to be sure everything will integrate well with each other. Drivers I've looked at thus far:

                    Dayton RS180
                    Dayton RS180P
                    DIY SG Anarchy 7"

                    On the somewhat more expensive end:

                    Wavecor SW182 (pending Part Express stock and pricing)
                    Peerless (Vifa) NE180W

                    Unsure the more expensive drivers are really necessary, given the application. The Anarchy is intriguing for the bass capabilities (obviously) and stated low distortion throughout its range. Unsure if that would meet up well with the Seas, but it would be nice to get some very deep bass without the need for a sub.

                    As far as the box goes - it's going to be very wide, built in as part of a new TV stand that is wide enough to accomodate three amps and such side-by-side, so up to 70" or so. Deep enough for those same amps, so around 24". Around 30" tall overall, so however "thick" the CC is cuts into the available room for shelving. What I'm saying is, quite a lot of volume will be available to play with if it is needed. The amps themselves will likely be covered by thick glass doors (shooting for 1/2", depending on what I can source), held shut with magnets, and the intent is to power everything with an Emotiva XPA-DR3 or similar (450 watts @ 8 ohms, 600 @ 4). Current plan is to build the entire thing out of Appleply with a clearcoat finish (not that it really matters, but there you go!).

                    Based on playing around with WinISD, pretty much any of the drivers above can certainly hit an F3 in the low-to-mid 30s in a ported enclosure. While it'd be super (and potentially possible) to hit the upper 20s, I'm not real sure that's necessary for my situation.

                    I should point out I'd be looking at using four woofers for several reasons:

                    1. Increase low-end and reduce need for a subwoofer, especially once coupled with matching mains
                    2. Allow me to use smaller-framed drivers in the CC, which gives me slightly more height to work with for shelving below the speaker without raising the height of the TV stand itself.
                    3. Lower bass distortion
                    4. Possibly negate the need for BSC
                    5. Aesthetics

                    Having low distortion is especially a concern to ensure these mesh well with the Seas midrange. That said, if I have four of them I'm not sure anything expensive is all that necessary, and the original plan of going with the Dayton RS180P in a series/parallel configuration may be okay. Hard to tell how much BSC would be needed until room measurements could be made, but I suspect minimal given the wide baffle, distance to the floor, and the thick glass doors may help as well. Coupled with a generally higher sensitivity of multiple woofers it might be plenty fine.

                    The other concern I had is whether that Fc would work okay for voices, or if a 3.5 way setup may be of benefit overall. From my understanding, low voices can extend into the 300 Hz range (with the fundamental below that), meaning these drivers would likely be filling in some of that. Would it sound odd if those deep voices emanated from across the entirety of the speaker, as opposed to just using the adjacent woofers, or the mid alone? Or should I wait to ask that question until I can measure the Seas to find out just what I can really expect it to reach and what order of crossover may be necessary?

                    So I guess after all of that - here are the questions:

                    1. Suggestions for suitable woofers to match with the Seas C18EN002 @ an Fc ~250-300 Hz, possibly without the need for BSC
                    2. Can this be done without BSC, or is that just a pipe dream?
                    3. Should I more strongly consider the potential benefits of bumping up to an 8" woofer in place of a 7'? I'm less concerned with improved bass response (though that is a consideration) and more concerned with low distortion in its range.
                    4. Would a 3.5-way arrangement be of use, or is it too early to know?
                    5. What else am I not thinking of?

                    Note: Ideally, cost of the four woofers would be under $500 combined. I think there are plenty of contenders in the $50-$70 range that should easily be possible. I can go more if necessary, but given that these will only be filling in the low range I see little reason to grab some exotic Scan-Speak (or whatever) for that purpose unless there is a really good reason to do so.

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                    • #25
                      SB ceramic would look good and probably blow the budget. I assume this is Left, Center, Right all built into the massive stand? My concerns would be miss match in driver quality, and coaxes like adjustable toe-in to get the imaging correct.
                      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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                      • #26
                        I apologize, the left and right speakers will be separate, traditional towers built at a later time.

                        I had forgotten about the SB ceramics! I had looked at them a while back but have not tried modeling them as of yet. I hear only good things about them though.

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