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RST28F in a Visaton waveguide

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  • #91
    "Flat" amplitude, no loss in top end "air" (associated with WGs) and low distortion even with low Fc.
    And in this case it's more about making sure our filter is behaving as predicted.

    And it looks cool.
    Guess xmax's age.

    My guess: 15. His grammar is passable. His trolling is good.

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    • #92
      Originally posted by tmhutson View Post
      Larger woofers often offer better efficiency, and increased dynamics. Often less distortion due to less cone movement. You just have to match the tweet to woofer in the woofer's usable directivity band.
      A trade off with the econowave design (constant directivity) is generally more focused imaging (less reflectivity from surroundings) compared to an open mid, tweeter. And smoother off axis. One's personal preference applies here. No real horn honk, generally as the wg is shallow. (Some golden ears claim DI doesn't sound good).

      I find it hard to believe that any large format woofer mated to a regular dome tweeter could in any way give as flat of a power response off axis as compared to an econowave type design. Not to mention trying to cross over low with out the loading effect of the wg.
      A small woofer or mid-range, sure.
      But not many speaker designs can touch a DI type speaker for pure dynamics and efficiency. The DI type speakers can be pretty flat in response, too.
      If Jeff Bagby can make them sound good, i suppose I can't argue with that.

      Just a series of compromises.
      Civit, my thinking is similar to yours, which is why i am entertaining the idea of your visaton and rst28 build.
      I have a rather expensive 7" seas excel woofer i want to try as well. Has nasty peak that the wg might help with by crossing lower. I got thesethese spe for free, and they came with a decent Tweeter to play with as well...

      Remember, many pro speakers got a bad rep for lack of linearity. The econowave speakers really opened up a door to designs that were loud, clean, efficient and in many cases, relatively cheap. With nice linearity when a decent passive crossover was implemented.


      I am watching your thread due wanting a di design that is nice off axis for critical monitors. Notice how so many studio mintors have waveguides?

      I also want more than one type of speaker design to play with. This is just one of many project ideas (some unfinished ones, too).

      As to the mid-range in waveguide, i want to try that, too. But the added complexity is not wanted right now...

      I hope i can have the skills in the future to do a synergy build. I can make one of foam core and a full ranger to start... I have seen some nice ones that turned out really nice.

      I am ordering some rsp225-4a's right now.
      I don't think the 10's would be a good idea at the moment.
      I have some deltalite 10s to play with.
      I just don't like the fact they can't go to 80 hz sealed without eq. Better as mids, i think, in a three way.
      Remember, most of the pro driver based di designs do best with a sub. I am going to go sealed with fb of 80.
      The rsp225-4a looks perfect.
      Today I ordered an RS270P-4A and a Peerless tweeter with a small wave-guide. My plan...... might flop, but 10" 2-way. Passive of course. This will be used for a center channel If it goes well.

      The tweeter looks like the wave-guide profile could be extended easily, making it much larger. The profile is about 45 degrees at the mounting flange, and has a sharp edge. I think that I can cut a hole in 3/4" material, and shape it with my router to match the exit of the guide. I plan to do some distortion testing on both drivers, and I'm hoping that they are suitable for use together.

      The tweeter has some good user reviews. I'm hoping it's in the same league as the RST28 above 2k,
      https://www.parts-express.com/peerle...-ohm--264-1386

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      • #93
        Curious how the 10" works out for you...
        i am still thinking about getting some even though i decided on the 8's.

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        • #94
          Ok guys. Got these in the mail; haven't had a chance to test for fit. If they fit well I will send the STL files for anyone interested and we can start running tests.

          These are printed with PLA.

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          • #95
            OK, so these printed just great. Next time I'd make all the hole diameters 1/4mm bigger but the tight fit works. I designed both of these so that you could re-use the fasteners which come with the tweeter, and that appears to have worked out perfectly. The PLA material I used is pretty strong and seems totally adequate to get a good seal between the tweeter and the WG, but a small gasket precision cut wouldn't hurt I don't think.

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            • #96
              These are some very rough distortion plots, taken with the waveguide sitting on my desk and the mic right near the dome. There is a null in the very high frequencies in the sb26STAC, but I'd take the magnitude measurement with a grain of salt (as with the distortion products past H3 or so - these were done at reasonable levels in a noisy room).

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              • #97
                Originally posted by xmax View Post
                This is the RST with Pete S's 8.4" x 1.5" deep, round profile WG. Still tweaking filter.
                Click image for larger version

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                It's hard to compare distortion measurements with different setups, etc.. Here's the Peerless that I mentioned earlier. The woofer hole was open, and the response might be smoother when I mount it properly, but I think this has potential for a smaller woofer design. There's a high-pass filter.

                Click image for larger version

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                • #98
                  Originally posted by rpb View Post

                  It's hard to compare distortion measurements with different setups, etc.. Here's the Peerless that I mentioned earlier. The woofer hole was open, and the response might be smoother when I mount it properly, but I think this has potential for a smaller woofer design. There's a high-pass filter.

                  Click image for larger version  Name:	H26 distortion.JPG Views:	2 Size:	201.5 KB ID:	1401871
                  From your distortion measurement (if at least a little accurate) I think it is safe to assume the tweeter
                  could be struggling below 3K, what is the HP design?

                  The FR I measured above was created with a 7.5uf Cap shunted with a .4uH, fed via a tank
                  consisting of a 18uF cap, .15uH coil and a resistor about 2.4 ohms if I recall. So even though
                  the RST can handle extremely low Fc's, the electrical filter is effectively around 2.6K, plus
                  the additional reduced energy via the tank, all thanks to the big deep guide.
                  Guess xmax's age.

                  My guess: 15. His grammar is passable. His trolling is good.

                  Comment


                  • #99
                    What is the best material to print a Waveguide adapter in, FDM, SLS or SLA ?

                    What percentage infill do you recommend?

                    Thank you,

                    David.

                    Comment


                    • Originally posted by DaveFred View Post
                      What is the best material to print a Waveguide adapter in, FDM, SLS or SLA ?

                      What percentage infill do you recommend?

                      Thank you,

                      David.
                      I used on online servide which did FDM out of PLA. The requirements for this part are not very strenuous. I had mine printed for something like 15 dollars. I do not know what infill was used.

                      Comment


                      • Update long overdue. I took some measurements of the RST28f and the SB26STAC units with the 3d printed adapters last night. Measurements for the rst28 looked good; for the sb26stac they looked okay but not amazing. Work will continue.

                        See dropbox link below for measurement data.

                        https://www.dropbox.com/sh/br71zv8x1...GqfLZ3CMa?dl=0

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