Midwest Audio Fest

It’s that time audio enthusiasts! Registration for the 2019 Speaker Design Competition is now open! Visit for details and to list your speaker project. We are excited to see all returning participants, and look forward to meeting some new designers this year, as well! Be sure your plans include a visit to the Parts Express Tent Sale for the lowest prices of the year, and the Audio Swap Meet where you can buy and trade with other audio fans. We hope to see you this summer! Vivian and Jill
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RS100-8 & ND25FA

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  • RS100-8 & ND25FA

    So after a few builds under my belt with other people's xover designs I decided to take a shot at doing one myself. I need another set of speakers like I need another hole in the head but my name is Michael and I'm a speaker addict. There should really be a disclaimer in the PE home page about how addicting this hobby is. Anyway, I have been reading and researching and reading some more trying to get an understanding about how all this works (what a rabbit hole!!!). I wanted to start relatively small and fairly low budget for my first attempt in case the results were disastrous, so I looked at drivers. Iwas tempted by the speaker Gods with all the shiny, sparkly objects and ultimately settled on the RS 100-8 because I liked the graph, specs seemed good as I wanted a fairly small enclosure, again I really have no idea what I'm doing here but it seemed like a decent place to start. I did some more research via the forums here (so much info) thank you all who contribute you time and share your knowledge on the forums. I watched some videos, thanks to Toid123 for your tutorials!!! They are great!!! I ended up going with the ND25FA based on user feedback and I thought I could get it in the right range for the xover. I also wanted a smaller profile for the tweeter because to the shape I had in mind for the cabinets. So I did the boxy cad, modeled the box to come up with the vol. which ended up around 3.4L if memory serves correct. I then moved on to unibox for the next step. Ended up with a ported enclosure and a 1.25" x 5" port for a tuning of 75 Hz. All the graphs seemed to come up ok there, so on to the Jeff's response modeler. I plugged in all my stuff, followed some awesome tutorials written by people much smarter than me (thank you again) and came up with a new set of squiggly lines to put into the PCD. I used Jeff's PCD for the xover design, learned about baffle step (man that's a bummer) and also used xsim to kind of double check my work. Please don't ask me why I chose which components to go where because I have no idea, my goal was to play with the values of everything until I got a frequency response that looked reasonable and that is pretty much the extent of my knowledge at this point . So once I came up with a response that seemed acceptable, I moved to the garage and began making dust (my favorite part) After some math and measuring I had my sketch up in my head and set about to making the cabs. Sorry I didn't really document the build very well while I was cutting and gluing and sanding and finishing, I get so excited when things start happening that I forget to take pictures. But I basically cut a bunch of triangles out of 3/4 MDF, sanded one all smooth and used it as a template on my router table, made a bunch of identical pieces and laminated them together and put some veneer on them. It was the first time I have ever veneered anything and using some tightbond and an iron it came out pretty good, there are a couple of small bubbles but hey. The front and back are just primed, painted with some black lacquer out of a rattle can. I ended up spraying about 10 coats of lacquer over everything and called it good.I wired up the xovers in between coats of finish and hooked them all up. Quick question for those of you who have read this far... does anyone have any tips on soldering speaker wire to the tabs on the speakers? I used some female terminals to the woofer but i didn't have any small ones for the narrow (-) tab on the ND25 and I was too lazy to go out and buy some. I had a dandy of a time trying to hold the wire, solder and iron all at the same time. Well I got them up and working and my first impression is they sound a bit hot on the high end to me. They were pretty high in the garage, seem a bit better in my room closer to the wall, I guess I had the intention of using these as a small desktop setup, even though I don't have a desk that I sit at. So my thought is that being closer to the wall is giving the low end some reinforcement thus kind of making everything seem more balanced? I don't know. I think I may get back in to these and change the 6.2 ohm resistor in the L-pad down to something like another 2.4 to lower the top end a bit. Which will be a slight PITA because I already soldered these together but hey, live and learn right? The RS 100 does a pretty good job, I think I was reaching xmax a few times playing some pretty bass heavy music at fairly loud volumes, but these speakers weren't really designed with that in mind so I can live with that. At moderate levels they sound pretty darn decent.Unfortunately I don't have the ability to measure the final outcome so I am just relying on my ears to tell me how they sound. I think that is pretty much it for now. If I change the crossover I will update. Thanks to everyone who has taken the time to post their experiences and wisdom on these boards, thanks to all of you I have made a pair of speaker that actually work and don't sound half bad!!!!!!! If anyone has any questions or thoughts please feel free, I'd love opinions on anything that you all would have done differently or areas where you seem room for improvement.

  • #2
    They look nice. No one will put anything on top of them.


    • #3
      Looking at a sim, I'd drop your PR (L-pad) down even a tad more, down to 2 ohms. (Just "jumper" across that 6.2ohm guy w/a 3.0ohm to get 2 ohms.)
      I'd also "unhook" your woofer's (shunt) RLC group. It's making a depression around 1.7kHz - for no apparent reason. Just "open" it on either end, OR even somewhere in the middle.


      • #4
        Thanks for the feedback!!! I was thinking about swapping the second resistor in the L-pad w/ somewhere around a 2 ohm, so you are saying that if I put a 3 ohm basically on top of the 6.2 that will get me there? I just tried that in xsim quickly and it seemed to work. Also I unhooked the RLC in xsim and it seemed to make a pretty good hump in the plot? Do you think this would be inaudible? One way to find out I suppose... Thanks again for the input!!!


        • #5
          IF your sim data is accurate, then THAT hump would NOT be a good thing. Your baffle (shape/size) and resultant diffraction looks VERY unusual. (They don't LOOK bad, I'm saying that the drivers do NOT present your "typical" baffle effects on those triangular baffles.) The 1.3k hump (IF "real") is likely caused by your woofer centered on that triangular baffle (according to "Edge"). The tweeter actually looks pretty good up there (on the narrow part - which I'd NOT guess would be the case, centered and all).

          If you NEED that LCR, then you need it. If you don't, opening it up will certainly make SOME kind of change to your response. Doesn't cost anything to try it, right?
          Maybe on this design, your ears should be your guide. Hopefully you've got like third-octave test tones you can play to see (hear) where you need to make changes?
          Would you say these measure about 12"h x 11"w(base) x 11"d - EXternal?


          • #6
            Chris, yes I was curious to see how altering the shape from a rectangle which was all I could figure out how to get the SIMS for to a triangle would alter the diffraction. I realize that the sims are more of a "starting point" and yeah I kind of planned on having to do some tweaking along the way. I will definitely try both of your suggestions to the crossover and see how they sound to me. Unfortunately I don't really know what I am supposed to do with the test tones. I can try and find some online to play through the speakers. And yes you are pretty much spot on with the external dimensions of the cabs. Thanks again for the tips. I'm excited to play around with them some more and see how changing things actually impacts the sound rather than just a line on a graph.


            • #7
              ........does anyone have any tips on soldering speaker wire to the tabs on the speakers?

              Nothing worse than the coil wire separating from the connector. After running the bare wire through the tab, I dab on a little paste type flux. Then with a fine tipped soldering iron, one can usually 'rest' a small blob of solder on the tip. Touching the soldering iron to the tab for 5-7 seconds will heat the flux and the solder on the tip usually flows into the wire and tab. Keeping the tab and wire level helps with the dispersion. Also, a thinner wire doesn't require as much time to heat.


              • #8
                I like to tin the connector and the connecting wire separately, then let cool. Then make the physical connection and a smaller "blob" will weld them together post haste. That keeps each heating cycle down - not having to wait for the flux to react first, then the solder on the overall connection.