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First attempt at crossover design

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  • First attempt at crossover design

    I am aiming to design and build a 3 way set of stereo speakers for my oldest brother. He has a vintage Sansui receiver that is somewhere around 150 watts per channel. I picked a pair of Dayton Audio DC160-4 wired for 8 ohm for the lows, a single DA PC105-4 for the mids, and a DA PT2C-8 for the highs. I have no history with planar speakers and wanted to try them out. My goal was to make a set of speakers capable of handling the high power from that old Sansui arc welder and look and sound great. I haven't figured out the cabinet software yet so I'm thinking of going with the 1.16 cubic foot Denovo cabinets. There is no rush with these at all. I'm using them as training but still want to end up with a good end result. I browsed through the project gallery and found some inspiration. Youtube helped too. Not sure if I need to upload the .vxp file too. Thanks for taking a look at this.

  • #2
    I'd suggest crossing the mid at 4k, and notch the bump at 1.8k if it's still significant.


    • #3

      When you wire a pair of 4n(ohm) drivers in series, you get NO net sensitivity gain. (Your sim (which I'm not familiar w/THAT one) LOOKs like it's giving you the +6dB gain you get for a pair of 8n drivers in parallel.

      That Denovo box looks good if you can fit a 3"id x 11" long port in it. That gives you an Fb and F3 in the mid 30s.

      Your filter topologies seem okay, but your scrnshot is too small for me to make out the values.

      Did you apply any baffle-step compensation to the woofer (& maybe mid) files?

      A 3-way w/6.5" woofers always seems like a bit of a waste to me. A mid lets you go after a larger woofer.
      A pr. of the 6-1/2" woofers hit Xmax @ 30w RMS above 30Hz - so you won't be able to use TOO much of the arc-welder's output.


      • #4
        My brother's speakers were stolen years ago. I think they were from Radio Shack and had a giant woofer at the bottom. I remember them being huge. I was considering a more modern approach but I'm not opposed to some old school design. I have kept my eye on the 3 way towers made by Raymund Berlo in the project gallery. I don't mind following another member's lead as long as I learn from it, which I'm sure I will. Chris, I'm not sure if I added all the speakers correctly in that program. I'm using VituixCAD2 and the tutorial videos I've watched was for the original version. I added a basic 3way 2nd order crossover and played with the values to try to get a decently flat SPL graph. I've learned what each component does but not quite why you put them in specific places. Kirby (from Kirby meets Audio) recommends Dayton Audio drivers because they all have the frd and zma(?) files needed for these free programs to work. It took me the better part of the day to actually get an output on the graphs. It is fun learning about all of this but I don't really have the cash to be buying all kinds of parts that are wrong (like my first subwoofer build).

        RPB, I'm sure that was English that you used but I'll have to look up the meaning. I haven't learned how to apply a notch filter yet. I'm a work in progress. Thank you both for the input!

        This is from a seperate post but I'm almost done with the veneer on the little Neo build I"m doing with the passive radiators. And I just tried to make my first knife handle while the adhesive set for the veneer. I found out that black walnut doesn't like being whacked with a hammer.


        • #5
          If you can live with larger boxes, and possibly a higher budget, that opens the door for more options. Maybe even some used drivers! I have some stuff that I'll never use.

          I'm using a single sealed 10" driver for my sub, and it plays pretty loud, and clean. A 10", or 12" 3-way in a big box might be cost effective.


          • #6
            Money is no issue with these....................... because I'm not paying for it. I'll try another build with a jumbo woofer. Do you think I should stick with an AMT or go with a 'traditional' tweeter?


            • #7
              Originally posted by BTRaulerson View Post
              RPB, I'm sure that was English that you used but I'll have to look up the meaning. I haven't learned how to apply a notch filter yet. I'm a work in progress. Thank you both for the input!
              It looks like the crossover between the midrange and tweeter is around 2,500Hz, rpb is suggesting moving that up to closer to 4,000Hz.
              Right around 1,800Hz you have a peak in the frequency response, rpb is suggesting a notch filter might be able to smooth that out.


              • #8
                Originally posted by BTRaulerson View Post
                Money is no issue with these....................... because I'm not paying for it. I'll try another build with a jumbo woofer. Do you think I should stick with an AMT or go with a 'traditional' tweeter?
                The RS225A is a popular 8" woofer that has good bass I'm told. I'd say it's the woofer that everyone likes. The PC105-4 looks very smooth other than the blip at 1.8k mentioned above. I'm not familiar with any ribbon tweeters, but the PT2C looks like it's robust enough. The x-over parts could get expensive, so it's a good idea to sim a few options before deciding for sure on drivers.


                • #9
                  Thank you all for the great information and helping me with my hobby. It is really awesome to be involved with a group like this without people thumbing their nose at you. I feel welcome here even though I only know a little bit more than a stone. It is delightful. I'm hoping to apply all I learn here and make delightful sounding speakers that can enhance the lives of people around me.


                  • #10
                    I don't think it was answered... ZMA is the impedance curve. On that Sansui you probably don't ever want to drop under 4 ohms at any place on the curve. The crossover components can change the impedance curve, so the sim should take that into account.

                    The impedance curve also shows how a driver will respond to filters. Your 8 ohm woofers are likely not 8 ohms at the frequencies you want to apply the filters.


                    • #11
                      If you go w/the drivers you've picked, it looks like your series pair of 4n(ohm) DC160s DOES show the proper sensitivity (around 88dB) for those (I did some research).
                      You have no "baffle-step" in your sim. The result of that (usually) means you end up w/insufficient bass.
                      On a 3-way you typically try to shoot for the mid to handle 3 octaves (so, maybe 400Hz to 4kHz?).


                      • #12
                        About the PT2C.

                        In the description wide horizontal and narrow vertical dispersion is mentioned. I don't know this particular driver, but you may find that the narrow vertical dispersion is a problem. I have a set of 50" ribbons, and the same is true of their dispersion. If you get your ears even a few inches above the end of the ribbon, you lose the treble almost entirely. This might happen for instance if you move from a seated to a standing position.
                        Just a consideration.



                        • #13
                          The PT2C also is not an AMT, but a planar. The peak, trough, hump and roll-off makes it hard to implement. 3kHz is recommended or up to 4kHz.
                          I've used the PC105-4, and I liked it. I recommend a 2 Ltr sealed box stuffed. It was not hard to use or cross over.
                          I also have used the DC160-4, and it's pretty versatile. A xover of 500Hz should be relatively easy.

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                          • #14
                            Here's an interesting 12" woofer. It's very efficient, so the midrange would need to have a high sensitivity too.

                            Where in the room will the speakers be placed? Close to the wall?



                            • #15
                              The specs on that woofer are great! I'll do some reworking of my planned speakers. Thanks again for all the help and tips.