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Xover design for DC200-8/DC28F-8

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  • Xover design for DC200-8/DC28F-8

    Perhaps this is in the forum already and missed it thru my search... but does anybody have a xover design for the Dayton classic 8 inch woofer(DC200-8) and the DC28F-8 1 1/8 tweeter or the ND28F-6 neo tweeter... Also I see Dayton does not provide .frd or .zma for these speakers... does anyone have this info??

    Thanks guys

    Bud

  • #2
    Re: Xover design for DC200-8/DC28F-8

    We were just having this conversation the other day, but I don't blame you if the search didn't bring it up. PE's tech talk search function leaves some things to be desired.
    http://techtalk.parts-express.com/sh...d.php?t=209010

    And yes, I still would like to design and build this 2-way (it'd probably be a floorstanding tower a la Noah's 8's).
    Isn't it about time we started answering rhetorical questions?

    Paul Carmody's DIY Audio Projects
    Twitter: @undefinition1

    Comment


    • #3
      Re: Xover design for DC200-8/DC28F-8

      The .frd and .zma for the 8" used to be available. I grabbed them a while back from the PE site. Here they are in a zip file.
      Attached Files
      Don't listen to me - I have not sold any $150,000 speakers.

      Comment


      • #4
        Re: Xover design for DC200-8/DC28F-8

        I traced the .frd and .zma files too. Here they are.
        Attached Files
        Don't listen to me - I have not sold any $150,000 speakers.

        Comment


        • #5
          Re: Xover design for DC200-8/DC28F-8

          Note, you should sim them in "Response Modeler" before bringing them into PCD.
          Don't listen to me - I have not sold any $150,000 speakers.

          Comment


          • #6
            Re: Xover design for DC200-8/DC28F-8

            Originally posted by dubeiram View Post
            Perhaps this is in the forum already and missed it thru my search... but does anybody have a xover design for the Dayton classic 8 inch woofer(DC200-8) and the DC28F-8 1 1/8 tweeter or the ND28F-6 neo tweeter... Also I see Dayton does not provide .frd or .zma for these speakers... does anyone have this info??

            Thanks guys

            Bud
            Here's mine. Put these in a 1.7 cf box, tuned to 30 Hz or a little lower using a 3"d REAR port. Length of 9" should be close.

            2nd order HP w/L-pad, positive polarity:
            5.6uF series cap, 0.50mH #20 shunt coil, SR = 4.7 ohms, PR = 7.5 ohms

            1st order LP w/Zobel:
            0.50mH #18 series coil, Zobel with 4 ohms and 47uF.

            Comment


            • #7
              Re: Xover design for DC200-8/DC28F-8

              You guys are the best... thanks for the info... I'll plow thru it and I'm sure I'll be back with more questions..

              Comment


              • #8
                Re: Xover design for DC200-8/DC28F-8

                See.. I'm back already.. general question on compiling .frd and .zma data... from the files you guys sent me there are a zillion data points from either trace programs or data provided by the mfg. .. question is.. what if you didnt have the .frd or .zma data and didnt want to go thru a trace program... but instead created a hand jammed data base where thru visual inspection you pick the frequences where there are transitions in the response curves... and come up with say 20 data points vs. the 100s can you get from a mfg. data... not perfect but a resonable representation... is that close enough for practical purposes???

                Comment


                • #9
                  Re: Xover design for DC200-8/DC28F-8

                  Originally posted by dubeiram View Post
                  See.. I'm back already.. general question on compiling .frd and .zma data... from the files you guys sent me there are a zillion data points from either trace programs or data provided by the mfg. .. question is.. what if you didnt have the .frd or .zma data and didnt want to go thru a trace program... but instead created a hand jammed data base where thru visual inspection you pick the frequences where there are transitions in the response curves... and come up with say 20 data points vs. the 100s can you get from a mfg. data... not perfect but a resonable representation... is that close enough for practical purposes???

                  What you're talking about would probably be OK for level matching (like "padding" a tweeter), but here's the catch.

                  As far as determining how any specific filter topology would roll off any given driver, and how they'd act/interact at the crossover freq., without "phase" data: sometimes two drivers will sum +6dB (in perfect phase), sometimes it'll be +3dB (Butterworth types), they'll also sum everywhere in between AND even less than +3 and EVEN LESS than +/-0 (when they're "destructively" out of phase).

                  This is just all too hard to keep track of "by hand". Also, even if you had exact phase data at 20 different freqs (2 steps/octave, lets say), as you add XO components (coils & caps), the actual output phase of the driver rotates forward and backward in different amounts and at different frequencies.

                  Initially I tried to do what you're describing with a spreadsheet using 11 points (1 per octave), then I went to 2/oct. By the time I got to 3/o it became VERY cumbersome and error prone.

                  Also, even at 3 samples/o (31 points from 20-20k), you could have a driver (like an RS) which read 76dB @ 8kHz, and 78 @ 10k and 12.5k, but you could be missing a +6dB "spike" (say, to 83dB) right at 11kHz. That wouldn't sound too good if something wasnn't done to "notch" it out.

                  I would say that 6 points/oct would be the absolute minimum that you could get by with, and even then, there'd be cases where that just might not be good enough.

                  Can I ask why you just don't want to use a modelling program?

                  Chris

                  Comment


                  • #10
                    Re: Xover design for DC200-8/DC28F-8

                    Originally posted by Chris Roemer View Post
                    Can I ask why you just don't want to use a modelling program?

                    Chris

                    Sure... just being a bit lazy and thought worth asking how much data you need to "reasonably" represent a speaker using xover programs... and your description is excellent... bottom line.. make the effort to trace.. I have only used SPL trace in the past can you recommneded anything better??

                    Comment


                    • #11
                      Re: Xover design for DC200-8/DC28F-8

                      Honestly, plotting an FR curve a few points at a time is a lot like the old-fashioned graph paper methods. Tedious to say the least. Like most things, computers have sped the process up. (The learning curve of a piece of software can slow things down, I admit)

                      But gosh, it doesn't get much more easy and straightforward than SPLTrace. Sorry.
                      Isn't it about time we started answering rhetorical questions?

                      Paul Carmody's DIY Audio Projects
                      Twitter: @undefinition1

                      Comment


                      • #12
                        Re: Here's what I'm thinking

                        First off, I shouldn't be doing this. :D The mere fact that I'm sitting here doodling this is an exercise in procrastination.
                        However, there does seem to be quite a bit of demand for a new 2-way using the DC200 + DC28f, and it's a combo I'd like to hear myself, so it IS in the plans.

                        But I'm racking my brain thinking of the right enclosure for this design. Obviously, it should be something pretty conventional, since an 8" 2-way is a classic speaker design. But the driver needs a pretty sizable box--plus, it's gotta look COOL

                        At the smallest size possible, it would work in the Dayton .75 cu ft (on the right). Classic look. Should get an F3 around 34 Hz.

                        But for something a bit more slick, it would actually work better in the Dayton 1.0 cu ft box (the MTM-shaped one), on the left. This gets the F3 down to 29 Hz or so.

                        So take a vote. Which one would you rather build? Or do you have a better idea? I'm open to suggestions.
                        Attached Files
                        Isn't it about time we started answering rhetorical questions?

                        Paul Carmody's DIY Audio Projects
                        Twitter: @undefinition1

                        Comment


                        • #13
                          Re: Xover design for DC200-8/DC28F-8

                          Hey Paul, I posted in the other DC200 thread, but it fell off pretty quickly. I have a TL cabinet design Paul K. did for me. If you like I'll send it you to see if you'd like to use it.

                          What crossover point is optimal for the DC200? I'm wondering what other tweeters might be viable for a design.
                          "If you cannot find the truth right where you are, where else do you expect to find it? - Dogen

                          "Why are you wearing that stupid human suit" - Frank

                          "We spread the time as we can, but in the end the world takes it all back" - Roland

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                          • #14
                            Re: Xover design for DC200-8/DC28F-8

                            Originally posted by tombond View Post
                            Hey Paul, I posted in the other DC200 thread, but it fell off pretty quickly. I have a TL cabinet design Paul K. did for me. If you like I'll send it you to see if you'd like to use it.

                            What crossover point is optimal for the DC200? I'm wondering what other tweeters might be viable for a design.
                            I have played around with that driver and anything above 1000Hz is out of the question. Really around 700 to 800Hz is about its limit.

                            Vifa and Seas have some 8" drivers that will work better for a 2 way and easily get you up to around 1500Hz so you can cross to a tweeter. Of course they are 2.5 times the price of this woofer. The Seas Poly is not a bad choice if you want an 8" 2 way it is on sale for $59 and it would work reasonably well even up close to 2000Hz. Though I would cross it at 1500Hz to a 27TBFC or if you want to keep the budget down try a Northcreek tweeter and cross it at 1500Hz.

                            http://www.madisound.com/catalog/pro...roducts_id=834
                            Dave

                            If you can read this, thank a teacher.
                            If you are reading it in English thank a Veteran
                            .

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                            • #15
                              Re: Xover design for DC200-8/DC28F-8

                              Madisound still sells a kit with this poly woofer and Seas tweeter, the Cygnet MKII.

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