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Duane Brown "Dayton 4" Deluxe version

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  • #31
    I have several projects in mind which should make for a fun 2020. Duane’s neat design is probably my “on deck” project.

    I need to build some more and continue to learn. With Duane’s I modeled the TCP-115 and get about a 3db hump before it rolls off (using Duane’s box size.

    Since I am new I would probably went smaller with a flatter response but I read Jeff Bagby’s comments that if a speaker rolls off between 100-70hz he likes a smaller 2-3db hump to fill out the bottom end for a fuller sound. I am assuming Duane is doing the same thing here and should keep the box volume as is.

    Any thoughts are appreciated.

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    • #32
      Many of Paul Carmody's designs (esp. those w/smaller woofers like the OS, Speedster, etc.) use a tuning "hump" of a few dB as part of "baffle step compensation". You can also account for it strictly in the XO, but usually w/a bit of a loss in sensitivity.

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      • #33
        Thank you Chris. Your comment makes me wonder if there is a best way to accomplish that. Even my little NAD D3020 amplifier has a bass EQ switch that boosts up to 7db centered around 80hz. NAD used it for the same reason as Jeff and Paul apparently (not speaking for either of them). Interesting NAD chose a larger boost.

        They say:

        “:Because we expect this amplifier will often be used with smaller speakers that have limited bass extension, we have brought back NAD’s Bass EQ feature, a low Q filter centered on 80Hz with about 7dB of boost. This gives just the right amount of ‘heft’ to small bookshelf speakers without adding chesty coloration to male voice.”

        Back to the Dayton 4. A hump it is. I may have been on the verge of screwing it up! I am sure this is why the bass seems better than expected.

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        • #34
          This thread and Duane's speaker prompted me to take another stab at these woofers a few weeks ago. Mt first attempt months ago had failed as the boxes were too small. Well, I must say I'm quite impressed with them now that I have a properly sized box. I had some ND28F-6s on the shelf and they modeled well together. I'm still in the voicing phase, but it's a very nice combo in such a small package. I've never designed a series crossover, so mine is parallel and unfortunately uses twice as many parts as Duanes.

          I know Craig (PWRRYD) designed a nice MTM with the TPCs and ND25FW. You can find the details on the Midwest Audio Club forum.
          Co-conspirator in the development of the "CR Gnarly Fidelity Reduction Unit" - Registered Trademark, Patent Pending.

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          • #35
            Originally posted by tom_s View Post
            This thread and Duane's speaker prompted me to take another stab at these woofers a few weeks ago. Mt first attempt months ago had failed as the boxes were too small. Well, I must say I'm quite impressed with them now that I have a properly sized box. I had some ND28F-6s on the shelf and they modeled well together. I'm still in the voicing phase, but it's a very nice combo in such a small package. I've never designed a series crossover, so mine is parallel and unfortunately uses twice as many parts as Duanes.

            I know Craig (PWRRYD) designed a nice MTM with the TPCs and ND25FW. You can find the details on the Midwest Audio Club forum.
            Very cool. I am excited to do this one.

            I cut the wood yesterday. I guess you can read the dimensions but until you see them in front of you it is hard to get a visual. These are small speakers!
            Last edited by stephenmarklay; 12-27-2019, 09:05 AM.

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            • #36
              DrJay, I am in the middle of building these now. I had a question about your modifications. Did you model the woofer response? I am pretty new to do this but when I do It looks like the original design already give a 3db hump before it falls off. I see about an f3 of 55hz. Duane reports down to 48hz but I don’t know what he is referring to (f3? f6? etc).

              If I were to go by the winIsd model I would actually want to go smaller. I still get about the same f3. The original, with my model, appears to droop a little in the 150-400hz range. I mean a little and nothing likely audible but also not something I would tend to do with my limited experience.

              What prompted you to increase the size?

              Again, I am new and trying to learn. I am not at all saying that the original nor your model implementation are wrong. I am constantly playing catch up

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              • #37
                I got a pair of the -4s not long ago and DATS'd them (after break-in). While not exactly on "spec", the box model doesn't change too much.
                Qes 0.49, Qms 3.2 (Qts 0.425), Fs 65, Vas 0.066cf, others to spec.

                My plan is to put these in 0.10cf tuned to hi 50s (anywhere from 55 to 65Hz could work).

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                • #38
                  Originally posted by Chris Roemer View Post
                  I got a pair of the -4s not long ago and DATS'd them (after break-in). While not exactly on "spec", the box model doesn't change too much.
                  Qes 0.49, Qms 3.2 (Qts 0.425), Fs 65, Vas 0.066cf, others to spec.

                  My plan is to put these in 0.10cf tuned to hi 50s (anywhere from 55 to 65Hz could work).
                  Thank you for theses Chris. Yes .1cf does look pretty spot on to me but I will look again. My boxes are closer to .15 which is perhaps a tad large. No big deal...

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                  • #39
                    My box is 0.15cf before adding beech supports. I typically just lump the driver and port in as a net 10% reduction in volume. That nets me about .125cf tuned to 66hz. This gives a 2.5 deep hump before rolling off with an f3 of 55hz. Based on the port velocity I will use a 1.5” port at 8”.
                    Last edited by stephenmarklay; 12-31-2019, 05:26 PM.

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                    • #40
                      There is a big difference between .15 and 1.5 cf.
                      craigk

                      " Voicing is often the term used for band aids to cover for initial design/planning errors " - Pallas

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                      • #41
                        For 0.125cf, I'd go 1.25id x 7" long, but that's just me. W/good roundovers (3/8"?) a 4" probably won't overtax a 1-1/4" port.
                        Also, i THINK PE's got a 1-3/8 tube?
                        Your tuning can take 36rms into the high 50s.

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                        • #42
                          Originally posted by craigk View Post
                          There is a big difference between .15 and 1.5 cf.
                          Yes they are mental lapse different

                          I meant 0.15cf. Sorry.

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                          • #43
                            Originally posted by Chris Roemer View Post
                            For 0.125cf, I'd go 1.25id x 7" long, but that's just me. W/good roundovers (3/8"?) a 4" probably won't overtax a 1-1/2" port.
                            Also, i THINK PE's got a 1-3/8 tube?
                            Your tuning can take 36rms into the high 50s.
                            Chris, is there a detriment to using a slightly larger port? It does not matter to me but I saw PVs at 20 with a 25w input so I figured that was about as high as they should be…
                            I am using this speaker on a shelf so I altered the plan to make that possible. My shelf would not accommodate the 8.5” depth so I went a bit taller and a but shallower. My external dimensions are
                            10”h x 6”w x 7”d. Same volume and baffle width. I personally like the dimension from an aesthetic viewpoint. Anyway, that may allow for a front port as well. That is not mandatory but would be nice with the back wall being close to the speaker.

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                            • #44
                              Nothing wrong w/a bigger port, if it fits.

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                              • #45
                                I did model it in my modified box size. Using a 1.250" port at a tuning frequency of 53Hz, WinISD somputed an F3 of 48Hz, SPL of 94db at Xmax, and port velocity of 30M/sec using a 5.75 long port. The modeled response was 1 db down at 80Hz and 1 db up at 58Hz. When I listened to the speaker, I liked a port length of 5.5 inches best, but the differences between 6", 5.5" and 5" were very subtle.

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