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The des3L3W17 - Speaker design for InDIYana 2017 "Nano" 3L contest

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  • The des3L3W17 - Speaker design for InDIYana 2017 "Nano" 3L contest

    Concept
    • 3L volume and 1ft^3 per speaker,
    • no subwoofer support.
    • $300 max total driver spend (incl. passive radiators but not incl. ports or xo, etc.)
    • No more than $100/driver.
    • No end-of-life/no-longer-available drivers.
    This is my first speaker design attempt (and first DIY speaker event), so part of the plan is to also use it to bring up various measurement and design tools and meet the community.

    (Pics will get updated, these are just what I have at the moment---pods and PR's not yet modeled. Front is within 11x11 inches.)
    --Derek

  • #2
    Driver and Concept Selection
    Summary:

    REVISED 16 Jan: I had a chance to open many of the "interesting" drivers today. The TB W2-2089 is a _monster_. So much so that I think I just have to use it.

    NEW:
    W: W4-2089 + PR TBD
    M: Tectonic BMR 3.5"
    T: TBD

    OLD:
    W: 2x (ND91-8 + 830878 PR)
    M: RS52AN-8
    T: XT25SC
    • Due to the volume limitation, woofers with a Vas within 2x the volume constraint were screened by Fs and the PE/other recommendations for sealed and vented enclosure sizes within/near 3L.
    • Isobaric designs were considered, particularly given the strong reputation of Totem'’s Mani II. However, two internal woofers consume a lot of volume, and I a’m concerned that higher frequencies may be impacted by a basket-external design or various complex effects as the wavelengths approach the driver separation, etc. External baskets have low SAF...
    • Tang Band RBM drivers show fantastic Fs and F3 numbers but their sensitivities are down near 80 and their cost is high. Ordered some anyways as they may be so exciting that I have to at least measure them.
    • Dayton RS100-4, RS125T-8, DS115-8, CF120-4, and ND91-8 all look exciting. As does SEAS H1207-08 L12RCY/P.
    • Given that ports would consume volume inside the box or have low SAF outside the box, passive radiators SD175-PR, 830878, and 830880 were identified, however 830880 appears to be end-of-life at PE (but not some other places, ref. Wolf's comment below).
    • TomZ’s Bantam’s use the ND91 and 830878. Scott Sehlin uses the ND91 in the Heliums. Bantam’s are less than half the 3L constraint: we could double up!
    • Exciting midranges are a pair of spare RS52AN-8 in my stable and the inexpensive Tectonic Elements 3.5” BMR (TEBM46C20N-4B), although a midrange may be silly with woofers this small (but necessary with the Tang Bang RBM’s). RS52 is closed back, the BMR isn'’t.
    • Tweeters I’'m interested in considering include the ND20F[A/B], BC25SC55-04, XT25SC90-04, XT25TG30-04, RT003C, NeoCD1.0, RS28[A/F], some of which are already in my stable from/for other projects.
    • From these, the most promising configuration I ha’ve identified (yet) is a pair of ND91, each with their own 830878 PR, with an RS52AN and an XT25SC or BC25SC55. Comes in just under $300.
    • By using a pair of Denovo 0.04 ft^3 flat-pack enclosures for each speaker, one cabinet for each ND91 and PR, I can basically duplicate TomZ’s proven Bantam’s for higher sensitivity woofing. I can also save some time and sawdust, and can perhaps gain a little volume if I remove some material where the cabinets are flush to each other.
    • The RS52AN is closed-back, so it and the tweeter can sit outside the precious 3L. The cabinets are inexpensive, so they can also make for a fast test box for the woofers (i.e. to do Vas measurement by the delta volume method). By placing the mid and tweeter outside the box, there’s an opportunity to easily shift them back to align voicecoils, again without digging in to the 3L. For example, the prototype cabinets could even mount the M and T "pods" on a sliding mount.
    • All driver front-plane locations are initially chosen for a combination of aesthetics, accommodating some room for foam or space for fore-aft offsets, etc. It is likely that the M-T center distance may need to be changed based on their crossover frequency, and mirror image versions are planned (duh!)
    Last edited by deschu; 01-16-2017, 10:01 PM.
    --Derek

    Comment


    • #3
      Driver TeardownDrivers planned for teardown/sacrifice: ND91-8, RS52-AN, XT25SC. Others by request (I ordered waaay too many drivers for this in my stupid enthusiasm!)



      [how do I get the signature out of these???]
      Last edited by deschu; 01-16-2017, 02:11 AM.
      --Derek

      Comment


      • #4
        Impedance measurements
        Last edited by deschu; 01-16-2017, 09:13 AM.
        --Derek

        Comment


        • #5
          Placeholder for In-Cabinet Response
          --Derek

          Comment


          • #6
            Placeholder for Crossover Design
            --Derek

            Comment


            • #7
              Placeholder for Final Measurements
              --Derek

              Comment


              • #8
                Placeholder for Final Cabinets/Speakers
                --Derek

                Comment


                • #9
                  830878 looks like PE is still selling it, and it's not on clearance. Where'd you hear it's going NLA?

                  I'll say this- those 830878 and 830880 have actually gone NLA once or twice before, and they still came back!

                  The driver prices to be used for the entries are to be non-sale prices, and PR's are included. Not saying you can't use on-sale items, just that the total price is to be calculated with daily retail pricing.

                  All I would say off the bat- put the M/T closer together. Other than that- have fun!
                  Later,
                  Wolf
                  Last edited by Wolf; 01-16-2017, 10:50 AM.
                  "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                  "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                  "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                  "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                  *InDIYana event website*

                  Photobucket pages:
                  https://app.photobucket.com/u/wolf_teeth_speaker

                  My blog/writeups/thoughts here at PE:
                  http://techtalk.parts-express.com/blog.php?u=4102

                  Comment


                  • #10
                    Typo, my bad, I swapped the two. It's the 830880 that is NLA at PE (not just out of stock). It's still listed on Madi and the Tymphany website. I was too lazy to order from Madi and take the risk...but now I might!

                    Re: M-T distance: I'm toying with machining off the top of the RS52 frame and going with the ND20FB or BC25, much easier to get tight, but I was going to see what LEAP predicts before cutting metal (although I have the tear down unit to practice on).

                    Thanks for the input!
                    --Derek

                    Comment


                    • #11
                      If it's still available elsewhere, and not on clearance, then it's not NLA.

                      Later,
                      Wolf
                      "Wolf, you shall now be known as "King of the Zip ties." -Pete00t
                      "Wolf and speakers equivalent to Picasso and 'Blue'" -dantheman
                      "He is a true ambassador for this forum and speaker DIY in general." -Ed Froste
                      "We're all in this together, so keep your stick on the ice!" - Red Green aka Steve Smith

                      *InDIYana event website*

                      Photobucket pages:
                      https://app.photobucket.com/u/wolf_teeth_speaker

                      My blog/writeups/thoughts here at PE:
                      http://techtalk.parts-express.com/blog.php?u=4102

                      Comment


                      • #12
                        Why Leap if you are starting out?

                        Comment


                        • #13
                          Derek,

                          Looks like some cool ideas there. I like your choice of woofers, we're thinking somewhat along the same lines there... PR's as well as they really don't subtract from precious box volume as vents do.

                          A thought... from experience I've noticed that even the small Peerless PR's can cause cabinet vibrations in use. They have a weight slug in the center which really acts like a great big cell phone set on vibrate to be honest. I used dual opposing PR's on my Indiana entry partially for that reason... the cabinet can walk around without good rubbery feet... and the higher up the PR's are, the worse the effect. My 'Bantams' had turned around 180 degrees and nearly walked off the table during one listening session before I noticed and stuck some rubber feet on the bottoms of them.

                          I like your project idea, it's different; the 'constraints' of the rules are kind of fun to find ways to make it work.
                          Look forward to meeting you in Indiana if my boss gives me the day off!

                          TomZ
                          Zarbo Audio Projects Youtube Channel: https://www.youtube.com/channel/UCEZ...aFQSTl6NdOwgxQ * 320-641 Amp Review Youtube: https://youtu.be/ugjfcI5p6m0 *Veneering curves, seams, using heat-lock iron on method *Trimming veneer & tips *Curved Sides glue-up video
                          *Part 2 *Gluing multiple curved laminations of HDF

                          Comment


                          • #14
                            Originally posted by deschu View Post
                            Typo, my bad, I swapped the two. It's the 830880 that is NLA at PE (not just out of stock). It's still listed on Madi and the Tymphany website. I was too lazy to order from Madi and take the risk...but now I might!

                            Re: M-T distance: I'm toying with machining off the top of the RS52 frame and going with the ND20FB or BC25, much easier to get tight, but I was going to see what LEAP predicts before cutting metal (although I have the tear down unit to practice on).

                            Thanks for the input!

                            The BC25 is very easy to work with, but you can't get a tight center to center distance with it because it has that little waveguide face.
                            The ND or XT tweeters would work better for close CTC.

                            I think I hear a difference - wow, it's amazing!" Ethan Winer: audio myths
                            "As God is my witness I'll never be without a good pair of speakers!" Scarlett O'Hara

                            High value, high quality RS150/TB28-537SH bookshelf - TARGAS NLA!
                            SB13/Vifa BC25SC06 MTM DCR Galeons-SB13-MTM
                            My Voxel min sub Yet-another-Voxel-build

                            Tangband W6-sub

                            Comment


                            • #15
                              Originally posted by ani_101 View Post
                              Why Leap if you are starting out?
                              I've got access to it without having to pay "full price" and it was recommended by a friend with a fair bit of industry experience, so I figured "why not?"

                              I suppose that this could also be an interesting test case for comparing results across modeling tools, I just haven't thought about it that way.
                              --Derek

                              Comment

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