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AudioEngine A2+ Modification and Mini Subwoofer

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  • #16
    Do you plan on building a Voxel?

    I'm saying that your Peerless isn't really great for a sub. Using your 0.17cf box w/the Peerless (or really any size box w/that Peerless) I wouldn't bother changing it's tuning over what you've already got. You'll not get a very significant extension in bass.

    You COULD use your .17 box w/a different driver, the W5-1138SMF (which IS the Voxel woofer). You'd have to tune the box quite a bit lower (which means you'd probably have to go w/an external port tube, OR a PR - which I'd recommend) but you'd end up near 40Hz (instead of the 50-60 range that you've got w/the Peerless).
    40 is all you need for (almost any "normal" kind of) music.

    If you needed to hit 30Hz, the W5 ideally would like a larger box (I get 0.37 cf w/WinISD), but it needs to be tuned to the low 30s. It's hard to fit a long port in a small box. That makes it hard to tune a small box LOW, unless you build (or RE-build, in your case) a "slot" ported box, OR use a PR.
    If you're going to follow the Voxel plans, good.
    If you want to fit the W5 in the box you've already got, I'd tell you which PR would work best.
    If you wanted to go deeper (w/a larger box), I'd still tell you which PR I'd go with.

    If you DO want to put a PR on your Peerless sub (and keep using it - I see you looked at one of TomZ's projects), I can recommend a PR as well. (I guess your MAIN complaint isn't how low it goes, but that it chuffs?)

    Comment


    • #17
      fassj Just a quick tip related to forum codes in case you didn't know. If you want to target a user (or several users) in a post to make sure they see it, you can do this:

      Code:
      @fassj
      Soon as you type @ you'll get a list of user names immediately after the symbol, starting with the first character you typed (if there is a user name starting with it) and it'll refine the list the more you type.

      I mentioned this since you asked Chris a question using plain text. He scrubs the boards a lot so he's likely to see that most times (probably), but just wanted to give a tip to help make it easier to ensure such a post is seen by the intended person when possible. Quoting posts and some other actions notify them as well.

      Good luck with the projects! Passive Radiators are a real nice middle ground between ported and sealed, allowing to reach lower than sealed while eliminating several complexities (some times prohibitive) introduced when going full Ported / Bass Reflex design.
      Feel free to rip my assumptions apart when wrong, or fix if close.

      Passive Radiators:
      All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
      For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
      A PR max weight is said to be its Mms x3

      PR Systems - tight focus with key parameters.
      PR Speaker Design - thorough coverage.

      Comment


      • #18
        Chris Roemer Thanks! This is the type of info that I think I'm really looking for. That was immensely helpful! I do have enough 3/4" MDF left to build another box so I'm all for trying something else out. I've always liked PR subs, I have Definitive Technology BP towers with PR's and really like them.
        So I guess the decision I need to make is do I get the W5 and try to see if I can return the Peerless or just keep the Peerless and try to build a new box. I've already installed the Peerless so not sure if PE would take this back as a return. I guess there's nothing wrong with having both...
        • You COULD use your .17 box w/a different driver, the W5-1138SMF (which IS the Voxel woofer). You'd have to tune the box quite a bit lower (which means you'd probably have to go w/an external port tube, OR a PR - which I'd recommend) but you'd end up near 40Hz (instead of the 50-60 range that you've got w/the Peerless) 40 is all you need for (almost any "normal" kind of) music.
          • I'm not particularly committed to this box for any reason.
        • If you needed to hit 30Hz, the W5 ideally would like a larger box (I get 0.37 cf w/WinISD), but it needs to be tuned to the low 30s. It's hard to fit a long port in a small box. That makes it hard to tune a small box LOW, unless you build (or RE-build, in your case) a "slot" ported box, OR use a PR.
          • I'd love to hit the 30's if possible since the AudioEngines that sub would be paired to already get relatively low for the size (2.75" driver).
            • These speakers get low albeit with immense amounts of blowing through the ports. No port noise though.
        • If you're going to follow the Voxel plans, good.
          • I would pass on the Voxel if it won't provide any meaningful improvement on the Peerless.
        • If you want to fit the W5 in the box you've already got, I'd tell you which PR would work best.
          • I'd likely build a new box with the necessary volume and PR setup to reach lower if I end up getting the W5 (which is quite likely).
        • If you wanted to go deeper (w/a larger box), I'd still tell you which PR I'd go with.
          • This is the way I'm leaning now. If it's not too much trouble would you recommend a PR and box size? Would .37 cf be ideal as you mentioned?
        • If you DO want to put a PR on your Peerless sub (and keep using it - I see you looked at one of TomZ's projects), I can recommend a PR as well. (I guess your MAIN complaint isn't how low it goes, but that it chuffs?)
          • Those are my exact complaints. Ideally my goal would have been to keep the Peerless, redesign a new box to get lower, and eliminate port noise. That doesn't really seem feasible for this driver though.
          • I did like TomZ's project.
          • I originally got the Peerless because it had higher sensitivity than the W5 and was going to be powered by a 30ish watt Logitech 2.1ch amp. The amp broke while building the replacement box so I now have this https://www.parts-express.com/lepai-...3118--310-4002

        Thump Thanks for the tip!

        Comment


        • #19
          ^ no problem
          Feel free to rip my assumptions apart when wrong, or fix if close.

          Passive Radiators:
          All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
          For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
          A PR max weight is said to be its Mms x3

          PR Systems - tight focus with key parameters.
          PR Speaker Design - thorough coverage.

          Comment


          • #20
            W5-1138SMF in 0.37 cf. This 5" sub driver has such a large Xmax, that the single 6.5" PRs that are available can't handle the excursion.
            So, an 8" is in order! The $20 DSA215-PR (# 295-549) models best in this situation (w/ 90g added mass - if it can take that much?).
            It tunes the box to the mid 30s, and yields an F3 in the low 30s. The system can take the W5's full-rated power of 40w RMS @ 30Hz.

            Comment


            • #21
              Thanks Chris Roemer ! I'll take a look at that and mock something up in SketchUp. Really appreciate the modelling data!

              I'd prefer to keep the radiators at 5.25" like tomzarbo has for aesthetics. Tom directed me to where I could get a pair of these Peerless SDS-P830880 5-1/4" which each have xmax 6mm. I read somewhere that the goal is to have the PR xmax match or exceed the driver. I'm assuming it would carry over that two 6mm xmax PR's would meet this requirement since they combine to 12mm?

              Sorry for having two threads on the topic. I had responded to TomZ's build thread and realized it started to overlap with this.

              Comment


              • #22

                Originally posted by Chris Roemer View Post
                … The $20 DSA215-PR (# 295-549) models best in this situation (w/ 90g added mass - if it can take that much?) …
                Short answer:
                The 295-549 should accommodate 90g extra, with a maximum of 201g total additional weight possible for this PR, based on its Mms of 67g IF what I've found is accurate.

                What I just said is based on a Greg T. (PE Staff) response to a different PR Q&A. He's implying we can essentially calculate the maximum safe additional weight a PR can handle by doing PR Mms x 3.

                I have an email to their technical team specifically on this matter to try and get clarification so we can finally know for certain how to get that number safely.


                Rant:
                That's one of the major issues with PR regarding technical reference material as I continue researching, so I can help myself and others with PR generally.

                Manufacturers not providing what the actual added maximum mass determined by them really is.

                So at this point until something more definitive is produced, I'm going with Greg T, so Mms x 3 = max additional weight a PR can handle.

                I'll hopefully have a response soon and will report results.
                Feel free to rip my assumptions apart when wrong, or fix if close.

                Passive Radiators:
                All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
                For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
                A PR max weight is said to be its Mms x3

                PR Systems - tight focus with key parameters.
                PR Speaker Design - thorough coverage.

                Comment


                • #23
                  Originally posted by fassj View Post
                  ... I read somewhere that the goal is to have the PR xmax match or exceed the driver. I'm assuming it would carry over that two 6mm xmax PR's would meet this requirement since they combine to 12mm?
                  There are two methods I'm aware of, both based solely on information provided directly by Dayton Audio themselves, regarding how to ensure we don't bottom out the PR and have it correct.

                  These are from their respective product pages on the matter.


                  Approach 1:
                  As a general rule the passive radiator(s) should be able to move double the volume of air as the active woofer(s)/subwoofer(s) in the system. For example: A passive radiator system for a 8" woofer/subwoofer that has 9mm of X-max would require 2-8" passive radiators with 9mm of X-max. For single passive radiator systems, it is common to use a passive that is larger than the active woofer(s)/subwoofer(s).

                  Approach 2:
                  As a general rule, the passive radiator(s) should have at least double the displacement of air (Vd) as the active woofer(s)/subwoofer(s) in the system.
                  To calculate Vd: Sd x Xmax = Vd


                  I've been using and recommending approach 1 to ensure there's never a chance of bottoming out. However, approach 2 may be more accurate. I'm not certain which is more accurate, yet.

                  Important note:
                  Approach 2 is more recent based on product release, so I'm going to start using and recommending that.
                  Last edited by Thump; 10-17-2018, 09:43 AM. Reason: Added note
                  Feel free to rip my assumptions apart when wrong, or fix if close.

                  Passive Radiators:
                  All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
                  For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
                  A PR max weight is said to be its Mms x3

                  PR Systems - tight focus with key parameters.
                  PR Speaker Design - thorough coverage.

                  Comment


                  • #24
                    Interesting. So the design with the TB W5 as the driver and 2 Peerless 830880 5.25" PR's would fall within the parameters of Approach 1 but not Approach 2... if I'm understanding correctly. This may be a dumb question but wouldn't box size play a role in this?

                    TomZ seems to have good results with his build.

                    Comment


                    • #25
                      I was kinda bailing on this thread, but ... EYE figure the PR ("system" - if more than 1 is used) should handle twice the displacement of the active driver.
                      It's just like a car engine (bore x stroke). You can use "Sd" (which is actually surface area) times Xmax (stroke).

                      Tom's pair of 5" PRs come up short in the Xmax dept. (but they'd be OK if they had as much as the active driver - the "2X" rule). While PE's 6.5" PRs ARE larger, they don't have enough stroke (for ME) to use as a single w/the W5 (which has monster Xmax - for a 5"). Another consideration is that Tom didn't plan on pushing his W5 to it's power limit ("Pe) of 40w RMS - he's only using Dayton's SA25 amp. He knows his stuff, and I''m sure his little subs are great, but if you copied his project but used the SA70 amp instead, you MIGHT has issues.

                      Comment


                      • #26
                        Originally posted by Chris Roemer View Post
                        I was kinda bailing on this thread, but ... EYE figure the PR ("system" - if more than 1 is used) should handle twice the displacement of the active driver.
                        It's just like a car engine (bore x stroke). You can use "Sd" (which is actually surface area) times Xmax (stroke).

                        Tom's pair of 5" PRs come up short in the Xmax dept. (but they'd be OK if they had as much as the active driver - the "2X" rule). While PE's 6.5" PRs ARE larger, they don't have enough stroke (for ME) to use as a single w/the W5 (which has monster Xmax - for a 5"). Another consideration is that Tom didn't plan on pushing his W5 to it's power limit ("Pe) of 40w RMS - he's only using Dayton's SA25 amp. He knows his stuff, and I''m sure his little subs are great, but if you copied his project but used the SA70 amp instead, you MIGHT has issues.
                        That's exactly why I've been using approach 1. I started to doubt moving to approach 2 about 2 minutes after I posted the approaches up there, but then got lost in a gigantic reply in another thread.

                        I've now asked them which approach is correct, since it's confusing now, to give a definitive answer in a reply back to them, too. They replied about 3x Mms for max weight judgement. Here's a snippet:


                        "The absolute max weight for any PR is going to be 3 times the Mms just as a general rule of thumb, unless the manufacturer says otherwise."


                        So we can indeed use that, which is great news. I've recommended they start putting that in their PR specs so customers know. I've further recommended they actually add that calculation to the Tips they put in the PR section, just like they do for the approaches. Either one would do, but both would be prudent I believe.
                        Feel free to rip my assumptions apart when wrong, or fix if close.

                        Passive Radiators:
                        All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
                        For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
                        A PR max weight is said to be its Mms x3

                        PR Systems - tight focus with key parameters.
                        PR Speaker Design - thorough coverage.

                        Comment


                        • #27
                          Chris Roemer
                          I just got the answer back on second part of the PR discussion. Please check my interpretation and correct if needed. This relates to which approach is the more accurate or usable, and is now more clearly scenario specific and finally makes some sense to me:


                          Approach 1 shorthand:

                          All PR(s) at-least 2x Xmax of woofer(s) Xmax.

                          Approach 2 shorthand:

                          All PR(s) Vd at-least 2x Vd of woofer(s) Vd, so PR(s) total Vd at-least 2x all woofer(s) Sd x Xmax.

                          Direct from PE Tech:

                          I emphasized my perceived most relevant aspects with italics and bold.

                          "They are both correct, the newer product simply states the math you can use to determine if you can get away with one PR or if you need two. They describe the same thing, that you need to be able to displace double the air volume, and just describe it in different ways.

                          Since our new reference series PR's have such a large Xmax, you don't always need to use two PR's. I have had times where the new PR is working with a driver that has lower Xmax and a single passive will work.

                          That said I have also found when using BassBox to create designs for customers, sometimes using two PR's gives me more options for deeper tunings. Having the extra cone area and being able to add more mass sometimes gives you more options for the design."

                          So, not surprisingly at all, you crushed it. This also means my original gut instinct (2x Xmax minimum) was at-least the safer approach given my limited understanding.

                          Let’s see if I’m finally on target with interpretation and a usable, accurate, combined recommendation with scenario specific
                          included.


                          Approach Final Draft:

                          All PR(s) Vd at-least double all woofer(s) Vd, so PR(s) total Vd >= 2x woofer(s) Sd x Xmax.

                          For woofer(s) with large Xmax vs Sd, use 2x Xmax instead, where PR(s) total Xmax >= 2x woofer(s) Xmax.

                          Is this correct?

                          If yes, is the wording easily understood?

                          Feel free to rip my assumptions apart when wrong, or fix if close.

                          Passive Radiators:
                          All PR(s) Vd must at-least double all woofer(s) Vd. Calc = Sd x Xmax to get Vd for all PR(s) and all woofer(s). If all PR(s) Vd at-least double all woofer(s) Vd they'll work.
                          For woofer(s) with large Xmax vs Sd, all PR(s) with Xmax at-least double all woofer(s) Xmax will work.
                          A PR max weight is said to be its Mms x3

                          PR Systems - tight focus with key parameters.
                          PR Speaker Design - thorough coverage.

                          Comment

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