Helios mk1 - A cautionary tale

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  • Bear
    Super Senior Member
    • Dec 2008
    • 1038

    Helios mk1 - A cautionary tale

    As I've mentioned in other threads, the Helios design by the late Jeff Bagby (and the not-late Javad Shadzi) is my current project. I am looking for "something reasonable" (put that in a QFD!): relatively high performance, not absurd expenses (~$1k/channel), and something that I can get done relatively quickly. That last one is obvious foreshadowing.

    I had contemplated doing my own design for quite a while. I was looking into something that might follow along in the path of the Neo D CC (a relatively compact three way that works as both a Center channel and as a monitor). However, the horrific sound bar that I purchased just after my move to San Diego is not to be tolerated any longer than necessary. So, I started looking at designs. The Dutch & Dutch 8c was very intriguing, but that was obviously proprietary. There were a few other classic designs available, and then I saw the Helios design get mentioned right when the waveguide-loaded tweeter was unexpectedly released into the market (nothing on SBA's "coming soon" page at all!). A quick re-cap of the major design elements:
    • Relatively flat in-room performance into the mid-20s
    • Relatively low distortion (big caveats on measurement methodology here!)
    • Two-way design using a waveguide Beryllium tweeter ($$, ouch!), a big (9.5") woofer, and a "10-inch" (29 cm seems to round to 12" in my math textbook...) passive radiator
    • Relatively good sensitivity
    • High SPL capability from 100W


    A few more words of caution: the design was mostly documented on a Facebook group, with a few details that needed to be interpolated. I'll document a few of the steps in this thread, but the reality is that I screwed up the crossover completely, so mark 2 will happen as soon as some additional wood shows up from Northwest Bamboo. But first, let's throw some pictures into the mix to get things rolling.

    Oh, yeah, since COVID-19 closed the SDFWA member shop, I built these in my second bathroom using a folding table as a workbench (more foreshadowing). The build uses carbonized vertical bamboo, with a mix of single-ply and three-ply product. The single ply comes from Woodworker's Source (Christmas sale), and the 3-ply comes from NW Bamboo (nice guy; very reasonable prices). Cali Bamboo is headquartered 10 miles from where I live, but they only deliver full sheets. NW Bamboo can breakdown sheets for shipment.

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    Last edited by Bear; 23 April 2020, 21:22 Thursday.
    Welcome to Rivendell, Mr. Anderson.
  • 5th element
    Supreme Being Moderator
    • Sep 2009
    • 1671

    #2
    I would expect those to have some serious dynamic capabilities compared to standard 6+1" designs.
    What you screamin' for, every five minutes there's a bomb or something. I'm leavin' Bzzzzzzz!
    5th Element, otherwise known as Matt.
    Now with website. www.5een.co.uk Still under construction.

    Comment

    • Bear
      Super Senior Member
      • Dec 2008
      • 1038

      #3
      Originally posted by 5th element
      I would expect those to have some serious dynamic capabilities compared to standard 6+1" designs.
      They model well. The design seems to hit Xmax at around 100W and 107dB according to Unibox. Insertion losses would obviously push the wattage requirement up to reach that level, but why anyone would want to play that loudly is beyond me. The low-end can also be tweaked by playing with the box volume and PR selection/tuning. More on that in a bit. In another thread , the Bliesma T34A was examined in a Monacor(?) waveguide. I think that would be the ultimate expression of this concept, and that would be more about lowering the noise floor further in the 1kHz - 1.5kHz range. Then there's a potential 2.5 way using 8ohm drivers in double the box volume....
      Welcome to Rivendell, Mr. Anderson.

      Comment

      • Bear
        Super Senior Member
        • Dec 2008
        • 1038

        #4
        Bass Alignment

        There are a few things that are interesting about the Helios design. The most obvious is that it's a TM using an almost 10" woofer married to a beryllium tweeter in a waveguide. But the bass alignment itself is what really caught my attention. Being someone who, due to COVID-19, is likely to be stuck in apartments for a year or two longer than desired (want to keep resources liquid), I'm interested in minimizing the amount of kit required to make a satisfying system. And since I how live in high-cost San Diego, minimizing the footprint of any gear is also desirable.

        So, what's the party trick, here? It's using an oversized PR in what is nominally an undersized box to give an step/transient response that mimics a sealed alignment, but with a considerable boost in low-end output. Here are the basics from Unibox (note that I've supplemented the summary chart with a handful of additional metrics). All of these are using factory data, of course.

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        Here's the predicted step response:

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        That looks pretty good. The step response really highlights what Jeff and Javad were trying to accomplish. However, the SB29 PR is listed as a 10" unit, and a 290mm frame diameter seems a lot like 11.5" to me. Plus, the design was a single-vendor show piece (literally), so let's see if we relax the single vendor constraint a bit. And maybe bump up the box volume just a touch. What do we get? Another 1.5dB at 20Hz.

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        Bear in mind that Xmech for the WO24P may be around 12.75mm (the best that my Google-Fu could come up with). The published Xmax is 8.5mm. At 100 watts, which is a target indicated by Jeff for power handling, any of these are starting to scare that Xmech limit. This will work great with a good receiver, but not one that goes to 11. Also, with the downsized PR, there's more flexibility in placement, which I thought was desirable (and still do). I give up the closed-box step response, but the extra oomph down low and some form-factor flexibility seem worthwhile to me.
        Welcome to Rivendell, Mr. Anderson.

        Comment

        • Bear
          Super Senior Member
          • Dec 2008
          • 1038

          #5
          In the original design, the only surface with enough area to place the passive radiator was the side of the box. That meant that it would be quite deep (14.25"). It also required some work on the structural bracing to accommodate that placement. Here's the cabinet drawing from Javad:

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          The dimensions work out to be 20"H x 14.25"D x 11.12"W. That width number bears a little discussion. As near as I can tell, that's made up of 13 strips of ApplePly at 0.75"(?) each, plus two 5mm spacer boards plus two 0.5" cheek plates in Padauk(?). All told, that gives a baffle width of 11.14". However, if the ApplePly is really 19mm (0.748), then the width drops to the 11.12 that I show, above. In any event, we're looking at a width of around 11-1/8". One should note, though, that the 35L size that this generates is gross, not net. That internal structure will likely knock a couple of liters off of what the drivers will actually see.

          Since the 26W/0-00 PR requires a 240mm cutout and since I am using 19mm LBL, my initial goal was to go with dimensions of 25"h x 11.75"w x 12.5" deep. Something that didn't seem unreasonably deep to me, while still maintaining the monitor-style form factor. However, then I started getting a bad case of The Yips. I just couldn't get my tracksaw and framing square to give me a square cut. Also, I had my medium size squares (12-8) with me, while my big (18-12) one is back in Houston. What I should have done is plan for more waste in my cut plan (search for the "5 cut method") to see if I could get square cuts. Instead, I created a bunch of waste that required me to rethink the dimensions based upon what I was able to get within some tolerance of square. Plus, I just out-and-out pooched some of the measurements (I did lead with this is a "cautionary tale").

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          What I ended up with was a box that was significantly deeper than planned (20"h x 11.75"w x 15.75"d). This is too deep for my current space or any of my expected future spaces in the next 3 - 5 years. However, because I wasn't hitting square with my cuts, I ended up doing the "oversize and trim" method (aka measure twice, cut three times) to ensure that my seams were as minimal as can be. And since I do not currently own a block plane or jointer or similar, I had to hit the residual irregularities with three discs of 60 grit with my random orbital sander.

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          Last edited by Bear; 24 May 2020, 13:07 Sunday. Reason: spelliing, grammar
          Welcome to Rivendell, Mr. Anderson.

          Comment

          • Bear
            Super Senior Member
            • Dec 2008
            • 1038

            #6
            Cautionary? You bet. I've done all of my cutting and sanding outdoors in prior builds. I just didn't respect how much fine dust my track saw would generate with the LBL. And I didn't appreciate the rooster tail of shavings that would come off of my flush trim/patterning bits for my little router. Every build is an excuse to buy more tools, right? So, in comes the Parallel Edge from TSO Products (ouch!), and a Festool Mini dust extractor. I had been eyeballing that last one for a while, so that wasn't an unexpected purchase. Needing to supplement my Woodpeckers Squares, though, was a disappointment.

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            Part of why I went with LBL is that it machines very well, with very clear (sharp!) corners. It is also a very attractive wood in its own right, which eliminates (for me) the need to veneer the exterior (good veneer can be pretty spendy!). Of course, that means that you have to have good control over the router and not slip when doing all of those trim operations. I wish I was that skilled...

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            So, again, this is a cautionary tale.
            • Get the dust shrouds for your tools
            • Get a dust extractor
            • Pay very close attention to how you engage with the wood on any trimming operations


            On all of those trimming operations, I had three big runaway moments, and the inner baffle one is the least visible of the two that show to the exterior. Building a patch is obviously in my future.

            Oh, yeah, you can never have enough clamps.
            Welcome to Rivendell, Mr. Anderson.

            Comment

            • Bear
              Super Senior Member
              • Dec 2008
              • 1038

              #7
              An astute observer will have already noted one my my major heresies in this project -- changing the baffle width. Yes, I'm guilty as charged here. If you download your favorite baffle diffraction simulator of choice, and start playing with a 20x11.125" wide baffle and drivers as big as these (the outer diameter of the waveguide is 170mm), you will see that there is still diffraction from the baffle, but it is not very sensitive to placement or width (within reason). Yes, it moves around a fraction of an octave here and there, but the shape is still largely the same unless one can start making meaningful changes (e.g., 3" chamfer/roundover). There will be measurable differences, but I'm not convinced that they will be audible.
              Welcome to Rivendell, Mr. Anderson.

              Comment

              • Dave Bullet
                Senior Member
                • Jul 2007
                • 474

                #8
                Originally posted by Bear
                An astute observer will have already noted one my my major heresies in this project -- changing the baffle width. Yes, I'm guilty as charged here. If you download your favorite baffle diffraction simulator of choice, and start playing with a 20x11.125" wide baffle and drivers as big as these (the outer diameter of the waveguide is 170mm), you will see that there is still diffraction from the baffle, but it is not very sensitive to placement or width (within reason). Yes, it moves around a fraction of an octave here and there, but the shape is still largely the same unless one can start making meaningful changes (e.g., 3" chamfer/roundover). There will be measurable differences, but I'm not convinced that they will be audible.
                Bugger about the slip. My heart sank and I said an "oh no" out loud!

                No heresy about modifying any DIY design IMHO. As long as you have the means to measure or simulate and adapt...why not make it your own.

                Comment

                • Zvu
                  Senior Member
                  • Oct 2013
                  • 434

                  #9
                  Dave is absolutely right. Since the changes are minor it should require only minor adjustments, if any.

                  I'm sensing serenity in spades behind Bear's posts. No matter what happens, he keeps his calmness. I think i'm gonna enjoy reading every bit of this journey.
                  Tesla; George Carlin;

                  Comment

                  • technodanvan
                    Senior Member
                    • Nov 2009
                    • 998

                    #10
                    Agreed, that sort of slip-up would (and has.....and probably will again) make me put a project on an extended hiatus. I appreciate the honesty behind the project as well as the patience and thought that has gone into it.

                    For what it's worth, I have the same Makita tracksaw and square - I have also had trouble getting 90 degree cuts with it. I hadn't noticed until a more recent project that required some accuracy, but it seems consistently off. Initially I just thought it was me, but it's so consistent now I'm not really sure what the problem is. Even with the TSO GRS-16 it happens.
                    - Danny

                    Comment

                    • drkingweeb
                      Junior Member
                      • Apr 2020
                      • 2

                      #11
                      how do you acess javad's facebook page?
                      drmike

                      Comment

                      • Bear
                        Super Senior Member
                        • Dec 2008
                        • 1038

                        #12
                        Originally posted by drkingweeb
                        how do you acess javad's facebook page?
                        drmike
                        It's a closed group (just ask to join), but there's a link to this project in the first post (looks for the underlined text). I hope it works -- FB is pretty idiotic with links to specific posts. Here it is freeform:
                        DIY Loudspeaker Project Pad is a place to post your speaker build projects, helpful tips, thoughts about speaker building and design and engage with others that are just as passionate as you are! We...
                        Welcome to Rivendell, Mr. Anderson.

                        Comment

                        • Bear
                          Super Senior Member
                          • Dec 2008
                          • 1038

                          #13
                          Originally posted by technodanvan
                          Agreed, that sort of slip-up would (and has.....and probably will again) make me put a project on an extended hiatus. I appreciate the honesty behind the project as well as the patience and thought that has gone into it.

                          For what it's worth, I have the same Makita tracksaw and square - I have also had trouble getting 90 degree cuts with it. I hadn't noticed until a more recent project that required some accuracy, but it seems consistently off. Initially I just thought it was me, but it's so consistent now I'm not really sure what the problem is. Even with the TSO GRS-16 it happens.
                          My first thought was the utterance of a stream of four letter words, but it was really my fault. The combination of bit and router needed to be driven into the wood with a fair bit of authority and "on a ramp". It just took me a number of mistakes to get the message. The next thought was, "okay, let me try the sawdust and wood glue patch method", but that really didn't work for the largest of the exterior gouges. The final option is likely to be to route a shallow rectangle around it and try to get a proper patch.

                          However, once I owned-up to how excessively deep these are, I have effectively abandoned this project in favor of mark 2, which will be a small-ish tower version (38x11.75x9).
                          Welcome to Rivendell, Mr. Anderson.

                          Comment

                          • Bear
                            Super Senior Member
                            • Dec 2008
                            • 1038

                            #14
                            Originally posted by Zvu
                            Dave is absolutely right. Since the changes are minor it should require only minor adjustments, if any.

                            I'm sensing serenity in spades behind Bear's posts. No matter what happens, he keeps his calmness. I think i'm gonna enjoy reading every bit of this journey.
                            I appreciate the compliment, but the serenity -- such that it is -- definitely comes as a secondary effect after some choice language.
                            Welcome to Rivendell, Mr. Anderson.

                            Comment

                            • Bear
                              Super Senior Member
                              • Dec 2008
                              • 1038

                              #15
                              So let's skip to one of the last stages of the mk1 build, driver installation. One of the things that drove me nuts (pun alert) about working with MDF for my first couple of builds was how poorly it held screws. Hurricane nuts or T-nuts were basically required if you wanted any hope of an airtight mechanical seal. With LBL, It's a hard wood, and its ability to grip screws is really good. Perhaps too good. Not really, I blame the supplier that Madisound uses for these BlackOx screws. And yes, I did tap them first.

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                              If you count, you can see three of the screw holes have shiny bits in them. The PR, on the back, has another couple. My impact driver snapped them clean off. The build that I did for Christmas in 2018 also had two snaps, with one of the failures leading to the driver bit puncturing the tweeter dome. All of this from a Makita 18V impact driver. If I had to guess, the grain almost looks like these things are sintered, rather than extruded. Fool me once, shame on you. Fool me eight times, and I have a hard time making the case that I'm not an idiot. For mark 2, I will suck it up and go with M4 machine screws (or Imperial equivalent), and the E-Z-Lock threaded inserts.

                              Now let's look at my attempt at a patch job. Here are the two places where the runaway router gouges show to the outside.

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                              How about zooming in so we can see this more closely:

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                              So, I went with what I thought was the right approach: fine sawdust that came from my track saw plus a lot of Titebond III. The upside of not having good dust control and saw control at the beginning of this process was that there were lots of opportunities to collect fine sawdust, lots of opportunities.

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                              So, the slurry got packed into the holes, and then I put a couple of clamps to cover the patches. I had thought that I had stuffed them sufficiently, BUT (remember, this is a cautionary tale...):
                              • I apparently did not use enough.
                              • I did not let it set/cure long enough.
                              • When I tried to run my trim bit over the patch, I further gouged the bottom plate.

                              What's that phrase that Jon uses? Slow work takes time? Yeah. Let me add, impatience comes at a cost.
                              Welcome to Rivendell, Mr. Anderson.

                              Comment

                              • drkingweeb
                                Junior Member
                                • Apr 2020
                                • 2

                                #16
                                Blocked from entering the fb site

                                Comment

                                • Bear
                                  Super Senior Member
                                  • Dec 2008
                                  • 1038

                                  #17
                                  Originally posted by drkingweeb
                                  Blocked from entering the fb site
                                  I clicked a button to join, threw some text in a box, and I was granted membership pretty quickly. You may want to DM/PM Javad's personal account. Beyond that, I don't have a lot of ideas/suggestions. Sorry!
                                  Welcome to Rivendell, Mr. Anderson.

                                  Comment

                                  • Steve Manning
                                    Moderator
                                    • Dec 2006
                                    • 1879

                                    #18
                                    I so feel your pain, bamboo is such an unforgiving mistress when it comes to chipping ..... you would not believe the amount of "fun" I've had machining it on the CNC.

                                    A couple of comments on your screw issues. Though I have not tried it, I'd bet that bamboo would be good at use a tap and thread the lbl for 8-32 screws and they will hold fine, especially if not taken out repeatedly. If you do go with the EZ Lock inserts, my fav., drill the holes 5% over size from the directions on the packaging. If not, chances are very good you will shear the inserts right off .... they are not fun to remove either. :W By the way McMaster Carr is a good place to get odd sized bits for making over sized holes as well as a good source for black oxide screws.
                                    Hold on to your butts - It's about to get Musical!



                                    WEBSITE: http://www.smjaudio.com/

                                    Comment

                                    • dwk
                                      Senior Member
                                      • Apr 2005
                                      • 251

                                      #19
                                      Originally posted by drkingweeb
                                      Blocked from entering the fb site
                                      try this. I can get to this link even though I don't have a FB account. Formatting seems a bit lacking, but the basic info is there

                                      Helios Speakers Finale! This Finale is long overdue! The Helios was an incredible project with Jeff earlier this year, leading up to the madness of Axpona! In about 2 months Jeff and I designed and...

                                      Comment

                                      • Bear
                                        Super Senior Member
                                        • Dec 2008
                                        • 1038

                                        #20
                                        Originally posted by Steve Manning
                                        I so feel your pain, bamboo is such an unforgiving mistress when it comes to chipping ..... you would not believe the amount of "fun" I've had machining it on the CNC.
                                        Sorry to hear that it just isn't me having issues. LBL is great .... right up until it isn't. The single-ply seems to be worse than the three-ply, especially when using a flush trim bit going around a corner from the end grain to going with the grain. Fortunately, it has split either where the router bit still can flush the board or it was on an interior brace.


                                        A couple of comments on your screw issues. Though I have not tried it, I'd bet that bamboo would be good at use a tap and thread the lbl for 8-32 screws and they will hold fine, especially if not taken out repeatedly. If you do go with the EZ Lock inserts, my fav., drill the holes 5% over size from the directions on the packaging. If not, chances are very good you will shear the inserts right off .... they are not fun to remove either. :W By the way McMaster Carr is a good place to get odd sized bits for making over sized holes as well as a good source for black oxide screws.
                                        Any tips on sourcing the E-Z Lock inserts? Amazon's prices are not kind, and delivery, at this point, may coincide with Independence Day. I tried the big orange box, but they had the junk ones or metal inserts, but nothing that I saw would fit for this application for wood.
                                        Welcome to Rivendell, Mr. Anderson.

                                        Comment

                                        • Steve Manning
                                          Moderator
                                          • Dec 2006
                                          • 1879

                                          #21
                                          Originally posted by Bear
                                          Sorry to hear that it just isn't me having issues. LBL is great .... right up until it isn't. The single-ply seems to be worse than the three-ply, especially when using a flush trim bit going around a corner from the end grain to going with the grain. Fortunately, it has split either where the router bit still can flush the board or it was on an interior brace.



                                          Any tips on sourcing the E-Z Lock inserts? Amazon's prices are not kind, and delivery, at this point, may coincide with Independence Day. I tried the big orange box, but they had the junk ones or metal inserts, but nothing that I saw would fit for this application for wood.


                                          I've found the type of bit you use to make a big difference on bamboo. I know Jon has been using these with good results. https://www.whitesiderouterbits.com/...lush-trim-bits. They are not cheap, but they get the job done. I've also found climb cuts vs conventional cuts make a difference, though it's grain dependent which you use and climb cutting has its own issues, safety wise.


                                          I've been getting my inserts from Amazon for a while now, but have seen the prices vary a lot. Right now their prices seem to match McMaster Carr, who has a good selection to choose from.
                                          Hold on to your butts - It's about to get Musical!



                                          WEBSITE: http://www.smjaudio.com/

                                          Comment

                                          • Zvu
                                            Senior Member
                                            • Oct 2013
                                            • 434

                                            #22
                                            Originally posted by Bear
                                            ............... a secondary effect after some choice language....

                                            .... My first thought was the utterance of a stream of four letter words...
                                            Oh, that's a common mantra to get to the stage of calmness you're in right now

                                            Anyhow, if you didn't order the wood for those floorstanders may i suggest something ?

                                            It is scratched but didn't lose those properties that make LBL suitable for speaker builders. I'd use some filler and sand to prepare the surface for a paint job. Go wild with the color - as Bukem did with Ceramica speakers.

                                            EDIT: Bukem hasn't written anything for i while. I hope he's doing well.
                                            Last edited by theSven; 09 April 2023, 03:56 Sunday. Reason: Update image location
                                            Tesla; George Carlin;

                                            Comment

                                            • Bear
                                              Super Senior Member
                                              • Dec 2008
                                              • 1038

                                              #23
                                              Originally posted by Zvu
                                              Oh, that's a common mantra to get to the stage of calmness you're in right now

                                              Anyhow, if you didn't order the wood for those floorstanders may i suggest something ?

                                              It is scratched but didn't lose those properties that make LBL suitable for speaker builders. I'd use some filler and sand to prepare the surface for a paint job. Go wild with the color - as Bukem did with Ceramica speakers.

                                              EDIT: Bukem hasn't written anything for i while. I hope he's doing well.
                                              The new wood has already arrived. There are some dings in the sides of some of the pieces, but fortunately I am learning that a 10% waste factor is woefully inadequate....
                                              Last edited by theSven; 09 April 2023, 03:57 Sunday. Reason: Update htguide url
                                              Welcome to Rivendell, Mr. Anderson.

                                              Comment

                                              • Scottg
                                                Senior Member
                                                • Nov 2006
                                                • 335

                                                #24
                                                Originally posted by Bear
                                                ..and the not-late Javad Shadzi..
                                                For those unaware, he has a Youtube site here:

                                                Comment

                                                • Scottg
                                                  Senior Member
                                                  • Nov 2006
                                                  • 335

                                                  #25
                                                  Originally posted by Bear

                                                  Oh, yeah, you can never have enough clamps.

                                                  -that is SOOOoooooooo True! ops:


                                                  I wanted to say I liked that post, but it was just too painful to look at those pic.s.. :cry: :W

                                                  Comment

                                                  • Bear
                                                    Super Senior Member
                                                    • Dec 2008
                                                    • 1038

                                                    #26
                                                    So, it's been a few weeks. I think that I've isolated my case of the "yips" to some late movement as my arm extends pushing my saw through a cut. Lots of people in online blogs and videos have indicated that the Festool and Makita tracks grip really well and that clamps aren't needed to hold the track steady. Let me be the counterpoint, at least a bit. I think having a hand on the track is probably sufficient, but don't try to push all the way through a cut without the track being held down. Those gripper pads are good, but not that good.
                                                    Welcome to Rivendell, Mr. Anderson.

                                                    Comment

                                                    • Bear
                                                      Super Senior Member
                                                      • Dec 2008
                                                      • 1038

                                                      #27
                                                      In the interim, I'm converting the wood for the second monitor-style cabinet into a dual-opposed subwoofer cabinet with a pair of SW223BD03 mini subs. According to Unibox, they have a similar low-end profile to the Helios speakers, but at 2x the cost (at full retail). These are older stock that I got on-sale from Solen a while back, so my acquisition cost is a lot less. But these are still premium drivers.

                                                      So, I debated about whether to double-up the side walls since the subs are going to be on opposite sides with (allegedly) cancelling forces. However, prudence, and a little bass modeling, indicated that going with 1.5" side baffles was the right idea. Plus, I'll be interested to see if I can get away without any other bracing internally (it's an experiment, after all!). But first, I have to trim the overhang.

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                                                      Here's yesterday's glue-up. This is every clamp that I've currently got here in California. I need more. There was about a 1/4" (6mm) gap at this face of the box between square and what the previous cuts wanted to do naturally. So, clamp pressure comes to the rescue. However, this will embed a fair bit of strain onto these butt joints. There will be one more piece of LBL that covers this one, so there will be more glue surface and mass to take the strain, but I am curious to see how this affects longevity of the piece.

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                                                      One final tip from the "let me screw up for you" department (at least for today!)....
                                                      Fixing my cutting errors has involved a fair bit of use of my top and bottom bearing flush trim bits. These really only seem to want to chew through about 1/16 - 1/8 of an inch of material at most with my little mini-router. Something as large as a 1/8" trim caused the router to jump, and I was expecting it. So, when one looks back at some of the mistakes from my first build, excessive optimism in these bits is a prime source of visible error. In the future, I'll use my track saw to trim things as close as possible, perhaps even skim cutting the piece, in order to minimize that risk.
                                                      Last edited by Bear; 21 May 2020, 12:51 Thursday.
                                                      Welcome to Rivendell, Mr. Anderson.

                                                      Comment

                                                      • Steve Manning
                                                        Moderator
                                                        • Dec 2006
                                                        • 1879

                                                        #28
                                                        Originally posted by Bear
                                                        In the interim, I'm converting the wood for the second monitor-style cabinet into a dual-opposed subwoofer cabinet with a pair of SW223BD03 mini subs. According to Unibox, they have a similar low-end profile to the Helios speakers, but at 2x the cost (at full retail). These are older stock that I got on-sale from Solen a while back, so my acquisition cost is a lot less. But these are still premium drivers.

                                                        So, I debated about whether to double-up the side walls since the subs are going to be on opposite sides with (allegedly) cancelling forces. However, prudence, and a little bass modeling, indicated that going with 1.5" side baffles was the right idea. Plus, I'll be interested to see if I can get away without any other bracing internally (it's an experiment, after all!). But first, I have to trim the overhang.

                                                        [ATTACH=CONFIG]30298[/ATTACH]

                                                        Here's yesterday's glue-up. This is every clamp that I've currently got here in California. I need more. There was about a 1/4" (6mm) gap at this face of the box between square and what the previous cuts wanted to do naturally. So, clamp pressure comes to the rescue. However, this will embed a fair bit of strain onto these butt joints. There will be one more piece of LBL that covers this one, so there will be more glue surface and mass to take the strain, but I am curious to see how this affects longevity of the piece.

                                                        [ATTACH=CONFIG]30299[/ATTACH]

                                                        One final tip from the "let me screw up for you" department (at least for today!)....
                                                        Fixing my cutting errors have involved a fair bit of use of my top and bottom bearing flush trim bits. These really only seem to want to chew through about 1/16 - 1/8 of an inch of material at most with my little mini-router. Something as large as a 1/8" trim caused the router to jump, and I was expecting it. So, when one looks back at some of the mistakes from my first build, excessive optimism in these bits is a prime source of visible error. In the future, I'll use my track saw to trim things as close as possible, perhaps even skim cutting the piece, in order to minimize that risk.
                                                        Don't you just love bamboo .... 8O
                                                        Hold on to your butts - It's about to get Musical!



                                                        WEBSITE: http://www.smjaudio.com/

                                                        Comment

                                                        • Steve Manning
                                                          Moderator
                                                          • Dec 2006
                                                          • 1879

                                                          #29
                                                          Originally posted by Bear
                                                          So, it's been a few weeks. I think that I've isolated my case of the "yips" to some late movement as my arm extends pushing my saw through a cut. Lots of people in online blogs and videos have indicated that the Festool and Makita tracks grip really well and that clamps aren't needed to hold the track steady. Let me be the counterpoint, at least a bit. I think having a hand on the track is probably sufficient, but don't try to push all the way through a cut without the track being held down. Those gripper pads are good, but not that good.
                                                          My question would be, if the tracks didn't need clamping why were they designed to be used with them?
                                                          Hold on to your butts - It's about to get Musical!



                                                          WEBSITE: http://www.smjaudio.com/

                                                          Comment

                                                          • Bear
                                                            Super Senior Member
                                                            • Dec 2008
                                                            • 1038

                                                            #30
                                                            Originally posted by Steve Manning
                                                            Don't you just love bamboo .... 8O
                                                            I do, actually. I haven't done enough with Baltic Birch, but my experience with BB is that it fuzzes pretty easily. LBL, on the other hand, machines almost like aluminum. Lots of caveats on that given splitting/splintering, but the cuts are really clean.


                                                            Originally posted by Steve Manning
                                                            My question would be, if the tracks didn't need clamping why were they designed to be used with them?
                                                            You are perilously close to saying that The Internet may have misinformation in it!!
                                                            Welcome to Rivendell, Mr. Anderson.

                                                            Comment

                                                            • Bear
                                                              Super Senior Member
                                                              • Dec 2008
                                                              • 1038

                                                              #31
                                                              Originally posted by Steve Manning
                                                              Don't you just love bamboo .... 8O
                                                              Alright, two more splinters yesterday, and I'm picking up some fuzz on the skim cuts. Yep, I'm starting to learn what you already know! ops:
                                                              Welcome to Rivendell, Mr. Anderson.

                                                              Comment

                                                              • tf1216
                                                                Senior Member
                                                                • Apr 2006
                                                                • 161

                                                                #32
                                                                Hi Bear,
                                                                Any updates on your Helios build(s)?

                                                                Comment

                                                                • Bear
                                                                  Super Senior Member
                                                                  • Dec 2008
                                                                  • 1038

                                                                  #33
                                                                  Originally posted by tf1216
                                                                  Hi Bear,
                                                                  Any updates on your Helios build(s)?
                                                                  The SDFWA shop opened up a couple of weeks ago, and I should be done with the cabinets by early next week. I need to upgrade from butt joints on the next project and pay greater attention to planar integrity in the sheet good (e.g., cupping/warping), but this is part of my learning experience. I also turned the wood I had on-hand for a second monitor into a smaller dual-opposed subwoofer cabinet. I'll try to get that thread started over the weekend.
                                                                  Welcome to Rivendell, Mr. Anderson.

                                                                  Comment

                                                                  • Bear
                                                                    Super Senior Member
                                                                    • Dec 2008
                                                                    • 1038

                                                                    #34
                                                                    Originally posted by Steve Manning
                                                                    I so feel your pain, bamboo is such an unforgiving mistress when it comes to chipping ..... you would not believe the amount of "fun" I've had machining it on the CNC.

                                                                    A couple of comments on your screw issues. Though I have not tried it, I'd bet that bamboo would be good at use a tap and thread the lbl for 8-32 screws and they will hold fine, especially if not taken out repeatedly. If you do go with the EZ Lock inserts, my fav., drill the holes 5% over size from the directions on the packaging. If not, chances are very good you will shear the inserts right off .... they are not fun to remove either. :W By the way McMaster Carr is a good place to get odd sized bits for making over sized holes as well as a good source for black oxide screws.
                                                                    Coming back to this: I now have enough "stick time" to start to understand how lucky some of my earlier experiences were. Yeah, fun with chipping.... Where did I put that 60 grit pad..... 8O
                                                                    Welcome to Rivendell, Mr. Anderson.

                                                                    Comment

                                                                    • Bear
                                                                      Super Senior Member
                                                                      • Dec 2008
                                                                      • 1038

                                                                      #35
                                                                      Originally posted by tf1216
                                                                      Hi Bear,
                                                                      Any updates on your Helios build(s)?
                                                                      New thread:
                                                                      Last edited by theSven; 09 April 2023, 03:57 Sunday. Reason: Update htguide url
                                                                      Welcome to Rivendell, Mr. Anderson.

                                                                      Comment

                                                                      • JonMarsh
                                                                        Mad Max Moderator
                                                                        • Aug 2000
                                                                        • 15261

                                                                        #36
                                                                        You know, watching some of the travails people are having with different kinds of LBL, I almost feel bad for introducing the stuff in parts of the front panels in the original Ardent build back in 2010...

                                                                        And I'll be the first to state I'm just a wires and sparks kind of guy, not a wood worker at all... (some, like Renron, are both true woodworkers and master finishers- that ain't me) and in saying so, and looking back on things, it would seem the gods have been watching over me, or I'm just extremely lucky...



                                                                        So doing a project completely with LBL back in 2013 was truly an act of hubris... even worse, where and how I built them.



                                                                        I full well understand the difficulties in building a complex speaker while living in an apartment... especially when the bathrooms aren't big enough to work in!


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                                                                        BTW, still using that Rockler Birch bench- one the best investments I've ever made...


                                                                        And there's never any such thing as having enough clamps- and I say that as someone who's never used a track saw!


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                                                                        I feel like I got lucky in my choice of bamboo supplier as well as having just procured a selection of brand new tools that were very, very sharp...


                                                                        But, maybe not having many right angles just freed up a little bit of creativity? I dunno...


                                                                        But Steve's got the right idea... the problems can be solved, and sometimes it just takes some patiences and a methodical approach. That will work even when the gods aren't smiling on you today.


                                                                        (these are in storage in Idaho, along with the parts for a complete crossover rebuild...)
                                                                        Last edited by theSven; 09 April 2023, 03:56 Sunday. Reason: Update image location
                                                                        the AudioWorx
                                                                        Natalie P
                                                                        M8ta
                                                                        Modula Neo DCC
                                                                        Modula MT XE
                                                                        Modula Xtreme
                                                                        Isiris
                                                                        Wavecor Ardent

                                                                        SMJ
                                                                        Minerva Monitor
                                                                        Calliope
                                                                        Ardent D

                                                                        In Development...
                                                                        Isiris Mk II updates- in final test stage!
                                                                        Obi-Wan
                                                                        Saint-Saƫns Symphonique/AKA SMJ-40
                                                                        Modula PWB
                                                                        Calliope CC Supreme
                                                                        Natalie P Ultra
                                                                        Natalie P Supreme
                                                                        Janus BP1 Sub


                                                                        Resistance is not futile, it is Volts divided by Amperes...
                                                                        Just ask Mr. Ohm....

                                                                        Comment

                                                                        • Bear
                                                                          Super Senior Member
                                                                          • Dec 2008
                                                                          • 1038

                                                                          #37
                                                                          For all the discussion about the Purifi woofer, the C173n-96E (95E?) is still the a benchmark against which to compare almost any other driver.

                                                                          That being said, if it cooperates, the aesthetic for bamboo is pretty appealing. It's not as good, in my book, as something like a figured walnut, but the price isn't close to that level. I've got about $500 $600 $800 invested in enough sheet goods, and IKEA cutting boards, for a full 5+1 system. I looked at figured walnut for the towers, and I was looking at $800 for veneer alone. We all have our points on the price/performance curve.

                                                                          I will say that when the machining comes out right with no tearouts, the feel of the bamboo can't be matched by typical hardwoods in my (extremely limited) experience.
                                                                          Welcome to Rivendell, Mr. Anderson.

                                                                          Comment

                                                                          • Bear
                                                                            Super Senior Member
                                                                            • Dec 2008
                                                                            • 1038

                                                                            #38
                                                                            Requiem: Introducing Grond...

                                                                            So, this Helios journey has been about a year in progress. I made yet more mistakes trying to convert the original box over to a dual-opposed subwoofer design (note: cutting through 2.25" / 57mm of bamboo is a bit of a chore when you have to do it all at once...). However, the cabinet is a good height to operate as an end table. I'll make a somewhat matching second box where I'll embed the Fusion FA502 amplifier that will power both. But first, I need to find a dang USB-A cable to drop a filter in the darn thing so it will work. The drivers are dual RSS265HO-44 wired for a 4 ohm nominal load (driver voice coils wired in series) in ~40 liters with the interior "heavily stuffed" with long fiber wool.

                                                                            Front. To cover the original driver holes, I glued a new outer baffle onto the front and cut new rebates. I ended up being off an inch on my Jasper Jig. Hilarity ensued. I still need a lot of help/practice on finish quality. I do now understand what happens when you "overbrush" a poly finish.

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                                                                            Back. The speaker terminals will take a feed from the FA502.

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                                                                            Welcome to Rivendell, Mr. Anderson.

                                                                            Comment

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