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  • Amiga Build, Gloss White

    Hello everyone! Several years ago, I built a pair of Overnight Sensations from the knock-down kit that PE offers. I paired them with a Lepai LP-2020TI and was amazed at the sound quality they produced given their small size and low cost. Since then, I told myself that once I had more space / tools I’d build myself another set of speakers.

    Fast forward to 2020 and I chose to build a pair of Amigas for my “winter project”. One of the reasons I chose the Amiga is because of the simple (and aesthetically pleasing) enclosure design. I’m a novice when it comes to woodworking and have approached the project as an opportunity to collect and learn new tools / techniques. I’m also curious how nice of a finish I can obtain using rattle can spray paints. I’ve been spending a few hours on this most weekends since early February. Since I've found this site useful, I thought I’d make an account and share my progress with you all.

    I purchased the PE Amiga kit with baffles and started with the crossovers first. I basically followed the point-to-point layout found on PE here: https://www.parts-express.com/pedocs...ver-layout.pdf

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    I put together a quick model of the enclosure in SolidWorks. All of the major dimensions are to Paul Carmody’s design. I adjusted the locations of the window braces so I could fit the crossovers behind the woofers for easy access. It’s hard to see here, but I went with rabbet and dado joints.

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    Detail of the back panel


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  • #2
    To cut the rabbets and dadoes I purchased a 6” Freud dado stack and made a throat plate for my Ridgid jobsite tablesaw. Next, I made a sacrificial fence and got a feel for it with a few pieces of scrap.

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    Last edited by JSteady; 04-01-2021, 11:03 PM.

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    • #3
      Test fitting

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      I laid out the window braces and cut them with my jigsaw before drum sanding and cutting the roundovers. This was my first time using a router. I purchased a Bosch Colt trim router and I’m very happy with it so far. The drum sanding step was long and tedious. There has to be a better way?

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      • djg
        djg commented
        Editing a comment
        Very nice work. One thing I always feel compelled to mention: it's so much easier and faster to make window braces out of separate sticks. Less waste, less dust.

    • #4
      Another test fit

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      I didn’t see any circle jigs I liked available for my router. After watching a few YouTube videos, I decided I’d build one. I started by modeling it up in SolidWorks. The design is a mix of a few I liked on YouTube. I used 3/4" Sandeply scrap I had laying around, but I wish I had used a higher quality plywood or even MDF. Overall, I think it turned out pretty good and it worked well for me. One advantage to this design over others I’ve seen is that you can get the pivot pin right up to the router bit for small diameter holes. This will come in handy for tweeters / terminal cups / ports.

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      • #5
        I recessed the flanged ports that came with the PE kit.

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        I used 8-32 threaded inserts on the front panel. I took my time laying the pilot holes out and drilled them with my drill press as you have to be quite precise with these. I made sure to check the internal threads on each of them before driving them in. They are cheaply made and come in packs of 100. If there was any resistance while testing with a bolt, I just tossed it to the side and grabbed another. I had some liquid nails so I coated the external threads before driving them in. They drove in nicely and bit into the MDF well.

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        Last edited by JSteady; 04-01-2021, 09:13 PM.

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        • #6
          Well I don't think calling yourself a novice is giving yourself enough credit. Well done they look great so far.

          One tip for the braces. I rough cut them like you did with a jigsaw but then I use a flush trim router bit and stick down straight edges along the inside lines and use the router to clean them up nice and straight. You only need to do this on a single piece and then you can use that piece as the template for the rest. Just stick it down with some double sided tape and router each of them. Then you can wip over them all with the roundover. This way I don't find any sanding is needed at all and they all turn out identical!

          I also like to add a chamfer to the back of the woofer cutout on the baffle. How much of a chamfer depends on how thick the baffle is. Just leave enough meat for the threaded inserts of course.

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          • #7
            I’ve read about others having issues with joints showing through paint with MDF enclosures. To avoid this, I understand it helps to use more rigid glues / epoxies rather than PVA glues. I used a urea-formaldehyde glue (DAP Weldwood plastic resin). This glue comes in a powder that has to be mixed with water. I applied it with disposable paint brushes and found it to be pretty easy to work with. The long working time is helpful. It was very brittle and rigid once cured. I left off the top / bottom and front panels for now so I could have better access to the interior for sealing and deadening.

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            I sealed the interior of the enclosures with Zinsser BIN shellac based primer. I used the adhesive backed acoustic foam that came with the PE kit. The adhesive on this foam was stronger than I was expecting and worked well. Next I glued in the top and bottom panels then mounted and wired the crossovers.

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            • #8
              Originally posted by DeZZar View Post
              Well I don't think calling yourself a novice is giving yourself enough credit. Well done they look great so far.

              One tip for the braces. I rough cut them like you did with a jigsaw but then I use a flush trim router bit and stick down straight edges along the inside lines and use the router to clean them up nice and straight. You only need to do this on a single piece and then you can use that piece as the template for the rest. Just stick it down with some double sided tape and router each of them. Then you can wip over them all with the roundover. This way I don't find any sanding is needed at all and they all turn out identical!

              I also like to add a chamfer to the back of the woofer cutout on the baffle. How much of a chamfer depends on how thick the baffle is. Just leave enough meat for the threaded inserts of course.

              Thanks for the kind words and tips! My mechanical background helps make up for my lack of woodworking experience. I'll have to try that with braces next time.

              What's the purpose of the backside chamfer?

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              • #9
                It's not something that HAS to be done on ALL woofers, but becomes NECESSARY as baffle thickness increases, usually as driver dia. decreases, and is exacerbated by "poor" frame design. Some drivers have fairly closed frames that come almost straight back, with the rear "exhaust" openings mainly horizontal. Put those in an inch-and-a-half thick straight-cut baffle (w/no backside "relief") and they can choke off by 80-90% !

                Your craftsmanship looks top notch. You are making a LOT of extra work for yourself, but maybe that's not a bad thing. I've never sealed the inside of any cabs, and while window braces aren't necessarily bad, you can achieve 95% of those results by simply running a 3/4" to 1" thick hunk of square or round stock (like a dowel) between each pair of panels (same as where the center of your window brace runs).

                Lookin' GOOD !

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                • JSteady
                  JSteady commented
                  Editing a comment
                  Thanks Chris! I see what you're saying with the backside relief.

                  I'm likely going overboard in a few different areas on this build, but as you said, it's not necessarily a bad thing as I'm learning. It feels great to finally have a workshop area again to keep me busy during downtime. From a mechanical standpoint, I completely agree on the window braces. However, I did find they helped me keep the enclosure flat and square while gluing up. The back and side panels had some bow to them (probably partially caused by the rabbets/dadoes).

              • #10
                Gluing the baffles

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                I made some pig-tails with XT60 connectors for the drivers

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                • jim85iroc
                  jim85iroc commented
                  Editing a comment
                  XT60s are great for this. I used them on the tweeters in the A pillars of my truck so I could easily remove the pillars whenever necessary.

                • JSteady
                  JSteady commented
                  Editing a comment
                  Yeah they seem great for quick disconnect applications

              • #11
                After some flush cutting, roundovers and sanding up to 220 grit

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                I noticed one of the baffles had a very small amount of de-lamination happening (at one of the most visible areas of course). It looks way worse here than it was because I dug it out a bit with a chisel before rubbing in some Tightbond II. I'm not sure if this is an ideal fix, but it seemed to do the trick.

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                • djg
                  djg commented
                  Editing a comment
                  Your work ethic will serve you well when you go to paint these. That white BIN shellac primer is good to seal the cut edges of the MDF.

                • jim85iroc
                  jim85iroc commented
                  Editing a comment
                  Wood glue and a clamp is the best way to address that delamination, so I think you'll be good. You may need a little bit of bondo or putty to smooth out that area before you paint. You'll be able to tell if tou can see anything after you prime. The enclosures look fantastic.

                • JSteady
                  JSteady commented
                  Editing a comment
                  Thanks guys.

                  Yeah I was very happy with that primer. It rolls on well, dries quick and sands great. A few coats and you have a nice paintable surface.

                  Jim, I did end up clamping it and sanding it back a bit after it dried. I also used a bit of spot putty in that area between primer coats.

              • #12
                You might want to place some damping between the woofer and the xover on the inside rear wall to prevent the hard surface reflecting it.
                Looking good!
                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:
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                My blog/writeups/thoughts here at PE:
                http://techtalk.parts-express.com/blog.php?u=4102

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                • JSteady
                  JSteady commented
                  Editing a comment
                  Thanks Wolf. I did wonder if that could be an issue when deciding to mount the crossovers in that location. I'll be sure to place some kind of dampening there

              • #13
                For the finishing process I have been loosely following Kaidomac's advice below. It was the closest thing I found to a procedure for painting MDF with rattle can to a mirror finish. Thanks for your detailed post, Kaidomac!

                http://techtalk.parts-express.com/fo...ttle-can-gurus

                Originally posted by kaidomac View Post
                Re: A question for rattle can gurus....



                It really depends on how nuts you want to go with it, and by that I mean (1) time, and (2) effort. If you are patient and don't mind working on it over the course of a few weeks or months, you can get really great results. I used to airbrush, but I mostly just use spray paint now because the paints are so good these days. I pretty much just use MDF or plywood for my projects - I'm not brave enough to try doing a "real wood" or veneer finish just yet :D Here's my basic process for spray painting MDF, everyone's secret recipe is a bit different, but it should point you in the right direction: (not sure if you're using MDF, but should apply to most any wood)

                The basic process: (get ready for an information dump after this, haha)

                1. Smooth coat
                2. Seal coat
                3. Prime coat
                4. Paint coat
                5. Clear coat
                6. Wax coat

                1. Smooth coat:

                First step is to get the unpainted surface nice & smooth. Basically this involves a lot of sanding and using a fill product - this covers the seams and any holes or nicks you might have in the cabinet (such as screw or nail holes, or chipped MDF corners). I just use Elmer's wood fill in the tub from Home Depot, it's sort of like bondo for wood. Works great - let dry & then sand it. I use a mix of a small orbital sander (like $30 at Home Depot - I'll use Home Depot as the reference, you can use Lowes or whatever you have nearby), a hand block, and just plain sheets wrapped around my fingers. The idea here is to get the surface really nice and smooth, and free of any gouges - the paint is going to show everything you see here, so work on it until it's where you want it to be. The block sander & electrical sander work the best for getting large surfaces done smoothly.

                As far as sandpaper goes, if you end up using a lot of wood filler, use a low-grit sandpaper like 80 or 120 to cut the shape down. When it's where you want it, use 200/300 to refine it and then finish up with 300 - that will give it some bite for the primer to stick on.

                2. Seal coat:

                I like Zissner B-I-N, available at Home Depot. Works great on MDF. MDF is like a sponge and really sucks up paint, so you'll still need a couple coats of this sealer paint, but it gives it a really nice paintable shell when you're finished. Usually takes at least 2 coats of sealer to completely coat the speakers.

                Sand with 300-grit sandpaper. You want it smooth, but don't sand so much you can see the wood.

                3. Prime coat:

                Two coats a day over a 2-day period, 4 coats total. First day: do 1 coat, wait 1 hour, do the second coat. Let dry 24 hours. Second day: sand with 200 then 300 grit, repeat (1 coat, 1 hour dry, another coat).

                For color, usually either go white, gray, or black. Depending on what final color you want. If you want a black piano finish at the end, obviously go with a darker color like black. If you want white or yellow, go with white. Sometimes people use gray ("silver") for the darker final metallic colors.

                Make sure that your spray environment is bug & dust free. I use some large cardboard boxes to cover the speakers with after I'm done with each painting pass so that stuff in the air doesn't float onto the finish while it's drying. Use a mask, even a cheap one is better than nothing.

                There's some pretty simple tricks to priming/painting: first, shake the can for a full minute. Not just a 10-second shake. Second, do the spray in a sweep: hold your arm straight as you pass, and not in a circle/arc pattern, and start pressing the can before you hit the surface, and then let go of the nozzle after you pass the surface. When the paint first starts coming out, it tends to splatter (same at the end), so this way the splatter doesn't end up on your cabinets. Third, overlap half of the previous spray pass with the next one so it will come out uniform. You don't want to move super fast, but you want to move quick enough that it stays wet as you make the passes. And then it will look nice while it's wet and then dry and look like crap, this is normal :D

                4. Paint coat

                Now the fun begins! You will begin to loathe sanding at this point ;) So basically the same as priming, but we're going to start using higher-grit sandpaper. So sand down the primer from the day before with 300-grit. Now you do 2 or 3 days of painting, go for 3 if you want a serious finish. Same deal - two coats, let the first coat dry for an hour then let the second coat dry for 24 hours. On the second day, work up from 600 to 800 to 1000 grit then paint. On the third day use 1000. On the fourth day, use 1000. If things get messy, you can use a tack cloth and alcohol to wipe things up. So at this point the paint should be nice and smooth. Oh, and the paint technique is the same - keep it wet, overlap passes, start/stop the nozzle off the workpiece, shake for a full 60 seconds.

                5. Clear coat

                This is where things get a bit tricky. Clearcoat is not a magic glossy wet-look cover for your paint. You basically have to bring the shine out with a lot of elbow grease. Make sure to get a clearcoat to match what you are painting (ex. enamel, acrylic, etc.). You don't necessarily need to wet sand to get good results. You can do a few days of clearcoating just like painting - just use 1000-grit the whole time. And you can go totally nuts with this. Back in my airbrushing days, I saw a motorcycle tank that had 17 coats of clearcoat on it. It probably took two or three weeks to do, but the finish was like 10 years old and STILL looked brand-new because the owner would polish & wax it on a regular basis, but would never grind through those thick layers of clearcoat. Probably overkill for a speaker project though ;) Watch some videos to get an idea of what the clearcoating process looks like.

                6. Wax coat:

                If you want to wax it (and if you've done a lot of work on the clearcoat, it deserves a wax job!), wait about a month for the paint to outgas. There are two kinds of wax available - synthetic and carnauba. The secret to getting an amazing finish is to use *both* :D If you've ever been to a car show where they have ridiculously shiny cars, this is the trick they use. First, you put a layer of synthetic wax on, which acts as the glossy layer. Let that dry (ah, "cure") for 24 hours. Next, put 2 layers of carnauba wax on - put the first layer on, wait 24 hours, put the second layer on. This adds depth and gives the finish the traditional car wet-look finish. So 3 days total for the wax coat, 30 days after you paint to allow for outgasses. It's hard to wait, but the results are worth it. No one will have a clue you use spray paint!

                If you want to mess around before you wax, you can also try polishing it (SwirlX is popular, or Ultimate Polish). I have seen claybars used on MDF too. You end up with a great finish. None of this is really expensive or anything, just takes some time & patience. Although again, you can go nuts with this - if you're doing a gorgeous black finish, P21S carnauba wax is the way to go for dark/black colors (starts at $33 a tub though...).

                Notes:

                I'm sure I left a couple things out, but you get the idea. If you give it the proper time (really a month or two) and do all the steps, you can get pretty ridiculous results from spray paint. Mostly it's just tedious - nothing's really hard, just a bit time consuming and a lot of steps, and then it feels like you're waiting forever. You can get a better idea of how the process works by watching some Youtube videos. You can also google for "spray paint a car" or "spray paint arcade controllers" (people who do DIY joystick controls do really great clearcoat & paint work!). Again the biggest frustration is not committing to doing it right by spreading out the steps over time. If you rush it, you'll risk ending up with a crappy paintjob and you'll have to start all over again (which I've done and is just about enough to make you throw up haha). Anyway, here's some starter links:

                http://www.caraudio.com/forums/enclo...spray-can.html

                http://shoryuken.com/forum/index.php...worklog.67501/

                http://www.diyaudio.com/forums/const...ishing-35.html

                As far as the paint schedule goes, about a month and a half total if you want to get serious about it:

                Day 1: Smooth coat (wood filler) - 80/120, 200/300 grit sanding
                Day 2: Seal coat (2 coats) - 200/300 grit sanding

                Day 3: Prime coat (2 coats) - 200/300 grit sanding
                Day 4: Prime coat (2 coats) - 200/300 grit sanding

                Day 5: Color coat (2 coats) - 300/600/800 grit sanding
                Day 6: Color coat (2 coats) - 1000 grit sanding
                Day 7: Color coat (2 coats) - 1000 grit sanding

                Day 8: Clear coat (2 coats) - 1000 grit sanding
                Day 9: Clear coat (2 coats) - 1000 grit sanding
                Day 10: Clear coat (2 coats) - 1000 grit sanding (tack cloth/alcohol for cleanup)

                <wait 30 days for outgassing>

                Day 40: Wax coat (optional claybar/polish, synthetic wax)
                Day 41: Wax coat (carnauba wax)
                Day 42: Wax coat (carnauba wax)

                Initially buying all the stuff can add up...wax, paint, wood filler, etc., but you usually get enough to last through several projects (aside from the paint colors and clearcoat specifically for the project at hand). Try it out on a scrap piece of wood to get a feel for it and see how you like the results, and to develop your own procedure. HTH.

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                • #14
                  I rolled on 2 to 3 coats of Zinsser BIN shellac based primer with sanding and spot putty between coats

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                  • #15
                    http://techtalk.parts-express.com/fo...-the-mdf-seams

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