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We introduced this new pendant speaker design last month, including some information on how we arrived at the final configuration. Now we will show you how to build, test and (optionally) tune it. Easy to assemble, with a largely pre-built enclosure Multiple configurations for different applications Uses a 6.5-inch (170mm) woofer and a dome tweeter Low-cost drivers and crossover Impedance: 4W (minimum, 20Hz-20kHz) 44cm wide, 40cm high and 7kg in weight High-Performance Pendant Speaker Part 2 by Julian Edgar T he starting point for the enclosure is a Bunnings pot that is made from recycled plastic. It is called the “Eden 40cm Black Faux Planter” (I/N 0118235); you want the 44cm size (it’s available in three different sizes). The shape is best described as a truncated, slightly curved cone. It is 44cm in diameter at the top, 22cm in diameter at the bottom and 40cm high. Bunnings states on their website that it has a volume of 26L; however, the enclosure actually has a total volume of about 37 litres. Taking into account the position of the baffle, we use an enclosed volume of about 27L. The construction steps are: 1. Cut out a strengthening panel, which fits in the bottom of the enclosure (the top when it is hanging). Glue and screw it in place inside the pot. 2. Cut a baffle, make holes in it and test fit the baffle, woofer, tweeter and port in the enclosure. 3. Disassemble the baffle, removing all the parts. 4. Glue the quilt wadding inside the enclosure. 5. Cut out and screw the grille spacing blocks to the baffle and glue the port into place (if you wish to test different port lengths, don’t glue the port yet). 80 Silicon Chip 6. Paint the baffle and port. 7. Cut the metal grille mesh and paint it. 8. Assemble all the components on the front and back of the baffle and wire it up, including the cable that goes to the amplifier. 9. Glue & screw the baffle, complete with all its components, into place. 10. Fit the grille. 11. Test it. The following steps are for the version that uses the ported enclosure and protection lamp. If you are building the non-ported enclosure, ignore anything that mentions a port. If you are building the speaker without the protection lamp, you may wish to place the baffle nearer the end of the enclosure. Doing this gives slightly better sound dispersion, and the change in internal volume is small enough not to matter a great deal. If you choose to do this, you will need to use shorter spacer blocks for the grille. However, before making the enclosure, we will make the crossover. Crossover construction The crossover comprises just three components: a 4.7μF non-polarised crossover capacitor and two 5W ceramic-bodied resistors, one that is 1W and the other 10W. Fig.2 (from last month) shows the circuit. As you can see, the capacitor and 1W resistor are in series with the tweeter, and the 10W resistor is in parallel with the tweeter. You can build the crossover on punched laminate board, as we did, or simply glue the components to a piece of hardboard or similar and then wire them point-to-point. The terminal blocks are optional – you can instead make the connections directly to the components and tie these leads into place with cable ties. None of the components are polarised. Enclosure construction #1 Making and fitting the Fig.2: the simple crossover circuit uses a non-polarised 4.7μF capacitor and two 5W resistors. Australia's electronics magazine strengthening panel The first step is to use a jigsaw to cut out the round bottom plate from particleboard. This plate needs to be siliconchip.com.au 230mm in diameter and should be the same thickness as the material that will be used in the baffle (18-22mm thick). This plate has two purposes. Firstly, it strengthens the area from which the Pendant Speaker will hang. This is needed because the bottom of the pot is thinner than the walls. Secondly, it stiffens the bottom of the pot – this is required for acoustic reasons. Glue and screw the bottom plate into place. Use plenty of Liquid Nails water clean-up adhesive; there’s quite a void to fill under and around the panel, so you will probably use a full cartridge. Then insert into the panel particleboard four screws from the bottom of the pot and four from around the periphery. Drill small diameter pilot holes before inserting these eight screws. Clean up the edge of the glue using a wet cloth that you repeatedly rinse in running water. While this part is not visible when the speaker is complete, cleaning the edge of glue is good practice for when you glue the baffle – that edge will be visible. Drill a hole in the base for the speaker cable to exit and attach the fastening from which the enclosure will hang. We used a 40mm saddle clamp with two M6 bolts; you could also use an M8 eye-bolt. In either case, use washers and Nyloc nuts or apply Loctite to the nut threads – you don’t want these nuts coming loose through vibration! Don’t attach the hanger with just particleboard screws. Photo 1: the High-Performance Pendant Speaker is straightforward to make and requires only normal handheld power tools. Photo 2: first, cut out the base reinforcement disc with a jigsaw. Doing the work on a milk crate can help to protect the blade when cutting. Photo 3: next, apply plenty of water clean-up Liquid Nails to the base of the pot before... Photo 4: ...putting the disc in place and smoothing the glue around it. Surplus glue should be cleaned up with a rag repeatedly rinsed in water. Photo 5: screws are then inserted from the sides to hold the particle board reinforcement firmly in place. Countersink these holes with a larger diameter drill bit rotated by hand before inserting the screws. Photo 6: insert particleboard screws into the reinforcement plate from the bottom. Note the glue visible through the two pot drainage holes – they must be sealed. #2 Making the baffle The next step is to make the baffle. To do this, cut a disc of particleboard 415mm in diameter. We used 22mm-thick, moisture-resistant particleboard but slightly thinner MDF should be fine. Don’t use material less than about 18mm thick. Any thinner than this and the peripheral glue won’t have enough ‘meat’ to adhere to. Also, because screws are inserted through the wall of the enclosure to further hold the baffle in place, there needs to be enough material for the screws to go into and be secure. The diameter of the baffle is less than the internal diameter of the pot because we want the baffle to slide down a little within the pot – that is, to be recessed from the outer lip by about 60mm. This gives us the needed clearance for the grille and optional protection lamp. siliconchip.com.au Australia's electronics magazine October 2025  81 Cut holes in the baffle for the: • woofer (the hole will need to be 150mm) • port (if using thin-walled 90mm PVC stormwater pipe, the hole will be 90mm) • tweeter (50mm hole) The woofer needs to be mounted in the middle of the baffle; if you mount it off-centre, the Pendant Speaker will not hang straight. The port and tweeter holes can be mounted wherever you like in the baffle – just position them to leave sufficient material around the openings for strength and ensure the 100mm-long port tube cannot foul an internal wall. Cutting the thick particleboard can be a bit difficult, especially the smaller diameter holes. The hole for the port can be cut with a jigsaw – it may be easiest to just cut it roughly undersize, then file it to the final size. Any minor mismatches in size or shape will be filled with the glue anyway, but practice cutting a small hole in a scrap piece of particleboard first. The tweeter hole is best cut with a hole saw. When using a hole saw on particle board, lift the saw often, stop the power drill (or drill press), and clean the saw’s teeth with a wire brush. Cut at a slow speed. Next, cut 90mm PVC thin-walled pipe to a length of 100mm – this will be our port. If you are cutting this by hand, first wrap a piece of tape around the pipe to give you a square line to cut against. Now temporarily mount the woofer, tweeter and port in the baffle and slide Photo 7: cutting out the baffle. To mark the required large circle, use a pencil, a scrap piece of timber and a screw to make a temporary compass. 82 Silicon Chip the baffle into the enclosure, checking that everything fits without problems. #3 Disassemble the baffle This should be self-explanatory. #4 Add the quilt wadding Cover the complete inside surface of the enclosure with one layer of 150gsm quilt wadding. Glue the wadding into place, ensuring it’s below the level where the baffle will sit (see the photos overleaf). In addition, insert a piece of bundled wadding about 500mm square on one side of the enclosure – when the baffle is placed in position, the port needs to be located on the other side. This is so that the wadding doesn’t block the port. No wadding is used on the underside of the baffle. If you are building the sealed enclosure version, attach a second 500mm square piece of loose quilt wadding to the inside of the enclosure. #5 Fitting the port and making the spacer blocks Unless you want to later experiment with different port lengths, glue the port into place now, flush with the outer surface of the baffle. Curved spacer blocks need to be made next. These support the grille while providing clearance for, especially, the protection lamp. We made the spacer blocks from two layers of the same 22mm particle board used for the baffle and strengthening plate, each about 60mm long and 40mm wide. The two layers are held together Photo 8: after cutting the hole for the woofer, make the smaller hole for the port. The jigsaw cuts a tighter radius if you move it back & forth in small steps, rather than a continuous sweep. Australia's electronics magazine with a pair of particleboard screws in each block. If you don’t want to go to the trouble of making curved spacers, 44mm tall square blocks of timber will achieve the same outcome. Use particleboard screws to attach the three spacer blocks at even intervals around the inside edge of the baffle. It’s neatest to insert these screws from the rear of the baffle. #6 Cut out the grille For the grille, we used steel welded mesh with 12.7mm square openings, available from Bunnings. This grille gives an ‘industrial’ look that is great for a shed or workshop. If you don’t want to be able to see the speaker’s components, use steel mesh with smaller holes (Bunnings sells that as well). To cut out the grille, place the enclosure upside-down on the mesh and mark around the edge. Then cut the grille about 10mm inside that line. Lay the cut-out grill over the mouth of the enclosure and keep trimming the grille until it slides into the mouth of the enclosure, leaving a small gap all around. It is better that the grille be slightly too small than too large. Patience and a pair of good side-­ cutters are needed when cutting out the mesh grille! If you are fitting the protection lamp, remember you cannot use grille cloth. Also, be careful not to select woven metal mesh, as it tends to unravel when cut into a circle. #7 Paint the baffle, port and grille Next, use spray paint to paint the baffle, port and (separately) the grille. Photo 9: cutting the hole for the tweeter. It is 50mm in diameter and is best made with a hole saw. siliconchip.com.au When painting the grille, most of the paint will pass straight through the mesh, so place it first on a surface that you don’t mind having a lot of overspray on. Only one side of the mesh needs to be painted, but move the can back and forth at a variety of angles so that the steel wire is coated from all views. Note that the mesh is galvanised, and some paints (eg, the otherwise excellent Rust-Oleum 2X) will not adhere long-term to galvanised steel. #8 Assemble all the components on the baffle and do the wiring Now we will assemble the complete baffle. First, glue the tweeter into its 50mm hole, using the panel-mount adaptor supplied with the tweeter. Some Liquid Nails applied to the back of the tweeter housing will hold it nicely in place. This hole must be fully sealed – we don’t want air leaks past the tweeter. Now mount the speaker protection lamp, if using one. To do this, enlarge the existing hole in the bulb’s bottom tang to 3mm. Nip off one of the nipple protrusions on the baseplate and also enlarge this hole to 3mm. Be very careful when drilling these holes – it is easy to damage the lamp (eg, by dropping it). A Z-shaped bracket needs to be made from scrap aluminium or something similar; this holds the lamp about 25mm off the baffle. We used a combination of a Z-bracket made from a bent right-angled bracket plus a spacer to achieve the stand-off. The Photo 10: the baffle with all the holes finished, for the port, woofer and tweeter. Once you’ve reached this stage, the rest is easy. siliconchip.com.au #8 Glue the baffle, complete with lamp is mounted via its bottom tab so that it is parallel with the baffle. Don’t mount the lamp close to the baffle. Wiring connections to the lamp are by two solder lugs that are attached with the 3mm screws; these wires pass through holes drilled in the baffle. Make the wires a tight fit through the holes and/or seal the back of the baffle where the wires pass through. The lamp is wired in series with one of the main (external-going) speaker wires. Next, cut a suitable speaker gasket from a thin foam rubber sheet before screwing the woofer into place. You can use silicone to seal around the woofer if you don’t want to make a gasket. Drill small diameter pilot holes for the screws first. If you use a gasket, you may find you need some washers under the speaker flange ears to stop them being pulled downwards as you tighten the screws. The crossover can be mounted next, on the back of the baffle. It mounts via spacers and four particleboard screws. If you want permanent access to the crossover, it can be mounted on the front face of the baffle – there is clearance from the grille to allow this. Now complete all the wiring connections, including the main cable to the speaker that passes through the hole in the strengthening plate. Seal this hole with glue or silicone. Before gluing and screwing the baffle into place, test the drivers and crossover by playing some quiet music through the system. There should be output from both the tweeter and woofer! all its components, into place Double-check that everything on the baffle is correctly assembled, wired and fully screwed into place. After the next step, there is no going back! If you want to have access to the crossover during tuning, do not glue the baffle in place at this stage and see the “Tuning alternatives” section. Apply a generous amount of water clean-up Liquid Nails glue around the inside of the enclosure at – and a little above – the height at which the baffle will sit. Slide the baffle down, remembering to orientate it so that the port is on the opposite side of the enclosure to the extra internal wadding. Ensure the baffle is evenly lower than the edge of the enclosure by 60mm. As you slide the baffle into place, glue will probably squeeze up between the baffle and the enclosure wall. With the baffle now positioned at the correct height, use a wet finger to wipe this glue smooth all around the periphery. If there are any gaps, add more glue and wipe it along the gap with your finger. Before the glue can dry (immediately), use a wet cloth to remove all surplus glue. Keep rinsing the cloth and repeating the process until there is a neat line of glue around all the exposed joins, including around the grille spacer blocks. Do not get glue on the woofer or tweeter. Don’t panic if it looks like glue is going everywhere; just keep wiping and rinsing the cloth. Remember, you must use water clean-up Liquid Nails (or equivalent) Photo 11: when making the grille spacer blocks, use the compass to mark the outer line; the inner line that the jigsaw is cutting along is estimated using the outer shoe of the saw. Photo 12: the painted baffle and enclosure, complete with lifting clamp. The port and grille spacer blocks have already been installed on the baffle. Australia's electronics magazine October 2025  83 Photo 13: the wire grille, cut to size so that it fits within the mouth of the enclosure. This can be done while waiting the for glue to harden. Photo 14: the interior of the enclosure lined with quilt wadding. The bottom piece has been inserted, and the glue applied for the long peripheral piece. Speaker lying on its side on the floor. Use a frequency generator (or a phone app like Signal Gen from Media Punk Studios) and an amplifier to quietly do a slow sweep from 20,000Hz down to 30Hz. There should be no buzzes, whistles, or rattles. If you hear problems, isolate where the sound is coming from (eg, a loose port, a leak around the frame of the woofer, or a leak between the edge of the baffle and the enclosure) and then fix that. If the grille rattles, cut it a little smaller so its edges don’t touch the inner walls of the enclosure. If you hear a buzz, ensure it’s not something in the room becoming excited, rather than the speaker itself. If all is fine, redo the frequency sweep a little louder; however, never use sinewaves at high volumes, as the speaker drivers can be damaged. Depending on the quality of your hearing, you should be able to hear speaker output from about 45Hz to 15,000Hz – even higher if you have young ears! Hanging the speaker Photo 15: the outer piece has now been put in position. Note the extra inserted piece of wadding on the left; this goes on the opposite side to the port. The speaker cable can also be fed through a hole drilled in the baseplate. Photo 16: the protection lamp is held in place by a bolt through the enlarged hole in its bottom terminal. The Z-shaped bracket is attached to the front of the baffle via a spacer and particleboard screw. glue. Don’t use the normal building adhesive! The next step is to hold the baffle in place with particleboard screws. Drill small pilot holes, countersink them by turning a large drill bit by hand, then insert four particleboard screws through the wall of the enclosure into the baffle’s edge. Space these screws evenly around the enclosure. These screws are for added structural integrity – we don’t want the baffle falling out! Now seal the speaker cable exit with glue or silicone sealant. Let the glue harden for at least 12 hours in warm conditions; longer if it is below 20°C. There is a lot of glue in the enclosure, and it takes plenty of time to harden – don’t get impatient and start testing the speaker too early! When the glue is hard, paint the edge of the baffle where the glue is showing. You can use a brush to do this, or if you mask of the drivers and lamp, you can use the spray can again. Any black overspray is barely visible on the black enclosure, but you can wipe off any you see with a rag moistened in paint thinner or turpentine. The heads of the countersunk screws through the enclosure walls can be left as they are, or painted black with a small brush. 84 Silicon Chip #9 Fit the grille The grille is attached to the spacer blocks using small particleboard screws and washers, or particleboard screws and small metal or plastic cable clamps. Paint these black after you have attached the grille. The grille is susceptible to resonant vibration, so it must be firmly attached. #10 Testing When you have assembled the speaker, test it by connecting it to an amplifier. Unlike later testing, this testing can be done with the Pendant Australia's electronics magazine The Pendant Speaker will likely be suspended from a high ceiling or roof. Before building the speaker, carefully consider how you are going to mount it – especially how you’re going to safely get up to the required height. Since you’ll probably be using a ladder, be aware that about one person a week dies in falls from ladders in Australia, and a staggering 120 people a week are hospitalised due to ladder accidents. The speaker must be suspended using a chain or steel cable of adequate load rating (eg, 20kg). Use chain that has welded (rather than just bent) links. Do not use plastic chain. Note that if you use a chain and it has any loose links (eg, a ‘tail’ has been left), the chain may resonate at certain frequencies. The chain or cable must be screwed or bolted to a joist or rafter of appropriate strength. The anchor must not be just plasterboard. Don’t be tempted to leave out the speaker strengthening plate – this helps reinforce the base of the pot (which becomes the top of the enclosure) and also better joins the sides to the base. In really rugged conditions (eg, a very windy outdoor area), we suggest that the woofer be bolted into place siliconchip.com.au rather than being held with only particleboard screws. Also, in this application, we suggest an internal chain be used to connect the hanger (the saddle clamp or eye bolt) and one of the woofer mounting bolts. Tuning alternatives The sound from this speaker, as with all speakers, will be greatly affected by its environment. For example, if the speaker is positioned close to a ceiling, the 100mm-long suggested port may make the speaker too boomy. Also, if the location in which you are playing music is jam-packed with ‘stuff’ (eg, a very busy home workshop), the treble will be absorbed to a much greater degree than if the speaker is playing in a bare shed. That’s not to mention that my smooth response may be perceived as your lack of bass, and your strong bottom end may sound to me like one-note bass! So if you wish, you can test some enclosure tuning alternatives to suit your space and taste. If you want maximum tuning flexibility, test without the baffle glued into place. Instead, use just screws to hold the baffle in position. That way, you can easily remove the baffle and make tuning changes to the crossover. Use tape or the equivalent to temporarily seal any leaks around the baffle’s edge. The grille will need to be removed for this testing. This time, don’t test the speaker with it sitting on the floor; instead, you must hang it in similar conditions to how it will be used. I will assume that you have built the ported version and have not yet glued the port’s plastic tube into place. Cut some alternative port tubes of varying lengths. In addition to the suggested 100mm, also try 125mm, 75mm and 50mm. Listening to a song that you know well, test the different vent lengths, including having no plastic tube in place at all (ie, the vent length is just the thickness of the baffle). You should be able to hear distinct changes in the bass response, especially when you swap straight from the longest to the shortest vent. With the shortest vent (the bare hole), the bass will be much peakier and muddier. As you increase the length of the port tube, it will become smoother but also quieter. Using a frequency generator app on your phone will make the results of these port changes clearer. Next, block the vent (eg, by stuffing a strip of rolled up foam rubber – or even just a rag – into the port). As you will hear, the resulting sealed enclosure gives the smoothest result, but also the least bass. If you are intending to use the speaker primarily on voice, now try the speaker with (1) the port sealed, and (2) with the open port length that gave your chosen best response with music. ABC News radio, either streamed or on FM, is a good source of voice. When testing on voice, you should be able to clearly hear that the speaker works better with a sealed vent. The L-pad resistors we have used for the tweeter reduce its output by about 3dB. If you want more treble, you can leave these resistors out (but don’t leave out the crossover capacitor!). Alternatively, if you want less treble, you can instead use a 2W 5W resistor in series and a 4W 5W resistor in parallel with the tweeter; this will give about a 6dB reduction in output. Of course, you don’t need to do any of this testing – you can just take our word for what works best! Conclusion This project is the first pendant speaker in Silicon Chip. We think it is an excellent fit for many scenarios, especially given its ease of construction and ability to have its response tailored to different uses & tastes. This is a design that should have many applications. No longer do you need to have silence in those spaces with high ceilSC ings, or even no ceiling at all! Photos 17 & 18: the photo at left shows the rear view of the completed baffle with the woofer, tweeter and cables that go through the baffle to the protection light and the crossover. The port, woofer, tweeter, protection lamp and two of the grille spacing blocks can be seen in the photo at right. Note the line of lighter coloured glue that runs around the join. After the glue has hardened, paint it black to match the baffle, then fit the grille and you’re finished! siliconchip.com.au Australia's electronics magazine October 2025  85