Because, after all, it would be a shame to let one of the best unintended double entendres in audio go to waste. I was tempted to title this the ménage à trois thread, but that seemed a bit over the top. 
I know of two and a half way swinging dipoles (mige0), a few minimally baffled three way dipoles (notably cuibono and keyser's builds), and StigErik's four way technically has got a three way swinging dipole embedded within but doesn't really count. I don't know of any three way swingers and so a new thread on them seems in order. All build threads broaden into a general discussion of various speaker designs sooner or later so I figured I'd just scope the thread to the category and kick it off with my current build.
The build in question is a BG Radia Neo3, BG Radia Neo10, Selenium 18SWS1100 crossed linear phase LR6 at 200Hz and 1.7kHz. Crossover and equalization are via a Focusrite Saffire 40 and Thuneau Allocator on my Dell Inspiron 1505 Core Solo laptop running Windows XP. The first couple figures are a shot of the right speaker to give you a sense of the build and how the swinging is done along with a detail of the lines on the left speaker. The next two are front and rear wave symmetry for SPL and phase, followed by front and rear directivity. All four measurement sets are in room, ungated, and 1/16 octave smoothed. The smoothing's mainly so it's easier to tell which curve is which and the chuckhole around 150Hz is the usual first reflection from floor, ceiling, and walls (mostly ceiling as I'm renting and hence haven't mounted a diffuser). The next three figures are SPL and THD of the individual drivers when equalized flat for nude dipole operation within their passbands. SPL on top, THD below, and the crossovers turned off. These are in room, ungated, and unsmoothed. SPL for the green 0dB curves is 5 to 10dB above peak SPL at my usual listening levels. I don't have an SPL meter but the measurements are around 80dB or so, give or take a few dB. The red +10dB curves are peak SPL at about the loudest level I ever listen at---it's somewhat uncomfortable to listen while the measurements are being taken---and the blue +20dB curves are loud enough I give up, put in my 35dB chainsaw earplugs, and wonder why I didn't put the earplugs in already for the +10dB curves. Granted, the +20dB setting's quieter than my chainsaw. But not by a whole lot.
DIYAudio only allows 10 attachments per post, so see the next post for the crossover, equalization, and a couple other interesting things. In the meantime, some discussion of the speakers seems in order.
In short, I like them. Quite a bit. Best setup I've heard yet. But then I'm 1) obviously biased since these things are sitting in my living room making dents in the carpet, 2) unable to afford a plane ticket to Norway to listen to StigErik's rig since I blew all my money on drivers, and 3) too polite to show up on cuibono's doorstep and invite myself in. There's also the minor logistical difficulty I don't actually know where cuibono's doorstep is, but that's beside the point. I believe the measurements mostly speak for themselves, but a few remarks seem in order. One is the front to rear SPL asymmetry above 10kHz due to the Neo3 shifting somewhat off vertical when I was turning the speaker around to measure the rear wave and I'm too lazy to redo the measurements. The asymmetry below 1kHz is due to slightly different mic and speaker placement and room interaction along with, possibly, some shadowing by the 18SWS1100 magnet at low frequencies where the diffraction radius is large. Another remark is the 0dB THD curves are higher than the +10dB THD curves because they're sitting at the ambient noise floor of my relatively quiet neighborhood on a quiet night---the floor would be higher if I'd left the fridge on. THD doesn't actually drop in the +10dB curves; it's that turning up the volume raises the SnR. The exception to this is the Neo10, where the +10dB curve becomes excursion limited below 400Hz. At +20dB all drivers are showing rising distortion from excursion. But they're also pushing 100dB SPL each and if all six of them that ran hard the system would be around 105dB. Respectable performance for not having a baffle.
The Neo10s make this system. I originally started out designing a four way with five drivers---the fifth being a second sub---which eventually shrunk to four drivers as my preference for keeping speakers vertically compact asserted itself and I realized a single big driver was shorter than two smaller ones. I eventually chose the 18SWS1100s for their good bang for the buck, generous xmax, and low (for an 18) Mms and Rms. Neo3s were a given for the tweeter as AMTs are expensive, Zaph's shown the Neo3 handily beats most ribbons, and Rudolf's amply demonstrated getting good directivity out of back to back dome tweeters is hard. But no matter how I looked at it I could not find a mid for a three way which didn't involve more sacrifices than I was willing to accept. Until BG Radia finally made Neo10s available for DIY and Meniscus got them back in stock. Greater vertical dispersion would benefit the Neo10s the Neo3s cross low enough to mitigate the problem. Otherwise the Neo10s are to die for. Excellent front to rear wave symmetry, low distortion, detail as good as you'd expect from their low Mms, and no cone breakup. Spendy. Though cheaper and more compact than two mids and the extra pair of power amp channels needed by an actively equalized four way.
I'm also pleased with the hanging. The mechanical benefits of swinging drivers are covered at length in StigErik's Open baffle with Beyma TPL150 build thread (more accurately titled the no baffle without TPL150) and mige0's Beautiful Swinging Speaker thread. I've little to add here but agreement and it doesn't hurt swinging saved me a bunch of MDF dust and spending two hundred bucks on a router. Good deal. mige0 used a cable and bolt system for hanging and StigErik progressed from bolts and chain to bolts and rubber straps. I'm not a fan of either approach, but my previous solution of picture wire was subject to creep and I had to keep readjusting the drivers. So I picked up 2mm, 3mm, and 6mm climber's auxiliary cord and set to with bolins and rolling hitches. Way better. The frames are obviously prototypes and I've not trimmed the lines yet but the reason I included a detail of the hanging is so you can see how the Neo3 is supported with a pair of lines, one for the driver itself and one to support the cable so that it doesn't pull the Neo3 around. The Neo10 is light enough to be subject to same problem and the combination of using parallel lines to get a pantograph type of motion in the swing works well for it too.
I know of two and a half way swinging dipoles (mige0), a few minimally baffled three way dipoles (notably cuibono and keyser's builds), and StigErik's four way technically has got a three way swinging dipole embedded within but doesn't really count. I don't know of any three way swingers and so a new thread on them seems in order. All build threads broaden into a general discussion of various speaker designs sooner or later so I figured I'd just scope the thread to the category and kick it off with my current build.
The build in question is a BG Radia Neo3, BG Radia Neo10, Selenium 18SWS1100 crossed linear phase LR6 at 200Hz and 1.7kHz. Crossover and equalization are via a Focusrite Saffire 40 and Thuneau Allocator on my Dell Inspiron 1505 Core Solo laptop running Windows XP. The first couple figures are a shot of the right speaker to give you a sense of the build and how the swinging is done along with a detail of the lines on the left speaker. The next two are front and rear wave symmetry for SPL and phase, followed by front and rear directivity. All four measurement sets are in room, ungated, and 1/16 octave smoothed. The smoothing's mainly so it's easier to tell which curve is which and the chuckhole around 150Hz is the usual first reflection from floor, ceiling, and walls (mostly ceiling as I'm renting and hence haven't mounted a diffuser). The next three figures are SPL and THD of the individual drivers when equalized flat for nude dipole operation within their passbands. SPL on top, THD below, and the crossovers turned off. These are in room, ungated, and unsmoothed. SPL for the green 0dB curves is 5 to 10dB above peak SPL at my usual listening levels. I don't have an SPL meter but the measurements are around 80dB or so, give or take a few dB. The red +10dB curves are peak SPL at about the loudest level I ever listen at---it's somewhat uncomfortable to listen while the measurements are being taken---and the blue +20dB curves are loud enough I give up, put in my 35dB chainsaw earplugs, and wonder why I didn't put the earplugs in already for the +10dB curves. Granted, the +20dB setting's quieter than my chainsaw. But not by a whole lot.
DIYAudio only allows 10 attachments per post, so see the next post for the crossover, equalization, and a couple other interesting things. In the meantime, some discussion of the speakers seems in order.
In short, I like them. Quite a bit. Best setup I've heard yet. But then I'm 1) obviously biased since these things are sitting in my living room making dents in the carpet, 2) unable to afford a plane ticket to Norway to listen to StigErik's rig since I blew all my money on drivers, and 3) too polite to show up on cuibono's doorstep and invite myself in. There's also the minor logistical difficulty I don't actually know where cuibono's doorstep is, but that's beside the point. I believe the measurements mostly speak for themselves, but a few remarks seem in order. One is the front to rear SPL asymmetry above 10kHz due to the Neo3 shifting somewhat off vertical when I was turning the speaker around to measure the rear wave and I'm too lazy to redo the measurements. The asymmetry below 1kHz is due to slightly different mic and speaker placement and room interaction along with, possibly, some shadowing by the 18SWS1100 magnet at low frequencies where the diffraction radius is large. Another remark is the 0dB THD curves are higher than the +10dB THD curves because they're sitting at the ambient noise floor of my relatively quiet neighborhood on a quiet night---the floor would be higher if I'd left the fridge on. THD doesn't actually drop in the +10dB curves; it's that turning up the volume raises the SnR. The exception to this is the Neo10, where the +10dB curve becomes excursion limited below 400Hz. At +20dB all drivers are showing rising distortion from excursion. But they're also pushing 100dB SPL each and if all six of them that ran hard the system would be around 105dB. Respectable performance for not having a baffle.
The Neo10s make this system. I originally started out designing a four way with five drivers---the fifth being a second sub---which eventually shrunk to four drivers as my preference for keeping speakers vertically compact asserted itself and I realized a single big driver was shorter than two smaller ones. I eventually chose the 18SWS1100s for their good bang for the buck, generous xmax, and low (for an 18) Mms and Rms. Neo3s were a given for the tweeter as AMTs are expensive, Zaph's shown the Neo3 handily beats most ribbons, and Rudolf's amply demonstrated getting good directivity out of back to back dome tweeters is hard. But no matter how I looked at it I could not find a mid for a three way which didn't involve more sacrifices than I was willing to accept. Until BG Radia finally made Neo10s available for DIY and Meniscus got them back in stock. Greater vertical dispersion would benefit the Neo10s the Neo3s cross low enough to mitigate the problem. Otherwise the Neo10s are to die for. Excellent front to rear wave symmetry, low distortion, detail as good as you'd expect from their low Mms, and no cone breakup. Spendy. Though cheaper and more compact than two mids and the extra pair of power amp channels needed by an actively equalized four way.
I'm also pleased with the hanging. The mechanical benefits of swinging drivers are covered at length in StigErik's Open baffle with Beyma TPL150 build thread (more accurately titled the no baffle without TPL150) and mige0's Beautiful Swinging Speaker thread. I've little to add here but agreement and it doesn't hurt swinging saved me a bunch of MDF dust and spending two hundred bucks on a router. Good deal. mige0 used a cable and bolt system for hanging and StigErik progressed from bolts and chain to bolts and rubber straps. I'm not a fan of either approach, but my previous solution of picture wire was subject to creep and I had to keep readjusting the drivers. So I picked up 2mm, 3mm, and 6mm climber's auxiliary cord and set to with bolins and rolling hitches. Way better. The frames are obviously prototypes and I've not trimmed the lines yet but the reason I included a detail of the hanging is so you can see how the Neo3 is supported with a pair of lines, one for the driver itself and one to support the cable so that it doesn't pull the Neo3 around. The Neo10 is light enough to be subject to same problem and the combination of using parallel lines to get a pantograph type of motion in the swing works well for it too.
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LokiRight.jpg115.1 KB · Views: 5,489
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LokiFrontRearSymmetrySPL.png25.3 KB · Views: 4,942
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LokiHang.jpg66.6 KB · Views: 5,054
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LokiFrontDirectivity.png26.6 KB · Views: 4,687
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LokiRearDirectivity.png26.5 KB · Views: 751
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LokiFrontRearSymmetryPhase.png27.9 KB · Views: 4,770
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Neo3-THD.png30.1 KB · Views: 793
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Neo10-THD.png32 KB · Views: 893
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18SWS1100-THD.png33 KB · Views: 885
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