These are my almost done, kind-of line source, two way, sealed, crossover-less speakers. They're built around RD-50 planar magnetic drivers in sealed enclosures. The bass is handled by what I am calling subwoofers, although they don't go down quite to 20Hz. The cabinets use activated charcoal in a similar way KEF uses it, to enlarge the apparent volume.
The crossover frequency is 200Hz handled by the preamp. The bass module is intended to be raised off the floor in line with the larger speaker, directly above it, see drawings and the visions in my head.
The subwoofers are two drivers each, firing opposite and in phase. When music is pumping, there is zero vibration in the cabinet, they cancel internally. These are Tang Band W8-2022 8" drivers.
The big idea is that these speakers should have as little getting in the way of the sound as possible. A single driver would be ideal for the spectrum, but the RD-50 is a pretty darn wide range driver.
They sound great, and that's a good thing because they took me quite a long time to put together. From initial design in 2013, I noodled on the design until I was ready to move into Rhino to draft all the plywood and aluminum pieces. Working off and on, I got them to this point at the end of 2019. I aim to post again once they're really done!
The design calls for the main speaker to be suspended over the subwoofer. The aluminum plate legs will be brazed to the subwoofer aluminum arms. That will be a rigid connection. The main speaker is intended to be suspended with neoprene or other bands as the drawings show and one day will be! I don't know if this will work or make a difference vs being rigidly attached. The screws and rivets of the driver are intended to be covered and flush out at the level of the adjacent plywood.
The original inspiration comes from my interest in the characteristics of line sources and line arrays. The 50" driver acts like a line source, but I realize the best line source would be floor to ceiling. However, locating the driver between about 22" and about 6'-0" gives a good range of sound vertically-sitting or standing. I love the look of plywood laminations and black metal. I sanded and stained the laminations with Osmo-great stuff. I may have first seen this with Magico's M-1, but there are a lot of nice precedents, such as Jean Nouvel's Philharmonia design. To that end, I sourced 1" thick American Birch, no void (actually low void) plywood.
Plywood was cnc'd by a local shop in Portland, which did a great job. What remained for me was a mammoth sanding job, mostly by hand, that took months. I would not recommend it. In fact, I wouldn't exactly recommend any of this! I value the encouragement I received from members of the Portland Audio Club along the way. Wish I could host people at home to hear them.
The crossover frequency is 200Hz handled by the preamp. The bass module is intended to be raised off the floor in line with the larger speaker, directly above it, see drawings and the visions in my head.
The subwoofers are two drivers each, firing opposite and in phase. When music is pumping, there is zero vibration in the cabinet, they cancel internally. These are Tang Band W8-2022 8" drivers.
The big idea is that these speakers should have as little getting in the way of the sound as possible. A single driver would be ideal for the spectrum, but the RD-50 is a pretty darn wide range driver.
They sound great, and that's a good thing because they took me quite a long time to put together. From initial design in 2013, I noodled on the design until I was ready to move into Rhino to draft all the plywood and aluminum pieces. Working off and on, I got them to this point at the end of 2019. I aim to post again once they're really done!
The design calls for the main speaker to be suspended over the subwoofer. The aluminum plate legs will be brazed to the subwoofer aluminum arms. That will be a rigid connection. The main speaker is intended to be suspended with neoprene or other bands as the drawings show and one day will be! I don't know if this will work or make a difference vs being rigidly attached. The screws and rivets of the driver are intended to be covered and flush out at the level of the adjacent plywood.
The original inspiration comes from my interest in the characteristics of line sources and line arrays. The 50" driver acts like a line source, but I realize the best line source would be floor to ceiling. However, locating the driver between about 22" and about 6'-0" gives a good range of sound vertically-sitting or standing. I love the look of plywood laminations and black metal. I sanded and stained the laminations with Osmo-great stuff. I may have first seen this with Magico's M-1, but there are a lot of nice precedents, such as Jean Nouvel's Philharmonia design. To that end, I sourced 1" thick American Birch, no void (actually low void) plywood.
Plywood was cnc'd by a local shop in Portland, which did a great job. What remained for me was a mammoth sanding job, mostly by hand, that took months. I would not recommend it. In fact, I wouldn't exactly recommend any of this! I value the encouragement I received from members of the Portland Audio Club along the way. Wish I could host people at home to hear them.
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It's great to see this kind of project, so much more than the stuff I do, ie build a rectangular box put some normal drivers in and design a crossover for it. This really is other level diy!!
I think this forum may be a bit slow compared to Multiway. I'm surprised no other comments!
Tony.
I think this forum may be a bit slow compared to Multiway. I'm surprised no other comments!
Tony.
Quite a lot of thought and effort went into these. They look great, stunning in fact.
First order electronic crossover or something fancier?
First order electronic crossover or something fancier?
Tony, thanks! I bit off a lot with these. I wanted no baffle-step affect, so a radiused front was something I wanted from the start. That combined with not wanting a huge cabinet led to a variation on an equilateral triangle section. Cutting ply allows for any sectional shape, and the precision meant that sanding would be minimal. Or so I thought. Under factory conditions, these would have turned out better, but hand sanding means that there are variations.
kevinkr, I aspire to something fancy with the electronic crossover, something I can control better than what I have. I am using an Emotiva XMC-1 which allows for some play in the crossover frequency and allows for a 24 dB/octave slope (and 12dB also). I want to be able to control the frequency point better to be able to play with what works best with the drivers. Right now the BG mains are fed down to 200Hz, as they're rating only down to about 150 as I recall...
And thank you for the compliment! You ever look at a project so long you're not sure it looks good? It's nice to hear.
And thank you for the compliment! You ever look at a project so long you're not sure it looks good? It's nice to hear.