Thanks. I think that makes sense. But if I understand correctly, the analysis linked above in at ASR showed that it’s the midrange woofer in the coaxial driver that’s exciting the resonance, even though it’s above the “wings”.
Yes, an S shape should somewhat mitigate the issue with the varying distance from woofer. The triangular shape also should do The same because it’s also a varying length from the woofer. But the sym shows the same issue as with a full height rectangular u-baffle wings. Just different because of the different size and shape.
Yes, my dipole would be a 2-way, which would be more like your Walnut Dipoles. This is why I was a bit more concerned with my design—the midrange would be inside the u-baffle, so definitely would excite the resonance.
Since the analysis shows that a midrange from a 3 way that’s outside the u-baffle can still excite the resonance—well, it doesn’t get any better when the midrange is fully inside the u-baffle.
In my case, I’d make the wings small, so only 1 of the 2 12” mids would be inside. But even the outside one can excite the resonance.
But, as you say, an extra octave is massive and may trump a theoretically more perfect polar. The added bass is definitely audible. Whereas the potential polar ripple—I‘d have to a/b listen to know for sure.
I think it may come down to whether one is willing to add subs. I may go that route—airy dipoles for guitar/bass duty, and add subs if I double duty them for watching movies or something.
This is a great analysis (thank you) - I think the most relevant figure is this one:
This is at 150Hz and this is the biggest mode. I'd love to see this with the other 2 woofers modeled as well. Considering that the midrange radiation you are seeing here is only about 1/6 of the total radiation from just the back side; and that rooms also have their own standing waves, I see this as a minor problem in the grand scheme of things. Again, I'm willing to live with this if it gives me an extra octave of bass.
This is at 150Hz and this is the biggest mode. I'd love to see this with the other 2 woofers modeled as well. Considering that the midrange radiation you are seeing here is only about 1/6 of the total radiation from just the back side; and that rooms also have their own standing waves, I see this as a minor problem in the grand scheme of things. Again, I'm willing to live with this if it gives me an extra octave of bass.
I think this is a good way to put it. I keep waffling about adding wings. Now I’m leaning toward small triangular wings about 1 woofer high that act as stands. The extra bass would make a difference for sure.
I do wonder how it would model if you only have 1 solid wing. Say, 1 solid triangular wing, and the other wing would be just a hollow triangle for support. This removes the parallel walls.
You lose half of the baffle size increase, but possibly reduce the resonance? And the baffle would be asymmetrical, which would be similar to having an offset driver. Not uncommon. It would probably tilt the rear lobe a bit too.
Might look kind of cool. One side could Look more open, visually slimming the profile on that side. With speaker toe in, you mostly see one side.
The design was crafted with Fusion 360, a versatile tool that danced beautifully with the concepts. Modeling it in VituixCAD2 or similar freeware software sounds like a fantastic idea.
You’d get rid of the cavity, but I don’t think you’ll get any bass extension with just one wing. I predict the wave will take the path of least resistance and cancel.
Most of this interesting discussion is way, way past my pay grade, but in case it helps somehow, Danny at GR Research uses asymmetrical baffles (different sidewall lengths) in some of his products like the NX Oticas.
It appears that the asymmetry is for the mid and upper frequencies. The mid-bass drivers have equal sidewall lengths, but they're angled out at about 10 degrees per side like the mid/upper baffle... possibly for the reasoning that @cab suggested?
That's a fascinating insight! Asymmetrical baffles indeed add another layer to the design considerations.
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I'm almost done with my Bitches Brew Speakers. However, I went to go build the top portion of the baffles and realized that Parts Express sent me B&C 14CXN88 drivers instead of the 15cxn88!! And of course, now they are on seemingly indefinite backorder on Parts Express. Perry, Do you think the 14cxn88 would work in this design with the same basic crossover parts? The frequency response looks very similar between the 14 and 15" drivers, and I believe the compression driver is the same. I actually wonder if the midrange might be very slightly improved with the slightly smaller driver?
What are your (or anyone's) thoughts on this?
What are your (or anyone's) thoughts on this?
You know what would be a fun system to build? Something very similar the Flanagangster, except:
instead of an OB 12 mid and bass reflex 12 and a waveguide tweeter in between, a 14CXN88 coax on top in Open Baffle with its cousin 14NDL88 in bass reflex to handle the bass.
instead of an OB 12 mid and bass reflex 12 and a waveguide tweeter in between, a 14CXN88 coax on top in Open Baffle with its cousin 14NDL88 in bass reflex to handle the bass.
That does look like it would be fun! I already have ALL the parts for the bitches brews except for the 15cxn88. I do have a whole lot of subs to handle bass, but that does look like it would be a cool project. Perry, did you consider the 14CXN88 when designing the bitches brew? It looks like the 12CXN88 and the 15CXN88 came out first, with the 14CXN88 being introduced later. Was it out yet when you built them? If so, why did you decide to go for the 15? I do think it would look cooler with (3) 15" drivers instead of (2) 15" and (1) 14", but c'est la vie.
Bitches Brew was always conceived as 3 15" drivers. They started with me being super happy with the Live Edge Dipoles but asking how I could extend bass all the way down to 20Hz. Using 2 fifteen subs made a ton of sense and then having the coax be a 15 was a natural conclusion. (I feel having both subs and midrange 15" with thin high SPL cones really helps them blend seamlessly. Since all cone materials have a "signature sound", these match each other well.)
Initially I tried the Beyma 15XA38ND but the polar pattern was a hot mess between 4-7K so I bought the 15CXN88 instead. It has none of those problems plus its top octave has a wider polar pattern than the Beyma.
A B&C rep told me his fave in the series was the 14CXN88, he said the midrange was just a little sweeter.
I always like my designs to have a certain amount of visual proportion and symmetry so two 13.5" drivers stacked would look great. A Bitches Brew little brother.
For you I think two 15s and a 13.5 sonically will be fantastic, and if you want the sizes to match visually, just put 15" grilles over the 13.5s.
Initially I tried the Beyma 15XA38ND but the polar pattern was a hot mess between 4-7K so I bought the 15CXN88 instead. It has none of those problems plus its top octave has a wider polar pattern than the Beyma.
A B&C rep told me his fave in the series was the 14CXN88, he said the midrange was just a little sweeter.
I always like my designs to have a certain amount of visual proportion and symmetry so two 13.5" drivers stacked would look great. A Bitches Brew little brother.
For you I think two 15s and a 13.5 sonically will be fantastic, and if you want the sizes to match visually, just put 15" grilles over the 13.5s.
That's really interesting what the B&C rep said about the 14cxn88 being his favorite. I of course won't have any way of comparing, but the midrange is where it's at as far as I'm concerned, and if the 14 is just slightly sweeter I may actually prefer it. I'm sure the difference is extremely small, but it will be kind of cool to try this version out.
What would the advantages (or disadvantages) of the 10" Radian 5210 be when compared to the smaller 8" 5208c?
And how would the aluminum and beryllium versions of the Radians stack up against the B&C 14/15cxn88 family?
Just trying to assess all the attractive-sounding options!
For some reason the Radian 5210 paired with the SB 15OB350 seems compelling.
The radian 10 has the exact same tweeter as the 8. So the only difference is the extra surface area of the larger cone and the extension to slightly lower frequencies. I haven’t used it but I think it would blend better with the 18 inch sub than the 8 does.
I think the 5208 has a slightly better top octave than the B&C drivers, which have titanium diaphragms. I would love it if they offered beryllium or Textreme.
The B&Cs have a very slight tinge of harshness, unless you have a really good amplifier. Then it goes away.
Despite that, I feel like the bitches brews are overall better integrated than the live edge dipoles. They are more seamless.
The 15OB350 + 5208 will sound great, no question. To anticipate your next question, 15OB350 + 5210 would probably blend a tad better and still have the beryllium high end. I think the extra surface area all by itself is a virtue.
One 15 all by itself will start running out of gas below 30 Hz in most rooms. The 5210 with a 21 inch woofer would go all the way to 20Hz in a dipole.
I think the 5208 has a slightly better top octave than the B&C drivers, which have titanium diaphragms. I would love it if they offered beryllium or Textreme.
The B&Cs have a very slight tinge of harshness, unless you have a really good amplifier. Then it goes away.
Despite that, I feel like the bitches brews are overall better integrated than the live edge dipoles. They are more seamless.
The 15OB350 + 5208 will sound great, no question. To anticipate your next question, 15OB350 + 5210 would probably blend a tad better and still have the beryllium high end. I think the extra surface area all by itself is a virtue.
One 15 all by itself will start running out of gas below 30 Hz in most rooms. The 5210 with a 21 inch woofer would go all the way to 20Hz in a dipole.
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Tom Larwa (@tlarwa) chronicled his build of the Live Edge Dipoles in this thead on HiFiHaven. He brought them to a hifi meetup in Wisconsin last winter and they sounded great.
