It's very likely that not the whole membrane of a midrange 15" is playing as piston at higher frequencies, so it's possible it has wider radiation as 4 10" which work more piston like at 800Hz and higher.
Okay, I can see that aggressive pattern-narrowing being a feature rather than a bug. I'd still want to get input from someone more knowledgeable than me on the possibility of degraded clarity from the multiple slightly different arrival times, especially for listeners off to one side who would be well off-axis of the near speaker (assuming the extreme toe-in configuration).
And I would LOVE to find an 18" woofer with a powerful motor and Faraday rings that is good up to 600-700 Hz.
It's the same as for a large diaphragm. You can think of a diaphragm of an 18" woofer as multiple smaller diaphragms, tightly packed together. You can then move these sources a bit apart and it makes virtually no difference, as long as the wavelengths involved are still long enough compared to the dimensions of the sources. This would probably need a simulation to see better if 800 Hz is already too high or not in this case. The "slightly different arrival times" across that area is what makes the (narrow) radiation pattern after all.
I would say that most of them are 🙂
@IamJF - good point
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My instinct (a highly unreliable guide in acoustics and psychoacoustics) is that there is a frequency region above which that is no longer true from a perceptual standpoint. If I recall correctly, Earl once wrote that, if he were to do a speaker with two 15" woofers and a horn on top, he would roll off the top end of the lower woofer. My guess is that whatever principle(s) led him to that conclusion would be in play for a 2x2 matrix of 10" woofers, but I don't know what the frequency where it starts to matter would be.
I think you'll see much more rapid pattern-narrowing in the 400-800 Hz octave with the 2x2 matrix of 10's than with a single 18. But again, that may be a feature instead of a bug! Which would be GREAT... so I'm hoping Earl sees this and comments.
I've communicated (or tried to) with about a half-dozen manufacturers of promising-looking 18" woofers and the impression I get is that most 18" cones have breakup modes which show up in their off-axis response even if their published on-axis response looks pretty good. I think all of the ones who replied to me have suggested using 15" woofers instead.
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With two vertical drivers the bottom one is ususally added for extra low frequency capability so it is rolled off to avoid it interfering with the top one as frequency rises.
Above 1/4 wavelength spacing the drivers will begin to interact with each other and not radiate as one single sound source. For 4 tightly packed 10" woofers this would be somewhere around 400Hz. Above 400Hz there would be increased interaction and a reduced beam width as a result. A simulation would make it easier to "see" but as the core issue is based on physical spacing and membrane size a calculator is good enough to work out where the trouble or feature will start.
I was poking around the LaVoce website and thought that their new DF10.144LK looked interesting. 35mm VC with a low recommended crossover point (1.2kHz). Perhaps a good alternative to the Peerless DFM-2535R00?
Yeah, it has the lowest recommended Xover from their whole 1" catalogue -
It would be interesting to know how they actually specify this / determine the number (if it's not a typo).
Certainly looking good.
It would be interesting to know how they actually specify this / determine the number (if it's not a typo).
Certainly looking good.
I got a request for an adapter for 18Sound ND3N (and similar). I've just added the model.
It was optimized including the conical exit section of the driver and I'm particularly happy about this one.
It was optimized including the conical exit section of the driver and I'm particularly happy about this one.
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How do you actually make these adapter profiles? any chance to get Ath script / profile for this ND3x adapter so I could revolve my own adapter in fusion?
I recently bought the A460G2 and STD extension adapter for 1.4" driver, but would very much like this optimized version as it exists now. Issue is, I'm customizing the extension adapter a bit for mounting points. I did this using A460G2 ath profile and got the rest by slicing the STD adapter mesh and made my own compatible adapter in fusion. which was quite lot of work 🙂 I guess I could smash it all together in slicer as well, but if the adapter profile is available somehow it would be cool. Thanks!
I recently bought the A460G2 and STD extension adapter for 1.4" driver, but would very much like this optimized version as it exists now. Issue is, I'm customizing the extension adapter a bit for mounting points. I did this using A460G2 ath profile and got the rest by slicing the STD adapter mesh and made my own compatible adapter in fusion. which was quite lot of work 🙂 I guess I could smash it all together in slicer as well, but if the adapter profile is available somehow it would be cool. Thanks!
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And a stripped-down version 🙂
@tmuikku - Each Gen2 adapter comes with its definition that can be used directly in an Ath script (and modified). It's all described in the README file that's part of a waveguide body package (e.g. A460G2, which you already have).
By purchasing a Gen2 waveguide you get all this machinery at your disposal.
@tmuikku - Each Gen2 adapter comes with its definition that can be used directly in an Ath script (and modified). It's all described in the README file that's part of a waveguide body package (e.g. A460G2, which you already have).
By purchasing a Gen2 waveguide you get all this machinery at your disposal.
I couldn't find description how the throat.ext.ctrl part is formulated, also I don't have parameters for the exit section of the driver so' I'd rather buy this ready made kit. The mesh file is pain to edit, so the profile for this one I'd like, to be able to make custom version of the adapter.
I have understood rest of the device would be the same and only the adapter portion changes and haven't had time yet to play with the scriot to find out how it works regarding with the extension part.
I have understood rest of the device would be the same and only the adapter portion changes and haven't had time yet to play with the scriot to find out how it works regarding with the extension part.
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The six numbers in a Throat.Ext.Ctrl are the X, Y coordinates of the three points that define a Bezier cubic spline (from left to right):
(This is only a random example. x=0 is where the adapter is always connected to the main body.)
Here's a handy Desmos script for this: https://www.desmos.com/calculator/ct3lhumv1r
(This is only a random example. x=0 is where the adapter is always connected to the main body.)
Here's a handy Desmos script for this: https://www.desmos.com/calculator/ct3lhumv1r
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I guess so. Actually, now I recall that the adapter "36-STD-1" was made specifically with the ND3T in mind, but at the time I didn't include the exit section of the driver in the optimization. So these two will be in fact pretty close, the "ND3N" adapter a bit more refined perhaps...
The ND3T is problably not as good as the ND3N in the top octave, I don't know.
The ND3T is problably not as good as the ND3N in the top octave, I don't know.
Any chance you could include the Throat.ext.ctrl definition string with the adapter package?🤓
T520-36-STD package doens't have it. I'll buy this new ND3N model soon and it would be nice if it had it.
A460G2 has the full ath file, but I think the resulting profile seems to be bit different than what the T520-36-STD adapter (mesh) is, although very close. At least the mesh doesn't exactly align with the profile generated with the ATH script:
While the error is very small and within error margin of my printer, it would be still nice to be sure. Yeah, this is customisation work so not your responsibility to support it, although it would be nice to be able to customize the adapter as it is nice part to make mounting with, while still being sure the throat profile is exactly what it should. At least before printing 😀
A460G2 has the full ath file, but I think the resulting profile seems to be bit different than what the T520-36-STD adapter (mesh) is, although very close. At least the mesh doesn't exactly align with the profile generated with the ATH script:
While the error is very small and within error margin of my printer, it would be still nice to be sure. Yeah, this is customisation work so not your responsibility to support it, although it would be nice to be able to customize the adapter as it is nice part to make mounting with, while still being sure the throat profile is exactly what it should. At least before printing 😀
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