I'm just about to test the following with a single 1" compression driver, will report back -
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That's because there's also the cardioid midrange. A small waveguide alone is simply not able to control the directivity very low.
Yeah, simplified the wavefront stuff is most important on top octave, where wavelength is about size of the throat or smaller. Waveguide depth relates to loading which might help how low a crossover can be, but also how steep the "wall angle" can be: shallow waveguide can do only wide coverage pattern, while more depth makes it possible to have less angle to walls so narrower coverage pattern. Size of mouth means how low frequency there is pattern control (think baffle step), and shape of the mouth (rollover), or actually the whole waveguide profile, determines how much there is problems with diffraction. If you start thinking about these features, narrower coverage pattern tends to result bigger device and system overall, while wider coverage pattern waveguide can be quite small in any dimension in relation to make into a nice system.
Difference between flat baffle and shaped one, like a waveguide, is that the flat is not optimized for sound but for easy build. Waveguides, or basically the whole physical structure of your speaker, can be optimized further, toward some desired radiation of the whole speaker. Flat can work fine, if you mitigate edge diffraction issues by making it less flat 😉 If you need smooth DI from schroeder frequency up, then one way to achieve it is the good old direct radiating system on big flat baffle, perhaps with diffraction control, but so can do with a cardioid mid and shallow waveguide which just makes higher DI system in smaller package and possibly smoother DI and other advantages. Some structure to try omni response would provide it as well, DI is even lower. Open baffle. And anything in between. DI always low on lowest frequenicies, and quite high on highest just due to wavelengths involved. Only problem is, which pattern makes best sound for you in your room with possible constrains for positioning? What are the trade-offs and costs and all that, to any design decision? 🙂 Or, do you care about it so much?
This is the hardest part of any speaker system, to know what it needs to do, then to be able to reason what kind of a physical structure makes it happen. If you start from waveguide, or from a best drivers in the world, and so on, it's backwards thinking in a way and you'll likely endup with compromises that do not help to achieve your goal, but if there is no goal it's just not gonna work, the result is just random 😉 First be sure what the pattern/capability needs to be and then design the whole system based on that, and you might arrive to some waveguide somewhere, some physical structure, some drivers, and most importantly have a goal and then try reach that. This is almost impossible for beginner without experimentation and experience in your own room tweaking your own system, so perhaps do anything to learn first, then gradually gravitate to something else if you learn something else could work better. You might be perfectly happy on the first build, it all depends on what are your expectations and persistence to pursue. Have fun!
Difference between flat baffle and shaped one, like a waveguide, is that the flat is not optimized for sound but for easy build. Waveguides, or basically the whole physical structure of your speaker, can be optimized further, toward some desired radiation of the whole speaker. Flat can work fine, if you mitigate edge diffraction issues by making it less flat 😉 If you need smooth DI from schroeder frequency up, then one way to achieve it is the good old direct radiating system on big flat baffle, perhaps with diffraction control, but so can do with a cardioid mid and shallow waveguide which just makes higher DI system in smaller package and possibly smoother DI and other advantages. Some structure to try omni response would provide it as well, DI is even lower. Open baffle. And anything in between. DI always low on lowest frequenicies, and quite high on highest just due to wavelengths involved. Only problem is, which pattern makes best sound for you in your room with possible constrains for positioning? What are the trade-offs and costs and all that, to any design decision? 🙂 Or, do you care about it so much?
This is the hardest part of any speaker system, to know what it needs to do, then to be able to reason what kind of a physical structure makes it happen. If you start from waveguide, or from a best drivers in the world, and so on, it's backwards thinking in a way and you'll likely endup with compromises that do not help to achieve your goal, but if there is no goal it's just not gonna work, the result is just random 😉 First be sure what the pattern/capability needs to be and then design the whole system based on that, and you might arrive to some waveguide somewhere, some physical structure, some drivers, and most importantly have a goal and then try reach that. This is almost impossible for beginner without experimentation and experience in your own room tweaking your own system, so perhaps do anything to learn first, then gradually gravitate to something else if you learn something else could work better. You might be perfectly happy on the first build, it all depends on what are your expectations and persistence to pursue. Have fun!
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That about nails the whole game....
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... and why and what that achieves... To not involve the recording chain in this thinking wont make for a SOTA rec/play system. This hasn't been done properly yet - at all.
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Yeah, while it's all relatively thin line in sense that anything could work just fine, depending on listening skill 🙂
If one is into the hobby and is interested in things and develops listening skill in sense that there is relatively clear sound ideal one wants to achieve and is able to detect it's not there yet, then there needs to develop some skill to figure out why and so on, to be able to take steps toward it. HEre is where increased knowledge also starts to matter. By listening skill I mean ability to understand perception, how (and what in) perception relates to written concepts such as directivity.
Before that there is Toole book and certain metrics one can follow, like CTA2034 stuff, but I think it's still somewhat vague regarding room acoustics and positioning and how all these relate so there is some wiggle room where one ultimately ends up. Especially with living room conditions where room acoustics and positioning have constrains so there the speaker polar pattern and positioning can really affect the sound. Simplest example is, someone else made you "ideal room" and "ideal speaker", but you fail to position the system to reach what you wanna perceive because it's not just the room or the speaker, but how these work together, through auditory system, to make satisfying perceptual effect. It likely sounds very good to you, but could sound even better if there is ability to position it better 😀
Another, I'm fairly many years into the game adjusting speakers at home. Now, took the system to friends place with very different room acoustics, and the balance was way off (no matter the positioning), so even if the DI is nice and all, good match to ideal at home, decent experience on listening and positioning, change of the room still made huge deal and required some further optimization of the system, on this occasion tweaks in DSP. This could have many reasons, like that my data is bad and I'm not actually sure what my system response is, so it could be off from ideals in that sense so varies with rooms more than it should. I might have error anywhere in the system, like in DSP and it goes unnoticed as minor but was highlighted due to the other room. My hearing might have adjusted for road noise over the trip there so I perceived it different due to changes in my auditory system. But the fact that it ever happened turns the focus to listening skills.
Maybe I'm fool but I think the system sounds only as good as listening skills of the operator, because beyond that limit it's just random, some error somewhere goes unnoticed, so "quality" tops with the listening skill. In this sense, no matter what the system consists of it is good if it sounds good, until it doesn't 😀
If one is into the hobby and is interested in things and develops listening skill in sense that there is relatively clear sound ideal one wants to achieve and is able to detect it's not there yet, then there needs to develop some skill to figure out why and so on, to be able to take steps toward it. HEre is where increased knowledge also starts to matter. By listening skill I mean ability to understand perception, how (and what in) perception relates to written concepts such as directivity.
Before that there is Toole book and certain metrics one can follow, like CTA2034 stuff, but I think it's still somewhat vague regarding room acoustics and positioning and how all these relate so there is some wiggle room where one ultimately ends up. Especially with living room conditions where room acoustics and positioning have constrains so there the speaker polar pattern and positioning can really affect the sound. Simplest example is, someone else made you "ideal room" and "ideal speaker", but you fail to position the system to reach what you wanna perceive because it's not just the room or the speaker, but how these work together, through auditory system, to make satisfying perceptual effect. It likely sounds very good to you, but could sound even better if there is ability to position it better 😀
Another, I'm fairly many years into the game adjusting speakers at home. Now, took the system to friends place with very different room acoustics, and the balance was way off (no matter the positioning), so even if the DI is nice and all, good match to ideal at home, decent experience on listening and positioning, change of the room still made huge deal and required some further optimization of the system, on this occasion tweaks in DSP. This could have many reasons, like that my data is bad and I'm not actually sure what my system response is, so it could be off from ideals in that sense so varies with rooms more than it should. I might have error anywhere in the system, like in DSP and it goes unnoticed as minor but was highlighted due to the other room. My hearing might have adjusted for road noise over the trip there so I perceived it different due to changes in my auditory system. But the fact that it ever happened turns the focus to listening skills.
Maybe I'm fool but I think the system sounds only as good as listening skills of the operator, because beyond that limit it's just random, some error somewhere goes unnoticed, so "quality" tops with the listening skill. In this sense, no matter what the system consists of it is good if it sounds good, until it doesn't 😀
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So far...
(Normalized to 10deg, it's the best what I can do with the SW at the moment...)
I was thinking more like below. Black is basket and red is suspension.
Will be regular cone - CD coax. Extension will be in magnet assembly as usual and cone should follow Ath profile. If we can make basket and surround as on picture and 15" size we will be very close to ideal coax.
Will be regular cone - CD coax. Extension will be in magnet assembly as usual and cone should follow Ath profile. If we can make basket and surround as on picture and 15" size we will be very close to ideal coax.
On a similar note, there are drivers in the 2" category that have diaphragms with shape of a flat disc (ignoring the surround) like the Tectonic TEBM35C10
Consider mabat's segmented WG construction where the cross section is a hexagon, octagon, etc. in a given range on the z-axis, instead of a circle, etc. If we were to modify the WG contour to have a straight segment in the same range then we could have ring of straight surfaces in the WG maybe allowing for easy flush mounting of such drivers. In other words instead of compromising the WG with holes as in the usual MEH, it's compromising the WG contour with a straight segment, the WG surface with a hexagonal or octagonal slice with straight surfaces with small direct radiators mounted in them. So similar to what you're showing but maybe with easier mounting of stock drivers, but more deviation from the original WG shape. Though not sure right now what would be the smallest possible diameter of a hexagon or octagon for such 2" drivers, which would set the highest frequency for the 1/4 wavelength goal. The Sd of that driver is 11.04cm2, so eight of them would be better than six, about the same Sd as 5-5.5" cone driver.
DF10.171K, it's a 28cm waveguide. The ring plug is easily replaceable (including no ring), so I'll try some more drivers.
Frankly, I doubt it makes much sense to make the DI so flat to 20 kHz, but it's certainly possible.
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If it doesn't come with significant trade-off I would think it is good goal. I've become really sensitive to sound on-axis vs. off-axis, for some reason it takes my attention and I do not know why. While it could be anything, like cone breakup of a woofer or multiple thigns combined, I think it still makes sense try to make on-axis and the whole listening window as uniform as possible.
I will try adapters made specificaly for the DF10 and NDX595 with the G2 waveguides (including the ring plugs), but the DI of those is already given by the horn design (it can't be decreased once it's designed to be above some value). All it can do is a smoother response overall.
BTW, this is a (different) ring plug for 1" FANE CD131. The whole idea is that at the original exit diameter the wall included angle is higher with the plug, so the wavefront gets more curved at this point already. Which helps to maintain the directivity a bit higher (up to 20 kHz in this case).
BTW, this is a (different) ring plug for 1" FANE CD131. The whole idea is that at the original exit diameter the wall included angle is higher with the plug, so the wavefront gets more curved at this point already. Which helps to maintain the directivity a bit higher (up to 20 kHz in this case).
I haven't commented yet how much I like your work, the way you have developed modular construct with ring inserts and all and provide it accessible for anyone, printable with tabletop printers. Extraordinary, so thank you. Will definitely buy the files, but first need to buy a printer first 😀
So far I'm still struggling a bit to get nice smooth absolute responses with these smaller, somewhat lower-DI waveguides. But that I mean responses that don't require a lot of additional EQ. There's just something about the bigger (G2) horns, that makes the final overall response much better than I'm able to approach with a small waveguide. What is it? It almost doesn't seem to depend on throat impedance, or perhaps (more probably) it's still something hidden to our simple, external-to-driver, simulations. I'm still puzzled even after all these years of experiments.
- Normalized responses are what we can already predict with very good accuracy, but absolute - not even close. It so much depends on the horn, but I have no clue where to look.
- Normalized responses are what we can already predict with very good accuracy, but absolute - not even close. It so much depends on the horn, but I have no clue where to look.
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DF10.171K, with and without the back cover, approx. 0-90/10deg:
I'm not sure it is such a good idea to free the back radiation like this.
I would prefer a closed well-damped chamber, only bigger than the original one.
This is the difference on axis:
Waveguide used is a variant of ATH280.
I'm not sure it is such a good idea to free the back radiation like this.
I would prefer a closed well-damped chamber, only bigger than the original one.
This is the difference on axis:
Waveguide used is a variant of ATH280.
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I'm excited to see the 8c referenced in this great thread. Thanks!
Around the LR4 crossover at 1250 Hz the mid section and the waveguide have about the same directivity. Below about 600 Hz the directivity of the mid is primarily a result of the cardioid. Above that the directivity results from the combination of the membrane becoming directional, as well as constructive baffle edge diffraction. The 8c's directivity down to about 600 Hz can be achieved by conventional means.
The waveguide in the 8c has a very constant directivity above 3 kHz, below that it gradually goes down. Below you'll see infinite baffle measurements at 0, 15, 30, 45, 60, and 75 degrees. I'm looking at the text under the graphs. Damn, October 2015, where did time go?
This result was obtained by progressively more educated trials, and lots of errors. My current approach with ATH4 is basically the same, but waaayyy faster!
Put this waveguide in a baffle with the dimensions of the 8c, with a small radius on all sides, and you get this (0-90 degrees):
That's baffle edge diffractions to the rescue! Now the tricky part is to leverage the diffraction around the first tooth of the comb, while at the same time minimizing the dip one octave higher. You can do that by getting the baffle edge shape just right, in combination with the dimensions of the front baffle and the location of the drivers on the baffle.
Now, unfortunately, the document where I pulled the above images from is incomplete. Apparently, I failed to document the final baffle, probably because I got excited and moved on to the next step of the 8c's speaker design. However, to get an idea, here's one that is not too far from the final version:
