Lynn discloses much of basic design: The DCM50/AH340 combination atop sealed ~ 5.8 cu ft cabinets for Altec 416-8B woofers https://greatplainsaudio.com/wp-content/uploads/2016/06/Classic-Series-416-8B-Spec-Sheet.pdf See See posts 15,323 - 330, 334, 336. He mentions alternate tweeter solutions; maybe something like Superlian's here?
About the Radian 745neoBe, I know of only two DIYers from anywhere who have designed with it and likely continue to be very happy with their builds. One is GregOh1, who has the Radians in AH425 horns with no EQ atop sealed Altec 416-8B woofers, though which are supplemented by Rythmik F12 sealed subs.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-718#post-4984865 14356
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-719#post-4985910 post 14363 And his final crossover design work with Dave Slagle, who built his autoformers, which Greg used only as attenuators. https://forum.intactaudio.com/viewtopic.php?f=8&t=1442
Then there's Pierre's Radians in Athos TN4001 horns with EQ atop sealed TAD woofers.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764#post-7483847 posts 15,266, 15,276.
But CAN you confirm that perhaps the most crucial factor in maintaining continual aural satisfaction with the RadianBe is to either perfect the application of EQ to extend its HF response or omit it? Indeed, note from the 13, May, 2015 post here https://forum.intactaudio.com/viewtopic.php?f=8&t=1442 , where Greg says "I've attempted various tweeter's firing them up/ back / front and decided to live with the horn alone." Certainly it worked out happily for Greg as with his AH425 horns, further attempts implement a tweeter (e.g. Raal ribbon) will likely prove unsatisfactory.
Contrast this with Pierre's build, where though his 4001 horns would likely provide ideal (?) tweeter/ Radian time and axial (?) alignment, he chose to EQ the Radians and thereby reap the benefits of two-way design. Though an EE, Pierre did say that it took numerous attempts to perfect the EQ, and to his continued delight.
As you may have by now guessed, my main question is that if you were building either system, would you choose to EQ the RadianBe or not-and use or not use a tweeter? And why?
OR might you opt to replace the RadianBes with the Yamaha JA6681B, with their aluminum diaphragms, with beryillum supporting "fingers" and then add/not add a tweeter, such as https://www.madisoundspeakerstore.com/bullet-tweeters/fostex-t90a-top-mount-horn-super-tweeter/ ?
Somewhat off topic:
Assuming ideal adapters are used for the A290 horn
https://josephcrowe.com/products/sm...hi-a290-horn?_pos=1&_psq=a290+ad&_ss=e&_v=1.0
-and Pierre’s T2 adapters for the Athos TH4001 horn
https://www.diyaudio.com/community/threads/jmlc-and-yuichi-horns-measurements.395046/page-12
https://josephcrowe.com/products/cu...del-make-any-size?_pos=4&_sid=f841be188&_ss=r
https://www.athosaudio.com/2021/01/01/tad-th-4001/
-would any reasons why the RadianBes and/or Yamahas would perform any better either horn?
Better vertical dispersion? Better X ,Y off-axis response? Larger 3D soundstage? Better imaging. Less room boundary effects?
I am in the position to make my own horn and compression driver the way I want them to be. Whether or not I would use a separate tweeter depends a lot on the horn. For a beamy horn, I would definately use a separate tweeter.
Here are some polar measurements of a 400x460mm horn I have designed. The measurements are done with 18s Nd1480Be. I think those are pretty good drivers, but the plan is to finish a ring radiator design I have been working on to further improve the response of the compression driver as well.
15 degree spacing. No smoothing, only gating. My point is that this type of horn could be used from 750 and would not require a separate tweeter. For example a JMLC horn from 750Hz would not give a lot of air and space at high frequencies, so an additional tweeter would be good to have, regardless of the quality of the compression driver.
Horizontal:
Vertical:
A pistonic small membrane will have a falling FR towards higher frequency. This is physics and can't be argued - and to be clear - the shape doesn't matter - if it really is pistonic.
So, why does a dome have dispersion? Because it breaks up - it goes inte bending wave mode and this mode implies very wide dispersion. If you want to call it break up or being mode... well... a really good behave transit to bending wave can be smooth... but I think we call these wild peaks "break up"... both will however disperse energy widely.
If a dome would "ballon" - it would be an other matter...
//
Okay, so then a tweeter for the RadianBe in that JMLC horn. But if the A290 or TN4001 horns were used and regardless about adding a tweeter, could you speculate on the subjective qualities of hearing the RadianBe with and without EQ? That is, would the RadianBe be more likely to sound better to most ears by adding a tweeter instead of being EQed? With EQ, would it more likely sound "hard" and possibly even fatiguing to many?
Last edited:
I think you are asking about specific things that are both down to individual taste, and very dependent on the implementation. But I can point out 3 things that I find generally important:
1: If the dispersion narows significantly, a separate tweeter will typically add something positive to the system.
2: Horns, especially if they are not beaming, tend to amplifi the low end of the range, and this needs to be rectified somehow in the filter.
3: When you achieve a reasonably flat response, and find the sound to be pretty spot on, see if you can achieve a very similar response with fewer EQ-points and listen to the difference. Especially avoiding EQ-points with Q of 1-3 can have a positive effect on the perceived performance.
1: If the dispersion narows significantly, a separate tweeter will typically add something positive to the system.
2: Horns, especially if they are not beaming, tend to amplifi the low end of the range, and this needs to be rectified somehow in the filter.
3: When you achieve a reasonably flat response, and find the sound to be pretty spot on, see if you can achieve a very similar response with fewer EQ-points and listen to the difference. Especially avoiding EQ-points with Q of 1-3 can have a positive effect on the perceived performance.
Indeed, and this is rarely considered in compression drivers. We also see those spreat tow carbon diaphragms that has promised to solve everything lately, they have so much limitations to how much curve they can be shaped to before fibers start breaking. They do not outperform any other materials as claimed.
Also, the selected material of a diaphragm vs the shape and the phase plug geometry. It will vary across different materials, but you never see anyone change the phase plug when the diaphragm material is being changed.
Could you put some substance behind this claim? And what variation of shape do you talk about between different materials?
I mean, if the shape of a diaphragm is different than the phase plug, it will be a disaster in high spl environment, sales will be dead in a year…
Off course the phase plug has to fit the diaphragm. That is given by the Venta and Thuras model. But for example JBL 2446, 2450 etc use pretty much the same phase plug for any diaphragm material. Rumour has it that it was first developed for beryllium. But the inner geometry was kept while the final product was released with a titanium diaphragm. They also offer an even slower Aquaplas variant. But the phase plug itself is, as far as I have understood, based on the Smith style. That model is based on a purely pistonic diaphragm, and even if beryllium 4 inch low profile domes are not pistonic, titanium and Aquaplas are even further from pistonic, meaning lots of errors are introduced. And those errors will grow with a slower diaphragm.
Do you have the book on horns by Mr Kolbrek and Mr Dunker? There the statistics modal distribution of the Smith style phase plug is discussed.
Do you have the book on horns by Mr Kolbrek and Mr Dunker? There the statistics modal distribution of the Smith style phase plug is discussed.
I opted for a Ciare 1.4" horn. Faital and Ciare both make a similar horn. I plan to experiment with different horn geometries, specifically long vs short throat distances, and narrow vs wide dispersion, once I start to finalize certain other aspects of my build.
You seems to imply that different diaphragm materials needs different phase plugs? The model you talk about is a true pistonic membrane, then the phase plug is made for perfect result. The measured response is then as we see with Be and Ti. The membrane sets the draw backs of different materials...
By slower diaphragm, you mean slower sound propagation as in Ti compared to Be?
The transient response ("speed") of different diaphragm materials and their breakup patterns create different time of flight at different locations and frequencies across the dome.
If phase plug path lengths could compensate for those differences, smoother response could be achieved.
Instead of changing phase plugs for each diaphragm material, JBL has opted to try to coax more linear (breakup..) response by stamping in diamond (ish) surrounds, ridges and adding an extra mass dimple at the center, kind of "6 modes of freedom"
Tricky stuff, early diaphragms made this way sounded quite good until the diaphragms turned to confetti, requiring repeated FedEx overnight shipments and early morning cabinet "pit crew" action to keep touring systems alive.
When they got tolerances, surround geometry and rib positions sorted out, both longevity and sound quality improved over the growing pain development era.
If phase plug path lengths could compensate for those differences, smoother response could be achieved.
Instead of changing phase plugs for each diaphragm material, JBL has opted to try to coax more linear (breakup..) response by stamping in diamond (ish) surrounds, ridges and adding an extra mass dimple at the center, kind of "6 modes of freedom"
Tricky stuff, early diaphragms made this way sounded quite good until the diaphragms turned to confetti, requiring repeated FedEx overnight shipments and early morning cabinet "pit crew" action to keep touring systems alive
.When they got tolerances, surround geometry and rib positions sorted out, both longevity and sound quality improved over the growing pain development era.
Well, sort of, but the thing is that concentric phase plugs only work perfectly up to a certain frequency. This frequency is limited both by the number of slits, the material, the shape of the dome and the size of the dome. So if you optimize a certain phase plug to try to extend this range slightly, then it will only work as intended with the material you used when optimizing it. If you change material to a slower material you could optimize it by increasing the profile height and compensate for the changed shape by also increasing the profile height of the back of the phase plug, while at the same time keeping the slit relationship and lengths according to the same geometry as the previous phase plug (that was optimized for a faster material).
The phase plug is still a compromize. Actually, there are two widely used models for concentric phase plugs, the Smith style and the Japanese style. They mostly work based on the same principle but they have one large difference. The Japanese style uses a larger center core, and then the rings are sligtly closer to each other. The Smith style uses a smaller core where the rings are then sligtly wider. The practical difference between the two will typically be that the Japanese style has slightly more output at high frequencies.
A crucial part of concentric phase plug design is that you eventually will hit frequencies where the pressure goes out one slit and back in to another slit, cancelling out energy from the driver. So the idea behind the phase plug calculation models is that you want to avoid this happening between slit 1 and 2, and between slit 3 and 4 at the same time. This is where acoustic modes needs to be considered (modes in the space between the diaphragm and the phase plug).
The next level of increasing performance will be to integrate the mechanical modes of the diaphragm with the acoustical modes in the compression chamber. And that is where the standard models just skips over and considers the diaphragm rigid.
Be is also inferior, but not nearly as inferior as the titanium version with the exact same shape.
But here are the Bliesma T34 A and B as measured by Hificompass:
Aluminium:
Beryllium:
The two obviously perform very similar to each other, and this is likely due to the difference in shape where the aluminium alloy version has a higher profile and therefore compensates most of the difference between the two materials.
Full reviews here:
https://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34a-4
https://hificompass.com/en/speakers/measurements/bliesma/bliesma-t34b-4
Yes, the wave propagation in the material. This is why all soft domes sound as edgy as they do (not necessarily hard or resonant, but they lack the top end due to heavy beaming and therefore lack of ambient high frequencies compared to lower frequencies).
Again, this can be seen by comparing Bliesma T25S and T25A:
Silk dome:
Aluminium alloy dome:
But again, it has to be pointed out that this is one of the best performing 1 inch aluminium domes on the market. If we compare it to the Satori TW29B this becomes obvious:
The transient response ("speed") of different diaphragm materials and their breakup patterns create different time of flight at different locations and frequencies across the dome.
If phase plug path lengths could compensate for those differences, smoother response could be achieved.
Instead of changing phase plugs for each diaphragm material, JBL has opted to try to coax more linear (breakup..) response by stamping in diamond (ish) surrounds, ridges and adding an extra mass dimple at the center, kind of "6 modes of freedom"
View attachment 1273898
Tricky stuff, early diaphragms made this way sounded quite good until the diaphragms turned to confetti, requiring repeated FedEx overnight shipments and early morning cabinet "pit crew" action to keep touring systems alive
When they got tolerances, surround geometry and rib positions sorted out, both longevity and sound quality improved over the growing pain development era.
This is quite interesting, and they pulled this idea quite a bit further with the Celestion Axi2050 where a series of domes forms a large ring. Unfortunately, this also has a concentric phase plug.
For those who have not seen it, this video is highly recommended in order to understand some of the stuff that happens inside a compression driver:
Mark Dodd says the Axi2050's diaphragm’s three-dimensional corrugation and its rotational “axiperiodic” symmetry inspiration came from the corrugated Nissen hut roof of the original KEF factory, a thin sheet of material made relatively rigid and strong by bending it in a repeating pattern.
https://www.prosoundweb.com/tech-focus-celestion-axi2050-wideband-axiperiodic-compression-driver/
It is different annular ring approach- I think it will be a long time before aftermarket diaphragms become available for it
https://www.prosoundweb.com/tech-focus-celestion-axi2050-wideband-axiperiodic-compression-driver/
It is different annular ring approach- I think it will be a long time before aftermarket diaphragms become available for it
The JA6681B's suspension is BECU, Beryllium copper also often called spring copper. Which is a Spring metal you can often find in remote controls, flashlights and plenty of things that take standard batteries. Also springs, spring wires, strain gauge cells etc. It has very little to do with Beryllium diaphragms, or Beryllium as you think of it.
Also easily machineable, annealable for proper spring and weldable.
At the time they were manufactured Yamaha only had access to CVD Beryllium diaphragms, not a material that would be selected for a rather fragile suspension.
As for you Radian /Yamaha comparsion for horn and which is better, with proposed horns.
At that price, since you seem to like biradials etc. , you will be much better off just getting Joseph Crowe (since you linked his pages) to design you a horn that actually fits your chosen compression driver