I measured the Radian 950BePB in the Klipsch K-402 horn vs many other drivers. Apart from a broad cancellation at 600-900 Hz with the 950BEPB, it was the smoothest measuring driver. Especially in the top frequencies.
Radian 950PB, plot from Radian themselves.
Not the BEPB.
It's the 951 with a factory fitted 1,4" to 2" expansion.
Whereas the 475BE measures worse then the standard 475.
Not the BEPB.
It's the 951 with a factory fitted 1,4" to 2" expansion.
Whereas the 475BE measures worse then the standard 475.
Take the Eighteensound ND4015BE review from voice coil mag as an excellent example.
1,5" exit compression driver, 4"dia. BE diaphragm.
Mated to the XR2064 2" horn.
Noted in the article the ND4015 2" version was tested, which does not exist and never did.
What exists is a couple optional external throat adapters, that was not designed to fit the ND4015.
It is very easy to see the issue resulting from the mismatch between throat adapter and driver from 10K and up.
https://en.toutlehautparleur.com/adaptor-for-compression-driver-1-5-inch-to-2-0-inch.html
Compare that to Docali's review" found here:
https://sphericalhorns.net/2023/07/15/drba-test-bench-eighteen-sound-nd4015be/
So Voice coil mag. should be taken with a grain of salt at times.
Not sure what Vance Dickason is up to, clearly there is huge room for improvement in some of his testing and declarations of what he does.
The Yuichi initial expansion is very similar to the Smith DSH ("distributed source horn"), an approximation of an exponential expansion.
The Yuichi used a hypex (hyperbolic-exponential) in the throat, very little difference.
Putting a 60 degree angle exit driver on a horn designed for drivers using ~1/3 that angle both increases the Fc and causes a throat reflection, bad for response.
The Radian spec sheet says as much:
Doing the opposite, long "old school" ~15 degree driver exit coupled to a wider throat expansion does not make such gross problems appear in the response, especially if the transition area is smooth.
Perhaps something like OS.
There may be a good bit of finger wagging at horns or drivers for their faults, when in fact they are simply not well matched to the device they are used with.
OS is not a smooth continuation to a cone. Cone has zero curvature, whereas OS has the highest curvature right at its start.
For a driver like the 2" Radian above, it should be the best simply to start the horn/waveguide at the exit of the phase plug and continue with a smooth curve from there, all the way to mouth. Or, make an intentional curvature change and add a resonance that helps to increase the efficiency.
For a driver like the 2" Radian above, it should be the best simply to start the horn/waveguide at the exit of the phase plug and continue with a smooth curve from there, all the way to mouth. Or, make an intentional curvature change and add a resonance that helps to increase the efficiency.
A "fast expanding" waveguide as Mabat described 😉
In other words, don't use the Radian 760NeoPB on any typical exponential-type horn, which have a low expansion rate commensurate with a low Fc.
And it's recommended "minimum crossover frequency of 800Hz using a 24dB/octave crossover, higher with lower filter rates" is another indication that it is not designed for horns like the 290Hz Fc Yuichi.
Conical is the perfect continuation of spherical of the same angle.
The graph you mention shows a plane wave into conical.. These days we would use OS instead. In between, as you model OS with intermediate angles of driving wavefront, it becomes closer to conical.
Are you not using horn theory to describe something that was designed using waveguide theory? ..and do you see both happening and where is the split?
- Lifted from this thread Radian 950 throat, Is This Right???Berd said:
Allow me to circle back to this fact.
I'm pretty confident that "kevinkr" would still be using his Radian 950's along with his Yuichi's if his Radian 950's were of the original design type.
FWIW, the designer of that driver is a member here ( though hasn't been around for a number of years ). Seems he did the design work about 25 years ago.
It's pretty clear to me that Radian has been changing up ( cheapening ) their product line ( all the while denying it ).
That's really the "Ground-Zero" of Kevin getting hosed and then wondering about his un-expected results.
🙂
I think Earl has nailed it. When I have some time I will pull one of them out of my storage cabinet and take a good picture, but I believe mine have the step as shown.
I describe the reality: https://www.diyaudio.com/community/...-design-the-easy-way-ath4.338806/post-6248583
A suitable device for a wide-open conical exit would be (e.g.) one of my profiles with k=0, basically a conical throat with a very smoothly rising curvature:
https://www.desmos.com/calculator/jju41ayesq
Yes, it's the 950 factory throat adapter.
It's a 951 with a adapter mounted to it.
Means one can produce 1 driver, fit a adapter, then you have 2 'separate' products while having to manufacture 1, and a adapter. Makes for easy profit.
Radian cutting corners is nothing new, you will find posts on lack of internal fit/finish and assembly around the web.
Like they're 5 slit phasing plug, has not always been very well made and finished.
It is also one of the only "premium priced" compression drivers that does not have any form of copper in the gap.
Visible from the impedance traces.
Lets you get away with a less powerful magnet etc.
Does make sense in the form of saving money on manufacturing, and boosting profits.
Not really makes sense on a "premium" BE diaphragm driver supposed to cover the top octave.
It looks like that test is referenced to 85DB. But, there are higher decible mics out there. I've probably read and forgotten how Joseph does it.
Dynamic Range (capsule) 1%THD:<18dBA-150dBSPL
He was looking for a mic with low self noise, and a low bottom range to accurately measure distortion, down into the 'noise floor'.
If you want to measure high spls, there are other mics better suited for it.
There are tradeoffs to be chosen, just as with our diy speakers.
It's been awhile since I was curious about the high SPL's. I was trying to get around the conundrum of room reflections and distance from the driver. I think for the most part using gating on the impulse response in tools like REW have really solved most of that for me. And, I've really become much more comfortable with the accuracy of even the UMIK-1 USB mid and REW. I try to hold in my mind that it's not so accurate, but I'm just never really needing that accuracy in my DIY efforts.
And, I think I'll be embarrassed at what I was thinking and saying even 6 months ago.
And, I think I'll be embarrassed at what I was thinking and saying even 6 months ago.
I will be shipping a pair of these https://www.usspeaker.com/radian 745neoBepb-1.htm and possibly also these
https://www.usspeaker.com/radian 760neoBepb-1.htm to Troy Crowe to test in one of these horns.
https://josephcrowe.com/products/3d-cad-files-horn-no-1994-es450-biradial-for-jbl-2446-2-throat
https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
While browsing Troy’s speaker design blog looking for what he said that he suspected might be true of a driver with a 2” throat and 3” diaphragm (see the BMS 4591 review below), I found this otherwise review https://josephcrowe.com/blogs/news/b-c-dcx-464-16-with-es-600-biradial-horn which says “1.4" throat provides wider off-axis coverage in the upper treble than a 2" throat”.
This was precisely the concern I wanted to discuss with Arez, Weltersys, John Sheerin those here and finally Troy about: Both wide upper HF off-axis and lower MF off-axis coverage is likely harder to achieve in a two-way system. But would Troy’s statement only apply to the DCX464 because it's a coaxial driver?
Or would that statement also apply to most compression drivers, such as these, both with 3" diaphragms?
https://www.usspeaker.com/radian 745neoBepb-1.htm
https://www.usspeaker.com/radian 760neoBepb-1.htm
And if so, is the converse also true of 2” throat (3” diaphragm) drivers-that most such drivers provide wider off-axis coverage in the midrange than their 1.4” throat versions?
But when Troy reviewed this NON-coaxial midrange driver
https://www.bmsspeakers.com/fileadm..._4591_2011-04_midrange_compression_driver.pdf , he voiced the same suspicions about audibly different if unmeasurable (subjective) differences between 1.4” and 2” throat drivers. https://josephcrowe.com/blogs/news/bms-4591-with-horn-no-1670 , saying “This driver has the same sound characteristics as the B&C DCX-464 midrange section, which is exemplary, providing immense authority to vocals. There is zero hint of harshness as well. This driver could easily become the underpinning of a great system……….The BMS 4591 is also a true 2" driver where other drivers use an adapter from 1.4" to 2". Does this equate to better sound? I’m not sure. But if a system is going to have a dedicated mid-horn, why not stay with 2 inch?
In any case, can maximal horizontal and vertical off-axis coverage be realized across the usable bandwidth of the 3” diaphragm of these drivers? https://www.usspeaker.com/radian 745neoBepb-1.htm
https://www.usspeaker.com/radian 760neoBepb-1.htm
by selecting a larger version of the ES-600 horn, which was used for that review? https://josephcrowe.com/products/es-600-bi-radial-wood-horn-no-1978
And if that’s true then:
1/) How to decide between those two Radian drivers to select and implement the appropriate passive frequency contour filtering to flatten and extend the HF response consistent with inaudible distortion and maximal clarity for an ideal two-way system-as Pierre did with his Radian 745Bes. https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764
BUT Troy would have to agree to likewise, though according to Robh 3606 this is not hard to do using LEAP ( https://www.physical-lab.com/products/linearx/cae-software/leap ) or the like.
2/) Select between these two Crowe or other suggested horns, who says: My subjective assessment is in the context of medium size format horns such as the ES-600 Biradial. If we are having a general discussion about ultimate sound quality, then it needs to be pointed that a larger horn will provide a larger sense of scale and clarity, and in turn a more engaging listening experience. If we are talking cost-no-object ultimate sound quality then the ES-450 or ES-290 Biradial [with the TAD TD-4003] will provide those attributes mentioned.
https://josephcrowe.com/products/3d-cad-files-horn-no-1994-es450-biradial-for-jbl-2446-2-throat
https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
3/) BUT no use of throat adapters as I want zero chance of creating resonances or other artifacts.
As both the Crowe horns and Radian beryllium drivers are very costly this is why throat sizes I obviously need to avoid any simple sizing mistakes. So, the selected horn must either natively mate with the driver’s throat, or the horn must be custom made to do so
As I cannot make the trip to Ontario, my strategy is that if Troy isn’t seriously won over by what he hears from the EQed 1.4” or 2” Radian 3” diaphragm drivers, then the 16 ohm BMS 4591 2” throat 3.5” diaphragm midrange and what would likely be Troy’s recommended tweeter. https://josephcrowe.com/products/lens-no-1896-for-fostex-t96a?_pos=1&_psq=t96&_ss=e&_v=1.0
would be the other option.
Of course, for the sake of achieving a highly listenable two-way beryllium system I hope that doesn’t happen.
Question: Is the 16 ohm DCM50 really not a 4” diaphragm? https://usspeaker.com/B&C-DCM50-1.htm