"Airiness" is usually equated with more VHF above ~6kHz.
Longer decay times allow us to hear the VHF longer, the hash "sounds louder".
4" diaphragms have more mass than smaller ones, so in general have less "air", unless using breakup patterns and decay time to increase the VHF.
Since much of the beryllium supply has been diverted to making bombs, the price of rolled beryllium foil has gone from ridiculous to astronomical, while the top octave improvements it offers are still rather small compared to the alternatives such as nitride coated titanium or Textreme for those that prefer less decay time.
And most don't prefer the shorter decay times, even three years ago before the skyrocketing costs.
When B&C made drivers with less VHF decay time, the customers didn't care for it, as Bennett Prescott explains in the time domain discussion starting around 55 minutes into this video:
Art
if you are looking for a 2" exit driver the Axi is a good deal considering it has affordable replacement diaphragms and potential upgrades in the future.
I viewed that section of the video and that waterfall of that B&C titanium which had about the highest amount of ringing at ~ 13kHz. It’s kind of hard to believe that most people would prefer that much ringing, though I think Bennett said that it was often used as an outdoor (PA) driver. And I suppose if the driver performs very well in all other respects then most would like it.
So, airy highs require a driver with both VHF response and relatively slow decay time?
And that what you said most listeners tend to prefer.
Then it would not be something like the Radian745Be, with or without Pierre’s HF contouring filter?
But also note that scholl said he prefers that JBL 2431 aluminum driver presumably because its 3rd harmonic distortion is substantially lower than its 2nd harmonic distortion, which as he describes give the highs a laid back “relaxed” sound.
So, to sum up, which might be the best of such available drivers (no used drivers as per your warnings against same), costly or not, for a two-way system?
But how might you also describe their midrange measurements and subjective performance? Would the same (2”?) driver also produce and excellent lower midrange for male vocal (and cello section?) authority?
And how low could it cross with my Altec 416-8B midwoofers?
However, IF we were talking about a dedicated tweeter, like the Fostex 925A, would it not have this airiness because of its short VHF decay times? See Troy Crowe’s waterfalls.
https://croweaudio.blogspot.com/2020/10/fostex-t925a.html
But scroll down there where he says that his waveguide adds “subjective” airiness because it removes much of the 925A’s lower HF response energy, which would otherwise likely generate early reflections.
“You will struggle to get the 'air' because of the imbalanced power response between the upper and lower treble. The horn lens balances out this relationship and allows the upper treble to have the same energy into the room as the lower treble, which subjectively translates into more 'air' ”.
https://croweaudio.blogspot.com/2020/10/fostex-t925a.html
But scroll down there where he says that his waveguide adds “subjective” airiness because it removes much of the 925A’s lower HF response energy, which would otherwise likely generate early reflections.
“You will struggle to get the 'air' because of the imbalanced power response between the upper and lower treble. The horn lens balances out this relationship and allows the upper treble to have the same energy into the room as the lower treble, which subjectively translates into more 'air' ”.
"Airy" is a subjective term.
A driver can have lots of high frequency, "flat to 20kHz" with -60dB decay times as long as 12ms, or less than one cycle.
Most large format drivers, those with diaphragms ~3" (76mm) or larger are designed and used for PA/sound reinforcement use. Large format diaphragms tend to have longer decay times than smaller diaphragms.
Longer decay times make VHF more "present", easier to hear, especially at longer distances in which air losses reduce the level of VHF in addition to the usual inverse distance loss of 6dB for each doubling of distance.
I don't know what the response of Pierre’s HF contouring filter is.
Every horn/driver combination require filters to reach a desired frequency response profile.
Subjectively, something like the Radian745Be with a shorter decay time than is typical for a 3" diaphragm may not be preferred by the usual purchaser of large format drivers. That said, some users may prefer shorter decay times in general.
Most drivers have progressively less high order distortion, the relative distribution when pushed at high SPL may impart different "charachter" to the sound.
The JBL 2431 has a plastic surround and uses ferro-fluid in the magnetic gap, which may sound "smoother" or "more relaxed" (more damped) than many of the JBL large format drivers without those features.
The "best" depends on your particular taste, and the arrival condition of the drivers.
No two drivers will ever be identical, though in general higher cost drivers have better unit to unit consistency.
I'd expect a Radian 745Be in good working condition would be among the "best" I have ever heard or tested.
Measurements can be compared objectively.
Subjectivity is by definition based on or influenced by personal feelings, tastes, or opinions.
My personal preference tends towards drivers with the smoothest frequency response and minimum of decay time for the format size chosen.
The exit size of a driver makes little difference in it's low midrange performance.
For most domestic use, a compression driver with only a 2" diaphragm on a horn with a low Fc could be used with "excellent lower midrange for male vocal and cello section authority" if crossed at 500Hz or above.
"Authority" could be translated from a subjective term to an objective term by using SPL, measured in dB (decibels).
Given the same horn and voltage/power, one could expect 93dB from a 2" diaphragm compression driver at "X" distance at 500Hz.
With a 3", ~100dB, a 4" 105 dB.
The 4" could play over twice as "loud" (a +10dB increase at 1kHz) with the same level of distortion as the 2", and considerably louder than the 3".
Concerts in 1000 seat venues have been presented using a pair of 2" diaphragm 1" exit 500Hz horns crossed to 15" woofers with performers, engineers and audience members subjectively thinking the presentation was excellent.
The 3" diaphragm strikes a nice balance between LF output potential and HF detail.
At domestic listening levels and distance I would prefer using a good 3" diaphragm driver used on a single horn out to 20kHz than two separate drivers and horns covering the same range.
A pair of Radian 745Be/AH425 could be crossed as low as 500Hz and still sound excellent as loud as you are likely to want, like similar levels to a live horn section in your living room.
You plan to use subwoofers, so your Altec 416-8B will not have the excursion related IMD (intermodulation distortion) they would if used down in the VLF range.
I'd probably cross it above 600Hz to reduce the HF section's IMD to near that of the mid-woofers at high SPL, that preference would apply to literally any horn/driver combination I've ever heard.
Art
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You can't get natural reproduction like this. The attention it creates takes away from the natural tone.. However many struggle to be able to get natural reproduction so they want to settle for some sparkle. I understand, I used to like the sound of an aluminium dome.
Note here that both BryanS and IronmanIV use the AH425 horns, this https://www.sbaudience.com/index.php/products/compression-drivers/rosso-65cdn-t/ and the 745 aluminum, respectively. https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-770
I don't want to veer off into horn issues on this thread, but note that while toeing them inward helps improve what these horns do, as discussed in the other thread ("You are there" sound), it's the 425's overall presentation that concerns me. And IronmanIV also points out other 425 behavior.
See post 15385 above.
Again, back to drivers, have you heard that 65CDNt?
https://josephcrowe.com/products/3d...3-es450-biradial-for-sb-audience-65cdn-t-1-40
here's some tests on it, along with other drivers.
https://josephcrowe.com/blogs/news/es-450-biradial-no-2143
Also, some subjective tests, though I wish he had used the same or a larger horn.
https://josephcrowe.com/blogs/news/18sound-nd1480be-beryllium-1-40-compression-driver-test-review
Or have you ever heard the Yamaha JA6681B? https://audio-database.com/YAMAHA/unit/ja-6681.html
As you may know there is a main thread here on this driver from the 1980s. Gary Dahl, Pierre, Radian, and many others found it especially "magical".
Not surprisingly, Lynn and many others won't risk using it as Yamaha and Meyer Sound discontinued making the diaphragms long ago.
Any experience with it?
Not that I'd prefer a three-way, but IF we were talking about a dedicated tweeter, like the Fostex 925A, would it not have this airiness because of its short VHF decay times? See Troy Crowe’s waterfalls.
https://croweaudio.blogspot.com/2020/10/fostex-t925a.html
But scroll down there to where he says that his waveguide adds “subjective” airiness because it removes much of the 925A’s lower HF response energy, which would otherwise likely generate early reflections.
“You will struggle to get the 'air' because of the imbalanced power response between the upper and lower treble. The horn lens balances out this relationship and allows the upper treble to have the same energy into the room as the lower treble, which subjectively translates into more 'air' ”.
Versus an AMT or other tweeter, would not the Fostex 925Atweeter + waveguide be an excellent solution atop Troy's biradial horn for a three way?
https://croweaudio.blogspot.com/2020/10/fostex-t925a.html
But scroll down there to where he says that his waveguide adds “subjective” airiness because it removes much of the 925A’s lower HF response energy, which would otherwise likely generate early reflections.
“You will struggle to get the 'air' because of the imbalanced power response between the upper and lower treble. The horn lens balances out this relationship and allows the upper treble to have the same energy into the room as the lower treble, which subjectively translates into more 'air' ”.
Versus an AMT or other tweeter, would not the Fostex 925Atweeter + waveguide be an excellent solution atop Troy's biradial horn for a three way?
Like any commodity that can be subjectively evaluated, it's not difficult to find conflicting opinions.
Since you have not listened to your horn/drivers, it's not the 425's actual overall presentation that concerns you, it's impressions from others that have listened to horns that express conflicting opinions that raise concerns.
No.
The last time I heard a Yamaha JA6681B in a Meyer Sound UM-1 stage wedge monitor I wouldn't have used "magical" to describe it, though it was a good sounding driver with very good (for the time) processing on a good "beamy" horn above a good 12" woofer. The processing made it difficult to make it sound bad or burn up, while still sounding "Hi-Fi".
Around the same time, I was using JBL 2425 1.75" diaphragm drivers on an Eden 70x30 CD horn, and JBL 2445 drivers on JBL bi-radial horns for the same application. The larger diaphragm, lower Fc horn/JA6681B could be crossed lower than the 2425, and had smoother frequency response.
In a previous monitor design I used a JBL 2421/2407, more similar to the UM-1 sound.
The 2445/bi-radial had more output, but the 4" diaphragm HF breakup, harmonic distortion and horn diffraction made it sound more "trashy" by comparison to the UM-1.
Meyer's narrow conical exponential horn had little diffraction effects and didn't "spill over" to neighboring musicians, but limited the HF coverage to a small stage section.
It's separate LF/HF limiting would result in an acoustic crossover shift when driven hard above or below the electronic crossover point.
Although I do have nostalgia for the era the JA6681B was made in, and it's peculiar surround, I wouldn't be inclined to search for the driver over others even if diaphragms were still available.
Well-designed small diaphragms have shorter decay times than larger diaphragms.
A small sports car can turn corners faster than a school bus.
You are repeating the same subjective questions that can objectively be answered by what you have seen in the waterfall charts you reference.
My predicting what your subjective impression of shorter decay times or any other aspect of a loudspeaker's response won't help your decision making process.
Art
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I started my live sound career in the time where 2"/12" tops where the norm for serious use and main speakers where big , clustered horn speakers, also often 2"/12" + filler speaker to the subs. (d&b C4 was popular in my area: https://www.dbaudio.com/global/de/produkte/heritage/c4-top/#tab-technicaldata)
These where the speakers which get you ear bleeding when cranked. They SOUND loud (ok they also playd loud). And all of them had these B&C 2" drivers with 4" membrane which burst in partial modes above 7kHz.
These drivers are very hard to destroy and can be crossed over low. They go loud and sound loud (distortion, hf decay). With a 12" midrange you need the low cross over frequency, and there is still a lot of SPL in the 1-2kHz range in PA (important voice range).
When BMS and later 18Sound came with better behaving and powerful HF drivers I personally was much happier (built a BMS 2"/1" + 2x12" which is still great today) - but these speakers sound less "loud". They don't "punch" you the HF in your face. Many (older) sound people where used to that and adapted their mixing to it - and simply didn't want to change. Similar to using a SM58 for voice ...
With the rise of Line Arrays this changed a lot! Dedicated midrange drivers and smaller HF drivers suddenly gave all the details and no resonances in the audio range - I loved to mix on these outdoors (esp the midlevel ones. The big JBL touring system ... used the same old drivers in the beginning).
Nowadays Line Arrays are often overused and wrongly set up, esp indoors. You often don't want horizontal wide radiation and wrong set up pushes a lot of energy in the backwall of an audience and produces reverb.
But sound quality and reliability of speakers got up a lot in these years! We live in good times for speaker building!
What line arrays you like as of 2025, they can be 10 or 15 years old , or you like the latest and greatest like the new meyer lineal boxes that claim 150dB SPL per cabinet
Talking of line arrays: Has anyone ever used one of the numerous line-array waveguites to feed a conical horn in a DIY attempt for a power HiFi solution. For instance in a multi-entrant horn ?
Regards
Charles
Regards
Charles
Those waveguides are designed to create a rectangular, almost flat wavefront. This is useful for stacking multiple drivers vertically, without having them interfere with each other. But if you are using only one driver in a Hi-Fi system, why would you want such a wavefront? It will result in a non-constant vertical dispersion, that narrows down to ~10 degrees at 10 kHz.
Charles,
The various throat adapters used in line arrays feed a variety of horns, many close to conical.
As TBTL pointed out, their purpose is to reduce very high frequency interference by restricting vertical dispersion to as little as possible, ~10degrees. At the low end of the horn, the dispersion may be closer to 90 degrees.
Different designs can achieve similar results without patent infringement 😉
Danley has used multiple Paraline throat adapters on single MEH to achieve a variety of vertical dispersion patterns, basically the equivalent of a curved line array in a single box.
Other companies are doing the same.
Art
No doubt why Marco had so strongly recommended that I go with JBL 2450J and swap out their aluminum for compatible 2” Materion beryllium diaphragms-which is what Bappe also enjoys with his two-way speakers over a previous B&CDCM50/Fostex T925A three-way. Bappe said the combo doesn’t have quite the awesome midrange weight that he loved from the B&C DCM50 with 2” paper/plastic diaphragms (what my builder Troy Crowe typically uses in his ES450/290 horns), but that the JBL Bes make up for it in every way above that range in his JMLC 300 horn two-way.
While my total speaker budget is healthy, the total cost for new JBL Be drivers would be ~ $5K. So, Marco said to get a used pair of 2450J and the Be diaphragms from USSpeaker for ~ $2.3K. But Troy would have to agree to restore them and do the diaphragm swap, but WelterSys advises against this surgery.
So what other driver options? IIRC, Marco, Docali and/or NicoB advise against using my pair of 1.4” Radian Bes. https://usspeaker.com/radian 745neoBepb-1.htm Troy said he’d be willing to design the requisite contouring network, do measurements and listening sessions with them in his ES290 horn. https://josephcrowe.com/products/3d-cad-plans-for-es-290-biradial-horn-horn-no-1670
Of course, I’d love to know how that Be driver/horn combo would sound, but I don’t fly and there’s no Amtrak from NY to Ontario, CA. So what if Troy ends up not being especially impressed with their sound no matter how well he can smooth their response? Worth shipping him the drivers, paying duty tax and Trump’s tariff tax?
That’s why I asked about alternatives to Be drivers. WelterSys mentioned Textrene.
https://audiohorn.net/test/compression-driver/1.4inch/
https://audioxpress.com/article/test-bench-faital-pro-s-new-hf1460-pro-sound-compression-driver-1
https://josephcrowe.com/blogs/news/eminence-n314x-on-horn-no-1876-es-600-biradial
Versus Titanium for a two-way??
https://www.audiosciencereview.com/...ee-way-compression-driver-horn-speaker.16753/
Otherwise-and I’m no kind of speaker designer-go with a three-way?
Drivers:
The B&C DCM50 or SB Acoustics 65NCDT or Yamaha JA6681B or midrange. For tweeter Fostex T96A or T925A or some kind of Mundorf or other AMT.
Troy has these Fostex waveguides.
https://josephcrowe.com/blogs/news/lens-no-1896-for-fostex-t96a?_pos=2&_sid=3fd75662b&_ss=r
This is a long video but Troy’s measurements of the 65CDNT abnd DCM50, including the latter’s listening tests (after addition of a 6.8uF cap) seem to make them very hard to beat for midrange drivers.
Other suggested drivers for a two or three way?
The B&C DCM50 midrange driver uses ~4" cone shaped annular diaphragm with a 2" (51mm) voice coil.
Because it's not required to go high (~18dB/octave roll-off begins at 8kHz), it's excursion can be a bit more than a typical 4" compression driver diaphragm, making up for its lesser Sd.
You don't need its extra low end extension with your 15" midwoofer and subs in an apartment.
Splitting between a mid horn driver and a tweeter horn will require a further listening distance to integrate, reducing the direct to reflected ratio, decreasing clarity overall.
I pointed out that you don't know the condition of a used driver till you open it up, and that your new pair Neo Radian 750Be may sound better.
We are coming up on the 50th anniversary of beryllium diaphragms being the best "hi-fi" solution in most of the metrics that make high frequency compression drivers desirable.
They are an increasingly expensive commodity.
The woven carbon fiber Textreme composition has no where near the track record, and I've yet to hear proof that they are better than beryllium, only that they are an alternative that has similar properties for less money since much of the beryllium production has been diverted to bomb production.
Art
OR it may not. I can find next to no one using those drivers. So far, no reply from.
IronmanIV has the AH425/Radian745 aluminum https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-770
Bryan S. has the AH425/SB Audience 65 CDNT
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-771
And Pierre and who did invite me to hear them is too far away.
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764
So, the only practical (for non-DIYers) way to proceed for eliminating guesswork is to audition those few speakers which I was invited to hear and which locations are reachable. Those would be:
Three hour train ride to hear Troy's customer's system: ES450/DCM50/Fostex 96A/waveguide/backloaded bass horn system.
And (I hope) 1 hour train ride to hear NicoB's customer's systems with these horns.
https://audiohorn.net/x-shape-horn/ and https://audiohorn.net/next-gen-bi-radial-horn/
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The Tariffs are coming.... better buy soon before we can't afford anything coming from outside the border.
There was an article last year about a new B&C compression driver which could be very interesting. But nothing to found about it anywhere else.
https://audioxpress.com/article/test-bench-b-c-speakers-de640-16-compression-driver
DE640 - big brother of their 1" ring radiator (which can't go very low but is the only one with no resonances >20kHz). So pretty promising.
https://audioxpress.com/article/test-bench-b-c-speakers-de640-16-compression-driver
DE640 - big brother of their 1" ring radiator (which can't go very low but is the only one with no resonances >20kHz). So pretty promising.