As you, Docali and Arez only say no to both 4" Radians, then why do I persist with Radian745Bes? Only because of the great success Pierre had with them in the Athos 4001 horns with TAD 1601B sealed woofers. Here Pierre had consulted you and others while perfect the throat adapters, and which he once mentioned makes his speakers “disappear”. Note: In this thread Pierre does admit to an embarrassing case of mistaken ID; he had a pair of Athos 4001s all along, mistaking them for A290s; post 33. https://www.diyaudio.com/community/threads/jmlc-and-yuichi-horns-measurements.395046/page-2
But no matter as he clearly hit the target. https://www.diyaudio.com/community/threads/jmlc-and-yuichi-horns-measurements.395046/page-12
Then after repeating many measurements, Pierre found the LCR values and/or filter configuration to extend the Radian’s response out to ~ 17kHz. But he said creating the passive filter is not hard to do (for you guys).
https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-727
Also note here that Pierre enjoyed plenty of time with the Radian 745Be in the JMLC 425 horns, though settled on the 4001 horns, and partly explains why here. https://www.diyaudio.com/community/threads/beyond-the-ariel.100392/page-764
Furthermore, in all of our chats I can’t recall Pierre ever mentioning do any room treatment.
Seven years later and throughout our chats Pierre clearly continues to love his speakers. His only complaint he said is a minor one; “some midrange aberrations” due to woofer beaming. And that’s what I’ll be following up with Weltersys on regarding the Altec 416’s “average beamwidth vs. frequency” (if that makes any sense) vs Pierre’s TAD 1601B https://www.technicalaudiodevices.com/lf-units/ and Kevin-kr’s recommended LF driver (s).
The other reason for the Radian745Be is because if I had restarted with new parts I’d be hemorrhaging thousands. In 2016 I bought a new 16 ohm pair of these. https://www.usspeaker.com/radian 745neoBepb-1.htm And then a new pair of Altec 416-8B from GPA, though for about 1/4 of what they sell for now. https://greatplainsacoustics.com/pr...LgMidk1cQ98jEeOqsTkmjavbRlob265BdGAALemkzoxl0
I've never heard the 416s but they are said by Lynn Olson, Gary Dahl and many others to have wonderful tonality and other coveted qualities. Of course, it was my own fault for being seduced by these descriptions, but I followed Gary's lead, had the drivers shipped to Jim Salk and paid $1800. to have him clone Gary's however too small 3 cu ft but I'm sure superbly braced low diffraction cabinets. Gary's intention was to ensure the Altecs produced ultra low harmonic and IM distortion down to 70Hz, at ~ 87db, while sacrificing the last ~ 1.5 octaves. And the last three plots at the end of this review show that he achieved this goal, however worthwhile. https://josephcrowe.com/blogs/news/altec-416-8b-in-100l-sealed
See Altec 416 datasheet attached.
Below 70Hz, Gary had his subs with 16" Acoustic Elegance drivers and passive radiators. What troubles me is that last year Gary said he only uses the subs for home theater. For music, he claims to get ample bass response from room gain due to fortuitous speaker placement. I doubt if I do placement like that in my room, hence my questions about using the Rythmik subs. https://www.rythmikaudio.com/F12.html
Then I had Jim Salk build me his version of the Rythmik F12 sealed subs, which of course were a good deal more costly than the imported version. https://www.salksound.com/model.php?model=Rythmik+12+Subwoofer
Speaking of which, what concerns me is if there will be any big tonality differences between the 416s and these subs due to where I'd have to cross them. I suppose the only way I could cross lower, and avoid any audible coloration, would be if I was satisfied with (~86db?) SPLs from the Altecs at ~ 70Hz in my 2660 cu ft room, however likely that would be. https://en.wikipedia.org/wiki/Equal-loudness_contour Again, please refer to the 416 datasheet and https://www.rythmikaudio.com/technology.html
Wouldn’t you say that both are equally fast and dynamic, or still a crapshoot?
And the third reason for staying with the Radians is that I may have the opportunity to either stay with the 745Be or exchange them for the 951 or 950 berylliums IF they will cross best with Camplo's elliptical, Yamamoto (which??) or another recommended horn you would suggest over the 4001 to minimize Altec woofer beaming without higher distortion, frequency extension and/or off-axis response or other consequences. Though, if need be, I wouldn’t be opposed to the right kind of tweeter. Please advise, if possible.
I really can’t tell whether I've spent myself into a not so good place. But I don’t see taking big losses of time and money by selling these parts and trashing those cabinets as a preferable choice, unless there’s a lot more proof that without using different drivers I’ll end up with a poor sounding system, even if not a truly top sounding one.
From what more I’ve managed to learn here and what further questions I can now ask Pierre or Troy, one of them will hopefully build me speakers using a horn most compatible with the 416 woofers, cause less problematic room interaction -be it one presenting a “You are There” or “They are Here” sound, respectively.
OTOH-assuming Pierre can perfectly produce any required adapter-which would be the best horn matches for which of these RadianBe drivers?
https://www.usspeaker.com/radian 951Bepb-1.htm
https://www.usspeaker.com/radian 745neoBepb-1.htm
And which horn would cross best with the Altec 416’s 500Hz sweet spot?
Finally, if doable, which horn can do all the above and also create a “You are There” sound?
I can see that from that polar response EV and/or Altec has a much wider beam width at 800 than at 1500Hz, so that looks quite promising for crossing with the Radian 745Be, though I suppose would have worked out better if the Radian could have crossed lower. That’s why I thought that the 4” diameter Radians could do this, though Marco, Kevin and Arez say those bigger drivers aren’t a good match for the 4001 and other horns.
An important thing to understand is just because a driver would have an appropriate matching exit angle to suit or complement the horn throat, its not the entire story as to how compatible both actually are with each other.
The phase plug geometry inside the driver by itself can affect wave propagation into the throat. The A290 likes a deeper driver throat which incidentally a small exit angle provides by design. The exit angle alone isn't going to affect the lower mid performance as much and is by itself just a consequential result, ie. a deeper driver throat with plenty of distance from the driver phase plug exit to the A290 throat entrance. This WG consists of separate, more narrow sectors behaving as individual smaller WGs of equal length.
The longer resulting throat length from driver phase plug to horn throat entrance and its transition creates lower differentials in distance to each sector entrance. That results in less phase shift between sectors across the horizontal plane. As a result, it improves top end extension along with horizontal dispersion with less throat reflections at higher frequencies.
I had a microwave WG design engineer look at the A290 and he explained to me the similarities between acoustic and microwave horn design. Both have a lot in common.
The phase plug geometry inside the driver by itself can affect wave propagation into the throat. The A290 likes a deeper driver throat which incidentally a small exit angle provides by design. The exit angle alone isn't going to affect the lower mid performance as much and is by itself just a consequential result, ie. a deeper driver throat with plenty of distance from the driver phase plug exit to the A290 throat entrance. This WG consists of separate, more narrow sectors behaving as individual smaller WGs of equal length.
The longer resulting throat length from driver phase plug to horn throat entrance and its transition creates lower differentials in distance to each sector entrance. That results in less phase shift between sectors across the horizontal plane. As a result, it improves top end extension along with horizontal dispersion with less throat reflections at higher frequencies.
I had a microwave WG design engineer look at the A290 and he explained to me the similarities between acoustic and microwave horn design. Both have a lot in common.
Hi Profiguy,
That is very consistent with my very limited experience and understanding. Earlier in this thread I do talk about that, but sans your excellent explanation.
That is very consistent with my very limited experience and understanding. Earlier in this thread I do talk about that, but sans your excellent explanation.
Perhaps there are few drivers to be found that suit this.. However if a driver gives a spherical wavefront of the needed angle, does it matter how long the throat is?
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By default, a modern driver unless otherwise specified should have a planar output wavefront unless an angle is given and then it should have a spherical wavefront which matches the wall angle.
(and yes not all drivers behave as they should. Also some deliberately have a different goal.. however true exponential sections will not necessarily give you a simple spherical wavefront.)
Would you agree?
So, unless there's a Yamamoto, Iwata, Troy Crowe or some other specific horn theory and model available for purchase, then is there agreement that the TH-4001 + Pierre's adapter is the best match for the Radian745? If not, then which?
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The TH-4001 with Pierre's bespoke and painstakingly designed adapter can be an acceptably good match for the Radian 745.
But, it still won't be as good as the JBL 2450, which is a perfect drop-in replacement (geometry-wise) for the TAD TD-4001 driver, for which that horn was designed.
But, it still won't be as good as the JBL 2450, which is a perfect drop-in replacement (geometry-wise) for the TAD TD-4001 driver, for which that horn was designed.
@AllenB The typical contemporary horn driver will have a throat transition designed for line array WG applications, which usually have extended phase plugs into the very end of the driver exit. This enables a very narrow exit without resonances caused by parallel walls. The trend I'm seeing is a large shift to compact neo drivers with low primary resonances to facilitate lowest possible crossover points using smaller diaphragms. Unfortunately many of these drivers use higher Q cutoff slopes to eek out the last bit of extension possible, even at the expense of transient response. The argument is with DSP, this behavior can be largely corrected, so its more important to do whatever is needed to get the extension from a mechanical acoustic POV.
Many of the larger, more traditional 2" exit drivers will have much longer throat transitions with less exit angle, designed for larger, lower cutoff horns. These will usually have a pair of resonances visible in the impedance curve, with the primary peak typically not exceeding a Q of 1.0 or so. This enables the use of passive networks for correction. The older 2441 is IMO squarely aimed at 500 to 700 hz cutoff with a top end limit of about 7 to 10k depending on diaphragm material.
The mass rolloff around 3 - 4k observed on many smaller 1" drivers is sort of the sweet spot to make the driver behave well with typical smaller format horns, usually favoring a wide horizontal and narrow vertical dispersion angle with medium directivity. Those would IMO be good for the typical 2 way design mating with a 12" to 15" cone driver. The exit angles of these drivers are usually medium to high with a short throat entrance transition, but the phase plug design can greatly modify the net resulting angle and consequently define horn compatability. The combination of driver and horn here can be highly dependent on each other. I've heard millions of times that the WG almost exclusively prevails in defining the acoustic behavior and character when they're combined - I find this to not be the case, with the driver's character often dominating the sound.
Shallow, short exit drivers are much more compatible with a wide variety of WGs, especially those highly reliant on diffraction for dispersion. In fact, many WGs with diffraction slots can sound awful with one driver and tolerable (not great though) with another. Diffraction slots are a whole different subject, but usually will induce excessive distortion at high SPLs. There are a handful of decent WGs which rely on some amount of diffraction with the better ones having minimal diffraction.
Lastly, the type of phase plug design can radically affect a driver's performance, more than any other design aspect. The traditional radial slot phase plug is good for short exits with higher angles, but generate higher levels of HF distortion with worse linearity than the better sounding (ie. tangerine or helical style) phase plugs. In most cases, the better sounding drivers with radial slit phase plugs have short, high angle exits.
Many of the larger, more traditional 2" exit drivers will have much longer throat transitions with less exit angle, designed for larger, lower cutoff horns. These will usually have a pair of resonances visible in the impedance curve, with the primary peak typically not exceeding a Q of 1.0 or so. This enables the use of passive networks for correction. The older 2441 is IMO squarely aimed at 500 to 700 hz cutoff with a top end limit of about 7 to 10k depending on diaphragm material.
The mass rolloff around 3 - 4k observed on many smaller 1" drivers is sort of the sweet spot to make the driver behave well with typical smaller format horns, usually favoring a wide horizontal and narrow vertical dispersion angle with medium directivity. Those would IMO be good for the typical 2 way design mating with a 12" to 15" cone driver. The exit angles of these drivers are usually medium to high with a short throat entrance transition, but the phase plug design can greatly modify the net resulting angle and consequently define horn compatability. The combination of driver and horn here can be highly dependent on each other. I've heard millions of times that the WG almost exclusively prevails in defining the acoustic behavior and character when they're combined - I find this to not be the case, with the driver's character often dominating the sound.
Shallow, short exit drivers are much more compatible with a wide variety of WGs, especially those highly reliant on diffraction for dispersion. In fact, many WGs with diffraction slots can sound awful with one driver and tolerable (not great though) with another. Diffraction slots are a whole different subject, but usually will induce excessive distortion at high SPLs. There are a handful of decent WGs which rely on some amount of diffraction with the better ones having minimal diffraction.
Lastly, the type of phase plug design can radically affect a driver's performance, more than any other design aspect. The traditional radial slot phase plug is good for short exits with higher angles, but generate higher levels of HF distortion with worse linearity than the better sounding (ie. tangerine or helical style) phase plugs. In most cases, the better sounding drivers with radial slit phase plugs have short, high angle exits.
I wish I had known this stuff when I bought the Radian Neo 950PB, they perform fine on compatible horns, but were not a good match on the A-290. In truth they were bought for use on the JBL 2380A where they worked reasonably well, but likely I was too naive and inexperienced to recognize that the Radian was not ideal on that horn either. (It did definitely sound better)
@oltos I would definitely take Marco's advice and purchase a pair of the JBL 2450 drivers he recommended, you can even put Be diaphragms in them.
@oltos I would definitely take Marco's advice and purchase a pair of the JBL 2450 drivers he recommended, you can even put Be diaphragms in them.
profiguy, thanks for your explanation.
For sure. However I would agree with this if it was qualified. Before anyone can talk about waveguide sound, it has to be fed with the optimum wavefront.. one that makes sense for the application. Furthermore, before anyone can judge the system it has to be equalised. There is no justification I can think of for not doing these things first.
So we get to the question of horn loading. Is it audible? I don't believe it is, in itself. I have worked on devices that can be used seamlessly through the transition region.
The lower midrange and downward necessitates horn curvature if loading is to be maintained, and I feel this would explain the demand for such drivers.
Yes, but as I implied the idea is to find the the perfect drop-in horn for the Radian 745, so I don't instead have to wait who knows how long to be able to sell these brand new drivers, and probably get a lot less than I paid for them. There's really no fully compatible "You are There" horns that sound like the 4001 or A290 for this driver?
Given the massive market offerings of drivers we have, there are definitely specialized suitable pairings which rely on the specific physical design and application. I've personally went through a good two dozen drivers and so many more WGs to find decisive pairings that sound best for my exact criteria.
Also, simple, small tweaks to driver dampening and WG interfacing makes significant differences in performance, specifically in the lower midrange and close to diaphragm breakup range.
For example, one of my favorite combos for smaller 2 way designs is the faital HF108(non R) with the B&C ME45. The HF108 goes lower than almost any other 1" driver while not having resonance issues at the lower end. I've measured this pairing down to 700 hz and crossed it as low as 900 hz @ 3rd order on the ME45 and Eminence WG10.
Not trying to side track too much, but the trick with running the HF108 and other Faital CDs very low is shimming and centering the diaphragm very carefully. This is to obtain sufficient diaphragm excursion, being careful not to affect BL symmetry (and consequently odd order HD).
In almost all cases, Faital drivers require VC re-centering once the diaphragm has been removed. Same holds true for many other drivers. Celestion also requires this as many other brands do too, but shimming is usually optional unless you want extended lower frequency response without bottoming the diaphragm.
With aluminum diaphragms, its very critical to shim for correct diaphragm depth because of how fragile most aluminum alloys are to bottoming against the phase plug. Titanium is much more forgiving because of how durable it is. Same holds true for polymer diaphragms.
Most TAD drivers are VERY sensitive to shimming, both for VC depth and concentricity. Without the proper.equipment and techniques, TAD drivers can be damaged very easily,.especially when crossed low. This becomes a greater issue if the horn doesn't load the driver sufficiently to reduce excursion. The older Beryllium diaphragms were much more brittle than modern produced Be diaphragms. They literally shattered into many tiny pieces when they bottomed out on the phase plug.
Radian Be drivers are well designed. They are likely one of the most accurately machined and assembled drivers I've seen. On the other hand, Faital drivers are often poorly machined. They require careful setup to get the best performance out of. Celestion is similar. 18sound and B&C are made to tighter tolerances with better fit and finish. I often use the NSD1095N on the ME45 for hifi purposes. Crossed higher than 2.5k, this pairing sounds like a higher end dome tweeter without a hint of roughness or edginess. In fact, the NSD1095N sounds alot like a TAD, but with noticeably clearer HF extension. It also works well with the STH100.
Also, simple, small tweaks to driver dampening and WG interfacing makes significant differences in performance, specifically in the lower midrange and close to diaphragm breakup range.
For example, one of my favorite combos for smaller 2 way designs is the faital HF108(non R) with the B&C ME45. The HF108 goes lower than almost any other 1" driver while not having resonance issues at the lower end. I've measured this pairing down to 700 hz and crossed it as low as 900 hz @ 3rd order on the ME45 and Eminence WG10.
Not trying to side track too much, but the trick with running the HF108 and other Faital CDs very low is shimming and centering the diaphragm very carefully. This is to obtain sufficient diaphragm excursion, being careful not to affect BL symmetry (and consequently odd order HD).
In almost all cases, Faital drivers require VC re-centering once the diaphragm has been removed. Same holds true for many other drivers. Celestion also requires this as many other brands do too, but shimming is usually optional unless you want extended lower frequency response without bottoming the diaphragm.
With aluminum diaphragms, its very critical to shim for correct diaphragm depth because of how fragile most aluminum alloys are to bottoming against the phase plug. Titanium is much more forgiving because of how durable it is. Same holds true for polymer diaphragms.
Most TAD drivers are VERY sensitive to shimming, both for VC depth and concentricity. Without the proper.equipment and techniques, TAD drivers can be damaged very easily,.especially when crossed low. This becomes a greater issue if the horn doesn't load the driver sufficiently to reduce excursion. The older Beryllium diaphragms were much more brittle than modern produced Be diaphragms. They literally shattered into many tiny pieces when they bottomed out on the phase plug.
Radian Be drivers are well designed. They are likely one of the most accurately machined and assembled drivers I've seen. On the other hand, Faital drivers are often poorly machined. They require careful setup to get the best performance out of. Celestion is similar. 18sound and B&C are made to tighter tolerances with better fit and finish. I often use the NSD1095N on the ME45 for hifi purposes. Crossed higher than 2.5k, this pairing sounds like a higher end dome tweeter without a hint of roughness or edginess. In fact, the NSD1095N sounds alot like a TAD, but with noticeably clearer HF extension. It also works well with the STH100.
What is always worth to mention that this is not Pierres adapter idea as the original idea came from me. I had the idea way before he ever thought about such an adapter during the collaboration with DonVK und fluid. We already proved the approach with BEM simulations. Pierre later did some further optimization together with his horn.
I send the following pictures to Pierre before he started to optimize the shape to:
More images provided in a private conversation. So I think it is appropriate to mention who is the owner of the IP.
I send the following pictures to Pierre before he started to optimize the shape to:
More images provided in a private conversation. So I think it is appropriate to mention who is the owner of the IP.
@AllenB Its hard to say whether horn loading is audible in itself. All the other critical parameters associated with interfacing drivers with WGs play a role to varying degrees, depending on design deficiencies and other mechanical compromises.
Focusing on distortion, CSD and stored energy is IMO the most critical set of parameters with driver and horn marriage. Power response, DI and dispersion are of course important, but they're often focused on almost exclusively and obsessively without giving the other consequencial parameters a healthy amount of consideration.
Some drivers which sound awful on a wide range of horns can sound very good on a specific suitable WG, but those are more exceptions than the norm. The WG itself should be considered as the starting element in design, but more often than not, people obsess about a chosen driver and forceably attempt to integrate it despite its marginal suitability. Its also easier to EQ a less than optimal driver to a given horn than live with the coverage issues caused by the driver dictating the use of a specific WG.
Focusing on distortion, CSD and stored energy is IMO the most critical set of parameters with driver and horn marriage. Power response, DI and dispersion are of course important, but they're often focused on almost exclusively and obsessively without giving the other consequencial parameters a healthy amount of consideration.
Some drivers which sound awful on a wide range of horns can sound very good on a specific suitable WG, but those are more exceptions than the norm. The WG itself should be considered as the starting element in design, but more often than not, people obsess about a chosen driver and forceably attempt to integrate it despite its marginal suitability. Its also easier to EQ a less than optimal driver to a given horn than live with the coverage issues caused by the driver dictating the use of a specific WG.
If you don't find a good pair anymore the DAS ND-10 is a good candidate. You could make a longer adapter to those fin horns. Better loading and maybe better dispersion.
Far would it be from me to misrepresent the origin of any IP. Apparently, I must have missed one or more of your posts where it was obvious that all of the basic design work was yours. All I recall is Pierre thanking you, Marco and a few others for assistance, after which he ran other tests and/or modifications and settled on the performance of the third and final adapter.
As for my situation, apparently no one here can strongly suggest a better "You are There" horn for this driver-that is, a horn that will deliver targeted performance as is, or can be ordered with modifications to work as desired.
Therefore, regarding the "acceptably good" match of the 4001 horn/Radian745/Pierre modified Docali adapter combo, since experts and ears here can only speculate on performance, on a scale of one to ten, with ten being excellent, how "acceptabily good" could it be expected to sound?
Often, yes. People that came in half way through the conversation perhaps, people who's first question is about directivity, and who haven't built traditional horns based on loading.
DI is a property that may be focused on above the others, but not in spite of them 😉
Agree.
I can only repeat my question: Which are the better alternatives for the Radian745?