Possibly a set of.... Radian 1245 - 16 diaphragms would be an improvement, but it may be inherent to the driver itself as I have heard it with other JBL diaphragms. (2445, 2440, less with 2441) I will admit it is much less the case with 2441 diaphragms than with the 2440 diaphragms I used for most of the time I used them on the 2380A. I was persuaded by a local audiophile that the 2440 diaphragm sounded better than the 2441 diaphragm, I came to the conclusion that this isn't necessarily true, but I insufficient exposure to know for sure.
The 2440 in the scheme of things is ancient, they were in production for more than 30 years before being phased out due to a long ago shortage of Alnico. Mine are later and IIRC have the 5 slot phase plug. (I forgot already despite putting diaphragms in them a few days ago.) There is a lot of misinformation about them on the net. Mine I would guess are around 40 - 50 years old.
Somehow they manage to sound pretty OK, certainly an improvement in most respects over the sound I was getting with the Radians, and I am able to cross a lot lower as well which seemed to be an audible benefit. (Went from 840Hz with the NEO950 to 676Hz with the JBL)
In the light of day I ran this again over half the distance. The result was 14 degrees horn throat angle.
Is there an expectation that it would be a lot wider? This horn has after all been designed to preserve loading while maximising it's distribution in one dimension.
I have never heard of 2440/41 with a 5-slit phase plug, I believe they are all 4-slit. The Radian has a 5-slit phase plug, but I'm not sure I would say it's a superior driver like you do. What makes it superior in your opinion? It has the awful step in the throat that has been discussed earlier in this thread, I can't imagine that does anything good to the sound. I have also found it difficult to match with horns, never had any success with it tbh. The JBL 2441 with beryllium on the other hand, sound glorious (tried BE in Radian 950 as well). The Radian 1245 also sound nice in JBL 2440/41.
Ref the distortion from the 2440, have you properly aligned the diaphragms? This can make a big difference.
I use REW sine tones and distortion measurement to align the diaphragms.
Hi "kevinkr", I tuned out for a few days. To answer your question, the machined aluminum 1.4" round to 2" square adapters are 2" in depth. I noticed the Joseph Crowe adapters for his wood horn, a derivative similar to the A290, are about the same size, for what that's worth.
I admit I'm puzzled what could be causing the big response dip in your horn. I frankly don't know enough about horns to explain it, except a gross mistermination of some sort ... an air leak, misalignment, something like that. The AH425's are super smooth, but of course they don't need adapters. So fingers crossed on my end, as far as the A290's are concerned. But I have a stash of three sets ... the original Azurahorns, the Yuichi A290's, and to round it out, the big 18Sound black plastic horns for their 1.4" drivers. The black plastic things are freaking hideous, so I hope it's not them that come out on top.
I admit I'm puzzled what could be causing the big response dip in your horn. I frankly don't know enough about horns to explain it, except a gross mistermination of some sort ... an air leak, misalignment, something like that. The AH425's are super smooth, but of course they don't need adapters. So fingers crossed on my end, as far as the A290's are concerned. But I have a stash of three sets ... the original Azurahorns, the Yuichi A290's, and to round it out, the big 18Sound black plastic horns for their 1.4" drivers. The black plastic things are freaking hideous, so I hope it's not them that come out on top.
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Hi Lynn,
The prevailing theory is that the 21° exit angle of the Radian is a big problem since the horn and adaptor were designed for a 10° exit angle. The Radian driver is a 2 inch design. The adapters provided by Athos are nicely machined and seem to be about as close as ideal for going from round to square in a distance of 1 inch. Seems like an ND3N with the appropriate adaptor would be an excellent choice based on commentary here.
I am currently using a pair of JBL2440 fitted with OEM 2441 diaphragms, the improvement is substantial. The JBL driver throat is nearly twice as long as the Radian - not sure how much this contributes one way or the other.
I purchased a pair of TAD TD-4001 in good condition with the original BE diaphragms a few days ago, and will report back with my impressions and some measurements once they get here, and I have had a little time to figure out how to EQ them. My expectation is that they will require even less EQ than the "2441"
The "2241" is not at all a bad combination on this horn and handily outperforms the NED950 on this horn - a much more economical choice than the TADS and more than hints about the performance these horns are capable of.
The prevailing theory is that the 21° exit angle of the Radian is a big problem since the horn and adaptor were designed for a 10° exit angle. The Radian driver is a 2 inch design. The adapters provided by Athos are nicely machined and seem to be about as close as ideal for going from round to square in a distance of 1 inch. Seems like an ND3N with the appropriate adaptor would be an excellent choice based on commentary here.
I am currently using a pair of JBL2440 fitted with OEM 2441 diaphragms, the improvement is substantial. The JBL driver throat is nearly twice as long as the Radian - not sure how much this contributes one way or the other.
I purchased a pair of TAD TD-4001 in good condition with the original BE diaphragms a few days ago, and will report back with my impressions and some measurements once they get here, and I have had a little time to figure out how to EQ them. My expectation is that they will require even less EQ than the "2441"
The "2241" is not at all a bad combination on this horn and handily outperforms the NED950 on this horn - a much more economical choice than the TADS and more than hints about the performance these horns are capable of.
I have a hunch you will hate TADs and you won't be able to equalize them to your liking. I never heard any good implementation of 4001. All the bragging about them were always from either young fools plying trash music or old deaf pricks who wanted "the best " and " their money worth" . In my opinion it's a PA disco driver suitable for intoxicated crowd. Good luck
Where is your sense of adventure? 
I have no way of knowing short of measuring and listening to them whether they will work. The fact that the horn I use was designed around the TD-4001, and the published measurements for that horn/driver combination show that it achieves very good performance is enough of a justification for me to proceed.
I may never fully understand the exact reason why the Radian works so poorly with the A-290, the simple fact is that it does, the evidence is measurable, and audible. Looking at the impedance plots and the near field response measurements is clear evidence of a discontinuity. I was able to EQ it effectively, but it still did not sound entirely right.
The JBL "2441" sounds better in many respects and was very easy to equalize.
Until I have measured and hear them I have no opinion one way or the other about whether they will perform satisfactorily and meet my likely unrealistic expectations.
Worst case if I am sufficiently patient I can sell the drivers and recoup my investment.
This hobby is literally my only entertainment, regardless I win by experiencing and learning something new.
I have heard a lot of very bad horn sound over the years, I have also heard some good horn sound here and there. My introduction to horns was accidental and in my own living room over 2 decades ago. I was loaned a pair of JBL Rhodes (reflex) with D140s and 075 horns to replace the Magnepans I sold to pay the rent when my audio business imploded in the fall of 2000 - I was quite surprised by their performance and it resulted in a big change of direction.. (I had heard other horns but not in my house)
You might also actually want to do a little digging into TADs history, it's probably not what you think. Bart Locanthi designed the first generation TD-4001 which is what I bought. (He also designed a number of the other drivers for TAD.) There is a strong connection between classic JBL designs and those TAD manufactures because they were designed by the same guy. They would be found I think mostly in recording studios and the homes of well to do audiophiles (which is where mine came from.)
I have no way of knowing short of measuring and listening to them whether they will work. The fact that the horn I use was designed around the TD-4001, and the published measurements for that horn/driver combination show that it achieves very good performance is enough of a justification for me to proceed.I may never fully understand the exact reason why the Radian works so poorly with the A-290, the simple fact is that it does, the evidence is measurable, and audible. Looking at the impedance plots and the near field response measurements is clear evidence of a discontinuity. I was able to EQ it effectively, but it still did not sound entirely right.
The JBL "2441" sounds better in many respects and was very easy to equalize.
Until I have measured and hear them I have no opinion one way or the other about whether they will perform satisfactorily and meet my likely unrealistic expectations.
Worst case if I am sufficiently patient I can sell the drivers and recoup my investment.
This hobby is literally my only entertainment, regardless I win by experiencing and learning something new.
I have heard a lot of very bad horn sound over the years, I have also heard some good horn sound here and there. My introduction to horns was accidental and in my own living room over 2 decades ago. I was loaned a pair of JBL Rhodes (reflex) with D140s and 075 horns to replace the Magnepans I sold to pay the rent when my audio business imploded in the fall of 2000 - I was quite surprised by their performance and it resulted in a big change of direction.. (I had heard other horns but not in my house)
You might also actually want to do a little digging into TADs history, it's probably not what you think. Bart Locanthi designed the first generation TD-4001 which is what I bought. (He also designed a number of the other drivers for TAD.) There is a strong connection between classic JBL designs and those TAD manufactures because they were designed by the same guy. They would be found I think mostly in recording studios and the homes of well to do audiophiles (which is where mine came from.)
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I guess i am one of those old deaf pricks then as i have Yuichi and TAD 4001 and think they are marvelous. Here you see them on top of my mid bass horns. Could not fit the bass horn in the picture. The room is not ready yet as I need to build a floor above the bass horn. But it plays pretty well in this setup too
as i have Yuichi and TAD 4001 and think they are marvelous. Here you see them on top of my mid bass horns. Could not fit the bass horn in the picture. The room is not ready yet as I need to build a floor above the bass horn. But it plays pretty well in this setup too
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Well, I've heard, and listened to at some length, my old friend Bob Sickler's tri-amped big TAD system. Definite coloration, but there was no EQ, which if it were my system I certainly would have applied. But nothing like the gross and unbearable coloration of a stock Altec A7, or 604 Duplex, or stock LaScala. My take at the time it just needed a little TLC to make it really sing ... also, back then, it was an all-transistor setup, which I would never do today. Ultra high resolution horns are close to unlistenable on Class AB transistor amps fed by a Sony CDP-101, which is what Bob had. I put the TAD setup in the "needs love" class, of something potentially great.
I heard the same TAD horn and driver many years later in Zurich, and whoa, that really was great, thanks to being part of the "Blue Thunder" design documented in Sound Practices magazine. Far above any commercial high-end product at the hifi shows. So a mighty good start, for sure. The Blue Thunder is pretty special. Of course, it didn't hurt that the system had an EMT turntable and EMT cartridge, as well as pretty exotic electronics.
I heard the AH425 in rough prototype form a few years ago, and that was basically free of horn coloration, as I expected it would be. The only annoyance was the restricted seating area, which I also expected. The AH425 doesn't sound like a horn at all, except for stupendous dynamics and vivid tone colors. So that's a great fallback, especially since I've got the very first pair Martin Seddon made, sitting in the basement, just waiting to be used. The AH425 is flat as a pancake and has uniform diaphragm loading throughout the working passband.
So I expect either the Yuichi A290, vanes and all, or the AH425 are going to work well. The GPA 416 is flat in the passband, and the 2-ohm source Z of the Karna Mark II amplifier will give a moderate boost to the 416 in the 40-50 Hz region, which is fine by me. The 27 Class A watts of the Karna Mark II ought to be enough to knock me out of the room, so plenty of headroom.
All of my designs since 1979 have been low-diffraction, so I expect it will just sound like a scaled-up Ariel. The underlying philosophy are flat-response drivers that need a minimum of EQ, with low-Q crossovers and low-diffraction cabinets, with the goal of low energy storage in the time domain (rapid settling time).
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Maybe what some people say about the TD-4001 is related to an older jbl technote:
"Controlled break-up modes of the diaphragm and the surround to shape high frequency response"
What I would expect from a well controlled driver including suspension is a falling response towards high frequencies.
"Controlled break-up modes of the diaphragm and the surround to shape high frequency response"
What I would expect from a well controlled driver including suspension is a falling response towards high frequencies.
Interesting. Since Kevin is crossing to a horn tweeter circa 8 kHz, I wonder how audible those breakup modes in the 2” exit drivers will be.
My hunch is that the TD-4001 will have a frequency response similar to, but perhaps a little flatter than the JBL 2441. It might have lower distortion, too.
What I don’t understand is why the Radian 950 has so many problems on the Yuichi horn.
My hunch is that the TD-4001 will have a frequency response similar to, but perhaps a little flatter than the JBL 2441. It might have lower distortion, too.
What I don’t understand is why the Radian 950 has so many problems on the Yuichi horn.
According to the literature, Kinoshita and Locanthi development the TAD 4001. Given that a few hundred studios around the world were equipped with these drivers due to the collaboration between Tom Hidley and Kinoshita, I'd say that at times it weren't just fools or deaf old pricks who liked the sound.
The controlled break up modes are used to extend the HF response obviously, the 2441 diaphragm utilizes them to extend its HF response. I cross below where this should be a major factor. If the TAD uses break up modes at all I would expect them to start higher. Supposedly the benefits of BE are low mass and stiffness which I would think reduce the likelihood of diaphragm break up modes? I have the JBL paper Docali references - I've always thought that was JBLs response to a driver they perceived as a potential threat to sales/reputation in some categories.
@docali once I have them I will do free air and on horn impedance and phase measurement and then a near field frequency response measurement - this I would think will be very revealing. I have not so far been able to find any measurements of this driver other than on horns like the Yuichi.
From Yuichi:
TAD-4001
TD-4001 Impedance on horn
In addition to free air (no horn) you might also run an impedance sweep with the exit blocked. That's about as much acoustic load as they would ever get.
Earl Geddes has mentioned that he free air, blocked and also with the back off in order to model compression drivers.
Earl Geddes has mentioned that he free air, blocked and also with the back off in order to model compression drivers.
The Yuichi and Smith horns puzzle me, because they open up so suddenly and don't seem to expand in what would be a typical horn profile. But both do work, and can sound quite good.
If one is trying to match the expansion rate of the horn, what is it? The A290 in its horizontal axis expands at approximately 90° near its throat, transitioning to ~106° at the mouth. One might consider that to be two conical expansions, but is it really? It certainly is not exponential, hyperbolic, tractrix or other typical curved horn profile when seen from the top down.
However, if you calculate the area of the first 200mm of the horn length, the part which remains 50mm tall, then the overall expansion of area is near exponential. If the cross section of the fins is removed from that area, then it's expo within a few percent. The first 200mm of the Yuichi expand in area very close to the rate of an exponential horn. The next 180mm don't seem to flare fast enough to be true expo, but I'm double checking that.