If this is a 16 ohms version then the 3dB drop in sensitivity (v) at 1kHz is normal, but the SPL for 1 watt is the same.
The drop above 10kHz is also what I measured when compared to Ti diaphragms, but this is mainly due to the absence of breakups of the dome (and spurious resonances of the surrounds in the case of the JBL diaphragms I had). The drop is much smoother than the Ti one though, and can be compensated without adverse effects.
Once you compensate for the 3dB response difference you should observe that the response is actually louder than your previous diaphragm in the ~2kHz to 10kHz range. This is due to a higher mass breakpoint frequency, because the diaphragm is actually lighter.
It would be very interesting to see a comparison between the TAD Be diaphragm and a Truextent Be diaphragm in the same driver. Very different material properties between the two as the TAD is vapor deposited and has a very different quality to the foil Truextent material. Of course the TAD material should be lighter, at the same time it is much more fragile due to the alignment of the Be in the vapor deposition process.
I ordered a pair of Radian PB950 with original diaphragm (alu) and another pair with Trueextant Be.
I briefly compared the two and not only it's far from being day and night, i'm not even sure i like better the Be!
I have a funny feeling that the Radian Al and Be diaphragms are using the exact same mylar suspension. If they don't tune the suspension for the lighter weight Be it may just be a waste of time. The lighter mass of the Be should have a thinner suspension to go with the lessor mass. If someone has both they could measure the thickness of the surround and see if they have just replaced the diaphragm material and not optimized the design.
the Radian PB950 sounds very nice and soft. But it has also a littlebit coloration in the midrange.
The biggest difference IMO, in sound quality, was that Be diaphragms have cleaner sound and much more inner resolution and "subtle clarity" than original JBL 2446J diaphragms had. Better "downward dynamics" ability perhaps. The superior clarity stays the same no matter how loud you play them.
JBL 2446J has very good phasing plug design for the Be diaphragms and gives a smooth response without any peaks or nulls in the response. This was not the case with the previous generation driver JBL 2445J. With 2445J's phasing plug design the Truextent 'phragms had couple sharp nulls.
Truextent was approx. 2-3dB more sensitive in the 2-10kHz region, but not in the 10-20Khz region since there is no break up peaks there. Truextent goes to approx. 18,5khz (with a proper high shelving filter depending on the horn) with the 2446J, which is higher than the original 'phragms went.
In my opinion Truextent diaphragms need at least some 10-50 hours break in before they start to sound like they should. They sound more "damped" in the first couple of hours.
Consider mating your Truextent diaphragms with a good SET tube amplifier, this is the best way to drive compression drivers/horn speakers IMO.
JBL 2446J has very good phasing plug design for the Be diaphragms and gives a smooth response without any peaks or nulls in the response. This was not the case with the previous generation driver JBL 2445J. With 2445J's phasing plug design the Truextent 'phragms had couple sharp nulls.
Truextent was approx. 2-3dB more sensitive in the 2-10kHz region, but not in the 10-20Khz region since there is no break up peaks there. Truextent goes to approx. 18,5khz (with a proper high shelving filter depending on the horn) with the 2446J, which is higher than the original 'phragms went.
In my opinion Truextent diaphragms need at least some 10-50 hours break in before they start to sound like they should. They sound more "damped" in the first couple of hours.
Consider mating your Truextent diaphragms with a good SET tube amplifier, this is the best way to drive compression drivers/horn speakers IMO.
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Boldname,
I don't know the thickness but they are both foils and I will assume for now that the Be is lower mass even if it was the same thickness. You could easily measure the thickness of the surround with a micrometer, the foil would be more tricky to measure without making a flat spot on the foils.
I don't know the thickness but they are both foils and I will assume for now that the Be is lower mass even if it was the same thickness. You could easily measure the thickness of the surround with a micrometer, the foil would be more tricky to measure without making a flat spot on the foils.
Without buying and destroying these things in the process it is hard making any engineering comparison without the surround geometry
I cannot imagine a 2" or 3" diaphragm in Be beating a 1" in aluminium alloy notably in the top treble,
In principle a standard 1" throat smaller metal diaphragm CD say one of the small Radian Neo Al tweeters, could be a yardstick for step test, impulse test quality. CSD. If say the Radian Neo745 Be CD falls short or equals the smaller Al Radian, using the same dB and the same test protocol this would represent a very good comparison.
Boldname,
Over on the Beyond the Ariel thread there has been a lively discussion of the Radian 1.4" exit Neo-Be driver. From the testing done those drivers are as expected having a difficult time getting up to 15Khz and require some real eq to even do that with a workable response curve. I think a 1" driver will reach higher but I don't think that Radian has made one with a Be diaphragm and perhaps they won't. Meterion may get there first. Personally I don't like the suspension used on the Radian diaphragms, I think it is under to much tension the way it is used. I don't feel like looking up the elongation properties of Mylar but it can't be much.
Over on the Beyond the Ariel thread there has been a lively discussion of the Radian 1.4" exit Neo-Be driver. From the testing done those drivers are as expected having a difficult time getting up to 15Khz and require some real eq to even do that with a workable response curve. I think a 1" driver will reach higher but I don't think that Radian has made one with a Be diaphragm and perhaps they won't. Meterion may get there first. Personally I don't like the suspension used on the Radian diaphragms, I think it is under to much tension the way it is used. I don't feel like looking up the elongation properties of Mylar but it can't be much.
It is really the other topic that made me suggest the Radian comparison in this thread. There may be better comparisons that will winkle out the most audible degrading and obvious differences, in the 5KHz to 15KHz range. If only some wealthy HiFi geek would do a driver project to bring this about. The driver jungle has however grown rampant.
But I have heard it mentioned that a well known top line 1" Be direct driver dome tweeter suffers with ringing. I dont know what the suspension is made of, and its geometry. It is again enough to suggest not taking any be driver on spec. It takes years for a track record to form an adequate picture, and the jury is still out on Be with other emerging ? cheaper but exotic material developments.
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Boldname,
I agree, just because you are using Be does not guarantee that you will have a satisfactory final result. I won't say the name, you can figure it out, but one of the very well known Be dome tweeters, has an inverted dome, has all the same problems that every previous version has had. It isn't the dome material that is the problem or the solution but it sells product. I am also personally working on a Be designed dome tweeter, whether it will be what I expect is a question, I won't know until it is completely tested. I may just end up going back to a soft dome design if it doesn't truly bring something to the party, the raw dome material cost more than the entire assembly of some of the most expensive dome tweeters on the market. final sales prices can have nothing to do with the actual cost to manufacture a device. Marketing and price fall hand in hand in most cases.
I know the Radian drivers fairly well as I have used them in the past and a friend and mentor I first met at Radian when I was looking to work with a company on some earlier designs was an engineer at that company now many years ago. The stories I could tell of some of the shenanigans that have happened out of that company, probably the same at many other audio companies. I do know where the original designs originated, I have been told that story more than once. it was not originally from Radian, all of this goes back to Rankus Heinz, the real original source of all these drivers. It was a clash of personalities that created the three different companies making these drivers, Rankus, Emilar and Radian. The rest in now just history.
I agree, just because you are using Be does not guarantee that you will have a satisfactory final result. I won't say the name, you can figure it out, but one of the very well known Be dome tweeters, has an inverted dome, has all the same problems that every previous version has had. It isn't the dome material that is the problem or the solution but it sells product. I am also personally working on a Be designed dome tweeter, whether it will be what I expect is a question, I won't know until it is completely tested. I may just end up going back to a soft dome design if it doesn't truly bring something to the party, the raw dome material cost more than the entire assembly of some of the most expensive dome tweeters on the market. final sales prices can have nothing to do with the actual cost to manufacture a device. Marketing and price fall hand in hand in most cases.
I know the Radian drivers fairly well as I have used them in the past and a friend and mentor I first met at Radian when I was looking to work with a company on some earlier designs was an engineer at that company now many years ago. The stories I could tell of some of the shenanigans that have happened out of that company, probably the same at many other audio companies. I do know where the original designs originated, I have been told that story more than once. it was not originally from Radian, all of this goes back to Rankus Heinz, the real original source of all these drivers. It was a clash of personalities that created the three different companies making these drivers, Rankus, Emilar and Radian. The rest in now just history.
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