It says on Parts Express that "Aero Striction tweeters vertically beam far less than the ribbons" (Aurum Cantus AST25120 Aero Striction Tweeter 8 Ohm)
Distortion is only 0.3% at 1 Khz. I reckon it begins to rise below that.
well it may say that BUT beaming is determined by diaphragm size. These should "beam" just as much as any ribbon of same length.
That said, in my experience you can use a diaphragm up to about 75-100 mm long in most listening environments before the vertical beaming becomes an issue
The .3% distort thing doesn't always tell the whole story. Maybe Arum has the diaphragm resonance issues in these designs figured out, IDK for sure, BUT basically these designs tend to be a bit colored at that low a frequency due to the shape size mass mechanical properties etc of the diaphragms structure. The very sharp roll off in the response curve below 1Khz is telling. There is a sharp non linearity in this region.
Also at what power level is that distort measurement?
These designs also tend to use a horizontally wide diaphragm that limits dispersion above 10Khz
Now to put what Ive said in perspective....
I speak from a designers standpoint always looking to make a better driver, so what I say doesn't mean the driver in question is not a good driver. The folded diaphragm designs certainly have strengths... reliable, high sens, high power, and if done well very good sound
That said, in my experience you can use a diaphragm up to about 75-100 mm long in most listening environments before the vertical beaming becomes an issue
The .3% distort thing doesn't always tell the whole story. Maybe Arum has the diaphragm resonance issues in these designs figured out, IDK for sure, BUT basically these designs tend to be a bit colored at that low a frequency due to the shape size mass mechanical properties etc of the diaphragms structure. The very sharp roll off in the response curve below 1Khz is telling. There is a sharp non linearity in this region.
Also at what power level is that distort measurement?
These designs also tend to use a horizontally wide diaphragm that limits dispersion above 10Khz
Now to put what Ive said in perspective....
I speak from a designers standpoint always looking to make a better driver, so what I say doesn't mean the driver in question is not a good driver. The folded diaphragm designs certainly have strengths... reliable, high sens, high power, and if done well very good sound
There are 3 reasons against that driver:
- It doesn't hit the 98dB until 12kHz. Equalized, reckon with ~93dB or less.
- The vertical dispersion will be around ~20-25°. If you don't have the listening distance (~3-4m minimum), don't bother looking at that driver.
- It's expensive. Look for other Air Motion Transformer drivers, there are others which are cheaper with similar performance.
I have the smaller AST from Aurum Cantus, and you are wrong about vertical dispersion. I don't know what Aurum Cantus has done to solve that problem, but they don't beam. I also have an Aurum Cantus ribbon, and that one does beam. The Aurum Cantus AMT's are excellent but pricy, and I suspect the pricy bit is why they are not used much.
See, the Aurum Cantus isn't bad. But don't be impressed by the 98dB since you'll get only 93dB or, with the baffle step, likely less. If you can live with a few dB less, the Dayton Audio AMTPRO-4 performs the same for 1/3 the price. It's identical except the magnets.
More linear, but more expensive, look at the mundorf AMTs.
Same price and equally high (or higher) spl, look at the ESS AMT-1.
More linear, but more expensive, look at the mundorf AMTs.
Same price and equally high (or higher) spl, look at the ESS AMT-1.
I am not impressed by high efficiency figures since the final spl is most likely dictated by other parts of the speaker, not the tweeter. The Dayton AMTPRO-4 beams, the Aurum Cantus does not, so it is certainly not identical. I have not tested or used the Dayton, but the measurements by HiFiCompass is not particularly impressive. I measured my AC AST some years ago and I remember it as measuring very good, and more important sounded better than any other tweeter I have tried. My measurements agreed with others, but don't ask me for them because I don't have the data any more. The Mundorf's look to be excellent, but very expensive. The ESS AMT-1 I believe is no longer available. Parts Express list it as no longer available. Better and cheaper? Nothing so far. Personally I would buy the smaller AC AST again because it is more cost effective and spl is plenty for anything I am ever likely to build.
The Dayton and the Aurum got the same dimensions of the diaphragm in width and length, and since the dimensions of the sound emitting surface physically determines the radiation pattern, that means they will beam practically exactly the same.
They need some equalizing, that's correct. The Aurum need less but still need it too.
They are more linear but not flat either. Equalized and level adjusted, you can't tell them apart from the Daytons.
Just because PE doesn't have them, they are not available anymore?
The ESS AMT-1 are still available in different shops. Since they are roughly the same price and more linear and got a higher spl (I know, not an argument for you) I'd go for them instead of the aurum. And yes, they are better. If I wouldn't need the spl I'd also go for the smaller ones since they don't beam that extreme vertically.
If you're into AMT's then ok.
DAYTON AUDIO AMTPRO-4 (Tweeter AMT, 4 Ohm, 100 Wmax)
I know of few tweeters (not AMT) that i'd use before this AMT.
DAYTON AUDIO AMTPRO-4 (Tweeter AMT, 4 Ohm, 100 Wmax)
I know of few tweeters (not AMT) that i'd use before this AMT.
These measurements look a lot different than the ones (several) I've seen. None of them got a that high peak and that much beaming. The decay is a lot worse, that's usually a sign they were not assembled correctly or the felt touches the membrane. If you do that, you can let every tweeter look bad.
You are not listening. The AC AST DOES NOT BEAM. I was expecting mine to beam, just like the ribbon I had, which was about the same vertical dimension. However, it does not beam at all like a ribbon, the vertical dispersion is not that much different from a dome. Very surprising, and I have no idea what AC have done for this to occur, but it is real. Others have noted this characteristic as well and it is difficult to believe because you would expect it to beam according to the dimensions as you said. But, it does not beam.
Glad to hear that the ESS is still available.
You could be right or it could be very poor QC. Aurum Cantus is no exception to that mater.
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Baaming of AMT tweeter of that lenght isn't negotiable. It is a matter of physics. Or you will provide us with measurements that will prove ICG wrong ?
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I've heard you. But that's physically not possible.
Well, the membrane isn't parted into different sections which reproduce different frequency ranges, that would be the only possible way to prevent them from beaming but they aren't doing that.
I'm sorry but I don't buy that.
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