Yes you can use the 2450H in a 2 way design, with a Be diaphragm.
The Materion Be diaphragms will have more of a damped response, and the top octave needs more atttenuation/EQ .
The TI SL diaphragms have a more extended response actually, but they are less clean in the top octave.
The 4001 has a diaphragm weighing less then half of the Materion, the shorting ring linearises the impedance also. But it's extended response in the top octave is mainly due to the Beryllium diaphragms half roll surround resonance, that gives the 18khz peak in the response. As demonstrated in the old JBL techsheet i added.
SONY SUP T11 are hard to find in a good shape, and replacement diaphragms are nonexistent.
If that is a interesting route, you should look at the GT sound versions from Japan that is based on the SUP drivers.
But those will cost you more then the TAD's.
The Materion Be diaphragms will have more of a damped response, and the top octave needs more atttenuation/EQ .
The TI SL diaphragms have a more extended response actually, but they are less clean in the top octave.
The 4001 has a diaphragm weighing less then half of the Materion, the shorting ring linearises the impedance also. But it's extended response in the top octave is mainly due to the Beryllium diaphragms half roll surround resonance, that gives the 18khz peak in the response. As demonstrated in the old JBL techsheet i added.
SONY SUP T11 are hard to find in a good shape, and replacement diaphragms are nonexistent.
If that is a interesting route, you should look at the GT sound versions from Japan that is based on the SUP drivers.
But those will cost you more then the TAD's.
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I'm at the beginning stage of a new design, and I've been trying to understand Compression Drivers a little better, so I can make a somewhat well informed choice. I suspect the answers are all hidden in this thread somewhere, but 104 pages is a lot to read through!
My experience with compression drivers comes from the B&C 12FHX76 coaxials I'm using. They have a 1.4" CD/ Horn, titanium diaphragm. Patterns is 60x40 degrees. Below is the response without DSP and with DSP. I used 9 PEQs to achieve this response. And attached is the REW measurement themselves.
(Un-filtered curve is similar to the published response curve)
I found an old thread where Earl Geddes was discussing compression drivers, and he said that EQ is mandator for a true compression driver. He said the physics of a compression driver dictate that they have a decreasing response, if I remember his words correctly And if it does not have this characteristic, then it is something different from a compression driver.
So in his view, we will never get a "flat" frequency response out of a compression driver? If this is true, how even or "flat" of a response can we realistically hope for (unfiltered)?
Can we understand anything about the CD based on knowing the material the diaphragm is made out of? And if so, what diaphragm materials are the best for hifi type use? Are there clear differences between titanium and other materials, or even carbon fiber like Eminance has come out with?
Can a person hot-rod a compression driver by using a different diaphragm material than the one the manufacturer ships it with? I know they are replaceable, but I haven't found any discussion about whether or not they are interchangeable. I am curious to know if I can improve the performance of my coaxials, for example. They share the magnet with the woofer, so I can't change the entire CD. But can the diaphragm be swapped with something different? I'm OK with the current results I'm getting, but I think it would be interesting if I could get better results with less DSP.
And finally, since the original thread was asking what "The Best" CDs are, is there a concensus for what is the best for hifi applications? I didn't find a conclusion, but then, there are over 100 pages to this thread over 2 years...
My experience with compression drivers comes from the B&C 12FHX76 coaxials I'm using. They have a 1.4" CD/ Horn, titanium diaphragm. Patterns is 60x40 degrees. Below is the response without DSP and with DSP. I used 9 PEQs to achieve this response. And attached is the REW measurement themselves.
(Un-filtered curve is similar to the published response curve)
I found an old thread where Earl Geddes was discussing compression drivers, and he said that EQ is mandator for a true compression driver. He said the physics of a compression driver dictate that they have a decreasing response, if I remember his words correctly And if it does not have this characteristic, then it is something different from a compression driver.
So in his view, we will never get a "flat" frequency response out of a compression driver? If this is true, how even or "flat" of a response can we realistically hope for (unfiltered)?
Can we understand anything about the CD based on knowing the material the diaphragm is made out of? And if so, what diaphragm materials are the best for hifi type use? Are there clear differences between titanium and other materials, or even carbon fiber like Eminance has come out with?
Can a person hot-rod a compression driver by using a different diaphragm material than the one the manufacturer ships it with? I know they are replaceable, but I haven't found any discussion about whether or not they are interchangeable. I am curious to know if I can improve the performance of my coaxials, for example. They share the magnet with the woofer, so I can't change the entire CD. But can the diaphragm be swapped with something different? I'm OK with the current results I'm getting, but I think it would be interesting if I could get better results with less DSP.
And finally, since the original thread was asking what "The Best" CDs are, is there a concensus for what is the best for hifi applications? I didn't find a conclusion, but then, there are over 100 pages to this thread over 2 years...
Similar?
Your unfiltered measurement curve deviates at points by more than 8dB from the published response curve, perhaps because it was made too "close up" to the horn.
Your 9 PEQ choices made for that measurement location will not result in the same response at other measurement locations.
A typical compression driver response on a "constant directivity" horn or "waveguide" will increase in it's midrange response and drop off in the high frequency.
On a horn with non-uniform directivity coverage, the on-axis response can be near flat over around a decade of response, depending on the driver/horn pairing.
Different materials have different stiffness to weight ratios, so there are difference in breakup and resonance frequency and patterns. Surround designs and materials, embossed diaphragm patterns, and phase plug design are all make contributions which can make as much, or more differences in response than diaphragm materials alone.
Many drivers have multiple interchangeable diaphragms available that will "fit", and response will be different for each.
B&C makes 3" diaphragms with a mylar surround that may be a bit smoother than the all titanium diaphragm. I have not verified if those other diaphragms fit your driver.
The mylar surround has reduces sensitivity, requiring more power for a given SPL.
Trade a bit of power compression and distortion for smoothness...
Design choices and compromises are interesting
.No, with endless horn/driver combinations and individual criteria for what makes "the best" there will never be a consensus for what is best for "hifi" applications.
For example, a coax driver such as yours has the advantage of single point source behavior, but the horn design required to fit it's geometry restraints won't be as smooth, wide range, or have as consistent off-axis response as a stand alone horn can have.
Each user can pick the compromises that are "best" for their own listening preferences, environment and budget.
Art
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Art, thanks for the suggestion on diaphragm with the mylar surround. I did some searching, but I wasn't able to find out if it is possible. It made sense to me that they would be interchangeable in some cases.... I guess I will do some more research to try to find out what might be best to try.
Kevinkr said elsewhere that he is using an FaitalPro HF10AK 1", which claims to use a keytone polymer diaphragm. The published measurements for that one look pretty even. So it seems a pattern is emerging.
The measurement I posted correlate to a fairly even measurement at the listening position in my room. Just now I ran some sweeps at different distances, and I did get somewhat different measurements based on distance, as you suggested. If there is an ideal distance to get the most accurate reading, while avoiding effects of the room, please let me know.
Kevinkr said elsewhere that he is using an FaitalPro HF10AK 1", which claims to use a keytone polymer diaphragm. The published measurements for that one look pretty even. So it seems a pattern is emerging.
The measurement I posted correlate to a fairly even measurement at the listening position in my room. Just now I ran some sweeps at different distances, and I did get somewhat different measurements based on distance, as you suggested. If there is an ideal distance to get the most accurate reading, while avoiding effects of the room, please let me know.
I incorrectly stated that the mylar surround lowered sensitivity on a B&C driver, recalling some other examples from previous generations of drivers from different manufacturers
.The B&C DE-82 mylar/titanium driver compared to the all titanium DE-82TN:
At 8volts, (~8 watts) third harmonic distortion is a bit higher on the low and high end of the DE-82 mylar/titanium driver (blue) compared to the all titanium DE-82TN (green):
And diving further into the weeds, the 16 ohm DE-82 has slightly smoother response than the 8, while the DE-82TN is the opposite:
A 44mm diaphragm, 1" 40x50 horn, highly smoothed published measurement with a -5dB dip ~2.5kHz in the response..
You may find a pattern emerging that 3" dome diaphragms don't use that material
The ideal distance to get the most accurate high frequency horn reading is in the far field, or at minimum 3 times the longest cabinet dimension. Can't avoid room effects at those distances.
Art
For the HF10AK. It is fairly clean, has a small issue around around 2,5 k,( i guess a cavity resonance?) as shown in the mfg. sheets too, just very smoothed.
Look here:
https://www.dibirama.it/component/c...-1-73-8-ohm-120-wmax.html?catid=22&Itemid=580
And the pattern would be?
Larger diaphragms often use a polymer surround, that (if properly designed), helps dampen resonances.
Looks like a new FP 1.4 CD. Haven't seen this one mentioned. Expensive though.
https://www.parts-express.com/FaitalPRO-HF148C-1.4-Neodymium-HF-Driver-8-Ohm-294-1358?quantity=1
https://www.parts-express.com/FaitalPRO-HF148C-1.4-Neodymium-HF-Driver-8-Ohm-294-1358?quantity=1
Retails at €375 and less than 1/2 price of US in Europe thru TLHP if you have an account. Looks interesting, 15 degree exit angle(!)
https://en.toutlehautparleur.com/media/catalog/product/datasheet/faital/HF148C-8.pdf
https://en.toutlehautparleur.com/media/catalog/product/datasheet/faital/HF148C-8.pdf
Released in 2023.
But what is special about it?
The impedance curve looks very unruly past 10k. mfg. graphs that are often smoothed,shows some serious TI breakup.
The HF1440 and HF1460 looks like better candidates for being used in the top octave to me.
