Every vintage driver is obsolete compared with the top performing drivers of today. There is a certain beauty in the substantialness, simple design and all out effort of drivers like the Altec 288, TAD TD4001, and JA6681B. This characteristic is a reflection of amplification power limitations of the time when the driver technology was originally invented. Despite advancements in amplification today, in my observation, optimizing for efficiency regardless of the circumstance, is always the way to go.
Certain drivers incorporate seldom seen interesting engineering choices like very minimal fingers of the of the JA6681B diaphragm surround. A technological detail such as this is valid today. The choice of metal in the instance of the JA6681B surround is ideal however as it is brittle and rigid. This reduces free motion of the diaphragm and potentially causes resonances that could otherwise be nullified to reflect back into the diaphragm.
Most compression drivers with their higher power handling are beyond excessive for home use and will not be as performative as alternative options. Certain very low power handling drivers like Altec 802 will sound way better than the vast majority of, though not all, contemporary compression drivers and conventional tweeters. It's worth remembering a major advantage of a certain compression tweeters is their ability to play in a stable capacity at a low crossover point, say 800hz. Conversely, a lower power handling tweeter with a smaller lower mass dome and adequately high powered motor will be more refined in the high frequencies.
Certain drivers incorporate seldom seen interesting engineering choices like very minimal fingers of the of the JA6681B diaphragm surround. A technological detail such as this is valid today. The choice of metal in the instance of the JA6681B surround is ideal however as it is brittle and rigid. This reduces free motion of the diaphragm and potentially causes resonances that could otherwise be nullified to reflect back into the diaphragm.
Most compression drivers with their higher power handling are beyond excessive for home use and will not be as performative as alternative options. Certain very low power handling drivers like Altec 802 will sound way better than the vast majority of, though not all, contemporary compression drivers and conventional tweeters. It's worth remembering a major advantage of a certain compression tweeters is their ability to play in a stable capacity at a low crossover point, say 800hz. Conversely, a lower power handling tweeter with a smaller lower mass dome and adequately high powered motor will be more refined in the high frequencies.
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the question is do we really need compressions drivers for home use the answer is no , but do we like fighting with them the answer is yess . it must be seen in global . what is magic with them is that with a flea amp and no passive crossover i can hear things i can not ear with low efficiency speakers let say wilson or magico for exemple. but you have to deal with the difficulty to add a tweeter next to a big horn , bass driver , multiple amplifiers , crossover DSP correction .. it"s a never ending story.
to return to the topic i find that the B&C DCM 50 is a very special compression driver running from 500 to 8K but ités very difficult to add them a tweeter , they sound so good by themselves ..
to return to the topic i find that the B&C DCM 50 is a very special compression driver running from 500 to 8K but ités very difficult to add them a tweeter , they sound so good by themselves ..
You have to remember that picking a single angle makes it seem irrelevant, but if you sum up the total quantity of energy at one frequency compared to the direct sound, the numbers tell a very different story.
Pardon my gross ignorance but what do phase plugs in compression drivers do that is different from what vanes do in horns like the TH-4001?
https://www.athosaudio.com/2021/01/01/tad-th-4001/
And why do some similar horns not have vanes (fins), like this one? https://josephcrowe.com/products/es-290-biradial-wood-horn
https://www.athosaudio.com/2021/01/01/tad-th-4001/
And why do some similar horns not have vanes (fins), like this one? https://josephcrowe.com/products/es-290-biradial-wood-horn
Would not this high power driver be a valid exception if precisely equalized https://www.usspeaker.com/radian 745neoBepb-1.htm and used in a horn like this? https://www.athosaudio.com/2021/01/01/tad-th-4001/ or this with the proper throat adapter?
https://josephcrowe.com/products/custom-yuichi-a-290-biradial-cad-model-make-any-size
I think that is an interesting question. Klipsch made some kind of horn entry adapter for the Celestion Axi2050 as well. But I believe the function is not exactly the same for the two either.
So the vanes are a bit like aircraft wing profile, but symmetrical. This means they displace a bit of the cross section area half way through. If you look at the profile of the horn, the start of the horn is pretty smoothly shaped. But by displacing some of the area, and then adding it back in, you slow down the expansion first, and then increases it rapidly. This is done in the horizontal plane only, and that improves the dispersion uniformity over a wide range.
The Klipsch Jubilee uses, as far as I have understood, this adapter to improve the integration between the beginning of the horn and the driver exit. Besides making sure any flow is kept laminar throughout the adapter, it is also slightly deeper in the middel. This will keep the expansion of the wave from pulling out all the energy from the center of the wave, but instead allows for more of a collaps along the sides. It really causes the same thing as the vanes, it improves dispersion over a wide range by controling the shape of the wave.
Here the expansion is left to the horn itself instead of using vanes to control it.
While these vanes, and the adapters are ways to control the transition of the wave from nearly flat to whatever is desired for the next section of the horn, the phase plug has several functions. However, one of those is to control the shape of the wavefront to match the exit angle of the driver. Other functions is to form a compression chamber between the diaphragm and the phase plug. Another function is to add actual compression in a ratio determined for that particular design. Since different kinds of modes will form inside the compression chamber, the phase plug will face an additional challenge when trying to transfer the wave from the diaphragm to a perfectly shaped outgoing wave.
Thanks, this helps, even though I don't I see most of the relevant physics. Which horns would have, regardless of driver:
Wider and deeper sound stage.
Better vertical dispersion
Least overall obstacles for delivering realistic sound
AH-340 https://www.azurahorn.com/azurahorn_horns.html
https://josephcrowe.com/products/custom-yuichi-a-290-biradial-cad-model-make-any-size
https://www.athosaudio.com/2021/01/01/tad-th-4001/
OR are such performance parameters for any of these horns at least half as much dependent on driver selection and how precisely tuned any required equalization is applied for the horn/driver combination?
Wider and deeper sound stage.
Better vertical dispersion
Least overall obstacles for delivering realistic sound
AH-340 https://www.azurahorn.com/azurahorn_horns.html
https://josephcrowe.com/products/custom-yuichi-a-290-biradial-cad-model-make-any-size
https://www.athosaudio.com/2021/01/01/tad-th-4001/
OR are such performance parameters for any of these horns at least half as much dependent on driver selection and how precisely tuned any required equalization is applied for the horn/driver combination?
Amen to this! I've been reading along, but this post exactly summarizes my experiences with a compression driver midrange in a 2 channel home setup. For starters I would never go back to cone drivers after experiencing what a CD sounds like north of 500 hz; but I have struggled for years to find a tweeter that does not disturb the coherency with my system. My midrange is a vintage JBL 2441 with the original hex diamond style diaphragm. The horn is the Bruce Edgar salad bowl (tractrix). I would like to find a tweeter that would compliment my midrange driver as I'm pretty sure that I'm missing some high frequency energy, but it seems to be an elusive endeavor to date.
I strongly disagree. A compression driver is the only way you can take full control over the interfacing between a diaphragm and a waveguide over a really wide band.
I looked into this a few days ago. The DCM 50 with the 464-horn from B&C seems to be an excellent match with the Faitalpro FD371. I would even consider suspending it in the horn.
Did you ever tried dome midranges? What you write reminds me of what a good 3" is doing.
98dBSpl sensitivity with 2g membrane weight ... not the same as a compression driver but pretty different to these 17cm "midranges". And of course way easier to integrate. But wide radiation, that will of course sound different in the room.
The frequency response chart tells a lot about the performance of a driver. The more extended into the highs a driver is the more resolving it will be period including in the midrange. The Radian rolls off substantially, consistent with the assumption that it is optimized for high power handling rather than resolution at lower level playback. I've obviously considered Radian drivers given the number of drivers that I've tested. They look fairly premium in build quality and have gained a lot of interest through reviving Beryllium "technology" per se. Before embarking on my tests, and with less knowledge, they were the drivers I lusted after because I assumed their Beryllium diaphragm would be similar to those in found in the TD4001s which I lusted after most. The TAD diaphragms and methodology is far more advanced. Speaking with Al, the owner of US Speaker, the site you linked, many times about drivers, he has led in me in the right direction with regards which drivers perform best. I've owned a Yuichi horn fabricated by Athos audio, also linked. I prefer other horn geometries to a biradial geometry in my experience thus far. And I've also spoken to Joseph Crowe on multiple occasions. That guy very much knows what he's doing obviously. He is far more experienced than I. I would say his Nighthawk Speaker is about as fine a design as one could conceive. There are other ways to go about it which would be equally performative though I am certain, that is an outstanding formulation and methodology.
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In what areas did the previous waveguide you were using ( Yuichi A290) not work out the way you had anticipated?
i will listen too few ATC SCM50 model ( with the famous ATC150 dome midrange ) this afternoon at my friend local shop along with FYNE coaxial speaker ( similar to tannoy ) and a Magico M2 . then i will return home and listen to my HR speaker with B&C DCM50 and TAD 1601 and will be happy again or in doubt ... no fear
The "phasing plug adaptor" (sic) (US11903728, WO 2022/033953 A1) is there to address an acoustic beaming issue that occurs above a certain frequency that corresponds with a half wavelength of sound fitting across the throat diameter at the horn's throat....The Klipsch Jubilee uses, as far as I have understood, this adapter to improve the integration between the beginning of the horn and the driver exit. Besides making sure any flow is kept laminar throughout the adapter, it is also slightly deeper in the middel. This will keep the expansion of the wave from pulling out all the energy from the center of the wave, but instead allows for more of a collaps along the sides. It really causes the same thing as the vanes, it improves dispersion over a wide range by controling the shape of the wave.
For a 2" horn throat diameter/compression driver exit diameter, this corresponds to the speed of sound at room temperature (~13582 in/sec) divided by the throat diameter--2", i.e., 6792 Hz. Above that frequency, the angular acoustic coverage pattern as measured from the horn's mouth begins to separate from the horn's walls and collimates into an acoustic beam. The "phasing plug adaptor" simply spreads out the acoustic pattern to more closely follow the horn's straight walls for about an octave higher in frequency (~13584 Hz), at which point the spaced concentric rings of the "adaptor" are no longer as effective in spreading out the acoustic output field to the horn's walls, and beaming again begins to occur--just at the same frequency of beaming in a 1" throat compression driver/horn. This transition to beaming appears to be complete by ~15 kHz:
The exact mechanism of this acoustic spreading above the half-wavelength-across-the-throat beaming frequency is explainable from the standpoint of the Huygens-Fresnel principle (i.e., re-radiating wavefronts from the curved portion of the adapter into the horn's throat area, on the left side of the above cross section diagram taken from the patent document). This is the action of an acoustic lens, not a phase plug as used in compression drivers--which are devices that avoid acoustic cancellations across the compression driver's diaphragm area.
There is no "laminar flow" inside a horn, since there is no net flow of air into or out of a typical horn.
Waveguides are typically constant cross-section elongated cavities that carry internal acoustic or electromagnetic energy from an emitter to a horn radiator. The horn disperses the entering energy into the free air field (acoustic) or free space field (E/M), i.e., not the waveguide. What you refer to as a "waveguide", above is actually a horn, (i.e., this is a confusing use of the term "waveguide".)
Chris
Axi2050 is perhaps the most disappointing compression driver I've ever tested. Partially also because I had high hopes for it after the introduction. I used a Klipsch K-402 horn (same horn as in the Jubilee). In direct comparison to Radian 950BePB where I had one in each horn and did a lot AB comparisons in mono with level matching and similar EQ/tuning over several days, I was surprised how much it lacked in openness, clarity and detail compared to the Radian. It was sort of listening to 4"-5" piston driver - sounds comfortable but completely lack high frequency energy. And the I saw in my measurements, that the distortion was high aleady at 700-800 Hz area compared to Radian 950BePB. It sounded just borring to me.
Doing a proper AB comparison with quick changing as possible is important though for a test. And they need of course to be equalized fairly/similar. I don't trust feedback if people haven't done that.
Either way. I find that the horn is vastly more important than the compression driver as long the driver holds a certain quality. A great horn with alu will sound much better than a medium quality horn with beryllium.
Doing a proper AB comparison with quick changing as possible is important though for a test. And they need of course to be equalized fairly/similar. I don't trust feedback if people haven't done that.
Either way. I find that the horn is vastly more important than the compression driver as long the driver holds a certain quality. A great horn with alu will sound much better than a medium quality horn with beryllium.
This is no big surprise to me as the K402 does not provide much midrange acoustic loading. I am aware of several people who use the Axi from very low to only midrange in large exponential horns are more than satisfied with this driver. Your comparison is not really appropriate wrt the scope of usage. A driver with a Be diaphragm will probably almost always outperform a titanium driver in the HF region. You should better compare with a Radian with AL diaphragm.