Fantastic stuff, so what companies use underhung drivers and what do these drivers look like? Kind regardsI'll throw my 2 cents into the wishing well.
I design drivers and finished systems and have since 1989.
Was a pretty accomplished musician years ago and still have perfect pitch. I notice things. And also can get fooled. Go figure on that!
So diminishing returns.
Not flogging any brand is number one.
Number two is most people listen with their eyes. That's a sad consequence really.
Importance of what you listen to.
If you like small ensemble jazz or classical, not to loud. Well there are a lot of speakers that do this exceedingly well. Even under $500. I have been humbled quite a few times working on a uber driver that is over $200 ex factory chasing changes that are noticeable. And then listened to very inexpensive drivers, I mean under $20 a piece that really sound pretty good!
No replacement for displacement.
If you want to go low and want it loud. There are precious few 6 or 8 inch sized drivers that have the X-max to do it justice. And that sums up the preponderance of available expensive high end loudspeakers. A few small drivers that are ok to about 45 hertz. If you are looking for lower you need something more.
Why do Ultra highend companies not publish measurements?
Many times they are that different from a great many other speakers. They are selling sizzle, not the steak.
Some other things to take note of.
Loudspeaker driver motor type does make a difference.
For one client we have gone from overhung small gap long coil, to XVL^2 to underhung short coil long gap. What does this mean? The area that the magnetic energy is concentrated in is either very small as in an overhung motor or very large as in an underhung motor.
What are the differences?
Distortion. There are distortions that are inherent in the overhung motor type. That are not present in a properly designed underhung.
Previously mentioned client called me up at the first listen to the underhung and told me something I will never forget.
He used the same piece of music to critique his speakers for over 30 years. Not only one, but this one was his litmus test. What blew him away was somebody moved. He turned to see who it was. Nobody there. It turned out to be a music stand was bumped and picked up by the recording mics.
Incredulous was I. So I asked. Same recording on the previous model? And did you hear it? He had an A/B system setup. And a blind switch operator. He could hear it on the new drivers, but not the old XBL^2 drivers.
Masked. The finer details were masked by nonlinearities that are a part of the relationship between the voice coil acting as an electromagnet and the permanents magnetic fields in the dual gap XBL motor. These distortions are there in all drivers. But are less there in underhung driver motors. There are quite a few papers that demonstrate this very effectively. So why don't we see this type of motor used more? Cost. Plain and simple. It costs a lot to make a good underhung motor versus a overhung motor that will essentially do the same thing. And loudspeakers are all about profit. To truly understand the cost of what is inside even the most expensive loudspeaker systems will shock you. Magico is a great example. Morel and Accuton make their drivers. And they are Ok drivers. But take them apart and compare them to many others and there is not that much difference. There is no truly secret sauce. There is good engineering. Sometimes the expense and the engineering meet and shake hands. And it works. Sometimes you are being sold the sizzle. Close your eyes and listen. You might be a little surprised.
Speakers are quite simple. Play with magnets and like poles repel, different pole N,S attract. Nothing magical about them. Your amplifier delivers voltage that is sent to a coil of wire that creates a magnetic filed and depending on the polarity of the voltage the cone moves forward or reward.
The biggest differences are what happens to the static magnet field in the motor. The one that is energized by the Ferrite, or Neodymium magnet.
Most amplifiers are quite capable of sending an acceptably low distortion signal. And most loudspeakers are actually pretty good at reproducing that signal with acceptable fidelity.
The diminishing return on my end of the loudspeaker is how well I can chase and exorcise those evil little distortions.
That being done. How I voice the crossover and apply the driver to their best effect.
2 cents over and out.