Well, whatever you do with your loudspeakers of with you whole playback system is kind of irrelevant if your drivers are not right. In my view the drivers are the very much heart of playback but in case of High-Efficiency and particularly horn-loaded driver the situation is kind of more interesting.
To simplify everything - the Efficiency of driver is it’ surface by exertion by radiation angle. A horn shrinks radiation angle and makes the driver able to exert less, taking of many advantages of the low- exertion designs. Of course it is very simplified view but basically the right view. Now, here is the key to understand if you wish to listen and to understand what I have to say. A low exertion driver that produced some kind of pressure, would it be a compression driver of a regular driver, got equalized being loaded in horn. If the scale of this equalization might be more or less accurately predicted by different characteristics of the horn but the scale of TTH (tone-transient-harmonic characteristic) changes of the driver-horn tandem are absolutely not predictable. The common know of horn design teaches us to observe the propagation of pressures but atmospheric pressure is not executable force of music, the TTH of the timbral pressure is, and you will not see any single manufactures or individual who is able to forecast accurately the TTH equalization or the rate of the timbral changes when a driver is loaded to a horn.
So, based upon the said above is it clear that we in High-Efficiency world des with random and absolutely accidental drivers. I do not even mention that 99.9% of the companies that make driver do not even recognize the difference between atmospheric pressure and tonal pressure of drivers and they do divers with the vise of a blind man play golf – that got the consumers are mostly low demands fools who would swallow anything….
I have to admit that in the world of direct radiation the situation is much better. People takes a driver, load it into an open baffle and whatever sound they get as a result is pretty much the sound of the driver. People even to a degree learned to associate the sound that the drivers make with many objectively measurable parameters. In the case of horn-loading the story turns ugly as a driver loaded into a horn changes sound. How it changes is answerable in the realm of atmospheric pressure but not answerable in the realm of TTH characteristic. Therefore we in absolute darkness and uniformity about the sound we are getting out of horns.
So, what the stage of current High-Efficiency horn drivers?
I discard the low sensitively drivers, let discard anything that is below 100dB sensitively. I also discard any drivers that use in the wide-throat horn as I do not consider it as proper horn-loading. A driver shall have at least a half or a third of the bandwidth equalized by a horn. If not, then it is direct radiator with “leaves”.
There are few pro companies that make today high quality compression drivers that are more or less useable for home playbacks. Probably JBL and TAD are leading among them. This drivers are expensive and made with substantive R&D , which not necessary mean the right R&D. Thos drivers are not free of faults and one of the maggot is that those companies do not produce serious home-targeted horn insulations. This own horns and horn assemblages are garbage and if you have their driver load into right horn that you might not have the “right” driver anymore. So, regardless how good of bad the newest JBL and TAD are they are still a food that need to be defrost and waked before eating. The older JBL production (that include Altec) looks no more interesting as the story with them is very much the same - no one cared at that time about the “right horns” and no one cared about anything more than atmospheric pressure.
There is a an army of the second echelon compression drivers – TOA, Selenium, BMS, Eminence, Mccauley, Beyma, Emilar, B&C, Renkus, Radian, Ciare, B&C, Fostex, P-Audio, Gauss, Electro-Voice and a few others. They make different High-Efficiency drivers but again they have no reference of how they will be used and therefore the drivers are just situation of totally random results.
The second echelon of High-Efficiency drivers are no name drivers. They exist, there are many of them and they are cheap. Unfortunately they all use poor ceramic magnets that are not optimum in the case of minimum currents, so it is very problematic to use those drivers for a serious sound.
As a separate class there are expensive arrays of mostly Japanese High-Efficiency drivers: GOTO, ALE, YL and a few others. I have a big problem with those drivers as I do not like the consents that a driver might be made with any respect to the way how it will be loaded. The people who use them looks like them but I less care what many ignorant people like and more care if the same GOTO, ALE, YL drivers to be more accommodateable for proper loading. Unfortunately the system design ideas of those who made, sell and used those drivers are absolutely foolish, and therefore I do not see that any reported advancement in driver in this case leads to advancement in final results.
The separate class of the High-Efficiency drivers are vintage drivers made before the era of powerful SS amp hit the market– before the 60s. Here are WE, RCA, Vitavox, BELL, Klangfilm/ Siemens, Telefunken, Magnavox, Jensen, Goodman and a few others. The advantages of those drivers that many methods of the barbaric design the manufacturing, that are a norm today, were not invented back then and some of those vintage (no all of them but just a few of them) drivers do have interesting TTH characteristic. Again, those drivers were not design to be use in proper horns and in prosper systems. The design, precession and stability of those driver making was horrible to begin with, the condition of them after 50-70 year is mostly very pity. Thos driver are just not up to level of contemporary demands, they are like driving a car from 50s – it is fan but you would do it more than 10 minutes just to experience this ride and then will drive away in your BMW X7…
So, do we, the High-Efficiency people, have today a stable, predicable and good quality part of drivers that we might use in our playback? Nope, we do not. The drivers we all, all of them are pain in ass and if the people who design amplifiers would have the same situations with tubes or transistors then it would be a ridicules situation. Taking a transistor a person more or less has a basic idea what might be taking out of this devise. In case of Low-Efficiency drivers, the direct radiators, the same concept might be applied to a degree. With the Low-Efficiency drivers - the driver’s result is black hole as it is absolutely not know where the sound of this driver will lead you and what the driver might need to be able to do what you expect.The Cat
"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche