During the 1960s, the whole electronics industry changed from the vacuum tubes that had been its standard (and only) amplification devices since 1906, when Lee de Forest first invented the "Audion" tube. What it changed to was the transistor the first "solid-state" device which was cheaper and easier to make and use; much more compact in size; cooler-running (tubes must be hot to operate); lower output impedance (so transistor amplifiers required no output transformer) and overall, so technically advanced that it won for its inventors, Bardeen, Brattain, and Shockley, the 1956 Nobel Prize in Physics.
The transistor absolutely revolutionized the electronics industry: With its commercialization, electronics products could start instantly, with no "warm-up" period; could be made very much smaller (so that computers, for example, would no longer need an entire large building to house them, and radios could be built small enough to fit into a shirt pocket). They were new; they were good; and they just about resulted in the total destruction (with certain exceptions, like the CRT tube or replacement tubes for existing products) of the vacuum tube industry and vacuum tube-based products.
Once the cheering died down, though, people began to notice that, in addition to their many and obvious benefits, they also had a few faults especially in audio applications. For one thing, early (germanium) transistors had a tendency to "hiss", adding a just-barely-audible sibilant overlay of noise to whatever was played through them. They were also indiscriminate in the harmonic distortion they introduced, treating all harmonics equally, instead of favoring those of "even"-order (second, fourth, sixth, etc.) and suppressing those of "odd"-order (third, fifth, seventh, etc.) as did tubes. In either case, distortion is distortion, of course, but because human hearing finds even-order harmonics pleasing (Most musical instruments gain their character by adding even-order harmonics to the "fundamental" tones played on them) and hears odd-order harmonics as "harsh" or "grating", early solid-state (transistor) electronics got a reputation for being hard to listen to, while tubes were often fondly remembered as being "sweeter", "warmer", or more "musical".
The result was that, even after transistors had just about totally wiped-out most tubed audio electronics, first Audio Research, and then many others led the Hi-Fi industry and its audiophile supporters back to tubes, which, for many, have been resurrected and are regarded, even today, a half-century later, as the pinnacle and sine qua non of high-end music reproduction.
The first real high fidelity sound reproduction may have been in the laboratories of Bell Telephone, back in the 1930s and, by 1939, Disney, working with RCA produced Fantasia with an optical soundtrack using eight stereo channels ("Fantasound") .The results were spectacular, and the speakers used as for virtually all theatrical, cinematic, and sound reinforcement applications of the day were horns.
The reasons for that were twofold; first, horns were the only things loud enough to provide satisfying theatrical sound levels from the low output tube amplifiers of the day (even in the mid to late 50s. the McIntosh MC60, at 60 Watts of output, was considered a huge amplifier and a major technological accomplishment) and second, because they were the professional choice, they, more than any other kind of speaker, had been developed and perfected for peak performance.
When Hi-Fi came to the home market in the decade following World War II, horns the Klipschorn, the Lansing Hartsfield, the Electro-Voice Patrician, all large corner horns were what audiophiles dreamed of, and even sometimes, because horns need to be BIG to make deep bass, built their houses around. That all changed, though, after 1954, when Edgar Villchur invented the "acoustic suspension" speaker and established a company (Acoustic Research, Inc.) to produce and market it.
Villchur's speakers were able to produce truly deep (30Hz) bass from an amazingly small box (a largish "bookshelf" speaker) and were so successful and became so popular that, at one point, his third offering, the AR-3, commanded a 32% share of the total home loudspeaker market, and horns were no longer king.
Small boxes went to smaller boxes, while, in the meantime, electrostatics first the Quads, then Acoustat and Stax, Soundlab, Martin-Logan, and others, followed by magnetic-drive speakers like the Magnepans and Eminent Technologies, and then ribbon dipoles, like the Apogees and, in turn more box speakers reached the top of the audiophile wish list. Then horns again took their place at the top, starting, perhaps, with the strikingly colored (Red, White, Orange) and boldly styled horns and horn-hybrid systems from Avantgarde Acoustics. And then it went around and around again, with, every few years, a change in what's popular, with the newest "wonder product" often being either the resurrection or a new iteration of some already once popular technology.
In Hi-Fi, particularly at the very High End, things tend to run in cycles, not just with tubes and speaker designs going from exotic to ubiquitous and back again, but with practically everything else doing the same thing.
Just as the advent of transistors signaled the "death" of tubes, only to find tube gear once again a best- seller years later, horn speakers went from the audiophiles' darling to effectively obsolete for the home market, and then, after other loudspeaker types had gone through their own cycles of popularity and decline, they came back again in full force and then declined to relative rarity.. In fact, most of the elements of our hobby seem to come and go, usually, it seems, to come back again, at some later time.
Headphones are a perfect example of this re-cycling of technologies. At the very dawn of the radio era, headphones were de rigeur for listening to crystal radio sets, which lacked the power to drive anything else. Then, as times progressed and every radio came to feature a built-in speaker, headphones dropped back into use only by professionals like airplane pilots, radio announcers, and musicians and sound engineers. The Sony Walkman and other personal portable music players brought headphones another burst of popularity, years later, only for them to largely drop out again until just the last several years, when a new kind of personal audio technology and demographic has made them, once again, very big business.
It isn't just our music playing gear that has these cycles, either. The same has held true for the actual recording and storage formats for our music: The LP record, for example, was, for more than half a century, THE most popular and best-selling format for recording and selling music. Then, in 1982, the CD came along and, just as transistors did with tubes, the CD nearly drove the LP to extinction.
Many, though, said that CDs had the same problems as did the early transistors: Despite their claim of "perfect sound forever", CDs and CD players were said to be harsh-sounding and, regardless of their ruler-flat frequency response; their clearly superior signal-to-noise ("S/N") ratio; their claimed greater dynamic range; and the fact that they would never suffer the skips, ticks, and pops, of vinyl records, LPs and the equipment for playing them came back to become a fast-growing segment of the current audio market not just at the High End, but even in the popular and budget price ranges.
While the resurgence of the LP has been happening, the CD has been quietly slipping away, until it's now CDs and CD players that are becoming rare and even premium digital gear manufacturers like OPPO are moving away from optical disc players. You can read Enjoy the Music.com's review of the OPPO UDP-205 Hi-Res Music & 4k Ultra HD audiophile Blu-ray disc player here.
The new thing is computer-based music storage and transfer, with no "hard" medium (no disc) at all. This has been growing in popularity as the CD has been lagging, and there are those who believe that except for hard-core vinyl lovers the time of actually touching a recording to play it instead of simply punching it up on your computer will soon be long gone.
Whether this will actually come to pass, or whether this latest trend will, like all the others, move on to be replaced or augmented by something we've already seen, I have no knowledge whatsoever. It might even be that the next big thing won't be anything familiar at all, but will be direct brainwave transmission, involving no physical equipment of any kind. Personally, I don't really care, as long as I can still sit back; close my eyes; select my favorite recording; and...