The Wireless Walkman... From 1988
In 1988, Sony unveiled a remarkably small unit, the WM-505 (I can't confirm this was ever released in the USA - mine has Japanese writing on it...). There was no shape-shifting transformation needed to play cassettes, and the unit boasted wireless headphones. That's right, 20 years before Bluetooth you could jam out to your mix tapes without getting tangled up in cords. Sadly, I can't report how well it works as I don't have the wireless earbuds, which also would have been relatively new in 1988.
Key to this model's compactness is the use of a slim ni-cad battery (sometimes called a "gumstick") in both the player and the headphones' wireless receiver. Fortunately an add-on unit lets you plug in a regular AA battery. Also the playback head is tucked into the door like on the WM-10 to save space. All metal construction is thinner and more durable than plastic would have been, and does a superior job of protecting the expensive unit from inevitable knocks.
Back In 1983, Sony had created the WM-10; a miniaturized Walkman not much larger than the cassette itself, though it was a bit of a cheat. In order to play a cassette, the WM-10 has to expand to actually fit the tape. A new sort of motor, and new ideas about how to drive it with a single AA battery made it possible to create a cassette player about the size of a cassette case. The result was tres chic, and predictably fragile. Sony was justifiably proud of their achievement, and even show off the WM-10's innards in a commercial from the 80s.
These two aren't the only examples of miniaturization of the portable cassette player. Other manufacturers toyed with reducing the size of portable cassette players, but Sony was always at the forefront in the portable cassette player game in those years. Even non-brand players tried to get small. We once featured a cheap knock-off unit that paid tribute to (stole?) many of Sony's space-saving strategies - which would have been great if the darned thing actually worked.
As we get further and further away from playing music from physical media, it's easy to forget just how far technology has actually progressed. I heard some members of "the youth" recently muttering how primitive cassettes were – which they adamantly are not. The idea of miniaturizing a reel to reel's tape transport path and enclosing it in an inexpensive cassette is still a clever idea.
Though there are many praiseworthy innovations that went into the design of the compact cassette, one aspect that couldn't change over time was its size. Philips established the cassette standard in 1964, which limited how small a player could be (it suddenly occurs to me what a horrible world it would be if Philips had created a dual standard with smaller cassettes played through an adapter, much like JVC's odious VHS Compact format. Brrr....). It would be more than a decade before the tech to play back a cassette would be anything close to pocket sized.
When Sony rolled out the first Walkman in 1979, it was an amazingly compact device for its time. Innovation in miniaturization quickly shrunk the Walkman down to about the size that we recognize today, even in the cheapest models. It makes sense that there would be a hard limit to how small the Walkman could get. The transport mechanism, motors, batteries, etc. all take up space.
Today's music players have freed themselves from such earthly needs as motors or bulky power sources. The physical size of computer chips and rechargeable batteries keeps on shrinking making it easy for just about anyone to create a pocket-sized music powerhouse with panache. But let's not forget those who met the real physical challenges of creating the smallest possible cassette players more than 20 years ago, and still managed to do it with style.
(thanks to Walkman Central for the WM-10 & TPS-L2 pictures)
Original 1983 Commercial for the WM-10
Video showing off the Wireless Walkman WM-505 in action
A Walkman knockoff that's the smallest and worst we've seen
The real inventor of the Walkman
Digitize cassettes via a new tape deck with USB output