The Venerable Koss Porta Pro
Long before I became professionally involved with headphones, the Koss Porta Pro was a great little portable headphone. In fact, it was one of the first headphones designed particularly for portable applications. It has remained relatively unchanged to this day ...
... thank goodness. If it ain't broke ...
Koss Porta Pro ($49)
Cast you mind way back to the early eighties --- Olivia Newton-John's "Physical" was at the top of the charts; if you were really cool, you were into roller disco; and Sony's Walkman had just appeared and was taking consumers by storm. It was in this environment that John C. Koss decided to jump on the portable audio bandwagon and produced the forerunner of the Porta Pro, called the "Koss Sound Partner" or KSP headphone, and a portable AM/FM radio called the "MusicBox."
Over the next couple of years, Koss continued to work on their designs and discovered they could improve on the KSP. From the Koss website "History of the Koss Porta Pro:"
"The Porta Pro transducer was designed to be assembled as a part of the ear cup assembly on its own pivoting ball and socket. A specially crafted ear plate was painstakingly developed to front load the transducers to optimize diaphragm excursion and limit distortion. Rear damping and specific resistance was accomplished through the creation of a series of tiny perforations molded into the element case and originally discovered in earlier engineering work in Koss electrostatic technology and computer optimization of acoustic performance with the Koss computer maximized loudspeaker systems introduced in the late 1970s. "
In 1984 the Koss Porta Pro was introduced. Now with it's new driver housing and "Comfort Zone" earpad pressure adjustment, the headphone was ready for prime time. It is truly a testament to these performance portables that they remain little changed today after all this time ... and that they remain strongly competitive long after cassettes and the Walkman have gone the way of the dodo. These are great little cans.
The Koss Porta Pro is a small earpad (on-ear), open (unsealed) headphone. Usually a sealed headphone is used for serious portable applications to cut down on external noise, so I would characterize these cans as light-duty, general purpose headphones rather than strictly portable headphones.
The physical design of these cans is quite unusual, and telling in that it was designed long before the wealth of headphones we see today. They are very obviously the result of innovation across the board, and developed without the context of an array of competitive products. Quite unique.
The headband is two simple metal bands in an arch to go over the head, which slide relative to each other to provide head size adjustment. This is a simple and effective mechanism, but can catch your hair from time to time.
The headband terminates in a plastic piece that acts as a "temple pad" and allows three settings of adjustment for how hard the earpad rests on the ear, called the Comfort Zone adjustments. This adjustment is spring loaded and won't remain in position when the headphones are removed. I felt that this adjustment is fairly useless as the headphones don't exert very much pressure on my ears when set at its firmest position, and the headphones sound best as they are more closely coupled to the ear.
A now-discontinued lower-cost version of these called the Porta Pro Jr. didn't have these adjustments, and I felt they were a real bargain at the time. There is now a low-cost version called the Sporta Pro, and a clip-on style called the KSC-75; both use the same driver and have very similar sonic qualities --- which are quite good.
Between the temple pad and the driver/earpad is what Koss calls the "ear plate." This is a small arm that changes its position with the Comfort Zone control. This arm folds inwards and up into the band area for storage. When folded up it reveals a small hook and loop on the undersides of the temple pads, which hook together and make the headphones into a very small package for transport and storage. I don't recall ever seeing another headphone with this type of design ... but it does work very well.
The earpad/driver is mounted to the ear plate using a balljoint, which provides ample swiveling to conform to the angle needed to lay flat on the outer ear.
Ergonomics and Comfort
The Porta Pro is a very light headphone weighing in at a mere 2 ounces. This headphone remains very securely in position on the head with very little clamping force due to it's amazingly light weight. Even at it's firmest setting, the earpads do not press hard on the ears, making these little cans easy to wear for extended periods of time.
The four foot "Y"-cord cable is just the right length for use with portable players and laptops, and is terminated in a fairly small 1/8" mini-plug, that should fit through the holes in most portable player/cellphone cases. The headphone does come with a 1/8" to 1/4" adapter