Koss PRO-4, PRO-4A and Pro/4 AAA Plus headphones Specifications

Sidebar 2: Specifications

Description: Over-the-ear, closed-back headphones.
Price: Koss PRO-4, $45 (1963); Koss PRO-4A, not noted (1968); Koss PRO-4x, $85 (1982); PRO/4 AAA Plus, $70 (1991); PRO-4AA, $99.99 (2020).
Manufacturer: Koss Corporation, 4129 N. Port Washington Ave., Milwaukee, WI 53212. Tel: (414) 964-5000. Fax: (414) 964-8615. Web: koss.com.

Koss Corporation
4129 N. Port Washington Ave.
Milwaukee, WI 53212
(414) 964-5000

dc_bruce's picture

were Koss Pro 4A's which I bought in 1968 or '69. They were a bit bass heavy and not particularly transparent. I replaced them a few years later with Sennheisers, which were lighter and far more comfortable. They also sounded better, albeit with less powerful bass. In 1971, I acquired a pair of used Stanton electrostatics, which were a revelation in transparency although lacking a bit in bass "thump." After a year or two they failed, and I never went back to headphones again.

I believe Koss gets credit for being the first to actually develop purpose-designed headphone drivers. It is sad that the company, after such a strong start, "lost the plot" so badly. They are still in business, I believe. One of their other problems was an accounting scandal a few years ago (the company's stock is/was publicly traded) which resulted in a wholesale clean-out of the executive suite. Sad to see this happen, especially when headphones have become a fashion accessory (Beats) as well as an audiophile "thing."

Bogolu Haranath's picture

Try Audeze LCD-1, $399, reviewed by Inner/Fidelity and Hi-Fi News ...... Easy to drive 13 Ohm impedance :-) ......

PAR's picture

You can't compare the Audeze LCD-1 with these Koss cans. The Audeze is current, these Koss reviews date from between 1963 and 1991 and the featured headphones haven't been manufactured for decades.

Bogolu Haranath's picture

Yes, I know ...... I was responding to dc_bruce's comments above ....... LCD-1s are in the same price range as some of the top model Beats headphones ...... LCD-1s are better quality for about the same price :-) ......

Metalhead's picture

Definitely a rite of passage as I was one of the folks moving from cheese-o to fancy Koss Pro 4AA headphones in 72. I think they were double A's but never saw that listed so maybe I may be the unreliable narrator. I did not have a mic connector and pretty sure I remember that correctly.

Enjoyed them but not too worried about quality as they were just playing Tull, Beatles, Zep and Floyd. I did move up to the first Koss electostatic phones and they were fantastic. Koss ESP-1 (think that was the model).

In any event LOVE the J. Gordon review where he calls out a set of Koss as being a dog and it is just refreshing to read a one or two sentence pan without the current three paragraphs or more of wrangling a redeeming feature out a component or piece in for a review.

Don't use headphones any more but appreciate you posting a blast from the past.

tonykaz's picture

They still sell on eBay for between $25 and $150. ( $11 Shipping )

I've owned two of these and remember them to be heavy, uncomfortably hot, awkward and replaced as soon as ANYTHING better came along. I've seen these things in a good many Audiophile's homes ( mostly unused ).

There wasn't much in headphones until Sennheiser came along. So people would have the Pro-4 or seek out the STAX ( that I carrried but were far too expensive ).

Seeing the KOSS photo reminds me of how incredibly far we've come.

Tony in Venice

ps. they were made in Wisconsin, my origin home, ( not chinesium ) so they seem to survive rather well and are not being thrown abandoned into another Waste Management Land Fill filler.

mrounds's picture

I bought a set of Pro/4AA (yes, double-A; sound is much like the original Pro/4A as reviewed) in college. Cans were necessary in the dorm, especially cans with the gel surrounds.

They were (and still are) heavy and uncomfortable for long sessions. Sounded much better than the 6" San Franciscan (Goodmans) speakers on my dorm stereo. A tad boomy, and somewhat rolled off in the treble, but that's what tone controls and a switch to turn off loudness compensation are for. The EPI 100 speakers I got after college (and still have) are far more neutral sounding.

The original set finally died - wiring problems - in the early '90s. Koss had never been very good about advertising their lifetime warranty, so I bought another Pro/4AA from Radio Shack - exactly like the original after about 20 years. Still have them. They work well when listening to stuff from the computer in the wee hours. They again developed a wiring problem about 10 years ago; sent them back, and Koss fixed them for free (except for the cost of shipping them there).

Yes, there are far better phones now, especially if the budget is unlimited, but these are here, and they work. Pretty well, actually.

otaku's picture

Yes, I ran out and bought a set after listening to them in the listening room at our college student lounge (anyone remember listening rooms?). After I drove two hours in the rain to go buy a set, my poor Dad had to make the same trip to get a set for my brother. I had them for probably 15 years, finally gave up fixing them.

Ortofan's picture

... the choice of Pete Campbell on the TV series Mad Men.



deckeda's picture

The air from the headband "squares" emptied, the air from the ear pads did the same (replaced them once) and I don't ever recall the sound as anything special. But they were my first. I was always interested in hearing the HV/1A and thought that style was the future. And in a way, it has been (for pretty much everyone else.)

I liked the tension adjustment innovation for the PortaPro, but never appreciated the "good sound" they were supposedly known for.

In subsequent years it was Grado for me, and modernity.