[Promick]

After all, the company Koss during the leadership of its founder John Koss was truly great, and then the optimizers came and it turned out what happened. Otherwise, how to explain the fact that the company could produce small-scale batches of headphones for "human testing". The case in the practice of the audio industry is unprecedented. If you enter the tricky query "KOSS K-500" - AKG-K-6 in Google, there will be just a few links in the search results. And there are even fewer informative ones, but they are there. Namely, links to the American newspaper Independence Examiner from 79-80 years, that a small-scale model Koss K-500 went on sale for$ 79.90. More than 5 years of "hunting" on Ebay brought results and I was able to buy this model completely new in a box and most importantly with instructions. From which we learn that the model uses a closed 50 mm driver with the world's largest 25 mm sound coil. I took them apart and can say with 100% confidence that the driver is really unique and has not been used on any other model of Koss.

 

[Bingturong]

Very interesting, I never heard of this Koss model and none of my usual databases list them. I'll go through my catalouges to see if they pop up some where. Big question is, how do they sound?

 

[Promick]

The sound of these headphones is great! And not like more than one sound of Koss headphones of that period. The sound is absolutely smooth just in moderation and bass and high and medium frequencies.

 

[Bingturong]

The more I look at them the more bewildered I become. I'm not sure if it's the lightning but they appear greyer than the regular koss beige. The headband and earpad cushions are standard koss for the time but the earcups themselves appear to be shared with only one other koss model, the Reference One, another exceptionally rare koss model. The driver baffles are very similar to the Pro 4/aaa though the holes are thicker. The driver itself looks almost identical to a Pro 4/aaa. In fact specifications are pretty much the same for both except for the sensitivity which is 0.58 compared to the Pro 4/aaa's 0.24. I do not know about the voice coil size though in regards to the Pro 4/aaa.

 

[Promick]

Yes, it's like a Reference One, but the color is different. About drivers is interesting. I have a pair of Koss Tech 2 headphones, there is the same driver as 4/aaa, tomorrow I will disassemble them and take a picture next to them.

 

[Bingturong]

So it isn't just my eyes then. I don't think they're any other Koss with the same color.

 

[Promick]

Yes, their color is unique. I will say more: the photo does not show this, but the wire is not black! It is dark in the color of the headphones..