Bought 2 of these from a flea market in France for 10 Euros!! Had this one refurbished by Beyer. It has a hypercardioid polar pattern and an almost flat frequency response from 40hz to 18khz . Sounds fantastic on anything with rapid transients. Tambourine, shakers, hi-hat,etc Also great on guitar cabs, providing a serious amount of low-mid punch and crisp clean highs.
There is also this version of the original M260 that comes with a M-S (Music & Speech) switch which in S mode produces an LF roll-off from 50hz
Here is an interesting picture of the M260 ribbon assembly. The strange shaped plastic horn, which is glued to the magnet, helps to produce the hypercardioid polar pattern by causing a shift in the phase relationship between the front and rear of the ribbon. N.B. The ribbon (as seen in the centre, beneath the wire gauze) is crimped at either end but pleated (to produce rigidity) down most of it’s length creating a piston-like movement as sound strikes the ribbon.
Tech Spec below from 1965 catalogue
This is my 1980s Beyer M260N(C) shortly before I put it back on ebay. These later models have a fixed roll-off from 80Hz. Nothing wrong with it….. but (to my ears) the older model just sounded better on almost everything! Maybe one to file under ………………… Beware of ‘Up-grades’ …….