some of the vintage manufactured EF86's were prized for their low microphony and low noise. they were often used in microphones and mic pre's for this reason... plus you could get good gain from this tube.

As Doug pointed out... this tube was used in many vintage designs as a voltage amplifier.

If you can get them cheap and they are of (especially) european manufacture... get'em. Even if you don't want or choose not to use them yourself... they go for pretty good bucks (check ebay for sales histories) and there is still plenty of demand for these guys.

best of,

msl