The 2309 horn (part of the 2309 horn + 2310 lens combo, called 2390), was an elliptic 305 mm long horn, and the outer size of the mouth was width: 267 mm, height: 191 mm.
However, I don't have the inner size of the mouth. Would somebody be so kind as to apply a ruler to the mouth of their 2309 horn?
Thanks in advance!