The Eminince Vintage 50 did not have a vented core. It's easily identified from the MS-12 as is does not have a hole in the middle of the back and no Knight who says Ni (Icki, Icki, Icki, Icki, Patang, Neee Wom, zurm zurm, zurm).
There are also Mesa Black Shadow EV-12L's floating around with 400 Watt stickers on them.