IMO they could be Electro-Voice cabinets, or they could even be DIY work.
My reasoning is based on the fact that the top section doesn't seem to be high enough to allow even a 811 sectoral HF horn. Moreover, to my knowledge, the only corner enclosures which Altec Lansing manufactured are bigger and contained their Duplex coaxial monitor 15 inch 604 driver. Altec never used foam grilles.