Quote Originally Posted by GM View Post
Early cabs should have holes [many small ones originally] and the fiberglass wedge since the Fs of early 803s were 50-60 Hz. Later ones dropped to around 35 Hz, so would be tuned lower with just the wedge covering a solid plate vent...
I want to say that the older cabinet is a 820A. Except check out the photos at the following:

1953 Altec 820c

He calls it a 820C, yet it has 803A woofers and holes at the bottom. But it also has a 811 horn and 802C driver. So it seems there was an evolution - horn evolved first, then the woofers.

Think I will pull the side panels off the older one this weekend to confirm which drivers and xover it has. I bet it looks like the one above.

... which begs the question, what are the date codes? They will be 391xxx.
On the drivers or the cabinets? There are no numbers on the outside of the cabinets.