I am familiar with what tubes are, but unfamiliar with prices. Without taking it about, I can see two tubes through the back grid. They are about 3 inches high, and about as round as a silver dollar. But unfortunately, the tubes are marked on the other side of the tube, from which is viewable.
Tubes should be pretty easy to find. But don't quote me.
If any one is interested, I can include two tripod speaker stands and 2 Kustom speakers too. I got this thing at a very reasonable price, and have no use for it. So, for the closest offer to what I have in mind I will sale it.
Would work perfect for band, practice pa or for the hidden DJ in all of us.