The black would have been used for a total blackout of the light. A simple metal shutter to be used like an on/off switch. When carbon arc lights were used they rarely were turned off until the end of the show. Hence the blackout switch.
The black was for blackout. There was no on/off switch with arc spots because you had to adjust the arc every time it was turned back on, so you had a blackout or solid disc to shut off the light when it was not needed during a performance.
The Greats played here such as Stevie Wonder, The Supremes, Duke Ellington, Sammy Davis Jr. along with Skinny Puppy, Sonic Youth, Nine Inch Nails and the Red Hot Chili Peppers, etc.
Christina Victoria Grimmie;
You are in heaven now singing among the stars.
The people send their love.
She came in like a wrecking ball !
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Some day, her Prince will come
to save her from this harm that haunts her.
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Don’t get too close
It’s dark inside
It’s where her demons hide.
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So you want to play with magic
Boy, you should know what you're falling for.
Baby; do you dare do this ?
Because she is coming at you like a dark horse.
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She is bulletproof, nothing to lose
Fire away, fire away
Ricochets, you take your aim
Fire away, fire away
You shoot her down but she won't fall.
She is Titanium !
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Hello from the other side.
She must have called you thousand times
to tell you she is sorry for everything that she has done.
But when she calls you never seem to be at home.
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She said no more counting dollars.
She will be counting stars.
Since you were on stage, I'm guessing the square things in line with the mirrored ball were tubes for a pipe organ. Did you find anything else for one?
Some of those old records are probably worth a small fortune to the right collector, but I'm sure none of them are in good enough condition to even play.