Old BOSE 501 Direct/Reflecting Loudspeaker System

[WillKennet]

I have three questions:
My 501's do not show any evidence of ever having the "Direct Energy Control" flap. Was this control an "upgrade" added on later models, or my speakers mine a "knock-off" using the original name plate/terminal board on back?
Where can I get a schematic of the original crossover?
Lastly, can anyone provide the specifications for the tweeters and/or where an equivalent is obtainable?

Any help is greatly appreciated. Stay Safe everybody.

 

[sKiZo]

The flap only came on the original design to direct the sound from a single tweeter. Later versions of the 501 had dual tweets that didn't require any fiddling about to create their signature direct/reflecting sound as long as you followed factory suggestions when setting them up. They did the same with the 201 and 301 series over time.