Studio 54.......

The club had a superb sound system, built and designed by some of the best people in the business - RLA [Richard Long & Associates]. Richard was also the one who was responsible for the sound system at the Paradise Garage, a system that still today is said to have been the best system ever in the world.

The equipment at Studio 54 were comprised of 6 3-way "Waldorf" horn loaded/bass reflex main bass boxes, 6 "Bertha/Levan" bass horns, 4 "Z" tweeter arrays & 2 "Ultima" 3-way full range boxes. This system also included the now famous RLA X-3000 DJ crossover. This sound system was the reason for this and many other clubs during this era's success.
Richard is unfortunately no longer with us today, but some of the RLA designs, electronics and speaker boxes are available from the New York based company GSA [Gary Stewart Audio]. GSA can help you if you're interested in building a sound system similar to the one in '54'.
Also, in the GSA shop they still have a bunch of things from the original Studio 54.
By the way, the original "Man in the Moon" sign is told to be installed in the existing Studio 54 club in the MGM Grand in Las Vegas these days.