After some additional research on the LaScala:
3. LASCALA:
1963: The La Scala is designed as a portable version of the Klipschorn to be used as a P.A. system for Winthrop Rockefeller's Arkansas gubernatorial campaign. Component designations were: Woofer K-33-J (Jensen), Midrange K-400 horn and K-55-V driver (Atlas), Tweeter K-77 (Electrovoice).
1966: The designation for the Type 1RC crossover network was changed to Type A.
Sept 1967: Transition to the K-33-M. The records are not clear as to the origin of this driver but it is believed to be an Eminence driver with an Alnico magnet.
Jan 1968: Transition to The K-33-P Woofer (CTS Paducah KY)
1971: The Type AA crossover network was introduced featuring Sneer diode tweeter protection.
1974: K-56 mid-range driver (Electrovoice 1828) is used for a short period as a temporary replacement as the supply of K-55-V drivers was interrupted.
1975: Transition to The K-33-B Woofer (CTS Brownsville TX)
1975? - 1979: K-33-E (Eminence) and the K-33-B were used interchangeably.
1979: The Eminence K-33-E woofer is used exclusively.
1983: The Type AL crossover network was introduced incorporating steeper filter slopes for enhanced tweeter protection and smoother response in the crossover regions.
1983: The Type AL-2 network was introduced to accommodate the new K-55-M mid-range driver. This Electrovoice sourced driver was essentially the same as the previous K-55-V with a smoother response.
1987: The aluminum K-400 horn was replaced with the K-401 structural foam horn resulting in slightly improved distortion figures.
1989: The AL-3 network was introduced to correct for a shift in the output of the K-55-M mid-range driver.
2000: Electrovoice ceases production of the K-77-M and K-55-M tweeter and mid-range drivers. The search for replacement drivers and the acquisition of the EV tooling is sought. Very limited production of a few pairs occurs at the end of 2000 and the early months of 2001 using existing part stocks
May 2001: The Atlas PD-5VH (Current version of the previous K-55-V) is modified slightly and christened the K-55-X. The various components of the K-77-M tweeter are either retooled or sourced from the new owners of the tooling and assembled by a third party. This variant of the tweeter is designated the K-77-F. An entirely new network (AL-4) was created to accommodate these driver changes. Fusing is eliminated in favor of a polyswitch for tweeter protection. The tweeter on the La Scala was flush mounted for the first time using "Z" brackets. A metal input panel with binding posts in a bi-wire configuration replaced the traditional screw type barrier block.
Dec 2005: The La Scala II debuted as the first "finished" version of this model featuring a two piece veneered cabinet utilizing 1" MDF instead of the traditional 3/4" plywood. The AL-5 network was introduced to compensate for the improvement in low frequency response resulting from the change in cabinet construction. The HF and LF cabinets stacked together using thick rubber isolating spacers. Finish variants were reduced from 6 to 3.
April 2006: The horn portion of the K-77-F tweeter was re-tooled to include a recessed flange eliminating the need for the separate "Z" bracket and attachment rivets, the new designation is the K-77-D. This also allowed the updating of pre-Z bracket La Scala’s (prior to May 2001) to flush tweeter status without motor board modification.
2008+: There have been a number of new versions produced, and Klipsch has transitioned the crossovers to a more modern design. For information on the recent changes, please go to the website (Klipsch.com) for product information.
