Essentially there are six different versions of the LA-2A, based on various design elements, parts, outward appearance, and parent companies. The six revisions can best be classified as: Revision 1 (the original); Revisions 2A, 2B and 2C (all inter-related in various ways); Reissue 1 and Reissue 2. The first four versions kept consecutive serial numbers, while the two reissues had their own numbering scheme.
The final, seventh version, appeared when Universal Audio was resurrected by Bill Putnam Jr., and the LA-2A made its modern reappearance in the line of "UA Classics".
Briefly the differences are most easily classified by company ownership:
- Revision 1 - the original, produced in 1962 by Teletronix under Jim Lawrence, inventor of the LA-2A.
- Revision 2A - Teletronix patent is acquired by Babcock Electronics
- Revision 2B - Teletronix patent is licensed from Babcock Electronics by Bill Putnam Sr. / Studio Electronics
- Revision 2C - Teletronix patent is acquired from Babcock Electronics by Bill Putnam Sr. / UREI
- Reissue 1 - late 70s reissue by UREI / United Recording Electronics Industries
- Reissue 2 - late 80s reissue after UREI is acquired by Harman Electronics / JBL
This unit is the first silver face version, dubbed Revision 2A, with the following features:
- Serial numbers 601-1000 (approx.)
- Faceplate is brushed aluminum with red "Teletronix Div.of Babcock" logo (the earliest units still had a greyface front panel)
- Teletronix patent acquired by Babcock Electronics Corp. of Costa Mesa, CA
- Type / Serial No. on a separate metal plate
- All rear panel graphics are screen printed
- Input transformer remains UTC A-100X
- This iteration had an added a compress/limit switch on the back
- ADL copy of original Opto.