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 a limited edition silver face version dubbed Reissue 1, with the following features:
- Serial numbers 101-400 (approx.)
- Faceplate is brushed aluminum with red "Teletronix" logo
- Type / Serial No. is on a single sticker, with the UREI logo and no address
- (final models have a different UREI sticker with a Sun Valley address)
- The T4A opto module is replaced with a T4B
- A safety switch is included so power shuts off when front panel is opened