The SA-3A is a dual channel replica of the UREI/Teletronix LA-3A optical compressor from Serpent Audio (formerly Shadow Audio). PCBs and kits consist of one channel + power supply, but two channels can be linked and built in a single 2RU case.

Notable Features:

• Simplifies the complex wiring of the original for DIYers
• Transformers:
  • Input: Cinemag (same as in Universal Audio’s reissues)
  • Interstage: Custom reproductions by Ed Anderson
  • Output: Ed Anderson
• Accepts many modern transistors
• All voltages and components are identical to the original LA-3A

Price:

• $300 for stereo PCB and transformer bundle
• $55 for stereo front panel
• $20 for stereo matched transistors
• $25 for power transformer

More info:

• PCBs available on the White Market
• The SA-3A support thread
• Schematic (PDF)