WORKING CONDITION: Excellent - Incredible pair of units that are fully functioning and in excellent working condition. These units were just fully serviced and refurbished by Doctor Bass here in Los Angeles. Shorted tubes were replaced, all electrolytic capacitors were replaced, and performance was tuned and calibrated per spec the original BA-5A schematic. Note that the two units do not match perfectly - the gain reduction and levels are slightly off from each other--Maybe 4dB or so. XLR pigtails are already in place, making these two units plug and play, ready to go to work.


PHYSICAL CONDITION: Very Good -  Each unit has the normal amount of wear to be expected for their age, but both are looking fantastic with their aged military green patina. One of the meters has a crack in the housing but is intact and working fine. The power supply is in very good physical condition, with some residue and hints of grease pencil here and there. One of the unit's upper flip lids was cut evenly to expose the rack rails, for reasons unknown. Overall, the condition is very good and all is intact. The giant bakelite knobs, the drab matte military green and industrial design is a wonder to behold never to be seen again. 

INVENTORY #57301

BRAND: General Electric

MODEL: BA-5A

FUNCTION: Limiter

PRODUCT DESCRIPTION: This listing is for a Pair of very rare 1950's General Electric BA-5A Limiters with tube power supply. 

The General Electric BA-5A Limiter, introduced in 1947, revolutionized broadcast audio processing as one of the earliest feed-forward peak limiters designed for AM and FM radio stations. Developed during the post-World War II era, it addressed the critical need to prevent over-modulation and distortion in transmissions, ensuring consistent signal levels without compromising audio quality.

What sets the BA-5A apart is its innovative use of an analog delay line—a groundbreaking feature at the time. This allowed for "look-ahead" limiting, where the audio signal was briefly delayed (typically by a few milliseconds) while a sidechain detected peaks, enabling precise gain reduction before distortion could occur. Unlike traditional variable-mu compressors, which reacted after peaks, the BA-5A's feed-forward design with variable feedback ensured no transients slipped through, delivering ultra-fast attack times and minimal artifacts.

Built with all-tube circuitry, including 6V6 output tubes and a separate power supply, it provided warm, transparent compression ideal for voice and music broadcasts. Its rugged construction and reliability made it a staple in studios, enduring into the 1970s.

In the late 1940s and early 1950s, nothing else on the market had the BA-5A’s combination of feed-forward topology + analog delay line, giving it uniquely fast, transparent peak control. Its closest functional rival was the RCA BA-6A, but the BA-5A was the sharper, faster tool—essentially the “distortion police” sitting right before the transmitter, while the others shaped tone earlier in the chain.

SPECS:

• 5U Dressen-Barnes Corporation [tube] Regulated Power Supply Model D3-150L
  
• 7U BA-5A Limiter Serial #2074B
• 7U BA-5A Limiter Serial #2495

ACCESSORIES INCLUDED: This item comes with a power cable and does not include any accessories.

WEIGHT: Power Supply: 42lbs 19x12x9, BA-5A (x2): 32lbs 19x11x12