Langevin AM-419A 1960's

Fixed-Gain Console Line Amplifiers

• Pure Utility Stage: This version drops the passive rotary attenuators entirely. It serves strictly as a 4-channel, fixed 24 dB gain card. [1]
• Signal Purpose: In large-format desks, these are used as isolation buffers or post-summing utility amplifiers where level control is handled either upstream (by a master channel fader) or downstream (by an external patch bay or machine input).

2. Dedicated Remote Racking / Card Blocks Adding the following to control the gain.

• AI Mode Conversation: Langevin passive modules 4 channel MG-61-4Langevin passive modules 4 channel MG-61-4The Langevin MG-61/4 (often noted as MG-61-4) is a vintage, 1960s 4-channel passive Board Master Gain Control module designed for theAM-419A.
• Functionality: It serves as a ganged master attenuator module. The forward slash in Langevin's catalog denotes the section count, meaning an MG61/4 dictates a four-section (4-channel) ganged configuration. [1]
• Impedance: It functions as a 600/600 ohm passive attenuator. [1]
• Control Handling: When these specific modules are salvaged or racked for modern studio use, engineers must wire external 10k or 600-ohm potentiometers to the card edge connector to act as manual gain/level controls.