The Locomotive Audio MODEL 40AM-1 is a professional-grade 500 series stereo octal tube preamplifier that combines vintage-inspired design with modern versatility, offering thick, warm, and harmonically rich sound through its 1940s American tube gain system, 6SJ7 octal tubes, premium in-house wound transformers, and an array of tone-shaping controls.

A Preamp That Redefines Vintage Sound

Designed for audio professionals seeking to capture the warmth and character of vintage 1940s recordings, the 40AM-1 takes inspiration from renowned preamps such as the RCA BA-11A and Gates SA-70. This meticulously crafted preamp integrates the pentode input and triode output topology of these iconic designs, blending their strengths to create a unique sonic signature. The result is a preamp that delivers a thick, compressed sound with a distinctive harmonic depth, ideal for a variety of audio sources.

Tailored Sound Control

The MODEL 40AM-1 offers extensive tonal shaping capabilities, allowing users to achieve the perfect sound for any recording. A 5-position Input Switch adjusts the transformer winding configurations in MIC and LINE modes, providing precise control over frequency response and signal level to the first tube stage. Meanwhile, the 5-position Response Switch refines the tonal balance and harmonic content, with settings that range from enhancing high and low frequencies to softening highs and emphasising midrange warmth. The Level Knob further fine-tunes the output signal, providing subtle tonal interplay with the response settings to allow complete sonic customisation.

Premium Components for Superior Performance

Every aspect of the 40AM-1 has been engineered with quality in mind. The preamp features MuMetal-shielded input transformers and nickel-and-steel output transformers, both meticulously wound in-house to ensure premium sound clarity and durability. The amplification stage employs two octal 6SJ7 tubes, one functioning as a pentode and the other as a triode, delivering up to 52 dB of maximum gain. A high-impedance direct input (DI) offers additional versatility for recording instruments, while a 20 dB pad and 85 Hz low-cut filter provide further options for managing dynamic and low-frequency content.

Visual Feedback and Ease of Use

The 40AM-1 ensures effortless monitoring and control with its three-colour LED output level indicator. This intuitive display transitions from green to yellow to red, providing immediate feedback on signal levels to help engineers avoid distortion or clipping. The preamp’s design supports seamless integration into professional workflows, ensuring a reliable and efficient user experience.

A Legacy of Innovation

The 40AM-1 represents a culmination of vintage-inspired circuit design and modern engineering. Its unique hybrid topology combines the lush compression of the RCA BA-11A with the feedback architecture of the Gates SA-70, resulting in a preamp that excels at producing rich, textured recordings. The 40AM-1 complements other Locomotive Audio products, including the WT-72 and 86B, to provide an exceptional suite of tools for professional studios.

Exceptional Craftsmanship and Reliability

Locomotive Audio builds every 40AM-1 with meticulous attention to detail, ensuring the highest standards of quality. Backed by a lifetime warranty, this preamp delivers dependable performance and gives professionals the confidence to invest in a tool built to last.

Inspiring Creativity

For audio engineers, the right tools can make all the difference in unlocking creativity and achieving a distinctive sound. The 40AM-1 empowers users with a blend of vintage character and modern control, enabling them to focus on creating extraordinary audio.