{"product_id":"locomotive-audio-40am-1","title":"Locomotive Audio 40AM-1","description":"\u003cdiv lang=\"en\"\u003e\n\u003cp\u003e\u003cstrong\u003eLocomotive Audio 40AM-1\u003c\/strong\u003e is a single-channel tube preamp in a 500-series module built on octal tubes, combining the pentode input and triode output stage of the RCA BA-11A with the feedback topology of the Gates SA-70 console, both 1940s American broadcast designs. It's the single-channel counterpart to the two-channel 40AM-2 from the same octal Locomotive preamp family.\u003c\/p\u003e\n\u003ch3\u003eOctal tubes instead of a miniature 12AX7\u003c\/h3\u003e\n\u003cp\u003eTwo 6SJ7 tubes (one strapped as a pentode on the input, the other as a triode on the output) deliver a maximum gain of 52dB and the heavy, dense character typical of American broadcast consoles from eighty years ago. MuMetal-shielded input transformers and nickel-and-steel output transformers, wound in-house at Locomotive, finish the signal path.\u003c\/p\u003e\n\u003ch3\u003eA 5-position Response switch instead of one fixed tone\u003c\/h3\u003e\n\u003cp\u003eA 5-position Response switch reshapes the circuit's tonal balance, and a 5-position input switch selects the transformer winding configuration for mic or line mode. A -20dB pad, an 85Hz high-pass filter, a high-impedance front-panel DI input and a 3-colour LED meter round out the control set packed into one 500-series slot. Octal tubes are less common in 500-series preamps today, which makes the 40AM-1 a distinctive pick for engineers specifically chasing that eighty-year-old heavy character, rather than another 12AX7-based replica.\u003c\/p\u003e\n\u003ch3\u003eKEY FEATURES\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSingle-channel octal tube preamp, 500-series format\u003c\/li\u003e\n\u003cli\u003eTubes: 2x 6SJ7 (pentode input, triode output)\u003c\/li\u003e\n\u003cli\u003eDesign combining the RCA BA-11A and Gates SA-70 (1940s USA)\u003c\/li\u003e\n\u003cli\u003e5-position Response switch\u003c\/li\u003e\n\u003cli\u003e5-position mic\/line input switch\u003c\/li\u003e\n\u003cli\u003e-20dB pad and 85Hz high-pass filter\u003c\/li\u003e\n\u003cli\u003eHigh-impedance front-panel DI input\u003c\/li\u003e\n\u003cli\u003eHand-built in the USA\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eTECHNICAL SPECIFICATIONS\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eType: single-channel octal tube preamp, 500-series\u003c\/li\u003e\n\u003cli\u003eTubes: 2x 6SJ7\u003c\/li\u003e\n\u003cli\u003eMaximum gain: 52dB\u003c\/li\u003e\n\u003cli\u003eTransformers: MuMetal input, nickel-and-steel output, in-house wound\u003c\/li\u003e\n\u003cli\u003ePad: -20dB\u003c\/li\u003e\n\u003cli\u003eHigh-pass filter: 85Hz\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/div\u003e","brand":"Locomotive Audio","offers":[{"title":"Default Title","offer_id":54961112678737,"sku":"61005","price":1391.0,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0729\/8741\/0769\/files\/LocomotiveAudio40AM-11.webp?v=1789901933","url":"https:\/\/wrdtunes.com\/products\/locomotive-audio-40am-1","provider":"Wired Tunes","version":"1.0","type":"link"}