

A 1940s American-Style Stereo Octal Tube Preamp Designed for Big, Thick Results
Looking for a preamp that will give you that vintage 1940s sound? Known for their big, compressed sound, the octal tubes in the 40AM will give you a thick and round result. Much like our popular 14B compressor, the 40AM was derived from a few of our favorite vintage inspirations and then combined into one ultimate creation. With the pentode input and triode output of the RCA BA-11A, feedback setup of the Gates SA-70, and output transformer design of the Telefunken V72, you can expect the 40AM to be versatile enough to use on most sound sources while allowing you to manipulate the results with its versatile set of features.
TRANSFORMERS
Super Premium MuMetal shielded inputs and nickel & steel outputs set the stage
TUBES
Two octal 6SJ7 tubes (one used as pentode & one strapped as triode) amplify the signal with 52 dB of max gain
SOUNDSTAGE KNOB
A 5-position rotary switch allow the user to alter frequency and transient response as well as distortion
LINE MODE
Dedicated XLR input connectors for sending audio 'out-of-the-box' without fear of phantom power being applied
The 40AM Experience
While it is possible to drive into distortion by overloading the input or hitting maximum output headroom, the 40AM's true beauty lies in the subtle nuances available by adjusting any combination of its features. Whether you’re choosing between input transformer windings or utilizing the 5-position Soundstage switch, you can easily tailor the sound to any source. With added functionalities like a 20 dB pad, 85 Hz low cut filter, and a high impedance DI, the 40AM is an essential addition to your rack, allowing you to sculpt the sound you desire.

40AM INSPIRATION
Combining vintage circuits takes time to get the right balance. But when done right, you can take the best of them all to make a super hybrid! Having a pentode front end, RCA BA-11A is capable of higher amounts of gain. The Gates SA-70, with is feedback setup allows for a great amount of tone shaping. Both offer a thick, compressed sound which is carried through to the Model 40AM, complimenting its Model 86B and WT-72 siblings!

Unlock Your Creativity
Finding the right piece of gear to give your sound that "special something" might be one of the hardest parts of engineering. In our opinion, having an exciting combination of tools at your fingertips is the best way to get your creative juices flowing. The 40AM-2 will help to unlock your audio engineering mind and allow you to focus on creating truly impressive audio.
April 1, 2024
John May
Glassy and growly!
Being that I already have a decent library of clean-ish preamps, I went looking for something with more character. I love my UAD 610 on bass, but it never was great on much else. I suspected that a tube pre was what I was looking for after checking out a bunch of other stuff.
I heard great things about Locomotive, with their name included in sentences with the likes of Coil, so I figured they must have something great going on. I picked up the 86B-2 and never looked back. That it was as affordable as it is was just another perk.
I've used in on everything - vocals, guitar, keys, bass, drums, recorder, french horn, accordion - and it has always come through with flying colors. It can be anything from clean and glassy to colored and growly, just tweak those in/out knobs until it's awesome!
March 30, 2024
J. Ludlow
Pleased With My Purchase
I do like my new preamp very much. It's dripping in even harmonics while also quite articulate when not slammed. Rare combo, I think. I love the variable input options which even allow plugging a guitar into the DI on one channel and then routing its output directly into the line input of the second channel. Extremely flexible for various studio needs. Reasonably priced for a boutique audio perfectionist's tool too.
March 27, 2024
Jeff R
Whew, It’s A Beaut!
Acoustic guitar (now my go to pre for this), banjo, violin, drum overheads, grand piano, bass (yes!), direct instrument inputs and make up gain for the 2buss, passive EQs and a tube tape echo are some of the things I regularly use my 86b-2 on and it has excelled and exceeded my expectations.
SDC, LDC, tube, condensers and ribbon mics all sound fantastic (a dream match for my km84 pair) and the switchable impedance is genius.
The addition of line outs on the rear made integration into my patch bay a no-brainer - why isn’t everybody doing this?
The 86b-2 one of my favorite pieces in the studio, my only complaint is I don’t have 8 channels.
March 27, 2024
Anonymous
It's the preamp I've been looking for
I've always had a love for saturated, character preamps, and have owned many. In most of those other cases, the character may have been present but the detail was lacking. Locomotive was highly recommended when I began asking around, so I contacted them (on the weekend) and they responded in just minutes (again, on the weekend!) and other interactions have been absolutely superb. The 86B itself has delivered more than expected. It's easy to dial in the needed amount of color but the detail remains. Its feature set is perfect, offering all the inputs and parameters a preamp should have. It's built like a tank and will last forever. So far it has mated well with every mic and source I've tried. This comes highly recommended from me.

LIFETIME WARRANTY
As an audio engineer, we know you want to use the best tools to shape your sound. And if you are going to spend money on gear, you deserve hardware that's always in tip-top shape. You shouldn't have to worry about when something goes wrong. Rest assured, we guarantee the gear we build by backing it with a lifetime warranty.