Locomotive Audio Model 86B-1

Locomotive Audio Model 86B-1 is a single-channel version of the 86B-2 circuit in a 500-series module, built on the same modernized Ampex 601 tape-recorder preamp philosophy. Unlike its two-channel sibling, its input stage runs a 6BR7 tube instead of an EF86, paired with the same 12AY7 output tube and the same 75dB maximum gain. It's the single-channel counterpart to the two-channel 86B-2, built for a 500-series slot instead of its own rack chassis.

Same family, different input tube

The 6BR7 and the EF86 are functionally similar remote-cutoff pentodes, but they're different tube types, so the 86B-1 isn't a literal copy of one 86B-2 channel, it's a separate take on the same Ampex 601/286A lineage, adapted to the 500-series format. MuMetal-shielded input transformers and nickel-and-steel output transformers, both wound in-house, stay common across Locomotive's whole preamp family.

Full control in a single 500-series slot

A two-knob gain/level layout, a -20dB pad, an 85Hz high-pass filter, switchable mic input impedance, a high-impedance front-panel DI input, 48V phantom power with a polarity switch, and a 3-colour LED meter pack the full feature set of a larger rackmount preamp into one 500-series module. The 500-series format packs the same level of control as the larger 86B-2 into a single rack slot, saving space where channel density per rack unit matters most.

KEY FEATURES

• Single-channel tube preamp in 500-series format
• 6BR7 input tube, 12AY7 output tube
• Same design lineage as the 86B-2, different format and input tube
• Switchable mic input impedance
• -20dB pad and 85Hz high-pass filter
• High-impedance front-panel DI input
• 48V phantom power with polarity switch
• 3-colour LED output meter
• Hand-built in the USA

TECHNICAL SPECIFICATIONS

• Type: single-channel tube preamp, 500-series
• Tubes: 6BR7 (input), 12AY7 (output)
• Maximum gain: 75dB
• Transformers: MuMetal input, nickel-and-steel output, in-house wound
• Pad: -20dB
• High-pass filter: 85Hz
• Power: 48V phantom