Audio MODEL 86B-1 – 500 Series Mono Tube Preamp

OVERVIEW

The Locomotive Audio MODEL 86B-1 is a 500 Series mono tube preamp designed to inject rich analog character into any signal chain. Inspired by 1950s American-style tube circuitry and rooted in the legacy of the Ampex 601, it offers everything from sweet, glowing vocal tones to punchy drums and overdriven tube grit. With up to 75 dB of gain delivered by a 6BR7 input tube and 12AY7 output tube, it brings presence, harmonics, and depth to any source.

Engineers can shape their sound effortlessly with its intuitive two-knob system, offering precise control over clean gain or saturated coloration. Additional features include a 20 dB pad, polarity reverse, high-pass filter, phantom power, front-panel DI, and selectable input impedances. Premium MuMetal and nickel/steel transformers ensure low-noise performance with a huge harmonic footprint. Built in the USA with rugged construction and backed by a lifetime warranty, the MODEL 86B-1 is a versatile preamp that won’t sit idle in your rack.

KEY HIGHLIGHTS

TRANSFORMERS:

Super Premium MuMetal shielded inputs and nickel & steel outputs set the stage.

TUBES:

A 6BR7 input tube and a 12AY7 output tube amplify the signal with 75 dB of max gain.

OUTPUT LEVEL LED:

A 3-colour LED indicator shows signal level – Green -> Yellow -> Red

FEATURES

• Microphone and high impedance instrument inputs
• One 6BR7 (CV4006) & one 12AY7
• Input Options: 500 Ω & 1.8K Ω Mic, 1.6meg Ω DI
• Polarity reverse switch
• 20 dB pad switch
• 85 Hz low-cut filter switch
• Front Panel DI for instruments
• +48 V phantom power​
• Premium input and output transformers
• Wima polypropylene capacitors in the signal path
• Built in the USA
• Heavy 16-gauge steel chassis
• Backed by lifetime warranty parts and labor – excluding tubes

TECHNICAL SPECS

Microphone Input Load Impedance: 500 Ω or 1.8k Ω

Output Impedance: 300 Ω

1/4″ DI Impedance: 1.6meg Ω

Output Level LED Colour:

• Greater than -10 dBu = Green
• Greater than +10 dBu = Orange
• Greater than +18 dBu = Red

75 dB of Gain

Frequency Response: 20 Hz – 20 kHz

Maximum 20 Hz & 1 kHz Input Level for 1% THD: -18 dBu (+2 dBu with Pad)

Maximum Output Level: +24 dBu

THD+N: < 1%

S/N ratio: > 70dB

Power Consumption (120/240VAC): +16v-260mA, -16v-250mA

Dimensions: Doublewide 500 Series

Shipping Weight: 5 lbs.