Burl Audio B1

The Burl Audio B1 is a high-performance 500 Series microphone preamplifier and DI module designed to deliver maximum warmth, punch, and spatial clarity to tracking chains. Built on an all-discrete, Class-A direct-coupled circuit path with zero capacitors, the B1 pairs Burl Audio’s custom BX3 input transformer with a proprietary BX2 nickel-core output transformer. Designed to complement the B2 Bomber ADC and Mothership systems, the B1 provides a harmonic, three dimensional and transient rich pathway to all sources. 

Featuring independent stepped Gain and variable Output Level controls, the B1 allows engineers to drive the BX3/BX2 transformer stage hard for thick, harmonic saturation while backing off the output trim to prevent digital converter clipping downstream.

Equipped with a transformer-coupled Impedance Select switch, the B1 optimizes load matching for low-impedance ribbon microphones as well as dynamic and condenser capsules. A front-panel $1/4"$ Hi-Z instrument input allows direct injection for bass, guitars, and synths, while a $-30\text{ dB}$ pad accommodates hot line-level inputs for running mix stems or synth tracks through the transformer path for analog glue.

Key Features

• Custom Burl Audio Transformers: Custom BX3 input transformer paired with a BX2 nickel-core output transformer for open highs and deep low-end punch.

• Class-A Discrete Signal Path: Direct-coupled, capacitor-free circuit topology for maximum transient speed and dynamic headroom.

• 70 dB Total Gain: High-gain design capable of driving low-output ribbon and dynamic microphones.

• Independent Gain & Level Controls: Stepped input gain control paired with continuous output level trim for precise saturation control.

• Selectable Input Impedance: Transformer-coupled impedance switch for ribbon mic optimization.

• Front-Panel DI Input: $1/4"$ instrument/line input for direct recording of bass, guitar, and electronic instruments.

• Essential Studio Tools: $-30\text{ dB}$ pad, $+48\text{V}$ phantom power, polarity reverse switch, and tri-color LED level metering.

Technical Specifications

• Form Factor: Single-Slot 500 Series Module (VPR Alliance Compliant)

• Preamp Type: Solid-State Discrete Class-A Transistor

• Gain Range: Up to $70\text{ dB}$

• Input Transformer: Proprietary Burl Audio BX3

• Output Transformer: Proprietary Burl Audio BX2 Nickel-Core

• Circuit Topology: Direct-Coupled, Zero-Capacitor Signal Path

• Inputs: Rear XLR (via 500 Series Rack), Front $1/4"$ Hi-Z Instrument DI

• Outputs: Rear XLR (via 500 Series Rack)

• Control Functions: Stepped Gain, Output Level Trim, Low/High Impedance Toggle, $-30\text{ dB}$ Pad, $+48\text{V}$ Phantom Power, Phase Reverse (0∘/180∘)

• Metering: Tri-Color LED Signal / Peak Indicator