Useful Arts BF-700 – Class A Preamp/DI & Class D Power Amplifier

OVERVIEW

The Useful Arts BF-700 represents the evolution of the celebrated BF Series, bringing together the unmistakable tone of a Class A tube instrument preamp with the authority of a modern 700-watt Class D power amplifier. Designed for bassists who demand studio-quality sound on stage and in the studio, the BF-700 delivers the rich harmonic depth and clarity that made the BF-1 and BF-S legendary, now paired with clean, powerful amplification capable of driving real speaker cabinets with ease.

At the heart of the BF-700 is an ultra-high impedance input and a meticulously designed linear power supply that enables near-noiseless high-voltage tube operation, preserving the true character of the instrument while providing exceptional headroom. The tube-based two-band EQ is ear-tuned for musical response, while the finely calibrated Colour control introduces pure, pentode-generated second-order harmonics, allowing everything from pristine transparency to thick, harmonically rich bass tones.

Built for real-world professional use, the BF-700 offers comprehensive connectivity, including balanced XLR and TRS DI outputs, a Thru jack, effects loop and ground lift, alongside a brick-wall 50 Hz high-pass filter for controlled low-end performance. Its robust construction and lightweight yet powerful Class D amplification make it equally at home on the road, in the studio, or at the heart of a modern hybrid bass rig.

KEY HIGHLIGHTS

Class A Tube Preamp with Signature Useful Arts Tone

The BF-700 features an audiophile-quality Class A tube preamp derived from the acclaimed BF Series, delivering rich harmonics, depth and dynamic response that faithfully captures the true sound of the electric bass.

700-Watt Class D Power Amplifier

A powerful yet lightweight Class D amplifier provides ample clean headroom for live performance, capable of driving speaker cabinets with authority while maintaining clarity and punch.

Ultra-High Impedance Instrument Input

An exclusive impedance conversion method preserves the full character of the instrument, ensuring exceptional clarity, depth and transient detail.

Musical EQ and Harmonic Colour Control

A tube-based two-band EQ offers ear-tuned curves for intuitive tonal shaping, while the Colour control adds pure second-order harmonics for adjustable warmth, thickness or edge.

Studio and Stage Connectivity

Balanced DI outputs on both XLR and TRS, a Thru jack, effects loop and ground lift provide maximum flexibility for live sound, recording and hybrid setups.

FEATURES

• Class A tube instrument preamp and DI
• Integrated 700 W Class D power amplifier
• Ultra-high impedance instrument input
• Linear preamp power supply for low noise and high headroom
• Tube-based two-band EQ with musical curves
• Colour control for pentode-generated second-order harmonics
• Brick-wall 50 Hz high-pass filter
• Effects loop for pedals or outboard processing
• Balanced DI outputs on XLR and TRS
• Thru jack for parallel signal routing
• Ground lift switch
• Relay-based audio path to minimise signal degradation
• Rugged, road-ready construction

TECHNICAL SPECS

Type: Bass preamp/DI with integrated power amplifier

Preamp Topology: Class A tube

Power Amplifier: Class D

Output Power: 700 W

Instrument Input: Ultra-high impedance

EQ: Tube-based, two-band

Harmonic Control: Variable Colour (second-order harmonics)

High-Pass Filter: Brick-wall, 50 Hz

DI Outputs: Balanced XLR and TRS

Additional I/O: Thru jack, effects loop

Noise Floor: Better than –70 dBu

Construction: Professional, road-worthy design