OVERVIEW

The Useful Arts SMP-1 brings authentic vacuum tube microphone preamplification to the SEPIA modular platform for the very first time. Inspired by the TEC-nominated SFP-30 and built using the exact audio and power circuitry of the BF-1, the SMP-1 delivers a fully discrete, Class A, all-tube signal path with transformer-coupled input and output for uncompromising analogue performance.

At its core, the SMP-1 features a pentode front end feeding triode amplification stages, creating the rich, dimensional tone that has defined Useful Arts preamps for decades. Borrowing the celebrated variable second-harmonic control from the SFP-60, it allows engineers to move seamlessly from subtle warmth to harmonically rich saturation, making it equally at home on vocals, acoustic instruments, electric guitars and beyond.

Designed specifically for the SEPIA environment, all key parameters – including input, output and colour – are digitally controlled and fully recallable, alongside phantom power, phase reverse, a 120 Hz high-pass filter and a 22 dB pad. The result is a modern modular workflow paired with true valve circuitry, delivering authentic tube sound without compromise.

KEY HIGHLIGHTS

Authentic Useful Arts Tube Architecture

Built from the same circuitry as the BF-1 and sharing an identical signal path to the SFP-30, the SMP-1 delivers genuine Useful Arts valve tone with transformer-coupled input and output and Class A operation throughout.

Variable Harmonic Colour Control

Derived from the legendary SFP-60, the variable second-harmonic circuit allows precise sculpting of tonal character – from clean, open warmth to rich, musical saturation.

SEPIA-Optimised Workflow

Input gain, output level and harmonic colour are digitally controlled and recallable via the SEPIA interface, combining classic analogue sound with modern session management.

Pentode-to-Triode Signal Path

A pentode front end feeding triode amplification stages creates depth, texture and dynamic response that flatters vocals and instruments alike.

Compact, Single-Channel Excellence

The SMP-1 delivers the highest quality Useful Arts tube design in a single-channel SEPIA module, ideal for portable, modular and hybrid studio setups.

FEATURES

• All-tube, Class A microphone preamplifier
• Transformer-coupled input and output
• Pentode front end with triode gain stages
• Variable second-harmonic control
• Digitally controlled input, output and colour
• Phantom power switching
• 120 Hz high-pass filter
• Phase reverse switch
• 22 dB input pad
• Single-channel SEPIA modular format

TECHNICAL SPECS

Type: Vacuum tube microphone preamplifier

Circuit Basis: BF-1 and SFP-30

Harmonic Control: Variable second harmonic (derived from SFP-60)

Channels: 1 (Mono)

Format: SEPIA series module

Hardware Platform: Karno SEPIA

Power Supply Rails: ±13 V DC

ADC: None