Overview

The Focusrite ISA One is a single-channel microphone preamp built around the legendary Focusrite ISA110 transformer-based design originally created for Sir George Martin's AIR Studios, delivering the same warm, detailed, and musical character that has graced countless hit records since the 1980s. The Lundahl LL1538 input transformer provides the sweet, harmonically rich coloration that defines the ISA sound, adding subtle warmth and presence that flatters vocals, acoustic guitars, and virtually any microphone source. The preamp offers up to 80dB of gain with exceptionally low noise, accommodating everything from quiet ribbon microphones to close-miked drums without breaking a sweat. A unique variable impedance selector allows the user to change the input impedance between four settings, fundamentally altering the tonal interaction between the preamp and the connected microphone and opening a world of sonic possibilities from a single input. The front-panel instrument DI input features a separate gain control and an independent output, enabling simultaneous microphone and direct recording. The optional A/D converter card adds high-quality digital output in AES, S/PDIF, and ADAT formats. Metering is provided by a detailed LED ladder display with switchable peak hold. The ISA One is ideal for project studios and professional engineers who want a world-class preamp for tracking vocals and critical sources. The single-channel design limits its usefulness for multi-source recording sessions, and the additional A/D card is sold separately.

Preamps

A single-channel preamp built around the legendary ISA110 transformer design with Lundahl transformer and variable impedance selector, delivering the warm, harmonically rich character from countless hit records.

Instrument Details

$499 Professional
Brand Focusrite
Type Transformer Microphone Preamp
Made In United Kingdom
Year 2009
4.7 1 vote

AI Reviews

4.7 /5

The Focusrite ISA One is a modern classic that brings the legendary Rupert Neve-designed ISA110 heritage into a portable, desktop-friendly format. At its heart is the Lundahl LL1538 transformer, which provides a distinctive 'sheen' and solid low-end authority that standard interface preamps simply cannot replicate. It isn't an aggressively colored unit like a 1073-style clone; instead, it offers a musical transparency"often described as 'clean with weight'"that makes it incredibly versatile for everything from delicate vocals to transient-heavy acoustic guitars.

The variable input impedance is a standout feature, allowing you to 'tone-shape' by optimizing or intentionally mismatching for ribbon and dynamic microphones. Ergonomically, the dedicated DI path is a masterstroke; it runs parallel to the mic pre, making it a dream for bassists who want to capture a clean DI and a mic'd amp signal simultaneously. Build quality is rugged, though the desktop form factor is surprisingly bulky for a single channel, which might clutter smaller workstations. While it lacks the harmonic grit of tube-based units, its ability to stack tracks without accumulating 'mud' is professional-grade. For the project studio owner looking to graduate from built-in interface preamps, this is the definitive bridge to high-end outboard gear.

Category Ratings

Preamps
4.7
Feb 15, 2026
AI-Generated Review Generated via Google API. This is an automated evaluation, not a consumer review. Learn more
Focusrite ISA One Screenshot

Added: Feb 14, 2026

us.focusrite.com/products/isa-one

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