Focusrite ISA 428 MKII (Used)

4-Channel Microphone Preamplifier with Optional AD Converter - Used

• Used product, fully tested and in working order
• Four Focusrite ISA microphone preamps based on Lundahl transformers
• Transparent sound with the characteristic analog warmth of the ISA series
• Selectable microphone impedance for maximum compatibility
• Four high-impedance front-panel instrument inputs
• Optional 8-channel AD converter can be installed
• Dedicated analog inserts on every channel
• Variable Focusrite high-pass filter and precision LED meters

This used Focusrite ISA 428 MKII is one of the most highly regarded solutions in the world of professional recording for those seeking the legendary Focusrite ISA sound. Equipped with four transformer-based microphone preamps, it offers a unique combination of transparency, dynamics, and musicality that has made the ISA series a standard in recording studios around the world.

The legendary Focusrite ISA sound

A direct descendant of the preamps designed by Rupert Neve for Air Studios, the ISA 428 MKII retains the classic analog circuitry that made the series famous. The result is detailed and precise reproduction, enriched by the characteristic warmth derived from the saturation of the input transformer.

Professional Microphone Preamplifiers with Variable Impedance

Each channel features selectable impedance with four different settings, allowing you to optimize the connection with any dynamic, condenser, or ribbon microphone. This feature not only improves electrical matching but also lets you shape the sonic character of your recording.

Four selectable impedance settings

• Low: 600 Ω
• ISA110: 1400 Ω
• Medium: 2400 Ω
• High: 6800 Ω

Ideal front-end for professional studios and advanced home studios

The ISA 428 MKII offers four microphone inputs, four line inputs, and four high-impedance front-panel instrument inputs, allowing you to quickly record guitars, basses, and electronic instruments without using external DI boxes.

Dedicated analog inserts also allow you to integrate compressors, equalizers, or other hardware processors directly into the audio chain before digital conversion.

Optional up to 8-channel A/D converter

The system can be equipped with an optional 8-channel analog-to-digital conversion card, compatible with numerous professional workstations. Thanks to the PCM4220 converters and Focusrite’s custom electronics, you can achieve a dynamic range of up to 122 dB and extremely low jitter performance.

Full Signal Control

Each channel features +48V phantom power, phase reversal, a variable high-pass filter, a Trim control for an additional 20 dB of gain, and high-precision LED meters designed to display even the fastest transients.

Used Focusrite ISA 428 MKII: Uncompromising Professional Quality

Even today, the Focusrite ISA 428 MKII is considered one of the best multichannel preamps available for professional studios, broadcast productions, and high-end music recording. This used unit represents an ideal opportunity to experience the renowned ISA sound at a particularly attractive price.

Technical Specifications

• Type: Professional 4-channel microphone preamp
• Condition: Used
• Microphone Channels: 4
• Technology: Focusrite ISA transformer
• Microphone Gain: 0 to 60 dB + variable trim up to +20 dB
• Selectable microphone impedances: 600 Ω, 1400 Ω, 2400 Ω, 6800 Ω
• EIN: -126 dB
• THD+N Mic Input: 0.0009%
• Mic Input SNR: up to 123 dB
• CMRR: 88 dB
• Instrument Inputs: 4 high-impedance front-panel inputs (>1 MΩ)
• Instrument Gain: +10 dB to +40 dB
• Line Inputs: 4
• Line Input Impedance: 10 kΩ
• High-Pass Filter: adjustable from 16 Hz to 420 Hz
• Filter slope: 18 dB/octave
• Dedicated analog inserts on each channel
• Phantom Power: +48V, independent per channel
• Phase reversal for each channel
• 6-segment LED meters
• AD converter: optional for up to 8 channels
• Mic connections: XLR
• Line Inputs: Balanced TRS jacks
• Instrument connections: Front TS jacks
• Dimensions: 480 x 88 x 280 mm
• Weight: 5.5 kg
• Power Supply: 100–240 V AC