Focusrite ISA 428 (2000s)

Name: Focusrite ISA 428
Brand: Focusrite

A four-channel microphone preamplifier with instrument and line inputs, part of Focusrite's ISA Range.

Overview

The Focusrite ISA 428, including the MkII version, is a four-channel microphone preamp built for professional recording. It comes in a 2U enclosure with a distinctive blue finish. The four channels are independent and identical, and each has rotary gain and trim controls. Each channel takes microphone, instrument, and line inputs. The optional ISA ADN8 eight-channel A-D card adds analog-to-digital conversion. The ISA 428 MkII draws on Rupert Neve's original ISA design, which influenced the sound of recorded music for decades.

Specifications

Product type	Four-channel microphone preamplifier
Weight	5.5kg (12.2lbs)
Power Requirements	100VAC~240VAC
Power Consumption	35 W
Frequency Response (Mic, Min Gain 0dB)	-0.35dB at 20Hz, -3dB at 40kHz
Gain Range	Up to 80dB (60dB rotary + 20dB variable trim)
Optional Accessories	ISA ADN8 eight-channel A-D card

Design

The ISA 428 MkII front panel has rotary gain and trim controls, a variable high-pass filter, and on/off push buttons for each channel. It uses four of Focusrite's classic microphone preamp circuits in a 2U rackmount format. Operation is straightforward. There are no user-replaceable parts inside, fuses included.

Context

The ISA 428 MkII belongs to Focusrite's ISA Range, along with models like the ISA Two and ISA 828 MkII. In professional studio discussions it was positioned as a high-quality alternative to units like the Neve Portico. Its lineage goes back to Rupert Neve's original ISA console design, which helped define the sound of recorded music over several decades.

Market

Used units have been listed from $999.90. Early 2004 listings were at $1,199, and later MkII models were priced around $1,722. Refurbished units are available. Some early production models were noted to run hot near the power supply - reportedly resolved in later versions.