The ISA428 MkII from Focusrite is a four-channel microphone preamp featuring Focusrite’s transformer-based preamps. With selectable input impedance, direct instrument inputs and an optional eight channels of high-quality analog to digital conversion, the unit is a perfect front end for the audio professional, whether utilizing digital or analog recording.
The ISA microphone preamp holds a reputation for delivering transparency along with subtle warmth derived from transformer core saturation. The addition of a variable impedance circuit allows users to perfectly match the preamp with any microphone, or to use different settings creatively to shape the sound of the microphone.
The extremely broad frequency response of Focusrite preamps (close to 200kHz at the top end) guarantees accurate phase response across the range of human hearing, with the roll-off point being moved entirely outside of the audible hearing range. Warmth, plus beautifully open, unrestricted high frequencies, is a classic hallmark of the mid 80’s Focusrite designs to which this preamp owes its design.
The optional eight channel analog converter utilizes high-quality Burr-Brown amplifiers and PCM4220 A-D converter chips seated within Focusrite’s custom analog circuitry. Specifications include a dynamic range of 122dB and jitter performance below 250 picoseconds. The card can be retrofitted at any time and due to the convenient 25-pin D-type connector, it integrates seamlessly with most digital workstations, including Pro Tools.