Focusrite ISA428 MkII Pre-Amp

The ISA428 MkII is a four-channel mic preamp and A-D converter.

Like its predecessor, the ISA428 MkII features four of Focusrite’s transformer-based ISA preamps. These are the same as those found in the Forte console. Each channel has phantom power and phase-reverse controls, plus switchable input impedance and an adjustable high-pass filter.

Mirroring the feature set of the original model, the MkII also has an optional eight-channel A-D converter upgrade, which converts signals from the preamps and an additional four line-level inputs to 24-bit digital data streams at sample rates of up to 192kHz. New to the ISA428 MkII is a switched-mode power supply, which lowers the internal noise and heat output of the unit, and reduces its weight.

The most noticeable difference is the removal of the large moving-coil peak meters of the ISA428. Metering duties on the MkII are handled by per-channel, six-step LED bargraph displays, which monitor the signal prior to the A-D stage, providing status of the preamp’s output level. Also removed is the soft limiter feature of the ISA428. In light of this, precise calibration figures are supplied in the user manual, to enable accurate system setup.

KEY FEATURES

Four ISA-series mic preamplifiers

Focusrite’s flagship preamps, featuring per-channel phantom power, phase-reverse and insert control, and variable high-pass filtering.

Optional eight-channel A-D converter

Featuring the same 24-bit/192kHz A-D technology as the ISA828 preamp, boasting a dynamic range of 122dB.

Switchable input impedance

Lets you change the input impedance, allowing you to match your mic to the preamp Features the 'ISA110' setting to provide the sound of the Forte’s ISA110 module.