Four classic microphone pre-amplifiers and high-quality A-D conversion
Overview
The ISA features four classic, transformer-based microphone pre amps with switchable impedance and direct Instrument Inputs are combined with an optional eight channel 192kHz ADC. An all-new, Soft Limiter circuit precedes the A/D, providing the perfect path into any DAW, Digital Console or direct to Hard Disc Recorder.
The input stage provides enhanced control and creativity allowing you to switch between four carefully selected input impedance settings. The original ISA 110 setting is supplemented by three further impedance settings to either perfectly match the pre-amp with any microphone and maximise level, or to use different settings creatively to shape the sound of the microphone being used. Should the need arise to place extra processing between pre-amp and conversion, insert points are also featured on every channel.
Protecting the ADC, Focusrite's Soft Limiter is a new optical circuit design, entirely preventing any digital overs, whilst reducing to an absolute minimum the undesirable distortion artefacts that common limiter circuits typically generate. This limiter requires the optional ADC to be fitted in order for it to operate.
The ADC embodies cutting-edge conversion technology, encompassed within Focusrite circuitry, providing eight high quality conversion channels, at sampling frequency rates of 44.1, 48, 96 and 192kHz. Running at 96kHz allows for up to 16 (2 x 8, parallel) digital outputs. Digital output formats are dual 9-pin D-sub (AES/EBU, SPDIF) and dual ADAT light-pipe.
Full digital metering is provided for every channel, alongside moving coil peak meters, designed to catch even the fastest transients.
A second ISA428 analogue unit can be connected utilising the four extra ADC input channels on the rear of the unit containing the optional ADC. This makes full use of the eight channels provided and expands front-end capacity from four pre amps and eight digital outputs to eight Pre amps and eight digital outputs.
Key Features
Four ISA-series transformer-based pre-amps
The benefits of Focusrite’s classic pre-amp topology include superb common-mode rejection, an excellent overload margin, an extremely low noise floor and super-wide bandwidth.
Dedicated analogue insert points
Switchable insert points are also featured on every channel, allowing routing (between pre-amp and output) to additional external processing.
Accurate ‘moving coil’ peak meters
Clear metering designed to catch even the fastest and most elusive of transients.
Four front panel instrument inputs
Instant access on the front fascia and no separate DI box required.
Eight line inputs
Four additional A-D converter inputs combine with the four pre-amp inputs to provide eight line inputs, routable discretely to the eight-channel A-D converter option.
Eight Channel optional 192kHz A/D conversion card
With the additional four ADC inputs, two ISA428’s can be used with a single ADC, providing eight channels of pre-amplification, A-D conversion and VU metering.
Custom Global A-D converter ‘soft clip’ limiter
Focusrite’s custom optical design protects the A-D converter by preventing ‘digital overload’. It requires that an A-D converter be installed.
Switchable Impedance
Ideal for mic matching or extended microphone creativity. Settings include the ‘Vintage ISA110’ setting, providing the original Focusrite signature sound.
Variable Focusrite high pass filter
Provided on every channel, this is the same filter as featured on the original ISA110 and the Focusrite forte console.