Focusrite ISA428 Pre Pack 4-Channel Microphone Preamp

The ISA 428 Pre Pack is the perfect multi-channel front end for any professional DAW. Four classic Focusrite transformer-based pre amps with switchable impedance and direct instrument inputs. An optional eight channel 192kHz ADC, preceded by the all new proprietory Soft Limiter circuit, provides the perfect path into your Pro Tools HD system.

The benefits of the pre amp's topology include superb common-mode rejection, an excellent overload margin and, with its shared gain structure (20dB from the hand-wound transformer and up to 40dB from the amplifier), an extremely low noise floor and super-wide bandwidth (10Hz to 200kHz). This pre amp design is the cornerstone of Focusrite's signature 'warm-yet-transparent' sound and is a point of reference for any discerning audio professional.

In addition, 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 use different settings creatively to shape the sound of the microphone being used. Should the need arise to place extra processing in between pre amp and conversion, insert points are also featured on every channel.

Protecting the ADC, the Soft Limiter opto circuit is a new design from Focusrite, entirely preventing any 'digital overs', whilst minimising the undesirable distortion that standard limiter circuits often generate.

Finally, the new ADC embodies cutting-edge conversion technology, encompassed within pristine Focusrite circuitry, providing eight conversion channels of the highest quality, at frequency rates of up to 192kHz. Running at 96kHz allows for up to 16 (2 x 8, parallel) simultaneous digital outputs in addition to the four main analogue outputs. Digital output options include dual AES/EBU, SPDIF and dual ADAT lightpipe. Full digital metering is provided for every channel, alongside new 'moving coil' peak meters, designed to catch even the fastest of transients.

A second 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 on a single optional ADC and expands your front-end capacity from four pre amps and eight digital outputs to eight Pre amps and eight digital outputs.

Classic preamp technology, custom Focusrite input and limiting circuits and the very best in A/D conversion technology, the ISA 428 Pre Pack raises the bar for multi-channel recording solutions into Pro Tools HD, or any other professional DAW. Equally, it can be used as an additional set of high quality pre amps for any analogue or digital console or hard disk recorder.

Features
Four classic Focusrite transformer-based preamps

8 channels of cutting-edge A/D conversion, running at up to 192kHz. Protected by proprietary optical Soft Limiter circuit (428 A/D card is optional)

Switchable Impedance for unparalleled mic matching or extended mic creativity - includes the classic ISA 110 setting

Multiple Front Panel Instrument DI. No separate DI box required

Analogue insert points on every channel

High Pass Filters on every channel

New moving coil peak meters & full digital metering (dBfs)

Technical Info

Inputs
Transformer-based ISA design

Gain range:
Line = +/- 18dB
Mic = 0 to 60dB (both in 6dB steps)
Inst = +10 to +40 dB variable

Input impedance:
Line = 10k ohm
Mic = Variable - 600, 2k4 and 6k8 ohm + original ISA 110 settings
Inst = >1M ohm

Analog Performance
Noise:
Line = -96dB
Mic = -128dB (EIN with 150 ohm input resistance at 60dB of gain)

THD:
Line = 0.003% with 0dBu, 1kHz input and 20Hz to 22kHz band-pass filter
Mic = 0.003%

Analog Input and Output connectors (balanced)
D.I inputs: 1/4 inch Jack (unbalanced)

Mic inputs: XLR (balanced)

Line: TRS Jack (balanced)

Insert Sends and Returns: TRS Jack (balanced)

Additional ADC inputs: XLR (balanced) Line level

Analog Outputs: XLR (balanced)

Digital Output Option
AES/EBU and S/PDIF dual 9 pin D-types

Optical - ADAT Lightpipe

Bit depths 16, 20 or 24 bit

Frequency options 44.1, 48, 88.2, 96, 176.4 and 192kHz

Clock options Standard or -256 x

Meter - 0 dBfs = +22dBu

Digital Performance

SNR - 120dB A weighted

Four warm-yet-transparent, transformer-based Focusrite mic pres in 2 rack spaces! Each has a mic/line and front-panel 1/4" instrument input, an insert, 4 switchable impedance levels, and a variable high-pass filter. Add the ISA428 ADC card for up to 8 channels of 192kHz A/D conversion with soft limiting. XLR and TRS I/O.