Four classic mic pres

ISA 428 MkII incorporates four of Focusrite's renowned mic pres in a simple-to-operate 2U enclosure, placing four mic preamps, instrument inputs and line ins at your fingertips. The original Focusrite mic pre was designed to suit the microphones of the time; today's model makes one small change, adding three additional input impedances to the classic ISA 110 setting, allowing you to match any microphone, old or new, and access a wide range of sounds, from the character and warmth of a vintage mic to the clear transparency of a modern design.

Each mic pre has the option of mic, line or the front-panel instrument input, with variable input impedance to ensure you are getting the best performance from the source. Up to 60dB of gain is available on the four-position rotary and gain range switches, with a further +20dB of continuously variable trim, meaning a huge 80dB of gain is available should it be required. The high-pass filter features variable cut-off frequency between 16 and 420Hz. An array of 6-segment LED meters show peak signal level for the four mic pres, in addition to the four direct inputs to the optional A-D card. Switchable rear-panel insert points allow the use of inline processors such as compression.

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Classic ISA mic preamp design featuring Lundahl LL1538 input transformer
Instrument and line inputs with dedicated input connectors and front-panel switch
Switchable input impedance including classic ISA 110 setting
Variable cut-off frequency high-pass filter
Dedicated switchable insert point
Per-channel six-segment LED peak-level meters
Optional A-D card with up to 192kHz, 24-bit sampling via ADAT or AES3

specifications

Mic Inputs


Frequency response at minimum gain (0dB) (Mic)

-0.35dB at 20Hz and –3dB at 122kHz

Frequency response at maximum gain (60dB) (Mic)

–2.5dB at 20Hz and –3dB 103kHz

Gain range (Mic)

0dB to 60dB in 10dB steps, plus 0dB to 20dB continuously variable trim

Maximum headroom (Mic)

7.4dBu

Noise EIN (Mic)

-126dB (measured at 60dB of gain with 150O termination and 20Hz/22kHz bandpass filter)

Noise at main output with unity gain (Mic)

-98dBu (measured with a 20Hz/22kHz bandpass filter)

SNR (Mic)

123dB (relative to max output 25dBu) 120dB (relative to 0dBFS ( 22dBu)

CMRR (Mic)

88dB

Input Impedance, variable (Mic)

600O, 1400O, 2400O, 6800O

Line Inputs


Frequency Response at unity gain (0dB) (Line)

-0.3dB at 20Hz and –3dB at 94kHz

Gain range (Line)

-20dB to 10dB in 10dB steps, plus 0dB to 20dB continuously variable trim

Maximum headroom (Line)

25.4dBu

THD N (Line)

0.002 (measured with 4dBu input signal, 0dB gain setting, with a 20Hz/22kHz bandpass filter)

Noise at main output with unity gain (Line)

-91dBu (measured with a 20Hz/22kHz bandpass filter)

SNR (Line)

116dB (relative to max output 25dBu) 113dB (relative to 0dBFS 22dBu). Input Impedance: 10kO

Frequency Response at 10dB gain (Instrument)

-0.2dB at 20Hz and 0dB at 200kHz

Frequency Response at 40dB gain (Instrument)

-3dB at 20Hz and –3dB at 38.4kHz

Instrument Inputs


Gain range (Instrument)

10dB to 40dB continuously variable

Maximum headroom (Instrument)

11.5dBu

Noise at main output with minimum gain ( 10dB) (Instrument)

-95dBu (measured with a 20Hz/22kHz bandpass filter)

Input Impedance (Instrument)

>1MO

High Pass Filter


Roll Off

18dB per octave 3 pole filter

Frequency range

16Hz to 420Hz (continuously variable, measured at the 3dB down point)

Front and Rear Connectivity


Analogue Audio Outputs (Outputs 1-4)

4 line XLR outputs on rear panel, 4 insert send 1/4” TRS jacks on rear panel

Other I/O

IEC power input connector 100Vac – 240Vac

Weight and Dimensions


Weight

5.5kg (12.2lbs)

Dimensions

480mm (W) x 88mm (H) x 280mm (D)

Downloads

User Guide


ISA 428 MkII User Guide - EN/FR/DE

ISA828 & ISA428 ADC Installation Guide - German

ISA828 & ISA428 ADC Installation Guide