The ISA428 MkII provides four of Focusrite’s prestigious transformer-based microphone preamps. It features the same classic circuitry and renowned audio quality found in the original at a new level of affordability. With selectable input impedance, direct instrument inputs and an optional eight channels of high-quality analogue to digital conversion, the ISA428 MkII creates the perfect front end for the discerning recording professional.
Four instrument inputs, instantly accessible on the front panel, allow quick and easy connection without the need for a separate DI box. Extra processing can be placed between preamp and conversion via the units dedicated insert points, featured on every channel. Finally, accurate six-segment LED metering is designed to catch even the fastest transients on every channel.We always quote 'real world' performance figures (measured to the AES17 standard). Some companies choose to quote chipset performance, which is misleading, and here's why.
Mic Inputs
- Frequency response at minimum gain (0dB): -0.35dB at 20Hz and –3dB at 122kHz
- Frequency response at maximum gain (60dB): –2.5dB at 20Hz and –3dB 103kHz
- Gain range: 0dB to +60dB in 10dB steps, plus 0dB to +20dB continuously variable trim
- Maximum headroom: +7.4dBu
- THD+N: 0.0009% (measured at 1kHz -20dBu input signal, at 30dB gain setting, with a 20Hz/22kHz bandpass filter)
- Noise EIN: -126dB (measured at 60dB of gain with 150Ω termination and 20Hz/22kHz bandpass filter)
- Noise at main output with unity gain: -98dBu (measured with a 20Hz/22kHz bandpass filter)
- SNR: 123dB (relative to max output 25dBu)
- SNR: 120dB (relative to 0dBFS (+22dBu)
- CMRR: 88dB.
- Input Impedance, variable: 600Ω, 1400Ω, 2400Ω, 6800Ω
Line Inputs
- Frequency Response at unity gain (0dB): -0.3dB at 20Hz and –3dB at 94kHz
- Gain range: -20dB to +10dB in 10dB steps, plus 0dB to +20dB continuously variable trim
- Maximum headroom: +25.4dBu
- THD+N: 0.002% (measured with +4dBu input signal, 0dB gain setting, with a 20Hz/22kHz bandpass filter)
- Noise at main output with unity gain: -91dBu (measured with a 20Hz/22kHz bandpass filter)
- SNR: 116dB (relative to max output 25dBu)
- SNR: 113dB (relative to 0dBFS +22dBu). Input Impedance: 10kΩ
Instrument Inputs
- Frequency Response at +10dB gain: -0.2dB at 20Hz and 0dB at 200kHz
- Frequency Response at +40dB gain: -3dB at 20Hz and –3dB at 38.4kHz
- Gain range: +10dB to +40dB continuously variable
- Maximum headroom: +11.5dBu
- THD+N: 0.006% (measured with –20dBu input signal, at minimum gain (+10dB), with a 20Hz/22kHz bandpass filter)
- Noise at main output with minimum gain (+10dB): -95dBu (measured with a 20Hz/22kHz bandpass filter)
- Input Impedance = >1MΩ
High Pass Filter
- Roll off = 18dB per octave 3 pole filter
- Frequency range: 16Hz to 420Hz (continuously variable, measured at the 3dB down point)
Meters
6 LED meter is calibrated 0dBFS = +22dBu (the maximum level which can be correctly converted by the optional internalA/D converter before overload occurs). The meter calibration points are as follows:
- Meter panel calibration value in dBFS / Equivalent dBu value
- 0dBFS / +22dBu
- -2dBFS / +20dBu
- -6dBFS / +16dBu
- -12dBFS / +10dBu
- -18dBFS / +4dBu
- -42dBFS / -20dBu
Front and rear connectivity
Analogue Channel Inputs (Inputs 1-4)
- 4 instrument 1⁄4” TS jack inputs on front panel
- 4 microphone XLR inputs on rear panel
- 4 line 1⁄4” TRS jacks on rear panel
- 4 insert return 1⁄4” TRS jacks on rear panel
- 4 ADC XLR inputs on rear panel
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
Front Panel Indicators
- 8 output meters, 6 segment
- 4 30-60 mic gain range selection indicator
- 4 +48V phantom power indicator
- 4 Phase indicator
- 4 Insert In indicator
- 4 Filter In indicator
- 4 Input selection indicators (Mic, Line, Inst)
- 4 Z In microphone input impedance selection indicators (Low, ISA110, Med, High) Clock select indicators (44.1, 48, 88.2, 96, 176.4, 192)
- Ext clock indicators (Lock, Word clock, 256X)
Weight
- 5.5kg
- 12.2lbs
Dimensions (W x H x D)
- 480mm (W) x 88mm (H) x 280mm (D)
- 19" (W) x 3.5" (H) x 11" (D)
