Focusrite Pro ISA 428 MKII Mic Preamp

The ISA 428 MkII incorporates 4 Focusrite mic pres in this user-friendly 2U enclosure so mic preamps, instrument inputs and line ins are all at your fingertips. Four impedances let you match any microphone – old or new – and access styles from the warmth of a vintage mic to modern designs with clear and transparent sound. The same circuitry as early ISA110 models is used in the ISA 428, providing a low noise floor and wide bandwidth. Gain adjustment excels on this preamp with up to 60dB available gain on rotary and gain range switches, and a continuously variable trim with an additional +20dB means a total of 80dB of gain is available.

LED meters display the peak signal level for the 4 mic pres and the direct inputs to the optional 8-channel A-D card. An overload LED in each meter flashes when SPLs strain audio quality of the system. A high-pass filler includes variable cut-off frequency for 16-420Hz. Choose from mic, line or instrument input, and variable input impedance on each mic pre. Inline processors such as compression are allowed with switchable rear-panel insert points. To emulate the style of the original Focusrite ISA 110 Equaliser and ISA 130 Dynamics Modules, the exclusive Brainworx bx_console Focusrite plug-in is included. RedNet Control and other software programs are also compatible.

Add the ISA ADN8 8-channel A-D card converter to this mic preamp for high-quality analogue-to-digital conversion. Controls on the front panel’s right side are for the additional channels provided by the optional converter card, and only function with the card installed.

Focusrite Pro ISA 428 MKII Features

• Switchable input impedance including classic ISA 110 setting
• Classic ISA mic preamp design with Lundahl LL1538 input transformer
• Instrument line inputs have dedicated input connectors and front-panel switch
• Dedicated switchable insert point
• Compatible with A-D card to add 8 channels
• RedNet Control compatible
• 3 Year Warranty

• ISA MKII preamp1
• Brainworx bx_console Focusrite plug-in1

• Analog audio outputs4 line XLR outputs, 4 insert send 1/4" TRS jacks
• Other I/OIEC power input connector 100Vac - 240Vac
• Mic inputs
  • Frequency response at min gain: -0.35dB at 20Hz and –3dB at 122kHz
  • Frequency response at max gain: –2.5dB at 20Hz and –3dB 103kHz
  • Gain range: 0dB to 60dB in 10dB steps, plus 0dB to 20dB continuously variable trim
  • Max headroom: 7.4dBu
  • Noise EIN: -126dB (measured at 60dB of gain with 150O 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) 120dB (relative to 0dBFS ( 22dBu)
  • CMRR: 88dB
  • Input impedance, variable: 600O, 1400O, 2400O, 6800O
• 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
  • Max 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) 113dB (relative to 0dBFS 22dBu)
  • Input Impedance: 10kO
• Instrument inputs
  • Gain range: 10dB to 40dB continuously variable
  • Max headroom: 11.5dBu
  • Noise at main output with min gain: -95dBu (measured with a 20Hz/22kHz bandpass filter)
  • Input impedance: ->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)