Focusrite ISA428 MKII Preamp

The Focusrite ISA428 MKII Preamp provides 4 of Focusrite’s prestigious transformer-based mic 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 8 channels of high quality AD conversion, the ISA428 MKII creates the perfect front end for the discerning recording professional.

The Focusrite ISA428 MKII Preamp incorporates four of Focusrite's renowned mic pres in a simple-to-operate 2U enclosure, placing four mic preamps, instrument inputs and line inserts 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.

Focusrite ISA428 MKII Preamp Features

• 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

Focusrite ISA428 MKII Preamp 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 150 ohm 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): 600 ohm, 1400 ohm, 2400 ohm, 6800 ohm
• 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: 10k ohm
  • 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): >1M ohm
• 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 100V AC – 240V AC
• Weight and Dimensions:
  • Weight: 5.5kg (12.2lbs)
  • Dimensions: 480mm (W) x 88mm (H) x 280mm (D)

Focusrite ISA428 MKII Preamp Includes

• Focusrite ISA428 MKII Preamp
• IEC Power Cable
• User Guide
• 2 Year Warranty