Focusrite ISA C8X

The Focusrite ISA C8X brings 8 channels of classic  transformer coupled pre amplification into a high-density 2U rack mount unit. Built around custom Lundahl LL1538 input transformers, it delivers the iconic warmth, deep low end, and open, detailed top end that has defined professional tracking studios for decades.

Each channel of the ISA C8X features switchable input impedance settings including the classic ISA 110 impedance curve—allowing engineers to match or deliberately mis-match microphone loads for tailored frequency dynamics and tonal shaping. With front-panel instrument DIs, dedicated high-pass filters, dynamic LED metering, and optional digital expansion capabilities, the ISA C8X serves as an uncompromising multi-channel tracking hub.

Key Features

• 8 Channels of ISA Preamplification: Iconic Rupert Neve-designed circuit topology featuring Lundahl LL1538 input transformers across all 8 channels.

• Variable Input Impedance: Select between four input impedance settings per channel, including original ISA 110 specs, to reshape microphone character.

• Up to 80dB of Clean Gain: Rotary step gain control with continuous fine trim provides precise level setting for low-output ribbon and dynamic microphones.

• Dedicated High-Pass Filters: Switchable $18\text{ dB/octave}$ high-pass filter ($75\text{ Hz}$) per channel to quickly remove unwanted low-frequency rumble.

• Front-Panel Instrument DIs: High-impedance front-panel DI inputs on channels 1 and 2 for direct tracking of bass, guitars, and synthesizers.

• Optional Digital Expansion: Dedicated rear expansion bay supports optional 8-channel A/D option cards for direct Dante, AES3, and ADAT digital routing.

Technical Specifications

• Form Factor: 2U Standard 19" Rackmount

• Channel Count: 8 Channels

• Input Topology: Transformer-Coupled (Lundahl LL1538)

• Maximum Gain: $+80\text{ dB}$ ($+60\text{ dB}$ stepped gain, $+20\text{ dB}$ trim)

• Input Impedance Settings: Low ($600\Omega$), ISA 110 ($1.4\text{ k}\Omega$), Medium ($2.4\text{ k}\Omega$), High ($6.8\text{ k}\Omega$)

• Frequency Response: $10\text{ Hz – }120\text{ kHz}$ ($\pm 0.5\text{ dB}$)

• High-Pass Filter: $18\text{ dB/octave}$ at $75\text{ Hz}$ (Switchable per channel)

• Analog Inputs: 8x XLR (Mic In), 8x 1/4" TRS (Line In), 2x 1/4" TS (Front-Panel DI In)

• Analog Outputs: 8x XLR Male (Line Out) or 1x DB-25 balanced line output

• Digital Expansion: Optional ISA A-D expansion card slot (Dante / AES3 / ADAT)