The Focusrite ISA 828 MkII is an eight-channel transformer-based mic preamp in a 2U rackmount chassis, featuring eight ISA preamp circuits with Lundahl LL1538 input transformers and a rear-panel expansion slot for the optional ISA ADN8 A-D converter card.

Preamp Controls

Each of the eight channels offers up to 80dB of gain (60dB in 10dB steps, plus 20dB of variable trim) with four-position input impedance switching (600Ω, 1.4kΩ ISA 110, 2.4kΩ, 6.8kΩ). Channels 1 through 4 include front-panel instrument inputs for direct recording of guitars and basses. A 75Hz high-pass filter (18dB/octave) is independently switchable per channel. Rear-panel insert points on every channel allow external processing.

Outputs and Digital Expansion

Analogue outputs are provided on a DB-25 connector (AES59 Tascam Analogue pinout). A second rear-panel DB-25 provides eight additional A-D inputs when the optional ISA ADN8 card is installed, enabling up to 16 channels of A-D conversion from a single unit with Dante, AES3, and ADAT connectivity.

Connectivity

• 8 x XLR mic inputs (rear panel)
• 8 x 1/4" TRS line inputs (rear panel)
• 4 x 1/4" TS instrument inputs (front panel, channels 1-4)
• 8 x balanced analogue outputs (DB-25, AES59 pinout)
• 8 x A-D inputs (DB-25, active with optional ADN8 card)
• Switchable insert points per channel
• Optional ISA ADN8 digital card slot

Specifications

• Mic gain range: 0 to 60dB (10dB steps) + 20dB trim
• Mic input impedance: 600Ω, 1.4kΩ (ISA 110), 2.4kΩ, 6.8kΩ
• Mic EIN: <-123dBu (A-weighted)
• Signal-to-noise ratio: 122dB (A-weighted)
• Frequency response: 20Hz to 20kHz +/-0.2dB
• High-pass filter: 75Hz, 18dB/octave, switchable per channel
• Phantom power: +48V, independently switchable per channel
• Form factor: 2U rackmount
• Power: Internal PSU, 100-240V AC