Focusrite ISA 828 MkII Microphone Preamp

Sharing the simple mic preamp design of the original Focusrite ISA 110 module from the Focusrite Studio Console, ISA 828 MkII incorporates eight of Focusrite's classic mic preamps, with Lundahl LL1538 transformers on every input.

Each channel has the option of mic or line inputs, while inputs 1-4 also feature instrument inputs on the front panel. Each mic pre has variable input impedance, to provide a range of subtly different sonic options when using microphones, including an 'ISA 110' setting, which replicates the impedance of the original Focusrite mic pre.

Up to 60dB of gain is available, with a further +20dB of continuously variable trim, providing a huge 80dB gain range. The high-pass filter with fixed 75Hz frequency and 18dB/octave roll-off. ISA 828 MkII features high-pass filters, calibratable per-channel, six-segment LED meters, and switchable rear-panel insert points, which allow the use of inline processors such as compressors or EQs.

Dedicated connectors for mic and line-level inputs allow all sources to be connected simultaneously, making ISA 828 MkII perfect for permanent installation in a rack. New to the ISA 828 MkII is an updated power supply that allows for more efficient power consumption, a reduction in heat generation, and extremely reliable operation. The optional ISA ADN8 analogue-to-digital expansion card provides eight Dante, ADAT and AES3 outputs at rates of up to 24-bit/192kHz.

Features

• Optional A-D card with up to 192kHz, 24-bit sampling offers high-quality, precision digital audio conversion to Dante, ADAT and AES3
• Classic ISA mic preamp design featuring Lundahl LL1538 input transformer
• Switching power supply design allows for efficient and cool operation
• Front-panel instrument inputs to first four channels
• Line inputs with dedicated input connectors and front-panel switch
• Switchable input impedance including classic ISA 110 setting
• High-pass filters
• Switchable insert points when used with A-D card
• Calibratable, per-channel six-segment LED peak-level meters

Specifications

Microphone Inputs

• All measurements taken at maximum gain unless otherwise stated, Rs = 150Ω. The below are measured using the analogue outputs.
• Gain Range: 0dB to +30dB (30-60 switch disabled) and +30dB to +60dB (30-60 switch enabled) in 10dB steps, with an additional +20dB of continuous trim
• Input Impedance: Low = 600Ω, ISA 110 = 1400Ω, Med (Medium) = 2400Ω, High = 6800Ω
• Max. Input Level: +7dBu, min gain, medium Z
• Frequency Response (20Hz - 20kHz): 20Hz - 20kHz ±0.2dB, min gain, medium Z
• Frequency Response (10Hz - 110kHz): 10Hz - 110kHz ±1.5dB, min gain, medium Z
• THD + N: -92dB (0.0025%) @ -1dBr, min gain, medium Z
• EIN: -123dBu 'A'-Weighted (typical)
• Signal-to-Noise Ratio: 122dB 'A'-Weighted (typical), medium Z
• Common-Mode Rejection Ratio: 997Hz CMRR: -93dB, min gain, medium Z
• Phantom Power : +48V, independently switchable per channel.
• High-Pass Filter: 75Hz knee frequency, 18dB/Octave, independently switchable per channel
• Phase: Inverts the phases of the selected input

Line Inputs

• All measurements taken at maximum gain unless otherwise stated, Rs = 50Ω. The below are measured using the analogue outputs.
• Gain Range: -20dB to +10dB in 10dB steps, with an additional +20dB of continuous trim
• Input Impedance: Low = 600Ω, ISA 110 = 1400Ω, Med (Medium) = 2400Ω, High = 6800Ω
• Max. Input Level: +25dBu, min gain, medium Z
• Frequency Response (20Hz - 20kHz): 20Hz - 20kHz ±0.1dB, unity gain, medium Z
• Frequency Response (10Hz - 122kHz): 10Hz - 122kHz ±3dB, unity gain, medium Z
• THD + N: -91dB (0.0028%) @ -1dBr, min gain, medium Z
• Signal-to-Noise Ratio: 122dB 'A'-Weighted (typical), medium Z
• Common-Mode Rejection Ratio: 997Hz CMRR: -65dB, min gain, medium Z

Instrument Inputs

• All measurements taken at maximum gain unless otherwise stated, Rs = 600Ω. The below are measured using the analogue outputs.
• Gain Range: +10dB to +40dB with continuous gain using trim pot
• Input Impedance: Low = 470Ω, High = 2.4MΩ
• Max. Input Level: +18dBu, min gain, low Z
• Frequency Response (20Hz - 20kHz): 20Hz - 20kHz ±0.1dB, min gain, low Z
• Frequency Response (10Hz - 110kHz): 10Hz - 110kHz ±1.2dB, min gain, low Z
• THD + N: -83dB (0.0071%) @ -1dBr, min gain, low Z
• Signal-to-Noise Ratio: 100dB 'A'-Weighted (typical), min gain, low Z

Crosstalk

• Microphone Crosstalk
  
  • Microphone Talkback: -60dB; 20Hz - 20kHz, min gain, medium Z
• Line Crosstalk
  
  • Microphone Talkback: -80dB; 20Hz - 20kHz, min gain, medium Z
• Instrument Crosstalk
  
  • Microphone Talkback: -80dB; 20Hz - 20kHz, min gain, medium Z

Front Panel Connectivity

• Instrument Inputs
  
  • Channel Count: 2 Channels In
  • Instrument Inputs: 4 x 1/4" jack inputs

Rear Panel Connectivity

• Mic Inputs
  
  • Channel Count: 8 In
  • Input: 8 x Female XLR

Line Level

• Channel Count: 8 In and 8 Out
• Input: 8 x 1/4" jack inputs
• Output: 1 x DB-25 connectors (AES59)

Inserts

• Channel Count: 8 In
• Input: 1 x DB-25 connectors (AES59)

Digital Card Slot

• Compatible Card: ISA ADN8

PSU

• PSU: 1 x IEC Input

Front Panel Indicators

• Control Functions: 16 x Pots (Gain and Trim). 60 Switches (On/Off Switch, 30-60 Gain, +48V, Phase, HPF, Insert, Z In, Input, Meters Pre A-D, Clock Select and Ext. Word Clock)

Rear Panel Indicators

• Control Functions: 1 x Pot (Meter Trim)

Power

• PSU: 1 x Internal, 100-240V, 50/60Hz, consumption 35W.

Heat Performance

• Operating Temperature: Operates at up to an ambient temperature of 40 degrees Celsius

Dimension

• 482mm (18.98") width x 325mm (12.80") depth x 88mm (3.46") height
• Weight: 7.05kg