Focusrite Pro ISA One Mic Preamp

The ISA One combines the classic Focusrite microphone preamp with a flexible, independent DI channel and optional 192kHz precision A-D conversion. Encased in a rugged, portable all-metal enclosure, at the heart of the ISA range is the microphone preamplifier with its Lundahl input transformer – essentially the same circuit, based on the original ISA 110, that has been used for 30 years in successive Focusrite designs. The input transformer imparts a special character to the sound that can't be truly emulated in any other way, while the modern twist of variable input impedance allows for a new degree of flexibility.

Whether you're an artist, engineer or producer, you'll appreciate the versatility of the ISA One, with its front-panel DI input. The DI includes low/high impedance switching and an amplifier output, and its own feed to the optional A-D converter and separate rear-panel XLR output.

Focusrite Pro ISA One Features

• Classic ISA mic preamp design featuring Lundahl LL1538 input transformer
• Flexible independent DI channel
• Switchable input impedance including classic ISA 110 setting
• Headphone output with volume control
• Mic, line, and instrument inputs
• Optional stereo 192kHz A-D conversion card
• 3 Year Warranty

• ISA One preamp1
• Brainworx bx_console Focusrite and RedNet Control software programs1

• Mic input response
  • Gain range: 0dB to 60dB in 10dB steps 20 dB of variable gain
  • EIN: -126dB measured at 60dB of gain with 150 Ohm terminating impedance and 22Hz/22kHz band-pass filter
  • Noise: noise at output with unity gain (0 dB) and 22 Hz-22 kHz band pass filter-97 dBu
  • Signal-to-noise ratio: 106 dB relative to max headroom (9dBu)
  • Frequency response: at minimum gain (0 dB)-0.5dB down at 10Hz and -3dB down at 125kHz
  • CMRR: 98dB (Channel 1, 1kHz, maximum gain with 24 dBu input)
• Line input response
  • Gain range: -20dB to 10dB in 10dB steps 20 dB of variable gain
  • Input impedance: 10 kO from 10 Hz to 200 kHz
  • THD: measured with a 0 dBu input signal, and a 22 Hz-22 kHz band pass filter 0.0001
  • Frequency response: at unity gain (0 dB)-0.3dB down at 10Hz and -3dB down at 200kHz
• Instrument input response
  • Gain range: 10dB to 40dB continuously variable
  • Input impedance high: greater than 1M
  • Input impedance low: greater than 300k
  • THD: at minimum gain (10)
• High-pass filter
  • Roll-off: 18 dB per octave (3 pole filter)
  • Frequency: fixed 75Hz measured at the 3dB down point