Classic mic pre with independent DI

Featuring a rugged, portable all-metal enclosure, ISA One combines the classic Focusrite microphone preamp with a flexible, independent DI channel and optional 192kHz precision A-D conversion. 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.

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
Dedicated insert point
Optional stereo 192kHz A-D conversion card
Brainworx bx_console Focusrite – exclusive plug-in that faithfully captures the sound, feel and styling of the original Focusrite ISA 110 Equaliser and ISA 130 Dynamics Modules.


Mic Input Response

Gain range (Mic)

0dB to 60dB in 10dB steps 20 dB of variable gain

EIN (Mic)

-126dB measured at 60dB of gain with 150 Ohm terminating impedance and 22Hz/22kHz band-pass filter

Noise (Mic)

Noise at output with unity gain (0 dB) and 22 Hz-22 kHz band pass filter-97 dBu

Signal-to-Noise Ratio (Mic)

106 dB relative to max headroom (9dBu)

Frequency Response (Mic)

At minimum gain (0 dB)-0.5dB down at 10Hz and -3dB down at 125kHz

CMRR (Mic)

98dB (Channel 1, 1kHz, maximum gain with 24 dBu input)

Crosstalk Channel to Channel (Mic)

With 10dB@1kHz input to chA, chB output =104dBrA. With 10dB@10kHz input to chA, chB output = 84dBrA

Line Input Response

Gain range (Line)

-20dB to 10dB in 10dB steps 20 dB of variable gain

Input Impedance (Line)

10 kO from 10 Hz to 200 kHz

Total Harmonic Distortion Noise (Line)

Measured with a 0 dBu input signal, and a 22 Hz-22 kHz band pass filter0.0001

Frequency Response (Line)

At unity gain (0 dB)-0.3dB down at 10Hz and -3dB down at 200kHz

Instrument Input Response

Gain range (Instrument)

10dB to 40dB continuously variable

Input Impedance (Instrument)

High = greater than 1M Low =greater than 300k

THD (Instrument)

At minimum gain ( 10)

High-Pass Filter


18 dB per octave (3 pole filter)


Fixed 75Hz measured at the 3dB down point

Weight and Dimensions

W x D x H

220mm (W) x 104mm (H) x 254 - 290mm


3.9 kg (8.6 lbs)


User Guide

9 Pin AES/SPDIF Pin-Out (German)

ISA 2-Channel ADC Installation Guide - English

ISA 2-Channel ADC Installation Guide - German

ISA One User Guide - German

ISA One User Guide - Italian

ISA One User Guide - English

ISA One User Guide - French


RedNet Control 2.8.5 for Mac

RedNet Control 2.8.5 for Windows

RedNet Control 2.8.5 Release Notes

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If you would like more information on how our audio solutions could add to your audio workflow, or to request a demonstration, please contact us to have one of our specialists get in touch.

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