Focusrite ISA One – Portable Classic Mic Preamp with DI, Variable Impedance & Optional A-D Conversion
The Focusrite ISA One delivers iconic analog tone and versatility in a rugged, portable desktop design. Featuring the same classic ISA 110 preamp topology and the legendary Lundahl LL1538 input transformer, this compact unit provides studio-grade mic, line, and instrument inputs with pristine analog signal path and precise control.
A favorite among engineers and producers worldwide, the ISA One includes a dedicated DI channel with switchable high/low impedance, amplifier output, and independent routing. It’s perfect for capturing both vocals and instruments simultaneously with professional quality, thanks to variable input impedance, which offers sonic flexibility for different mic and source types—including a recreation of the iconic ISA 110 setting.
With its high-pass filter, switchable impedance, and independent headphone monitoring, the ISA One adapts effortlessly to studio or live recording situations. Add the optional ISA ADN2 A-D converter for 24-bit/192kHz digital output via Dante, ADAT, AES3, and S/PDIF, unlocking flexible integration into any modern digital audio workflow.
Whether you're tracking in the studio or recording remotely, the ISA One delivers legendary Focusrite sound quality, backed by a 3-year warranty, and supported by compatibility with RedNet Control, Dante Controller, and plug-in software like the Brainworx bx_console Focusrite.
At-a-Glance Highlights
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Classic ISA mic preamp design with Lundahl LL1538 transformer
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Mic, line, and instrument inputs with flexible front and rear I/O
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Independent DI channel with amp output and A-D converter routing
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Switchable input impedance including the classic ISA 110 setting
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High-pass filter: 75Hz, 18dB/octave for rumble reduction
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Headphone output with volume control for direct monitoring
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Compatible with optional ISA ADN2 A-D card for 192kHz digital output
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Portable, rugged metal chassis for studio or location work
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3-Year Warranty for peace of mind
Mic Inputs
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Gain Range: 0dB to +60dB (in 10dB steps) + 20dB continuously variable trim
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EIN: -126dB
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(Measured at 60dB gain, 150Ω termination, 22Hz–22kHz bandpass)
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Noise (Unity Gain): -97dBu
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(Measured with 22Hz–22kHz bandpass filter)
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Signal-to-Noise Ratio: 106dB (relative to max headroom of 9dBu)
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Frequency Response (Min Gain):
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-0.5dB @ 10Hz
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-3dB @ 125kHz
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CMRR: 98dB
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(Channel 1, 1kHz, max gain, 24dBu input)
Line Inputs
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Gain Range: -20dB to +10dB (in 10dB steps) + 20dB variable trim
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Input Impedance: 10kΩ (from 10Hz to 200kHz)
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THD: 0.0001
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(Measured with 0dBu input, 22Hz–22kHz bandpass filter)
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Frequency Response (Unity Gain):
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-0.3dB @ 10Hz
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-3dB @ 200kHz
Instrument Inputs
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Gain Range: 10dB to 40dB (continuously variable)
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Input Impedance (High): >1MΩ
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Input Impedance (Low): >300kΩ
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THD (Min Gain): Not specified (low distortion expected)
High-Pass Filter
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Roll-Off: 18dB/octave (3-pole filter)
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Cutoff Frequency: 75Hz (fixed, measured at -3dB point)
