Focusrite
Focusrite 428MKII 4-Channel Microphone Preamp
Capture studio-quality recordings with the Focusrite ISA428 MkII's four transformer-based preamps and selectable input impedance.
$2,299.99*
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*Price sourced from Amazon.com. Last updated:Jun 27, 2026.Price and availability are subject to change.
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Overview
Key Features
PRISTINE SOUND QUALITY - Experience ultra-low noise and minimal distortion with a THD+N as low as 0.0009%, ensuring clean and transparent audio capture for professional recordings.
VERSATILE GAIN RANGE - Achieve optimal signal levels with a wide gain range from 0dB to +60dB, plus an additional 20dB variable trim, perfect for diverse microphone sensitivities and sources.
PRECISE IMPEDANCE CONTROL - Tailor the preamp to your microphone with variable impedance options (600, 1400, 2400, 6800 Ohms), optimizing signal transfer and capturing the true character of your mics.
FLEXIBLE CONNECTIVITY - Seamlessly integrate into any studio setup with comprehensive I/O, including XLR mic inputs, 1/4" line/instrument inputs, and insert points for external processing.
ROBUST BUILD QUALITY - Rely on the durable 19" rack-mountable design, ensuring longevity and stability in demanding studio environments, complemented by a 2-year Focusrite warranty.
ENHANCED SIGNAL CLARITY - Shape your sound with a variable high-pass filter (16Hz-420Hz) featuring an 18dB/octave roll-off, effectively removing unwanted low-frequency rumble and noise.
No further features available.
No further features available.
No further features available.
Specifications
Brand
Focusrite
Model
ISA428 MkII (428MKII)
Channels
4
Preamp Type
Transformer-Based
Input Types
Microphone, Direct Instrument
Input Impedance
Selectable
A-D Conversion
Optional (8-Channel)
Pros & Cons
👍 Pros
- Transformer-based preamp design delivers the signature ISA sound with analog warmth and detail
- Four independent channels allow simultaneous multi-mic recording in a single rack unit
- Selectable input impedance provides tonal versatility across different microphone types
- Direct instrument inputs eliminate the need for external DI boxes
👎 Cons
- Optional A-D converter adds significant cost if digital output is required
- Premium pricing puts it above budget-friendly preamp alternatives
- Four channels may be insufficient for larger session recording without additional units
- Rack-mount form factor requires a dedicated rack space in your studio setup
Frequently Asked Questions
What type of preamp topology does the ISA428 MkII use?
The ISA428 MkII uses transformer-based microphone preamplifiers derived from the classic Focusrite ISA series, known for their transparent, detailed sound character with a touch of analog warmth from the input transformers.
What does the selectable input impedance feature do?
Selectable input impedance lets you change how the preamp interacts electrically with different microphones. This affects the tonal character and frequency response, giving you creative control over the sound of each mic you connect.
Can I plug instruments directly into the ISA428 MkII?
Yes. Each channel includes a direct instrument input, so you can connect guitars, basses, and other instruments without needing a separate DI box.
Does the ISA428 MkII include analog-to-digital conversion?
A-D conversion is available as an optional add-on. The base unit is a purely analog preamp, which allows you to pair it with whatever converter you prefer.
How many channels does the unit provide?
The ISA428 MkII provides four independent microphone preamplifier channels, each with its own controls for gain, impedance, and input selection.
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