The Focusrite Scarlett 18i20 (3rd Generation) is a professional-grade audio interface that combines extensive I/O capabilities with solid technical performance. This 1U rack-mountable interface is positioned for professional studios, project studios, and live recording environments requiring multiple simultaneous inputs and outputs. I’ve mixed audio projects for worldwide TV broadcast using this interface and it’s earned me many times over what I paid for it.
Comprehensive Connectivity
- 8 microphone preamps with phantom power and pads
- Dual ADAT and S/PDIF digital connectivity
- MIDI I/O for instrument integration
- 2 dedicated instrument inputs
- 8 line inputs
- 10 analog outputs
- Dual headphone outputs
- USB-C connection (USB 2.0 protocol)
Professional Features
- Main/Alt speaker switching functionality
- Built-in Talkback system
- Loopback capability for streaming/podcasting
- Hardware input pads on all preamps
- External power supply for clean power delivery
Microphone Preamps
The eight microphone preamps offer professional-grade specifications:
- Clean gain path with 56dB range
- Very low noise floor with -128dBu EIN (A-weighted)
- Excellent THD+N performance (<0.0012%)
- Flat frequency response (20Hz – 20kHz ±0.1dB)
- Professional 3kΩ input impedance
- 9dBu maximum input level at minimum gain
Line Inputs
The line inputs provide robust performance for professional applications:
- High input impedance (60kΩ)
- Strong dynamic range (110.5dB A-weighted)
- Clean signal path (THD+N <0.002%)
- Professional +22dBu maximum input level
- 56dB gain range for flexibility
- Flat frequency response (20Hz – 20kHz ±0.1dB)
Instrument Inputs
The dedicated instrument inputs offer specifications suitable for direct recording:
- High impedance design (1.5MΩ) ideal for guitars and basses
- Solid dynamic range (110dB A-weighted)
- Acceptable THD+N (<0.03%) for instrument applications
- 56dB gain range
- 9dBu maximum input level
- Consistent frequency response (20Hz – 20kHz ±0.1dB)
Analog Outputs
The line outputs deliver professional-level performance:
- Strong dynamic range (108dB)
- Clean output stage (THD+N <0.002%)
- Professional +15.5dBu maximum output level
- 430Ω output impedance suitable for professional environments
Headphone Outputs
The dual headphone outputs provide solid monitoring capability:
- Very low output impedance (<1Ω) for excellent damping
- Good dynamic range (104dB A-weighted)
- Clean monitoring path (THD+N <0.002%)
- +7dBu maximum output level
Specific Audio Interface Use Cases:
Professional Recording Studios
- Multiple simultaneous input recording
- Digital expansion via ADAT
- Professional monitoring options with speaker switching
Project Studios
- Comprehensive I/O configuration
- Quality preamps for multiple sources
- Digital connectivity options
Live Recording
- Rack-mountable design
- Multiple preamps with pads
- Reliable USB connection
Podcast Production
- Built-in talkback functionality
- Loopback feature
- Multiple headphone outputs
Less Suitable For:
- Mobile recording (The unit requires standard 110v or 220v external power)
- Basic home studios (potentially excessive I/O if you only need a few channels)
- Ultra-critical applications requiring the absolute highest specifications
Overall Strengths:
- Comprehensive I/O configuration
- Clean preamp performance
- Professional digital connectivity and expandability
- Robust build quality
- Practical feature set including talkback and speaker switching
Overall Limitations:
- USB 2.0 protocol (though adequate for channel count)
- External power required
- Fixed rack-mount format
- THD+N specifications, while good, aren’t class-leading
Summary
The Focusrite Scarlett 18i20 (3rd Generation) represents a solid choice for professionals requiring multiple I/O in a reliable, well-featured audio interface for multitrack recording, live recording, studio and DAW use.
Its technical performance, while not class-leading in every metric, is thoroughly professional and suitable for serious studio work. The inclusion of practical features like talkback, speaker switching, and hardware pads on every preamp channel demonstrates a clear understanding of real-world studio needs.
The interface particularly excels in its comprehensive connectivity and practical feature set, making it a strong contender when reliability and functionality are paramount. While some specifications like THD+N and dynamic range are good rather than exceptional, they remain well within professional requirements, and the overall package represents strong value for studios requiring a workhorse audio interface.
The Scarlett 18i20 (3rd Gen) audio interface offers professional-grade specifications and features at a mid-tier price point. The combination of high-quality preamps, excellent conversion, and comprehensive I/O makes it a compelling choice for serious audio production professionals.