Creative Expansion
Echo III Desktop
3-slot Desktop Thunderbolt to PCIe Card Expansion System for Computers with Thunderbolt 4 or Thunderbolt 3 Ports
Creative Expansion
Echo III Desktop
3-slot desktop Thunderbolt to PCIe card expansion system for computers with Thunderbolt 3 or Thunderbolt 4 ports
MacBook Air with Sonnet Thunderbolt 3 PCIe Card Expansion System
Avid Pro Tools Application with Avid Pro Tools HDX Cards

Connect Three Full-length PCIe Cards to Computers with Thunderbolt 4 or Thunderbolt 3 Ports

For creative pros using the latest portable, mini desktop and all-in-one computers in their workflows, onboard processing power alone is not enough to get the job done. While these Mac®, Windows®, and Linux® computers include high-performance Thunderbolt™ 4 or Thunderbolt 3 ports to support peripherals, what they lack is PCIe expansion slots to install specialty cards that add needed video and audio inputs, transcode data, and connect to high-speed shared storage and networks. Sonnet has a solution—the Echo™ III Desktop—a professional Thunderbolt to PCIe card expansion system that enables you to connect three (up to) full-length (12.28 inches long) PCIe cards at the same time, via a single cable.

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Avid HDX, AJA Kona 5 & Sonnet Fusion Dual 2.5" SSD PCIe Cards

Supports Every Thunderbolt Compatible, Non-GPU PCIe Card

Video PCIe Card IconAudio PCIe Card IconSAS/SATA PCIe Card IconNetworking PCIe Card IconSSD PCIe Card Icon

Echo III Desktop supports every Thunderbolt compatible, non-GPU PCIe 1.1/2.0/3.0 card available including video capture and transcoding; audio DSP; 6Gb or 12Gb SAS or SATA host bus adapter; 10Gb, 25Gb or Ethernet; SSD storage; and other specialty types to your system.

Do you have a card in mind but aren’t sure it’s compatible? We’ve put together a compatibility list that identifies cards conforming to Thunderbolt technology requirements, and organized by fit and power compatibility with specific expansion systems. 

See a list of supported pcie cards (PDF) ❯ 
Sound Mixer
Sound Mixer
Avid Pro Tools Qualified
Ready for up to three Pro Tools | HDX PCIe Cards – no extra parts required

At the flick of a switch, the Avid qualified Echo III Desktop system is instantly optimized to support up to three Pro Tools | HDX PCIe cards, with no extra parts necessary! This chassis has been tested and is qualified by Avid Audio group for use with Avid Pro Tools HD 2020 software, and Avid Pro Tools HDX and HD Native systems.

Avid Cards Installed In Sonnet Thunderbolt 3 Expansion System

Avid Pro Tools | HDX cards sold separately

Media Composer Icon

Avid Media Composer Qualified

Echo III is separately qualified by the Avid Video group for use with Avid Media Composer/Symphony with many current and older Mac computers with Thunderbolt 3 and Thunderbolt 2 ports.

Mac Pro with Sonnet Thunderbolt 3 Expansion System

Key Features

Connectivity Icon

Adds Connectivity & Capabilities

Connects up to three high-performance non-GPU PCIe cards via a Thunderbolt 3 cable to your computer lacking expansion slots.

Avid HDX PCIe Card Icon

Pro Tools | HDX Compatible(1)

HDX compatibility mode enables use of up to three Pro Tools | HDX PCIe cards with no additional parts needed.

PCIe Card Icon

Broad PCIe Card Compatibility

Every Thunderbolt compatible, non-GPU card supported regardless of length or height.

Number 3 Icon

Three PCIe 3.0 Slots(1)

One x16 plus two x8 slots support three full-height, single-width cards, or one double-width card plus one single-width card.

Power Icon

Pro Power

Integrated 400W power supply with 75W auxiliary power. Saves energy by powering on/off automatically with the computer.

Sound Icon

Remarkably Quiet

Dual temperature-controlled, variable-speed Noctua fans rated at 17dBA automatically and quietly cool the cards.

40Gpbs Icon

40Gbps Thunderbolt 3 System

Offers 2750 MB/s of PCIe bandwidth for the installed cards(1). Learn more about Thunderbolt 3 performance benefits over Thunderbolt 4.

Thunderbolt 3 Ports Icon

Two Thunderbolt Ports

One port connects to computer; second port supports daisy-chaining of up to five additional Thunderbolt peripheral devices.

Rugged Icon

Rugged Aluminum Housing

Provides robust and secure protection.

Free Lifetime Tech Support
Sonnet Thunderbolt 3 Expansion System with Case Removed

Three PCIe 3.0 Slots and Power to Spare

The Echo III Desktop features one x16 and two x8 PCIe 3.0 slots(1), enabling it to support a wide variety of cards at the same time. To support really power-hungry cards, it integrates a universal 400W power supply and includes a 75W auxiliary power connector for non-GPU cards that require extra power, including the Avid Pro Tools | HDX. Designed without a power switch, the Echo III powers on and off automatically with the connected computer, saving energy in the long run. With no power switch, you can’t forget to turn off the system!

Sonnet Thunderbolt 3 Expansion System Interior
Full-length PCIe Card Illustration
Low-profile PCIe Card Illustration
75W Auxiliary Power Connections Illustration
Noctua FanNoctua Fan
Rated 17.1 dBA Icon

Dual Fans. Ultra-quiet Operation.

Featuring dual Noctua fans, the Echo III Desktop is designed to deliver ultra-quiet operation so that it can be comfortably used in noise-sensitive environments. Rated at 17.1dBA—below the 20dBA ceiling prescribed for use in recording and broadcast studios—the fans spread the spectrum of their noise to minimize the impact at any single frequency. To further ensure negligible noise levels, the fans are temperature-controlled, automatically speeding up and slowing down smoothly as needed, and the enclosure is engineered to optimize airflow over the installed cards to effectively and efficiently cool the system.

Noise Levels Comparison Chart
Comparative examples of noise levels source:

All the Right Connections

40Gbps Thunderbolt Cable and ThunderLok 3 Included

Sonnet includes a 0.7-meter Thunderbolt 3 cable that supports Thunderbolt's full 40Gbps bandwidth, and is fully compatible with Thunderbolt 4 computers. Sonnet also provides a ThunderLok™ 3 Thunderbolt connector retainer clip(4) that prevents accidental cable disconnections—just slide it over one end of the cable, and then plug in the connector and secure it to the chassis by turning a thumbscrew. Because of its unique design, ThunderLok remains on the cable so it won’t get lost when not in use.

Thunderbolt 3 Cable with ThunderLok 3Supports Full 2750 MB/s & 100W Power Delivery Icons
Thunderbolt 3 Port with ThunderLok Mounting Hole
ThunderLok Advantage
Sonnet Thunderbolt expansion systems are designed with Thunderbolt ports that include threaded mounting holes for securing Sonnet's ThunderLok retainer clips that prevent accidental cable disconnections.

40Gbps Thunderbolt

Fastest External Interface Available

The Echo  III Desktop features a 40Gbps Thunderbolt interface(3)(4) that delivers up to 2750 MB/s of PCIe bandwidth, enabling it to support 4K video capture and processing cards at high frame rates, multiple audio DSPs, and 25GbE and dual-port 10GbE network cards at full performance.

Thunderbolt 40Gbps Ports Icons
Dual 40Gbps Thunderbolt Ports
One port is reserved for the connection to your Thunderbolt 4 or Thunderbolt 3 computer; the second port enables expansion of up to five additional Thunderbolt peripheral devices in a daisy chain.
10Gbps USB 3.1 Gen 2 Icon
10Gbps USB 3.2 Gen 2 Support
10Gbps USB 3.2 Gen 2 support allows you to connect a USB device(5) to the second port using the proper cable or adapter.
15W Power Icon
Provides 15W of Power
For peripherals requiring extra power, 15 watts is provided to bus-powered devices.
4K & 5K Display Icon
Supports Connecting One 5K 60Hz Display
Maximize the utilization of one computer Thunderbolt port.
Thunderbolt 4 Computers

Forward Compatible with Thunderbolt 4 Computers

The Echo III Desktop is fully compatible with Thunderbolt 4 computers and was purposely designed with a Thunderbolt 3 controller and its four lanes of PCIe (not available in a Thunderbolt 4 peripheral) to achieve maximum performance. Learn more about the performance benefits of Thunderbolt 3 over Thunderbolt 4.

Apple M1 Logo

also compatible with M1 Macs

see tech specs for details

Older Macs with Thunderbolt 2 Ports

Backward Compatible with Older Macs

No Thunderbolt 3? No problem—the Echo III Desktop is also compatible with Macs with Thunderbolt 2 ports when used with the bi-directional Apple® Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter and a Thunderbolt cable (both sold separately).

Sonnet Thunderbolt 3 Rackmount Expansion System

Rackmount Version Available

Choose between the Echo III Rackmount and Echo III Desktop to suit your workflow needs. The Echo III Rackmount mounts in a rack space 2U tall, and is only 16.5 inches deep, making it ideal for use in a wide range of popular mobile racks, carts, and rack cases, and in server rooms as well. The Echo III Rackmount even offers space for optional expansion modules.

Sonnet DuoModo Family

Part of the DuoModo Family

The Echo III Desktop is part of Sonnet’s DuoModo™ family of modular Thunderbolt expansion systems, comprised of three interchangeable expansion modules — the Echo III module (included in Echo III Desktop and Rackmount systems), an eGPU card system, and a Mac mini® mounting system with integrated 40Gbps Thunderbolt storage dock — and three enclosures (dual-module desktop and rackmount housings, and a single-module desktop housing). You can add any one of the modules to the extra space in the Echo III Rackmount enclosure to create your ideal expansion system! Does your workflow fit neatly in one box? If not, you’ll appreciate DuoModo systems’ modular design. Sonnet offers separate desktop and rackmount enclosures so you can remove the Echo III module from the enclosure you’re using and install it another one.

Learn More
Learn why Sonnet's Pro Products Rely on Thunderbolt 3 Technology for Maximum Performance

Echo III Desktop