Creative Expansion
Echo III Desktop
3-slot Desktop Thunderbolt to PCIe Card Expansion System for Computers with Thunderbolt Ports
Creative Expansion
Echo III Desktop
3-slot desktop Thunderbolt to PCIe card expansion system for computers with Thunderbolt 4 or Thunderbolt 3 ports
MacBook Air with Echo III. Echo III shown without cover  with three Avid Pro Tool | HDX PCIe cards installed.
MacBook Air with Echo III next to it. Avid Pro Tools application featured on display.

Connect Three Full-length PCIe Cards to Computers with Thunderbolt 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™ 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 offers an innovative solution with the Echo™ III Desktop, a professional Thunderbolt expansion system that allows you to connect up to three full-length (12.28 inches) PCIe cards simultaneously. Using a single Thunderbolt cable, it’s compatible with Apple M series Macs or Intel Macs with Thunderbolt 3 ports, as well as Windows or Linux computers with Thunderbolt 5 or Thunderbolt 4 ports.

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Thunderbolt logo icon.

The Thunderbolt Interface Connection

Three Slot Professional Desktop PCIe Card Expansion – when connected to one of your computer’s Thunderbolt ports, Echo III enables you to connect professional PCIe cards (three full-height, single-width cards, or one double-width card plus one single-width card).

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

Supports Every Thunderbolt Compatible, Non-GPU PCIe Card

Video PCIe card icon.Audio PCIe card icon.SAS/SATA PCIe card icon.Networking PCIe card icon.SSD PCIe card icon.

Echo III Desktop supports every Thunderbolt compatible, non-GPU PCIe 4.0, 3.0, 2.0, and 1.1 card available including video capture and transcoding; audio DSP; 6Gb or 12Gb SAS or SATA host bus adapter; 10Gb or 25Gb 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. 

PCIe Cards Compatibility PDF ›
Sound Mixer
Woman singing behind microphone.
Sound engineering mixing at  audio behind computer and audio peripherals.
Musicians playing guitars in sound studio.
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.

Echo III shown without cover with three Avid Pro Tools | HDX PCIe cards installed.

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 Echo III shown beside computer.

Key Features

Computer icon.

Adds Connectivity & Capabilities

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

Avid Pro Tools | HDX card icon.

Avid Pro Tools | HDX Compatible

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 3.1 Slots

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.

Ear icon.

Remarkably Quiet

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

Thunderbolt logo icon.

Thunderbolt to PCIe Device

Offers full PCIe bandwidth for the installed cards.

Two Thunderbolt ports icon.

Connect Additional Thunderbolt Devices

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

Rugged icon.

Rugged Aluminum Housing

Provides robust and secure protection.

Apple logo icon.

Mac Compatible

Supports all M series Macs and Intel Macs with Thunderbolt 3 ports.

Windows logo icon.

Windows Compatible

Supports Windows computers with Thunderbolt 5 or Thunderbolt 4 ports.

Linux logo icon.

Linux Compatible

Supports Linux computers with Thunderbolt 5 or Thunderbolt 4 ports.

Free lifetime tech support icon.

Sonnet Support

Founded in 1986 in Orange County, Southern California — the vibrant hub of technology and engineering south of Silicon Valley — Sonnet has been at the forefront of innovation. Over the years, we've developed numerous award-winning products that enhance performance and connectivity for Mac, Windows, and other industry-standard computers. Many of our team members have been with us for over two decades, providing us with extensive expertise about our current and past offerings. If you ever need technical support for any of our products, don’t hesitate to reach out; we’re here to assist you.

Echo III shown with cover off. Cover positioned next to it.

Three PCIe 3.1 Slots and Power to Spare

Echo III Desktop features one x16 and two x8 PCIe 3. slots, 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!

Interior of Echo III showing key features: (1) Three PCIe slots, (2) 75W auxiliary power connector, (3) Dual ultra-quite fans, (4) 400W power supply
Interior of Echo III showing a full-length PCIe card installed.
Interior of Echo III showing a low-profile PCIe card installed.
Interior of Echo III showing 75W auxiliary power connectors connected to three Avid Pro Tools | HDX cards.
Ultra quite fan.Ultra quite 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 level comparison chart: Ultra-quiet fans at 17.1dBA, rustling leaves at 20dBA, library at 40dBA, conversation at 60dBA, dishwasher at 80dBA, and jet take-off at 100dBA.
Comparative examples of noise levels source: iacacoustics.com
Sonnet Thunderbolt cable and ThunderLok icon.
Secure Connections for High Performance

Thunderbolt Cable and ThunderLok Included

Sonnet includes a Thunderbolt cable that supports Thunderbolt’s maximum bandwidth and is fully compatible with Thunderbolt 5, 4, and 3 computers. Sonnet also provides ThunderLok, a Thunderbolt connector cable lock, that prevents accidental cable disconnections.
Sonnet Thunderbolt cable with ThunderLok sitting beside it.
Thunderbolt port with threaded hole icon.

ThunderLok Advantage

Many Sonnet Thunderbolt products featuring Thunderbolt ports come equipped with threaded mounting holes to securely attach a Sonnet ThunderLok connector lock, preventing Thunderbolt cables from accidentally disconnecting.

Thunderbolt Technology

Fastest External Interface Available

Sonnet Thunderbolt products feature a high-speed Thunderbolt interface that delivers PCIe bandwidth needed to support data transfers at full speed.

Two Thunderbolt ports icon.
Connect Additional Thunderbolt Devices
One port is reserved for connecting to your computer; the second port enables connection of additional Thunderbolt peripheral devices in a daisy chain.
10Gbps USB 3.2 Gen 2 icon.
10Gbps USB 3.2 Gen 2 Support
10Gbps USB 3.2 Gen 2 support allows you to connect a USB device to the second Thunderbolt 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 through the secondary Thunderbolt port.
Display icon.
Supports Connecting Up to One 8K Display
Maximize the utilization of one computer Thunderbolt port, connecting the largest display supported by your computer.
Group of computers that feature Thunderbolt ports.

Designed for the Fastest Connection to Thunderbolt Computers

Echo III is purposely designed with a Thunderbolt 3 controller and its four lanes of PCIe (not available in a Thunderbolt 4 peripheral) to achieve maximum simultaneous ingest speeds. Watch this video to learn more about the performance benefits.
Echo III Rackmount.

Rackmount Version Available

Choose between Echo III Rackmount and Echo III Desktop to suit your workflow needs. 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. Echo III Rackmount even offers space for an optional expansion module.

Echo III Desktop Thunderbolt Expansion System