Echo III Desktop

Creative Expansion
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Creative Expansion

Echo III Desktop

3-slot desktop Thunderbolt 3 to PCIe card expansion system


Connect Three Full-length PCIe Cards to Computers with 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 computers include high-performance 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™ 3 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.

The Thunderbolt 3 Link

Plugged into one of your computer’s Thunderbolt 3 ports, the Echo III Desktop system enables you to connect professional PCIe cards (three full-height, single-width cards, or one double-width card plus one single-width card).

Supports Every Thunderbolt 3 Compatible, Non-GPU PCIe Card

Echo III Desktop supports every Thunderbolt 3 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.

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.

Adds Connectivity & Capabilities

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


Pro Tools | HDX Compatible(1)

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


Broad PCIe Card Compatibility

Every Thunderbolt 3 compatible, non-GPU card supported regardless of length or height.


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.


Pro Power

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


Remarkably Quiet

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


40Gbps Thunderbolt 3 Interface

Offers 2750 MB/s of PCIe bandwidth for the installed cards(1).


Two Thunderbolt 3 Ports

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


Rugged Aluminum Housing

Provides robust and secure protection.


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!

Included at No Extra Charge

Sonnet Thunderbolt 3 Cable & ThunderLok 3

Sonnet includes a 0.7-meter Thunderbolt 3 (40Gbps) cable that transfers data at Thunderbolt 3’s full 2750 MB/s PCIe bandwidth. In addition, Sonnet provides a ThunderLok 3 Thunderbolt connector retainer clip(2) 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.

ThunderLok Advantage

Sonnet Thunderbolt expansion systems are designed with Thunderbolt ports that include a threaded mounting holes for securing Sonnet's ThunderLok retainer clips that prevent accidental cable disconnections.

Fastest External Interface Available. Thunderbolt 3 – the USB-C That Does It All

The Echo III Desktop features a 40Gbps Thunderbolt 3 (USB-C®) interface that delivers up to 2750 MB/s of PCIe bandwidth(1), 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.

Two Thunderbolt 3 Ports

One port is reserved for the connection to your computer; the second port enables expansion of up to five additional Thunderbolt peripheral devices(5) in a daisy chain.

10Gbps USB 3.2 Gen 2 Support

10Gbps USB 3.2 Gen 2 support allows you to connect a USB device(6) to the second port using the proper cable or adapter.

Supports One 5K or Two 4K Displays

Supports connecting up to two 4K @ 60Hz displays or one 5K @ 60Hz display.

Provides 15W of Power

For connected peripherals requiring extra power, 15 watts is provided to bus-powered devices.

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).

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 III Rackmount even saves space for optional future expansion.


Mac Compatibility


Mac with Thunderbolt 3 ports

Mac with a Thunderbolt 2 or Thunderbolt port with an Apple Thunderbolt 3 (USB C) to Thunderbolt 2 Adapter plus a Thunderbolt 2 cable (both sold separately).

macOS 10.12.6+

macOS Big Sur compatible

Windows Compatibility


PC with Thunderbolt 3 ports

Windows 10 (64-bit Edition Version 1809 or greater, see note)

Important Note: Windows computers require the latest BIOS and Thunderbolt drivers to support this product. Check with your computer manufacturer for update information.

Linux Compatibility


Linux computer with Thunderbolt 3 ports

Linux Kernel 5.0+

PCIe Card Compatibility


For a list of compatible PCIe cards, view the PDF of Sonnet's PCIe Card Thunderbolt Compatibility Chart



Part Number






Form Factor


Desktop expansion system

External Connectors


Two Thunderbolt 3 ports

12V power port

Internal Connector


6-pin Mini-Fit Jr (same type as on legacy Mac Pro motherboard; provides up to 75W of power for PCIe cards that require supplemental power)

Expansion Slots (Facing Rear, Left to Right)(1)


One x8 mechanical (x8 electrical) PCIe 3.0

One x16 mechanical (x8 electrical) PCIe 3.0

One x8 mechanical (x4 electrical) PCIe 3.0

PCIe Cards Supported


One full-length, full-height, double-width PCIe card, plus one single-width card or

Three full-length, full-height, single-width PCIe cards

Power Supply


Universal 400W, 115-230V AC, 50-60 Hz(8)

Operating Temperature


0C to 35C (32F to 95F)

Dimensions (WxDxH)


3.5 x 16.7 x 9 in. (8.9 x 42.4 x 22.9 cm)



9.7 lbs (4.40 kg)



RoHS 3 (Directive 2015/863)

IEC62368-1 and IEC62368-2

Package Contents


Echo Express III Desktop chassis

Power cord

0.7-meter Thunderbolt 3 (40Gbps) cable

ThunderLok 3 Thunderbolt Connector Retainer Clip(2)


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