Sonnet Echo I Desktop Thunderbolt One-Slot Full-Length PCIe Card Expansion System

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Sonnet Echo I Desktop Thunderbolt One-Slot Full-Length PCIe Card Expansion System


Sonnet Echo I Desktop Thunderbolt One-Slot Full-Length PCIe Card Expansion System

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.

The Thunderbolt Connection

Plugged into one of your computer’s Thunderbolt 4 or 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 Compatible, Non-GPU PCIe Card

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. 

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.

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!

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.

All the Right Connections

40Gbps Thunderbolt Cable and ThunderLok 3 Included

Sonnet includes a Thunderbolt cable that supports Thunderbolt's full 40Gbps bandwidth, and is fully compatible with Thunderbolt 4 and Thunderbolt 3 computers. Sonnet also 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.

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.

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 Echo III Rackmount even offers space for an optional expansion module.

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.

Technical Specifications


Mac Compatibility

  • Mac (M1, M1 Pro, M1 Max, and M1 Ultra) with PCIe cards that have M1 compatible drivers
  • Mac (Intel®) with Thunderbolt 3 ports
  • Mac (Intel) with a Thunderbolt 2 or Thunderbolt 1 port with an Apple Thunderbolt 3 (USB-C) to Thunderbolt Adapter plus a Thunderbolt 2 cable (both sold separately)
  • macOS® 10.12.6+
  • macOS Monterey compatible

Windows Compatibility

  • Windows 10 computer with Thunderbolt 4 or Thunderbolt 3 ports
  • Windows 11 does not support multiple-slot Thunderbolt expansion systems. We are working with Microsoft to resolve the issue.

Linux Compatibility

  • Linux computer with Thunderbolt 4 or Thunderbolt 3 ports
  • Linux Kernel 5.0+


Part Number

  • ECHO-3D-TB3


  • 2-year

Form Factor

  • Thunderbolt desktop enclosure

External Connectors

  • Two Thunderbolt ports
  • Power (C14-type)

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

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

Power Supply

  • Universal 400W, 115-230V AC, 50-60 Hz(6)

Operating Temperature

  • 0ºC to 35ºC (32ºF to 95ºF)

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 III Desktop Enclosure
  • Region-specific power cable for US, Australia, Europe, Japan, Switzerland, or UK
  • 6-pin PCIe auxiliary power cable
  • Thunderbolt cable
  • ThunderLok 3 Thunderbolt connector retainer clip(2)
  • Documentation

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