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Echo Express III-D TB3 with MacBook Pro

Connect Three Full-Length PCIe Cards to any Computer with a Thunderbolt 3 Port

PCIe Card and Notebook Icons

For pros working in the creative fields, a computer’s processing power alone is not enough to get the job done. A prime example is the latest MacBook Pro®, which, while offering great performance, lacks the PCIe expansion slots necessary to support specialty cards that connect pro video and audio inputs, transcode data, and connect to high-speed storage and networks. Instead of slots, these computers include high-performance Thunderbolt™ 3 ports to support peripherals. Sonnet’s Echo™ Express III-D (Thunderbolt 3 Edition) leverages the Thunderbolt 3 ports’ PCIe data to connect PCIe expansion slots outside of a computer. This powerful desktop Thunderbolt-to-PCIe card expansion system enables you to connect three professional PCIe cards—including video capture, audio interface, SAS or SATA HBA, 16Gb or 8Gb Fibre Channel, 10 Gigabit Ethernet, and RAID controllers—at the same time to any computer with Thunderbolt 3 ports.

The Echo Express III-D (Thunderbolt 3 Edition) features a 40Gbps Thunderbolt 3 interface, which offers double the PCIe bandwidth and connectivity of Thunderbolt 2, and yields up to 2750 MB/s of bandwidth, enabling it to support 4K video capture and processing cards at high frame rates, and 16Gb FC cards and dual-port 10GbE cards at full performance(1)(2). With the ability to handle multiple demanding, high performance PCIe cards, support for connecting two 4K displays @ 60Hz or one 5K display @ 60Hz(3), and support for a vast array of Thunderbolt(4) and USB(5) devices, Thunderbolt 3 is a leap forward in every way.

Key Features

Connects Three Full-Length PCIe Cards to any Computer with Thunderbolt 3 Ports—Use multiple high-performance PCIe cards at the same time

Three PCIe 3.0 Slots—Supports three full-height, single-width cards, or one double-width card plus one single-width card

40Gbps Thunderbolt 3 Interface—Offers 2750 MB/s of PCIe bandwidth, doubling the performance of Thunderbolt 2

Two Thunderbolt 3 Ports—One port used to connect to the computer; second port supports daisy-chaining of up to five additional Thunderbolt(4) peripheral devices to your computer, attaching a single USB(5) peripheral device, or connecting up to two 4K displays or one 5K display(3)

Remarkably Quiet—Large, temperature-controlled, variable-speed fans that automatically cool the cards, plus computer-modeled design that reduces airflow turbulence and velocity, combine to provide quieter cooling for all cards

Built-in Universal Power Supply—Integrated 300W power supply with 75W auxiliary power connector

Rugged Aluminum Housing—Provides robust and secure protection

Power for Peripherals—Provides up to 15W of power to connected peripherals

Every Thunderbolt 3 Compatible, Non-GPU Card Supported—Works with every Thunderbolt 3 compatible PCIe card, regardless of length or height

Thunderbolt 3 Cable & ThunderLok 3L Included—Includes 1-meter Thunderbolt 3 (40Gbps) cable and ThunderLok 3L Thunderbolt connector retainer clip to secure cable from accidental disconnections


300W Power, 75 Aux Power, and Enviro-Friendly IconsEcho Express III-D TB3 (Inside View)

Three PCIe 3.0 Slots, No Compromise

Sonnet’s Echo Express III-D supports three full-size PCIe cards, up to 12.28 inches (full-length) long. The III-D integrates a universal 300W power supply and includes a 75W PCIe power connector for cards that require supplementary power, such as the RED® ROCKET-X.

Even with all that power, the III-D is enviro-friendly; it automatically powers on or off whenever the connected computer powers on (or wakes), or powers off or sleeps, respectively.



Thunderbolt 3 Daisychain Diagram

Connect computer to one port on the Echo Express III-D (Thunderbolt 3 Edition) and daisy chain up to 5 additional Thunderbolt devices
(plus two 4K monitors, one 5K display, or one USB 3.1 device)

40Gbps Thunderbolt 3 —
The USB-C That Does It All

The Echo Express III-D (Thunderbolt 3 Edition) includes two Thunderbolt 3 ports; the first is used for connection to your computer, while the second supports daisy chaining of up to five additional Thunderbolt peripheral devices to a single port on your computer(4). The III-D includes 10Gbps USB 3.1 Gen 2 support, meaning you can connect a USB device to the second port using the proper cable or adapter. The III-D also provides full support for connecting two 4K displays @ 60Hz or one 5K display @ 60Hz(3). For connected peripherals requiring extra power, 15 watts is provided to connected bus-powered devices.

One Port Delivers Up to 40Gbps Icon

Echo Express III-D TB3 (Front and Back Views)All-Around Smart Design

Aluminum and Auto Power IconsThe Echo Express III-D is wrapped in a rugged, yet lightweight aluminum outer shell, resulting in a system light enough to carry without weighing you down, yet sturdy enough to securely protect the installed PCIe cards.

Its two large, slow-spinning fans, enhanced with computer-modeled airflow management, ensure that even hot-running cards remain reliably cool without the need to install an extra PCIe blower card that would prevent the use of one of the three slots. Because the fans automatically speed up and slow down as needed, you don’t have to guess which speed setting to select, and there’s no need for tools to change settings. There is no power switch on the chassis, nor is one needed, because the III-D automatically powers on and off with your computer.

Quiet Operator

In operation, the Echo Express III-D is remarkably quiet—it may be comfortably used in noise-sensitive environments, and it is one of the quietest Echo systems. The natural convection of warm air through the PCIe cards is assisted by ultra-quiet, temperature-controlled, variable-speed fans, and vented out the top of the chassis with reduced air velocity and turbulence, resulting in little fan noise.

x8 and x16 PCIe Cards

Echo Express III-D features two x8 plus one x16 plus PCIe slots for versatile card support

Every Thunderbolt 3 Compatible, Non-GPU Card Supported

The Echo Express III-D supports three single-width, full-length PCIe cards, or one double-width, full-length card plus one single-width card, enabling it to support every Thunderbolt 3 compatible, non-GPU PCIe 1.1, PCIe 2.0, and PCIe 3.0 card available.

Do you have a card in mind but aren’t sure it’s compatible? We’ve worked closely with PCIe card manufacturers to provide a list of compatible cards on our PCIe Card Thunderbolt Compatibility Chart. The chart provides a list of cards that have been tested to be recognized over a Thunderbolt connection and compatible with Thunderbolt technology requirements.

PCIe Card Thunderbolt Compatibility Chart

Echo Express III-D TB3 Back View with BNC Mounting Holes


RED ROCKET Supporter

Sonnet designed the Echo Express III-D to accommodate the RED ROCKET or RED ROCKET-X and its BNC connector bracket (for HD-SDI output) card/bracket pair in a single slot. This Echo chassis includes two BNC connector mounting holes, enabling the installation of the card in one slot and its BNC connectors in the chassis’ mounting holes, leaving the two remaining slots open.

BNC Connector Cable

Designed for BNC Connector Cables

Echo Express III-D’s back panel has two BNC connector mounting holes, enabling the use of a RED ROCKET card without the need to install the BNC connector bracket that would normally occupy a valuable PCIe slot.

Echo Express III-D TB3 with RED ROCKET Card

1-meter Thunderbolt 3 (40Gbps) Cable and ThunderLok 3L Included

ThunderLok 3LTo connect the Echo Express III-D (Thunderbolt 3 Edition) to your computer, Sonnet includes a 1-meter Thunderbolt 3 (40Gbps) cable, and a Sonnet ThunderLok 3L Thunderbolt connector retainer clip(7) to secure the cable to the Echo chassis.

Accidental cable disconnection can lead to data loss. Sonnet’s ThunderLok 3L is easy to install and use—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, the ThunderLok remains on the cable so it won’t get lost when not in use. Additional ThunderLok 3L retainer clips and Thunderbolt cables are available and can be found under the Accessories tab.



Thunderbolt 3 Cable

Thunderbolt 3 Cable with ThunderLok 3L Connected to Thunderbolt 3 Port

Benefit from a Secure Connection

Sonnet's ThunderLok 3L easily fastens to a 1-meter Thunderbolt 3 (40Gbps) active cable to ensure a secure connection to compatible Sonnet Thunderbolt 3 products. The retainer clips remains on the cable and won't get lost.

Echo Express III-D - Thunderbolt 3 EditionRackmount Version Available

The Echo Express III (Thunderbolt 3 Edition) is available in two versions, the III-D (desktop) and III-R (rackmount), to suit your workflow needs. The III-R mounts in a rack space 2U tall, and is only 16 inches deep, making it perfect for use in a wide range of popular mobile racks, carts, and rack cases, and in server rooms as well. The III-R even saves space for other equipment—with an optional Mobile Rack Device Mounting Kit, you can install one or two mobile rack devices in the III-R’s rack enclosure.

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Sonnet Thunderbolt Expansion Partners

Sonnet works closely with the following partners to ensure Thunderbolt compatibility for their products. See the PCIe Card Thunderbolt Compatibility Chart for a list of products that have passed Thunderbolt compatibility testing with Sonnet products.

AdobeAJAAppleApogeeArecaATTOAudinateAvidBlack Magic DesignBlueFish 444CalDigitDeltacastExaSANFocusriteFusion ioHigh PointLynx Studio TechnologyMatroxMyricomNewer TechOWCREDRMESiennaSmall Tree Softron Media ServicesSolid State LogicStorageDNATandberg DataTolis GroupTools On AirUniversal Audio

 PCIe cards and computer hardware shown in photos for illustration purposes; items sold separately.
See Tech Specs Tab for footnotes
Part No.  
ECHO-EXP3FD-TB3 Echo Express III-D (Thunderbolt 3 Edition) Thunderbolt 3 to PCIe Card Expansion System
Warranty 2-year
Form Factor Desktop expansion system
External Connectors Two Thunderbolt 3 ports
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:
  • 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
Compatible PCIe Cards PCIe cards listed on our supporting PCIe Card Thunderbolt Compatibility Chart and as specified by card manufacturers
Power Supply
Universal 300W, 115-230V AC, 50-60 Hz(6)
Operating Temperature

0˚C to 35˚C (32˚F to 95˚F)

Dimensions (WxDxH) 3.8 x 16 x 10.2 in. (9.7 x 40.5 x 25.9 cm)
Weight   7.5 lbs (3.4 kg)
RoHS Compliant Yes
Package Contents
  • Echo Express III-D (Thunderbolt 3 Edition) Thunderbolt 3 to PCIe Card Expansion System
  • Power cord
  • 0.7-meter Thunderbolt 3 cable
  • ThunderLok 3 Thunderbolt Connector Retainer Clip
  • Documentation

Note: PCIe cards sold separately


Specifications subject to change without notice.






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

macOS 10.12.6+

macOS Mojave Compatible

PC Compatibility

See FAQ (for SE III/III-D & III-R Thunderbolt 3 Editions)

PCIe Card Compatibility

For up-to-date PCIe card compatibility see our PCIe Card Thunderbolt Compatibility Chart

Technical Notes

  1. While the Echo Express III-D (Thunderbolt 3 Edition) features a 40 Gbps Thunderbolt 3 interface, some computers equipped with Thunderbolt 3 use an x2 PCIe lane implementation of Thunderbolt 3 technology that limits PCIe performance to 20Gbps. Find more computer information here.
  2. Full performance requires the use of the included Thunderbolt 3 (40Gbps) cable, or comparable Thunderbolt 3 (40Gbps) cables; look for the Thunderbolt icon AND the number 3 on the connector housings to identify these cables.
  3. One 4K monitor directly supported. Two 4K monitors requires either a 4K monitor with multi-stream transport support (DP out), or a Thunderbolt 3 to Dual DisplayPort adapter. 5K monitor requires a Thunderbolt 3 to Dual DisplayPort adapter. All Thunderbolt 3 Macs support two 4K monitors. Most Thunderbolt PCs support two 4K monitors.
  4. Second Thunderbolt 3 port supports Thunderbolt and Thunderbolt 2 peripheral devices on Macs used with the Apple Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter, sold separately.
  5. Second Thunderbolt 3 port supports USB 3.1 Gen 1 (5Gb) or Gen 2 (10Gb) devices when connected with proper cable or adapter (sold separately).
  6. Power supply will operate as low as 90VAC, with linear power deration from 300W @ 115VAC to 240W @ 90VAC.

Mac LogoWindows Logo PCI Express LogoroHS Logo



Accessories Part No. Description
ThunderLok 3L (2-Pack) ThunderLok 3L Thunderbolt 3 Connector Retainer Clip (2-Pack) TB3-LOK3L Secures Sonnet 1-meter Thunderbolt 3 cables with ThunderLok 3-compatible products; not compatible with Sonnet 0.5- or 0.7-meter passive cables
ThunderLok 3 (2-Pack) ThunderLok 3 Thunderbolt 3 Connector Retainer Clip (2-Pack) TB3-LOK3 Secures Sonnet 0.5- or 0.7-meter Thunderbolt 3 (40Gbps) passive cables with ThunderLok 3-compatible products; not compatible with Sonnet 1-meter active cables
HDX Power Cable Avid Pro Tools|HDX PCIe Card Power Adapter Cable TCB-HDXB Avid Pro Tools|HDX PCIe Card Power Adapter Cable for Echo Express III-D or III-R, xMac mini Server or Pro Server
Power Cable (OWC Excelsior) Power Cable (OWC Excelsior) TCB-EXCEL Cable, Power, for OWC Excelsior in Sonnet Echo Express III-D/R, xMac Pro Server, and xMac mini Server
Thunderbolt 3 Cable Thunderbolt 3 (40 Gbps) Cable TCB-TB3-1M 1-meter Thunderbolt 3 (40Gbps) cable
Thunderbolt 3 Cable Thunderbolt 3 (40 Gbps) Cable TCB-TB3-05M 0.5-meter Thunderbolt 3 (40Gbps) cable


Product Overview Slide Show - Featuring Echo Thunderbolt Expansion Systems (4:25 mins)

Thunderbolt 3 Cable Connection Security — Echo Express Thunderbolt 3 Expansion Systems (1:09 mins)

Pro Audio - with Andrew Scheps, Grammy Winning Mix/Recording Engineer & Producer (3:49 mins)

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