TBT4-HUB3C Plug-in Thunderbolt 4 Hub Capsule Review


Plugable today presents its Thunderbolt 4 product line, with the TBT4-HUB3C Thunderbolt 4 hub leading the pack. There are two Thunderbolt 4 cables – the 2m. long TBT4-40G2M, and the 1m. long TBT4-40G1M.

Intel had provided detailed updates on Thunderbolt 4 in mid-2020 before releasing it in Tiger Lake-based products. Since the maximum bandwidth (40 Gbps) has not been upgraded from Thunderbolt 3, many consumers have simply viewed it as a brand update. In fact, under the hood, the specs were being fine-tuned to incorporate some functionality from the USB world. These are the new features that Plugable is focusing on:

  • Hub functionality in addition to the daisy-chaining scheme prevalent in previous versions of Thunderbolt
  • Active cables up to 2m long and supporting speeds up to 40Gbps – maximum possible depending on host / device interfaces (Thunderbolt 3 active cables with non-Thunderbolt 3 Type-C devices are often limited to USB 2.0 speeds)

TBT4-40G2M (active) and TBT4-40G1M (passive) cables are Intel certified Thunderbolt 4 cables, priced at $ 59 ($ 49 after coupon is applied) and $ 34 ($ 29 after coupon is applied) respectively. The price premium is due to increased certification costs (the factory has to have random build batches repeatedly tested for Thunderbolt 4 cables, compared to just the initial build run previously).

These cables complement Plugable’s flagship Thunderbolt 4 product – the Goshen Ridge-based TBT4-HUB3C. The Controller JHL8440 Goshen Ridge used in the hub is a four port solution – one upstream and three downstream.

The TBT4-HUB3C comes with a 0.8m passive Thunderbolt 4 cable, 110W power brick, and USB-C to HDMI adapter supporting resolutions up to 4Kp60 with HDR. The main hub itself is quite small compared to the power brick, measuring just 118mm x 18mm x 73mm. Despite its small size, the unit has a solid look and feel with its brushed finish. The hub tips the scales at 201g, light enough to be considered a pocket.

Plugable also includes a USBC-HDMI adapter (USB-C Male to HDMI 2.0 Female Converter Supporting DisplayPort Alternate Mode on USB-C side) with package. The intention is to route incoming display signals from the host to one of the downstream Thunderbolt 4 ports and then to an HDMI monitor. This also brings out the advantages of the hub scheme – With the daisy chain no longer present for most deployments (each hub beam can still be a daisy chain in Thunderbolt 4), users don’t have to s ‘worry about placing different Thunderbolt Devices / Displays in the chain. In addition, it allows devices to be disconnected independently of each other – which is not possible in the daisy chain topology without breaking the links to the devices intended to remain active.

Performance Test

The number of use cases for Thunderbolt 4 hubs such as the TBT4-HUB3C Plugable is too large to count. Our performance evaluation is limited to the configurations specified below. The upstream port of the TBT4-HUB3C is connected to the Thunderbolt 4 port of the ASRock Industrial NUC BOX-1165G7 – a risky choice, given that the port is only certified for USB 3.2 Gen 2 / DisplayPort Alternate Mode. The downstream ports have been connected according to the list below.

  • Port # 1 – DIY Thunderbolt 3 SSD using the TEKQ Rapide and the WD_BLACK SN750.
  • Port # 2 – PowerColor play station EGFX solution with the PowerColor Radeon RX Vega 56 Nano.
  • Port # – USBC-HDMI connector on an LG34WK95U configured to display a desktop 3840×2160 at 60Hz (8-bit RGB)

Thunderbolt Control Center can be used to approve connected devices. All primary connections to the Thunderbolt port (other than displays and associated routing equipment) are visible there.

Various combinations of workloads were considered to determine the actual effects of sharing bandwidth between devices connected to the hub. The DIY Thunderbolt 3 SSD was subjected to fio workload, while the Gaming Station’s eGPU was subjected to OpenCL bandwidth test (data transfer from the host to the device’s VRAM, and vice versa. ).

Plug-in Thunderbolt 4 Hub (TBT4-HUB3C)
Bandwidth Sharing Analysis (Gbps)
Port # 1
(DIY TEKQ Fast Thunderbolt 3 SSD)
Port # 2
(PowerColor Gaming Station eGFX box)
Port # 3
(Connection to LG34WK95U via USBC-HDMI from Plugable)
Readings Writing Device to host Host-to-device
11.44 10.98
16.2 16.74
13.7 17.64
13.78 14.4
22.12 14.4
14.1 14.4
23.0 14.4
8.99 9.21 14.4
11.0 19.14 14.4
13.5 12.46 14.4

It should be noted that Thunderbolt data rates are bidirectional – logically we have one 40 Gbps link from host to device, and another 40 Gbps link from device to host. In our experiments, we attempted to enable traffic in pairs – one set with display routing disabled and another set with the USBC-HDMI portion active.

It can be observed that enabling display output link reduces the performance of host-to-device traffic from 20.57 Gbps to 13.78 Gbps, while the total bandwidth used on the host-to-device side is increased. from 20.57 Gbit / s to 28.5 Gbit / s. On the return side, the maximum observed bandwidth was found to be 22.11 Gbps.

The investigation of the hub’s downstream port 5K display outputs and its bandwidth implications will be covered in future reviews.

Final remarks

The Plugable TBT4-HUB3C brings out the capabilities / advantages of Thunderbolt 4 over previous versions of Thunderbolt in an efficient and user-friendly way. The hub functionality brings Thunderbolt and the traditional consumer understanding of USB functionality to the same table, and it can only be good for the market as USB4 begins to gain traction.

The TBT4-HUB3C is capable of supporting 40 Gbps in total on the three downstream ports without favoring one port over the other. While we’ve evaluated a number of interesting use cases involving displays, Thunderbolt SSDs, and eGPUs, the possibilities offered by the hub are much more varied. With backward compatibility – we even tested the functionality of the device as a USB 2.0 hub when connected to a USB 2.0 port – in the picture it can be safely said that the functionality of the hub is not limited only by the characteristics of the upstream host port.

TO $ 174 (after applying a $ 15 coupon off the $ 189 MSRP), the hub presents a great value proposition in this space. Plugable is a bit behind the Thunderbolt 4 market, as other Goshen Ridge solutions have been available in the market for some time now (although supply chain issues have meant that actual availability has been limited). All Thunderbolt 4 hubs / docks make full use of the four-port JHL8440, allowing one upstream Thunderbolt 4 port and three downstream Thunderbolt 4 ports. For $ 230, CalDigit Thunderbolt 4 Element Hub beacons on additional USB 3.2 Gen 2 ports. Razer has two docking stations – a 10-port version with an SD card slot, audio jack, Ethernet port, and three USB 3.2 Gen 2 ports for $ 320, and an RGB version of the same for $ 330. The Kensington SD5700T priced at $ 330 is similar to the Razer Dock, but with an additional USB-A charging port only.

The closest competitor to the Plugable TBT4-HUB3C is actually the OWC Thunderbolt hub which has a similar form factor and port layout. It also has a USB 3.2 Gen 2 Type-A port for its $ 179 price point. Despite the $ 5 reduction in the OWC unit, Plugable managed to include an added value of $ 20 in the USBC-to-HDMI adapter. Overall, Plugable has an effective entry-level Thunderbolt 4 product aimed at expanding market adoption and understanding of the latest Thunderbolt 4 and USB4 ecosystem. We look forward to the company expanding its offerings and creating a TBT4 lineup similar to the one it currently offers for Thunderbolt 3.


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