L1 Product Request: TB4/TB3/USB4 Relay/Switch (Turn any Dock/Hub into a KVM)

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I actually sent this on the Contact Us form, and then I remembered there was a forum. Also, I was back and forth about whether to post this here or in Hardware > Other Hardware. But, ultimately, I chose here because it was a specific request for an L1 product. Apologies in advance if it was better suited for other there!

Forgive my ignorance of the particulars here, but I’m going to dream a little bit, if you don’t mind. It’s something that I, and many others, have been looking for but can never seem to find.

Here it is:

  • A TB3/TB4/USB4-capable USB-C switch/relay (NOT a KVM)

And before people start listing examples of existing USB switches, hear me out…

The Problem

1. There are tons of Thunderbolt and USB docks and hubs out there

Many support PD, and many have all kinds of different peripherals. This is great because people typically buy the hubs/docks that they need. Then, when they try to expand their setup, they have to wade through the existing selections of KVMs out there on the market in order to replace the Hubs/Docks that already fit their needs.

2. There are already USB switches out there, but they’re all garbage

Then you go down the rabbit hole of USB switches. The vast majority of them out there are either incredibly low quality, aren’t capable of fully taking advantage of TB4 or USB4, or don’t properly manage power and ground between hosts and devices, to the point that (first-hand experience here) when your host machines are a laptop and a desktop, you have audible noise because of the differing ground between the laptop and desktop :sweat_smile:

Please save us

I can’t think of anyone else I would reach out to that might have the means and capabilities to actually build this with quality, and have the customer base that would readily use this than L1 (I’ve already seen other necro threads asking around for something like this, both on this forum, Reddit, and many others).

tl;dr: The Solution: Deferred KVM: Let the user choose the Hub/Dock that suits their needs

So here’s my Christmas list:

  • A future-proofed extremely low-latency Thunderbolt 4 / USB4 relay capable of switching a fully-utilized TB4 Dock or Hub
    • Many of these Docks already have things that suit the user’s needs: Several USB-A/C or TB inputs, multiple DisplayPort or HDMI connections, SD-card readers, etc…
    • Being TB4-capable, it should obviously be able to handle switching a Hub/Dock with multiple high-resolution, low-latency DisplayPort monitors, in addition to other peripherals.
  • Versions with 2 or 4 host machines (I personally have a Linux Tower, Macbook, Linux Laptop, and Windows Laptop)
    • No idea if there’s anything that needs to be done in order to protect a hub with PD from being connected to a tower that doesn’t need/support it. I’m assuming not, since usually the machine only pulls what it needs. But it would be very unfortunate if someone switched to a Tower from a Laptop that’s using the PD and the Tower got fried
  • One single USB-C input (so that it can accept a hub/dock/etc)
  • (Bonus) Multiple USB-C inputs
  • (Bonus) Built-in 50/70/100W PD input
  • (Bonus) A corded toggle switch that can be relocated onto a desk or something, so that they switch/relay doesn’t need to be on the desk, but can still be actuated.

This way, someone can take their existing TB3/TB4/USB-C hub or dock that already has all the monitor connections and extra peripherals that they hunted for, and plug it directly into the switch/relay, and switch between N number of machines. All this without having to scour for a KVM that has most of what they had with the Hub/Dock, and supplement the KVM to fill in the gaps.

Benefits

  • Smaller form factor than a KVM (making it possible to use it in scenarios where a full-size KVM might be too large)
  • Any Hub/Dock, large or small, becomes a KVM
  • Cheaper than a full-blown KVM with minimal impact to existing Hub/Dock setups

There is absolutely no expectation that this would be ridiculously cheap :joy: But I imagine it probably wouldn’t be any more expensive than one of the more basic KVMs, since it’s only having to handle a single or few (albeit major) signal(s).

Please, for the love of God, be the one in the market to produce a “deferred KVM” that is stable enough to switch an existing Hub/Dock between multiple devices that have varying power options. We don’t necessarily need another KVM; just a switch that is capable of turning any existing Dock/Hub into a KVM.

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Thunderbolt is pcie and switching pcie devices is even buggier than USB. USB has a spec built in for dynamic device mapping. The spec is poorly written, incomplete, and has varying bugs in devices.

Pcie switches are what is happening in the enterprise. Stuff like liqid? But switching a pcie device rapidly back and forth is nigh impossible.

Thunderbolt is less bandwidth than most people realize too. Kinda sucks.

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I can imagine!

This is where my ignorance shines. I actually started looking into how this could potentially be achieved because, in my mind, a relay like this would effectively be “unplugging” from Host A and “plugging” into Host B, which could solve the problem of having on-board MCs to logically handle the hand-offs; potentially even with a time-delay and capacitors of some sort to prevent surging. And especially when it comes to existing KVMs, I figured this might actually be simpler for those experienced in building KVMs than having to switch multiple ins/outs simultaneously between the hosts.

Though it might be undesirable, I was even looking into 24-channel time-delayed relays at a more elementary level for switching USB-C pinouts. Granted, I imagine this same line of thinking is probably the reason that the majority of the USB switches out there on the market are as bad, unreliable, and even dangerous as they are.

I ran a couple Sabrent USB 3.0 switches for a little while until they got pulled for causing surges and frying ports. (Though, I believe they have a new version out on their website that may have solved the issue.) I only discovered that after I started troubleshooting and diagnosing issues where several peripherals would intermittently fail to function after switching on occasion. I was pretty worried that a few of them were acting up because of surges, and sure enough, I had to replace one of the peripherals after I disassembled it and realized that it was fried.

I’m currently running a couple of other switches, but I’m very wary of them given the track record of many other switches on the market. I’ve shopped KVMs for years now, but there’s always something missing from one or the other in terms of peripherals. And the ones that do support the peripherals I’m looking for have reported latency or bandwidth issues.

That’s kind of what ended up landing me on USB switches, most of which are very low-spec, which prevents them from supporting the more capable Hubs/Docks.

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I have seen Gigabit-Ethernet capable 8-pole relays, and I have seen them “abused” for USB 3.0 “switches” (Let’s call them “toggles” instead, because it is a physical switch, but not a switch-switch). Those were better-ish than the 4-pole push button switches, but still mediocre at best.

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Looks like Sabrent implemented exactly this strategy. Apparently they recently came out with a new TB4 KVM, which is more of a physical switch.

I found two critical reviews. One that described the switching mechanism and the lack of EDID, keyboard, or mouse emulation. The other was an unfortunate review that described my fears with the PD feature. Apparently he ended up frying two motherboards when switching between a laptop and a desktop while using PD.

There’s 25 reviews so far, and it goes for about $350, which is about the base I was expecting for something like this lol

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I bought and returned the Sabrent Thunderbolt 4 KVM. It’s only $299 direct from Sabrent, and there’s a coupon for an additional 10% discount. It worked great with my Windows desktop. However, the USB Type-A ports never worked correctly with my M1 MBP. USB devices would not detect unless I first disconnected them, switched to the MBP, then reconnected them. I’m lucky it didn’t fry my board with all the switching to try and get it to work.

I have a Caldigit Thunderbolt 4 Element Hub which has the host port on the right side. This makes it easy to quickly swap cables between two hosts. Unfortunately it died after a year of use and it look like there are no alternatives. I don’t want a dock with useless devices on the bus like 1 Gb Ethernet, low quality audio, slow memory card readers, etc.

I’l like to repurchase the Sabrent unit, but I don’t see any firmware updates or acknowledgement of any issues on their website. Support did not attempt to diagnose the USB Type-A issue and simply accepted the return.

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There are several alternatives but most of them don’t have as many USB Type-A ports.

Did you try to get the Element fixed under warranty??

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That’s a nice list. Unfortunately I need all 4x USB Type-A ports and all 3x USB Type-C ports (2x in Thunderbolt mode). The side host port for quick switching sources is also unique. The Sabrent unit is the only other one with sufficient ports and no junk features.