Questions about Dream Air split cable

Pimax Hardware Pimax Discussion
1

I’m considering buying the Pimax Dream Air, but there are some questions that concern me.

From what I’ve seen in various videos, the cable before it splits into two is quite thick.

  1. What will be the thickness of the cable in the production units? I’m interested in the diameter in millimeters.

  2. How flexible will it be?

  3. Will it be a hybrid cable (with copper wires for power delivery and fiber-optic strands for data to reduce thickness)?

My dream has always been to connect a VR headset to a computer using a single long thin hybrid (fiber-optic + copper) USB Type-C cable.

I have a computer with a USB4/Thunderbolt 4 Type-C port that simultaneously supports DisplayPort Alt-Mode for video (all 4 lanes), up to 40 Gbps data transfer, and Power Delivery for power.

  1. Will I finally be able to achieve my dream of connecting the Pimax Dream Air directly to the computer with a single USB Type-C cable, without using the Pimax Link Box?

From what I can see, the Pimax Link Box not only splits the single USB Type-C cable into a standard DisplayPort cable and a USB cable, but also adds power through a DC jack and an AC power adapter.

  1. What is the wattage of that power adapter?

  2. Does the combined USB cable between the Link Box and the headset use Power Delivery protocol?

  3. If yes, which specific USB PD profile is used (voltage and amperage)?

  4. Or is it using VirtualLink?

VirtualLink is known for using a 12V supply, which is not part of the standard USB Power Delivery profiles.

  1. If this is indeed VirtualLink, does that mean I could connect the Dream Air directly to a GPU that has a VirtualLink port, without using the Pimax Link Box?

When the Pimax Dream Air was first announced, I read somewhere (I can’t find the source anymore) that the headset would work not only with VR-ready PCs but also with other devices that have a DisplayPort output as an external monitor, similar to headsets like Xreal, Viture, Rokid, RayNeo, etc.

  1. Is it true?

  2. If so, will it work as an external stereo monitor (i.e. support side-by-side stereo) rather than a mono monitor?

It would be great to be able to connect the Dream Air, for example, to a Steam Deck and play games on a large virtual display.

  1. Is this even technically possible? As far as I understand, a rectangular image must be pre-transformed in advance in order to be displayed correctly through the headset lenses.

  2. Is this transformation done in the Pimax Play software, or in the firmware of the headset itself?

@PimaxQuorra @SweViver @jaapgrolleman cc

2

I can pick up those questions after the CNY break, they’re quite technical. I think the cable is about as thick as the PSVR2 cable, there’s no fiber optic cable planned at the moment. The whole single-USB connection to PCs or phones right now is still being evaluated, the main focus is getting the headset all stable and shipped.

3

The exact characteristics of the cable for the final version of the Pimax Dream Air have not yet been officially confirmed. The cable will probably remain quite thick due to the high bitrate of the video and power supply, the hybrid option (optics + copper) is possible, but this has not yet been confirmed. Connecting one USB-C directly to a PC without a Link Box is probably not planned, because the headset needs more power than the USB-C port usually provides. Therefore, Link Box adds power through an adapter and splits the signal into DisplayPort and USB. The power of the adapter and the exact profile of the power supply have not yet been publicly specified. VirtualLink is hardly used in new devices, so a direct connection to the GPU with VirtualLink is unlikely. As for connecting to other devices as an external display, it is only possible in part and rather through the software, and image correction for lenses is usually done in the program on the PC together with the firmware of the headset

4

The exact characteristics of the cable for the final version of the Pimax Dream Air have not yet been officially confirmed.

That’s why I asked this question here.

Because the first batch of production units has already been shipped to end users. See https://pimax.com/blogs/blogs/dream-air-starts-shipping.

So this shouldn’t be a secret anymore. Because we’ll see everything with our own eyes anyway in video reviews. I mean the external characteristics of the cable, like the thickness.

These end users are getting the final version of the cable, right? Or are they not, just like with the temporary fabric headstrap? ))

Connecting one USB-C directly to a PC without a Link Box is probably not planned, because the headset needs more power than the USB-C port usually provides.

I understand that this kind of luxury isn’t for everyone. And I fully understand the purpose of the split box.

The output (not input!) power of most USB Type-C ports — even USB4 / Thunderbolt 4 — does not exceed 15W.

Fortunately, I myself am a software and hardware engineer. So, as I said, I’m among that 1% of lucky people who have access to cutting-edge hardware.

And I’m trying to figure out whether the PD 3.1 45W provided by my USB Type-C port will be sufficient, or whether the Dream Air doesn’t use Power Delivery at all and relies on some other protocol?

That’s exactly why I asked about VirtualLink right away — just in case it turns out not to be Power Delivery.

The power of the adapter and the exact profile of the power supply have not yet been publicly specified.

I don’t think that’s true.

The DC power adapter for split box is identical to the one used with Crystal Super and Crystal Light.

This is mentioned here: https://youtu.be/hVUWrGqDDXg?t=465

The problem is that I don’t own either Crystal Super or Crystal Light, and can’t check it myself. Also I haven’t been able to find any close-up photos of this power adapter online.

That’s why I asked what are its voltage and power rating in watts?

By the way, in this video we can see the thickness of all the cables.

But again this isn’t the final version of the headset, and possibly not of the cable either!

The cable will probably remain quite thick due to the high bitrate of the video and power supply

That’s not true.

Just look at fully copper, not hybrid (optical + copper), USB Type-C ↔ USB Type-C cables that support Thunderbolt 5 at 240W and 120Gbps. They aren’t that thick and are fairly flexible.

In USB, higher power is achieved not only by increasing current but also by increasing voltage, so a thick cable isn’t necessary.

I’m almost certain that Dream Air doesn’t even draw 45 watts. After all, it’s not a standalone VR headset.

But I would still like an official confirmation. :slight_smile:

Data transfer speed has no effect on, and does not depend on, cable thickness at all.

Moreover, when we talk about a DisplayPort signal inside a USB cable, that’s a completely different mode, unrelated to data transfer speed. USB cables that support DisplayPort 1.4a Alt Mode are fairly thin.

By the way, personally for me, thickness isn’t as important as flexibility. There are thick cables that are still flexible, and thin cables that are stiff. It all depends on the quality of the materials.

That’s why it would be great to see a live video showing the cable being bent in someone’s hands. @SweViver :wink:

5

I have an HP Reverb G2, which comes with a split box that has a thick, stiff non-detachable OCuLink male cable for the VR headset, a DC female port for power adapter cable, a non-detachable full-size DisplayPort male cable, and a non-detachable USB Type-A male cable.

By using USB Type-C male to DisplayPort female adapter and USB Type-C male to USB Type-A female adapter, I can get two USB Type-C male cables.

That’s exactly what I did when connecting the VR headset to my MacBook Pro 16 (2019) running Windows as a second OS, because it only has four USB Type-C ports — all four supporting Thunderbolt 3 40Gbps and DP Alt-Mode 1.4a DSC.

And it works! :slight_smile:

But because of the adapters, the whole setup was pretty bulky. :frowning:

I also have a Steam Deck, and I successfully connected the HP Reverb G2 to it as well, installing Windows as a second OS.

But the Steam Deck only has one single USB Type-C port.

So I had to use a USB splitter in addition to the adapters to combine the two USB Type-C male cables into one single USB Type-C male cable.

You can imagine that nightmare. But it works too! :slight_smile:

That’s why the idea of connecting a VR headset to a computer with a one single USB Type-C cable and eliminating all those adapters and splitters has become my dream. :slight_smile:

Pimax could release an alternative split box for users whose USB Type-C ports support DP Alt Mode but don’t supply enough power, yet who, like me, want to connect a VR headset to a computer with just one single USB cable.

As an idea, it could have three USB Type-C female ports: one for the headset cable, second for the computer cable, and a third for a power adapter that provides sufficient wattage and supports the Power Delivery protocol, like modern smartphones or the Steam Deck.

All three female ports could have latches, just like on the current split box.

By the way, this fits perfectly with ideas of repairability and reducing e-waste.

Because current split box has non-detachable DisplayPort and USB cables.

The power adapter also has a non-detachable cable.

If the cable breaks, you have to replace the entire split box or power adapter.

On top of that, the power adapter uses a DC cable instead of a USB Type-C cable, which is what the industry is moving toward nowadays.

But in fact, this alternative split box could be replaced by a USB Y-cable that simply adds power.

Pimax, what do you think about the idea of an alternative split box or a USB Y power cable?

6

Could a USB/Thunderbolt hub with USB Type-C ports that support DP Alt Mode and provide sufficient power in watts, when connected to the correct USB Type-C port on a computer that also supports DP Alt Mode, completely replace the Pimax Dream Air split box?

7
  • This cable bundle contains wires of different diameters, with the longest main cable being the thickest at 5.5 mm in diameter.
  • The cables currently being shipped are all copper wires, but the possibility of developing new cable types in the future is not ruled out.
  • Currently, it is not possible. There are two connectors (USB 3.0 and DP), and there is also an external 12V power supply that connects to the Link Box.
  • 12V 2A.
  • The cable is not a standard USB 3.0 cable and does not support the Power Delivery protocol.
  • Not supported.
  • The current cable connecting to the Link Box is not a standard Type-C interface, so it cannot be used directly as a Type-C display device.
  • Technically it is feasible, but the current cable design has other considerations, so it is not supported at the moment.