Optical USB cable for DAC - bitperfect at any length

[tombo56]

But the handshake requires sending a common-mode voltage (i.e. D+/- vs. GND) from the device back to the host. The device needs access to the host GND line.

IIUC any required signal can be generated/converted based on received optical signal and is referenced to device ground resulting in no difference compared to differential signal sent with reference to common ground. Device sends back to the host signal by another optical fiber line and again access to host ground shouldn’t be necessary.

 

[phofman]

Yes, it's doable with another isolated side-channel and some logic (there are several HS isolation chips available today ). But it is a major complication to the rather simple differential line -> long-run of optics -> differential line design of that existing cable (IIUC the current design).

 

[capslock]

So no galvanic isolation but longer reach - right!?

This?

//

Ok, there seem to be three versions:
$16.50 USB 3.0/2.0/1.0 -- this is cable based, so not wanted
$42 USB 3.2 Gen. 1 5 GBPS -- what's wrong with this one? in the pic there is the disclaimer "only supports 3.0" . Is that what is wrong? How can it be USB3.2 when it only supports 3.0? why doesn't it have fallback to 2.0?
$55 This is the USB3.2 Gen2 10 GBPS the op meant

Now unfortunately I this seller (Beilink store) does not ship to Germany. I have been tying to find other shops on and off Ali but to no avail. Can anyone help out with a different source?

 

[tombo56]

There are similar available at amazon.de. Just confirm that USB 2.0 is supported as well. Price is higher but goods can be returned easily if doesn’t work. In example: this one

 

[merlin el mago]

I'm interested, thanks for the info.

 

[TNT]

what's wrong with this one?

Does it share earth between the ends? Thats what' discussed...

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[Markw4]

Shared power and ground at both ends, seems most likely. How else would the optical receiver back to wired USB work? Its gonna need power from somewhere.

OTOH, if the receiver/device end requires external power then probably no need for shared ground at both ends.

 

[capslock]

There are similar available at amazon.de. Just confirm that USB 2.0 is supported as well. Price is higher but goods can be returned easily if doesn’t work. In example: this one

Good find! Not sure if it is a different manufacturer than Beilink. It is also USB3.2 Gen 1 and 5 GBps, which we were told not to buy from Beilink

 

[tombo56]

Shared power and ground at both ends, seems most likely.

Not likely but confirmed from the beginning that there is no ground isolation – post #8.

I can’t find any problem with that, while using 7.5 m long cable, by detailed DAC measurements (noise, distortion and jitter) or careful listening. There are no reasons to exchange standard quality USB cable, below 2 m length, with optical USB. However, I need more and there is no going back for me from this solution.

 

[tombo56]

Good find! Not sure if it is a different manufacturer than Beilink. It is also USB3.2 Gen 1 and 5 GBps, which we were told not to buy from Beilink

Doesn’t matter if it is USB3.2 with only 5 Gbps. What matters is backward compatibility with USB 2.0, required by DAC. It is mentioned in the specification but I can’t vouch for that.

 

[Pano]

Never seen that before.

But in large A/V setups we have used HDMI over fiber for years. It usually works well. IIRC the ends are electrically independent, powered separately.