6 ms·

The 40 Gbps speeds of Thunderbolt 3/USB 4 are sustainable over only very short runs with passive cables -- anything longer than about 50 centimeters requires ac

The 40 Gbps speeds of Thunderbolt 3/USB 4 are sustainable over only very short runs with passive cables -- anything longer than about 50 centimeters requires active circuitry. There is no level of manufacturing scale that will make an active signal cable cheaper than an equivalent-length passive one, and cable manufacturers, who live and die on razor thin margins, are never going to be convinced to forgo the cost savings of building cheaper passive cables when their client's devices don't even use the higher speeds the active circuitry is required for.

TeMPOraL 7y ago
Huh. Fair point about data rates, but then again, I'm not sure if forcing manufacturers into a single, active cable would be impossible. Standardizing a single cable type shouldn't impact the margins on cable sales - whether the cable costs $0.1 or $10, every manufacturer will have the same costs (in the limit). > to forgo the cost savings of building cheaper passive cables when their client's devices don't even use the higher speeds the active circuitry is required for. That's why I think standardization should disallow this very attempt at costs savings. A given device may only need a passive cable, but as a user, I want to be able to use that cable with a different device. Moreover, cables are often bought separately (e.g. replacements). It's already a huge problem with USB 2/3 - buying a cable is a lottery wrt. transfer rates and charging amperages. (The last time I lost that lottery I happened to be in China, so I went to a local seller with a voltage measurement app, and started testing cables they offered one by one. After finally finding a cable that could push proper 2+ amps, I bought something around 60 of them, because back home, everyone sells USB cables packaged in hard plastic, so I wouldn't even be able to run this test.)
- msbarnett 7y ago
  > I'm not sure if forcing manufacturers into a single, active cable would be impossible. > ... > That's why I think standardization should disallow this very attempt at costs savings. There's a somewhat famous Common Lisp FAQ along the lines of "Why didn't the standardization committee just force implementers to do X thing?" And the answer is: your premise is wrong. Standards bodies don't have the power to force anybody to do anything. If implementors don't like your standard, they'll just ignore it. Standards live or die by their ability to raise consensus. If Generic Device Manufacturer #4823738 looks at the USB 4 standard and decides there isn't a big market for USB peripherals whose 2 meter charging cable (say, a gamepad that charges via a fairly long 5 W USB, like a gaming console uses) runs $75 because it requires fairly heavy gauge wire to additionally support (unneeded by the gamepad) 100 W charging and has to contain (unneeded by the gamepad) 40 Gbps active signalling circuitry, they're just not going to implement the bloody USB 4 standard. They're not going to implement it if there's a $1 to be saved by going some other route, honestly. Instead of the "universal protocol" dream dying on the rocks of a hodge-podge of subtly incompatible cables, you've simply killed it by convincing manufacturers to ship USB 2 devices until the end of time, instead. The standard committee can impose onerous, financially punitive requirements on anything calling itself USB 4, but they can't then make manufacturers adopt USB 4, so in the end they can't solve this by forcing anyone to do anything, which is why the entire idea of "one universal protocol" is hamstrung by its own internal contradictions.
- organsnyder 7y ago
  Let's say the USB standard mandated that all USB-C cables be fully-featured, such that they can't be manufactured for less than $10 each. What's to stop a vendor from selling cheap "cell phone charger" cables? They could print "Compare to Belkin USB-C cable* *not affiliated with Belkin or licensed by the USB Implementers Forum" on the box, and maybe even be able to survive a lawsuit. And even if they're not in the clear legally, these cheaper cables would be found in every "black-market" outlet, which these days includes Amazon, your local gas station, and many big box stores. How long would the USB-IF be able to maintain that stance, while their licensees clamor to be allowed to sell cheaper authorized cables? I think the solution is to improve branding. When I look at the USB-C cables in my bag, I can't tell at a glance which ones are full-featured: one of them has a tiny logo that maybe indicates something like that, but it's not obvious or prominent. I tend to end up plugging in the wrong one and discovering that the device isn't charging, performing as well as expected, etc. If the USB spec defined consistent, prominent branding for full-featured cables, this would be much less likely to occur. (yes, I know I should replace the inferior cables, but I only use them when I work away from home, which is infrequent enough that it hasn't crossed the threshold to be worth the time)
closetohome 7y ago
And - fun addendum to this - Active Thunderbolt cables don't work as basic USB cables - https://appleinsider.com/articles/17/08/15/psa-thunderbolt-3-cables-longer-than-05m-generally-dont-support-usb-31-speeds https://appleinsider.com/articles/17/08/15/psa-thunderbolt-3...

TeMPOraL 7y ago

Huh. Fair point about data rates, but then again, I'm not sure if forcing manufacturers into a single, active cable would be impossible. Standardizing a single cable type shouldn't impact the margins on cable sales - whether the cable costs $0.1 or $10, every manufacturer will have the same costs (in the limit). > to forgo the cost savings of building cheaper passive cables when their client's devices don't even use the higher speeds the active circuitry is required for. That's why I think standardization should disallow this very attempt at costs savings. A given device may only need a passive cable, but as a user, I want to be able to use that cable with a different device. Moreover, cables are often bought separately (e.g. replacements). It's already a huge problem with USB 2/3 - buying a cable is a lottery wrt. transfer rates and charging amperages. (The last time I lost that lottery I happened to be in China, so I went to a local seller with a voltage measurement app, and started testing cables they offered one by one. After finally finding a cable that could push proper 2+ amps, I bought something around 60 of them, because back home, everyone sells USB cables packaged in hard plastic, so I wouldn't even be able to run this test.)

msbarnett 7y ago
> I'm not sure if forcing manufacturers into a single, active cable would be impossible. > ... > That's why I think standardization should disallow this very attempt at costs savings. There's a somewhat famous Common Lisp FAQ along the lines of "Why didn't the standardization committee just force implementers to do X thing?" And the answer is: your premise is wrong. Standards bodies don't have the power to force anybody to do anything. If implementors don't like your standard, they'll just ignore it. Standards live or die by their ability to raise consensus. If Generic Device Manufacturer #4823738 looks at the USB 4 standard and decides there isn't a big market for USB peripherals whose 2 meter charging cable (say, a gamepad that charges via a fairly long 5 W USB, like a gaming console uses) runs $75 because it requires fairly heavy gauge wire to additionally support (unneeded by the gamepad) 100 W charging and has to contain (unneeded by the gamepad) 40 Gbps active signalling circuitry, they're just not going to implement the bloody USB 4 standard. They're not going to implement it if there's a $1 to be saved by going some other route, honestly. Instead of the "universal protocol" dream dying on the rocks of a hodge-podge of subtly incompatible cables, you've simply killed it by convincing manufacturers to ship USB 2 devices until the end of time, instead. The standard committee can impose onerous, financially punitive requirements on anything calling itself USB 4, but they can't then make manufacturers adopt USB 4, so in the end they can't solve this by forcing anyone to do anything, which is why the entire idea of "one universal protocol" is hamstrung by its own internal contradictions.
organsnyder 7y ago
Let's say the USB standard mandated that all USB-C cables be fully-featured, such that they can't be manufactured for less than $10 each. What's to stop a vendor from selling cheap "cell phone charger" cables? They could print "Compare to Belkin USB-C cable* *not affiliated with Belkin or licensed by the USB Implementers Forum" on the box, and maybe even be able to survive a lawsuit. And even if they're not in the clear legally, these cheaper cables would be found in every "black-market" outlet, which these days includes Amazon, your local gas station, and many big box stores. How long would the USB-IF be able to maintain that stance, while their licensees clamor to be allowed to sell cheaper authorized cables? I think the solution is to improve branding. When I look at the USB-C cables in my bag, I can't tell at a glance which ones are full-featured: one of them has a tiny logo that maybe indicates something like that, but it's not obvious or prominent. I tend to end up plugging in the wrong one and discovering that the device isn't charging, performing as well as expected, etc. If the USB spec defined consistent, prominent branding for full-featured cables, this would be much less likely to occur. (yes, I know I should replace the inferior cables, but I only use them when I work away from home, which is infrequent enough that it hasn't crossed the threshold to be worth the time)

closetohome 7y ago

And - fun addendum to this - Active Thunderbolt cables don't work as basic USB cables - https://appleinsider.com/articles/17/08/15/psa-thunderbolt-3-cables-longer-than-05m-generally-dont-support-usb-31-speeds https://appleinsider.com/articles/17/08/15/psa-thunderbolt-3...