What are the Thunderbolt cable length limitations?


Thunderbolt has a length limitation of 3 meters. In my studio, my computer lives in a machine room that is more than 3 meters away from my desk (approx. 10 meters).

Typically, the audio interface could just live in the machine room and I could run my audio via XLR multicore, but with a unit like the UAD Apollo twin, or even the 8p, it's designed to sit on my desk allowing me to access the knobs and buttons. Perhaps my problem is that the AD/DA converters and the preamps are all in the same unit. If they were separate, the converters could live in the machine room, while the preamps could live on my desk, allowing me to just run long audio cables to the machine room instead of thunderbolt.

I've looked into those corning optical thunderbolt cables, but the expense makes me think I'd be better off just investing in a quieter computer (mac mini perhaps) that can actually sit on my desk quietly.

Perhaps I'm just trying to spark a discussion on this topic, but how do other studios solve this thunderbolt dilemma? Separate the AD/DA conversion from the preamps? Buy long optical thunderbolt cables? Keep a quiet computer in the control room? Perhaps the Apollos are more of an all-in-one convenience thing for portable applications?

PS: I haven't purchased the Apollo yet, I'm simply in the market for an upgrade.


Posted 2017-12-04T14:45:27.220

Reputation: 455

Question was closed 2021-01-25T12:46:55.313

I searched for a thunderbolt repeater but with no luck which I found quite curious. I'm not really familiar with thunderbolt but In principle this would be the way to go. I suspect the protocol might be very timing-critical making the repeater harder to implement (?) – Schizomorph – 2017-12-04T16:03:15.597

Agreed, I searched the same thing with no results. It's actually quite common to daisy-chain devices with thunderbolt. Thunderbolt hard drives typically have an "in" and an out", I'm surprised there isn't a standalone version of that. To be fair though, linking 3 thunderbolt cables together with adapters would probably cost pretty close to the same as a long optical thunderbolt cable, so perhaps the best option is to go that route. – Johannes – 2017-12-04T16:19:49.190

Yeah, I suppose you're right. It didn't cross my mind earlier that you'd need 3 of them. – Schizomorph – 2017-12-04T16:31:32.060

Unless you don't care about latency, you probably don't want a repeater. Those things are latency generators. – Todd Wilcox – 2017-12-11T17:33:52.913

Aren't the appolo preamps remote-controllable with software? – None – 2018-03-19T20:34:22.783

This question is a purely technology question, not on topic here. – Rory Alsop – 2021-01-25T12:46:55.313



how do studios solve this thunderbolt dilemma?

It depends on the budget of the studio, but the real pros use high end interfaces and converters that don't usually have much in the way of controls, so they sit in the machine room with the computer. 1/4" TRS cables are run from a patch bay in the control room to and from the analog I/O on the interface or DAC/ADCs.

Another solution is separate the D/A and A/D converters from the interface. The interface in this case lives in the machine room with the computer and has entirely digital I/O. The converters can go almost anywhere, perhaps right next to the patch panel or can be used instead of a patch panel, and then digital audio cables can run from the converters to the interfaces. ADAT optical cables (lightpipe) can only go about sixteen feet, but the new MADI format supports up to 100 meters, and there's now some audio over Ethernet technologies like Dante which would allow 100 meters also.

Finally, there are some proprietary digital cabling systems, like Digilink for Avid's Pro Tools HD interfaces. These systems can allow for separation between the interface and the computer and/or allow for remote controlled mic preamps. In the latter case, you use software to change interface settings that would normally be changed with knobs on the front of the interface.

For smaller project studios, a quieter computer is a popular solution. Macs are popular choices in this space, since Mac Minis and iMacs have known noise footprints and are quiet enough for low-budget solutions.

Todd Wilcox

Posted 2017-12-04T14:45:27.220

Reputation: 1 998

Can you give a couple of specific examples of these interfaces and converters mentioned in the first two paragraphs? Just trying to get a feel for what is considered to be high-end. I assume the UAD product line is considered mid range or "pro-sumer" perhaps – Johannes – 2017-12-11T13:33:33.127

Looks like Thunderbolt itself is mid-range. Big time stuff is either going MADI or Digilink or something like that. The Burl Audio Mothership System is a good example of a recent player. Digilink is Avid's proprietary cabling for connecting Pro Tools HD interfaces and that supports lengths up to 50 feet for 192 kHz operation. Notice how few of those PT HD interfaces have front panel controls.

– Todd Wilcox – 2017-12-11T14:31:59.213

Interesting. And here I thought thunderbolt was replacing PCI cards (it certainly is more convenient for portability). I suppose it is in the sense that some of those interfaces do have thunderbolt options (like the apogee symphony series) and maybe it doesn't matter so much as to how it connects to the computer, but more to do with the separation of the preamps from the interface/converters. – Johannes – 2017-12-11T17:21:47.483

@Johannes I think when you're trying to run 100+ tracks at 192 kHz, Thunderbolt becomes less workable. – Todd Wilcox – 2017-12-11T17:32:32.617

Note that the UAD stuff offers the ability to run high quality plug-in emulations of actual studio hardware. Actual studios more often have the actual studio hardware and do not always rely on plugins. For video post, plugins are more popular but for music production, the actual hardware is usually preferred when it's available. – Todd Wilcox – 2017-12-11T17:35:27.290