# USB 4 vs Thunderbolt



## pderbidge (Jul 20, 2019)

I would love if someone had some real insight to how this is going to play out with Audio Interface manufacturers. From what I understand, USB4 will support the Thunderbolt standard. Does that mean that existing Thunderbolt products will work with USB 4 or will there have to be new interfaces made to support it? If new devices have to be made then my question is are manufacturers planning to do just that. What I found disappointing with USB 3 is that even though theoretically it was faster than Firewire, in practice (due to technical differences between the way USB3 worked vs Firewire) it seemed that firewire still outperformed USB3 in Latency tests so the consensus among manufacturers was to keep making USB2 drivers because there was no advantage to USB3. I'm hoping that USB4 changes this and we can start seeing lower latency audio interfaces like we do with Thunderbolt and PCIe.


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## colony nofi (Jul 21, 2019)

Unfortunately this is a much trickier topic than a simple forum post is going to answer.

Between these 3 articles, you should be able to get your head around what we *expect* from USB4 (as the official documentation papers have not yet been released, so things can and will definitely change!) The verge article in particular makes a few issues (and things we don't know) quite clear.









The new USB4 spec promises a lot: Thunderbolt 3 support, 40Gbps bandwidth, and less confusion


Meet USB4, which promises to simply the USB naming scheme and integrate the high-bandwidth Thunderbolt 3 specification.




www.pcworld.com












USB 4: Everything We Know So Far


USB 4 promises a host of benefits that include faster transfer speeds, better management of video and optional compatibility with Thunderbolt 3.




www.tomshardware.com













With USB 4, Thunderbolt 3’s benefits become open to all


Double the speed of USB 3.2 up to 40 Gbps




www.theverge.com





So - for audio - what does this mean?

1. The connector is going to remain USB-C. I think all and sundry breathed a sigh of relief on hearing that.

2. USB4 is going to be able to handle TB4 (EDIT : TB3) as well as USB4 type data streams. See - we're already getting confusing. (USB3.2 was / is hard enough!) Among other data and power transport streams.

See, USB4 is a data transport stream in its own right (running at the same speed as Thunderbolt 3 - 40Gb/s - but NOT thunderbolt 3. AND a connection standard using USB-C cables that allows a bunch of different data streams. (This is already confusing right? At least it will be better than the current gen!)

I would assume that people will keep calling "thunderbolt" audio interfaces exactly that, and usb4 interfaces exactly that. Now, it remains to be seen what the USB4 spec will actually mean for interface manufacturers. Will it be cheaper than TB3 to implement (doubtful at the start at least) and will it be better (again, doubtful.) The bandwidth will be identical, but USB is a slightly different animal in regards to the way it interacts with the rest of the computer. Very early conversations I've had see people skeptical that it would do any better for latency than a well designed TB2 or 3 interface would.

Remember - data all moves at a set speed. Its the width of the pipe that changes. So once you have a pipe that can handle all the audio data you need (which USB2 does for the most part) then it becomes about implementation, not bandwidth. (Ok, so thats a simplification, but its the spirit of the argument I'm after)

Latency is in its own way an interesting animal. Some well designed USB2 interfaces offer better round trip latency than poorly implemented TB1/2/3 (I use the word "poorly" word carefully, as there are so many decisions involved in why a certain implementation is decided upon that one can't really say an idea is "poor" - more than the considerations were different to the ones we'd like the manufacturer to take into account...)

Now to answer just a few of your questions.
We do know that USB 4 will work with TB3 devices. And as far as I'm aware TB2/1 devices. (I have yet to have a TB2 or 1 device I cannot run over TB3. You just need to use a convertor which are not cheap)

We do not know for sure that all previous USB 3.x or 2 or 1 will work with USB4. And because the standard isn't locked down, there's more than a fair chance that some manufacturers will just go ahead and mess with the spec anyway, so it won't be a case of EVERYTHING working but just MOST or SOME. A crapshot for consumers (kinda like the issues with cables using the USB-C connector... damn it we NEED some sort of colour code / design to let us know if they're charging only cables, USB2 speed, USB3 or 3.1 speed, can carry TB3 (ok, so that one is sorted with the lightning bolt symbol) etc etc.


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## GtrString (Dec 12, 2019)

This is going to be a relevant topic for 2020. Anyone aware of any usb 4 interfaces announced yet?


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## colony nofi (Dec 12, 2019)

I *very* much doubt we will see any usb 4 audio interfaces next year. 2021 at the earliest. 
Having spoken with a couple highly respected developers at well known companies... its not on their radar, and they don't see why it needs to be. They can't see any benefit to an end user to make something "usb 4". It just reduces market share. USB 3 handles all the audio throughput 99% of interfaces will ever need. So making a USB 3 interface with a USBC connector means (a) it will be backwards compatible with USB 4 computers, and those with only USB 3 on their computers will be able to use it.

If they're designing something that uses the USB4 spec specifically, then that precludes anyone without USB4 ports (USB 4 isn't forwards compatible... you cannot connect a USB4 device to a USB3 port!)

Long story short? 
1./ No one I've spoken to has come across any technical reason to move audio interfaces to the USB 4 spec.
2./ You wont see computers with USB 4 until late 2020 early 2021 - and they will initially be a tiny percentage of the market

So - its a matter of hurry up and wait. Maybe we can start this discussion again sometime late next year, although one also wonders what would make devs shift their ideas as to the necessity of usb4 for audio.


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## GtrString (Dec 14, 2019)

Right, but Im looking to get a new audio interface in January. Any items with Usb second gen (3.2)?


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## sostenuto (Dec 14, 2019)

Cool info here ! Many thanks. 

Not so  now with daily usage of (2) Focusrite Saffire Pro 14(s). 
Will sit tight now until 2021, rather than add current USB 3 choices.


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## colony nofi (Dec 15, 2019)

GtrString said:


> Right, but Im looking to get a new audio interface in January. Any items with Usb second gen (3.2)?


There really should be NO discernable difference to an end user between a USB 3.2 interface and a usb 3.0 interface. You will not get better latency figures (the intoconnect is the same speed - just bandwidth that has increased). A USB3.0 interface at 5gbps bandwidth has room for all your audio needs and then some. There's room for what... approx 4-500 24bit 96k channels to run at once over one USB 3.0 connection. (Edit for bad math)

There is another question of latency. Aside from understanding that the buffer setting that you set in your DAW is far more important in terms of raw figures, its also worth looking into why companies such as RME (and now others) have been able to bring their latency figures down incredibly low while also maintaining incredible stability. The Babyface Pro really is amazing as a USB 2.0 interface, and is still right up there with any other interface available. 

Things really only improve once you completely remove USB from the picture entirely. (If you're interested in why I can point you in the direction of more information!). PCIE will always be technically superior to connect audio than usb. It is why thunderbolt (which includes a PCIE connection of sorts) has some potential and is somewhat interesting for audio.

Then again, GBE is also great for audio (and round trip latencies with the right hardware have come along amazingly over the last 10 years, and the flexibility for audio over IP is so far beyond anything that comes with a direct connect interface.)

My advice? Don't get too hung up on your interconnect. Read more about different manufacturers and how they connect using USB (note : Not all are the same...) and look into latency figures if you want to get into the minutae. USB is by its nature backwards compatible, so you don't need to worry about USB4 etc making your USB2 interface redundant. Far from it. One new cable (USBC to USBB usually) and you are good to rumble!


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## GtrString (Dec 16, 2019)

All true Im sure, but Im looking to hook it up with a new Apple Mac Mini, which has tb3 and not many usb ports (wich I use for other things), so it is really to make the most of the computer’s (sparse) i/o.

I also want the most recent protocol because the Mini so expensive that I need to think as far ahead as possible (as budget says it has to last for 10 years). And it looks like connection protocols change every 5y.


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## GtrString (Jan 3, 2020)

Presonus Quantum with TB3 is here..


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## khollister (Jan 3, 2020)

Since it appears all future USB4 controllers (on the host side) will also support TB3 and I suspect USB4 will not offer any latency improvements over TB3, I don't imagine you'll see any USB4 interfaces any time soon. 

You can connect a USB device (via the USB-C connector) to end of a TB3 daisy chain, so you could have a TB3 device connected to your Mini with a USB interface (e.g. the BabyFace Pro) on the end of the chain with the appropriate adapter/cable (USB-B to USB-C).

Likewise you can put TB2 devices on a TB3 chain with the Apple adapter. As long as the TB3 devices are "in front of" the TB2 (or TB1) devices, they will still run at TB3 speeds.

TB3 ports are downward compatible with TB1, TB2, USB3.1, USB3.0 & USB2 - the USB-C connector supports all the protocols. USB4 is adding another protocol to the stack of options, still using the same USB-C connector.

Buy an interface with the performance, features and price you need/want. Don't get hung up on the bus protocol it uses.


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## colony nofi (Jan 3, 2020)

GtrString said:


> All true Im sure, but Im looking to hook it up with a new Apple Mac Mini, which has tb3 and not many usb ports (wich I use for other things), so it is really to make the most of the computer’s (sparse) i/o.
> 
> I also want the most recent protocol because the Mini so expensive that I need to think as far ahead as possible (as budget says it has to last for 10 years). And it looks like connection protocols change every 5y.


Well, a TB3 interface will be (backwards) compatible with USB4 (confusing... I know!) and all flavours of TB are backwards compatibe... eg a TB1 interface can connect to TB3 with the right adaptor. 

And in fact, its the same interconnect (slightly different plugs) just with higher bandwidth. Protocol isn't going to change - since it IS a PCIe interconnect.

Therefore, go with a TB 1, 2 or 3 interface. Whichever suits you. Since bandwidth is irrelevant just pick whichever without any fear of being "old" or "new" tech. They're the same tech. Bandwidth will continue to go up (I've read papers looking into future TB standards with 80 and 160gbps external interconnects with direct pcie connection - but these will all be compatible with the TB1 standard still! Thats a LONG way into the future. 5-10 years.) . No standard studio audio interface saturates a TB1 bus. I've run 384 tracks through thunderbolt (!) and then split that off to different DANTE adaptors, with 128 channels going out thru each of the dante adaptors. One cable to the mac. This is VERY esoteric use cases that are only useful to demonstrate how far beyond standard usage the current interconnects are!

Or just use a TB hub with plenty of USB to get more usb ports and use a usb interface. It will never be as low latency as TB, but with good drivers, it can come damn close. (again, look at how RME haver managed to do it!) . The bandwidth of TB3 is so big that there is absolutely no problem at all running a multi-channel usb interface off a caldigit TS3 as well as a bunch of other USB peripherals! All one cable back to your mac!


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## GtrString (Jan 4, 2020)

I think I’ll get the TB3 Quantum for my new Mac Mini, as I don’t like converters in my chain.

I have a TB1 Focusrite now, and latency is incredible, so Im not keen on going back to USB, and as you say USB4 won’t match TB3 anyway, so its just a question of connectivity.


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## GNP (Jul 28, 2020)

GtrString said:


> I think I’ll get the TB3 Quantum for my new Mac Mini, as I don’t like converters in my chain.
> 
> I have a TB1 Focusrite now, and latency is incredible, so Im not keen on going back to USB, and as you say USB4 won’t match TB3 anyway, so its just a question of connectivity.



Hey there, I'm contemplating on switching from USB to Thunderbolt. May I ask, *for the latency aspect*, do you feel, as you play your guitar, a huge difference between USB and Thunderbolt?

Thanks.


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## GtrString (Jul 28, 2020)

GNP said:


> Hey there, I'm contemplating on switching from USB to Thunderbolt. May I ask, *for the latency aspect*, do you feel, as you play your guitar, a huge difference between USB and Thunderbolt?
> 
> Thanks.



Its been a while since I've had a USB interface now, I think the last one was a Focusrite Scarlett 6i6. As far as I remember, I don't recall _significant_ worse latency regarding tracking guitars. This may be due to delay compensation in the software, so even through there is a latency happening, you don't hear it because the software is compensating for it.

So, I think the difference is subtle, however if you play very fast sweep picking lines, you may experience the difference more. I think of latency as a flaw, so I do everything I can to eliminate it, but for many uses that is too extreme a position.


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## GNP (Jul 28, 2020)

GtrString said:


> Its been a while since I've had a USB interface now, I think the last one was a Focusrite Scarlett 6i6. As far as I remember, I don't recall _significant_ worse latency regarding tracking guitars. This may be due to delay compensation in the software, so even through there is a latency happening, you don't hear it because the software is compensating for it.
> 
> So, I think the difference is subtle, however if you play very fast sweep picking lines, you may experience the difference more. I think of latency as a flaw, so I do everything I can to eliminate it, but for many uses that is too extreme a position.



Hmm okay. Thanks so much for your info. I guess for my uses, it's not really worth switching to Thunderbolt at this point, if there's not much significant difference in latency. I guess it's still all about buffer sizes and software compensation and other factors involved. 

Thank you!


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## GtrString (Jul 28, 2020)

Yes, of course you can track with bigger buffer sizes with TB, and run plugins pre-fader without additional latency, if that matters in your workflow/setup. Also depending on your daw, you will have less roundtrip latency in your system with TB, if you use outboard gear for hybrid mixing and such.

I don't think TB matters much for tracking one or two instruments/ vocals ect at a time (maybe more if you track a large band). It is also highly dependent upon the drivers from the manufacturer, as the likes of RME achieve very low latencies with USB 2.0. Others like Zoom, has the same latency with TB as RME gets with USB. 

So many factors involved, for sure.


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