USB and professional audio for musicians

9 min readDec 2, 2023

Although most professional audio interfaces for music creators have featured USB for several years now, there’s still a lot of confusion about the different types of USB, what they offer, and what musicians really need. Hopefully this article will go some way to enlightening you.

Types of USB

Before we go any further, it’s important to correctly understand the difference between the different types of USB physical connector and the different types of data format that can be transferred along the cable.

USB hardware connectors

The different kinds of USB physical connector are referred to with letters:

USB-A — the flat rectangular one. This is only used at one end of the cable and must be connected to the USB Host (which is usually a computer or some other device that issues commands).
USB-B — various different weird-ass connectors including USB-B Mini, USB-B Micro etc. Also only used at one end of a cable, and connected to the USB Secondary peripheral device (e.g. a hard drive, interface, keyboard etc.)
USB-C — the small curved oval one. Can be used at either or both ends of a USB cable and plugged into any device.

USB software formats

The different kinds of USB data format are referred to with numbers:

USB 1.0
USB 2.0
USB 3.0
USB 3.1
USB 3.2
USB 4

Note that there is no direct correlation between the type of USB data and the type of USB physical connector that can transmit it. For example USB 1.0 data can be transferred through any type of USB cable. So be careful not to confuse the software data stream (the numbers) with the hardware connector (the letters), they are two completely different things.

Bus power

Many common audio interfaces claim to be “bus-powered” via their USB port. This can be extremely problematic in some cases, since most digital audio conversion chips require significantly higher power than most older USB systems can provide, leading to degradation of audio quality and/or random disconnects. If your audio interface offers the option of either bus power or a “wall wart” style external power supply, always go for the external power option. If your audio interface doesn’t allow use of an external power supply, you probably want to change it for one that does, unless your interface supports the USB-C Power Delivery standard, which can supply vastly more power than earlier modes of USB.

What is USB-C?

USB-C is without doubt becoming the standard system for transferring all sorts of data between computers and peripherals. However there is a lot of misunderstanding and misinformation about what exactly USB-C is and how it works.

The first thing to understand is that USB-C is not a data format itself. USB-C is simply a physical connector designed to allow all kinds of data to be passed though it. So instead of needing lots of different cables and connectors for each type of thing you want to connect, a USB-C cable can basically carry any signal you need. That makes it incredibly useful, and there’s no doubt that it will become the standard for pretty much all data transfer in the future.

Pretty much any kind of data can run though a USB-C connector, even data that isn’t USB! The types of things that can travel over a USB-C port may include (but not always):

USB 1.0 (Full Speed)
USB 2.0 (Hi Speed)
USB 3 (SuperSpeed)
USB 3.1 (SuperSpeed+)
USB 3.2
USB 4
HDMI
Ethernet
Thunderbolt
Power (normal 5v or the enhanced Power Delivery mode)

Multiple streams of these can even be passed at the same time! Note that not all cables with USB-C connectors can pass all of the above things: for example you must have a certified USB-C Thunderbolt cable in order to pass Thunderbolt 3 data, and these cables usually cost at least triple what a standard USB 3 certified cable costs.

USB-C Power Delivery

This is a newer power standard which is capable of supplying significantly more power to peripherals than the low power original USB standard. Note that not all USB-C power supplies can supply the full Power Delivery standard, and not all devices with a USB-C port can accept this extended power system. Before you attempt to power something via USB-C, do check what your requirements are, and if your equipment is capable of supplying it.

Which is the fastest USB: Hi-Speed, Super Speed, or something else?

This is a question I hear a lot, and the answer will surprise you: all USB runs at exactly the same speed. There’s no lower latency or anything like that when you use a so-called “faster” format. The only difference is in how much data can be carried simultaneously. Think of it like a truck driving maximum speed down a highway. That’s USB 1. Since the truck can’t go any faster than its maximum speed, how can we deliver more cargo in the same time frame? Solution: add more lanes to the freeway and put a truck in every lane. Now we can transport much more cargo in the same time frame but the trucks are still moving at the same speed. So in reality we don’t have higher speed USB, we have more bandwidth. That’s how USB 2 works. USB 3 adds more lanes and trucks still. And so on. So when you hear USB described in terms of “speed”, that’s really not very accurate.

For most digital audio purposes, USB 2 is more than capable of handling all the data you need for multiple channels of full bandwidth audio, which is why the vast majority of audio interfaces run that protocol. Even some interfaces that use USB-C connectors are still actually only running USB 2 data down the cable, because they don’t require the extra bandwidth that USB 3 provides. Remember: there is effectively no difference between any of the USB protocols when it comes to speed, latency, audio quality, etc.

Do I need a faster USB if I’m running “hi-res” audio?

Two points here:

Firstly, “hi-res” audio is a con. Recording at anything over 48k is pretty much a waste of time and computer resources. Yeah, I know the guy in your local music store said you should get an interface that goes up to 192 kHz because “it sounds better”, but he’s a sales guy who will tell you anything if he can get more money out of you. I’m not going to bore you with a whole lot of numbers and science, but trust me, it doesn’t sound better.
There’s still probably more than enough bandwidth in USB 2 to handle the vast majority of 96k or 192k recording — but you will only be able to use 1/4 of your plugins because your computer processer performance will be seriously affected. So USB will be the least of your worries in this scenario.

Mobile devices and USB-C OTG

All USB devices must be defined as either be a Host or a Peripheral. In previous versions of USB, a Host port always used a USB-A connector (the rectangular port that you normally find on a computer); whereas the Peripheral always used one of the various types of USB-B connector (either a full-size square connector or a USB-B Mini or Micro connector) like you would find on an external hard drive, MIDI keyboard, or other accessory.

USB-C is different — there is only one type of USB-C physical connector, and devices can either choose to be Hosts or to be Peripherals. Whether they are defined as a Host or Peripheral is determined by the internal wiring of the USB-C port itself. So for example, the USB-C ports on your laptop are generally wired to act as Hosts, whereas the USB-C port on your mobile phone or tablet is usually wired to act as a Peripheral.

However sometimes you might want your mobile device to be a Host instead of a Peripheral — for example if you want to use it with your audio or MIDI interface. USB-C has a very clever way to do this, using the On-The-Go protocol (usually shortened to OTG). An On-The-Go cable is wired up in such a way that it can convert what is normally defined as a Peripheral to act as a Host instead. So plugging a USB-C OTG adapter or USB-C OTG hub into your iPad or Android tablet will enable it to act as if it is a laptop computer instead of an accessory.

The most basic solution is a simple OTG cable with a USB-C connector on one end and a USB-B connector on the other. Plug the USB-C connector into your phone or tablet, and plug the USB-B end of the cable into your appropriate socket on your audio interface and it should just work.

If you decide to get a USB-C hub, which I strongly recommend, you will have a USB-C connector at one end of the hub (which you plug into your mobile device), and several USB-A sockets built into the hub. Connect a standard USB interface cable to one of these USB-A sockets, and connect its other end to the USB-B socket on your interface as usual.

Note that a basic inline OTG adapter will not charge your mobile device. In order to charge your mobile device while you use it you will need a USB-C OTG hub that also supports the USB-C Power Delivery specification (most OTG hubs do). With a USB-C OTG PD hub you can plug in any standard USB-C power supply to the hub and it will not only power your interface but it should also power your phone or tablet as well.

iPad Pro / Android and audio interfaces

I have done preliminary testing on the iPad Pro equipped with a USB-C port, and various USB-C equipped Android devices. Using a standard USB-C adapter with OTG functionality seems to work very well with all of the interfaces tested.

Troubleshooting laptops and desktop computers with USB-C

Many audio interfaces may have problems with some early computers equipped with USB-C ports. The reason for this is that there was a bug in one of the original Intel USB controller chips that meant many digital audio interfaces did not work correctly and will produce distorted sound or random disconnects when plugged into them.

My investigations indicate that there may be problems with the USB subsystems on the following machines (and probably several others I have have not yet tested):

Razer Blade laptops (early USB-C models)
Razer Core external GPU enclosure
Apple mid-2018 Mac Mini
Apple mid-2018 MacBook

If you have one of these machines, or another computer equipped with USB-C ports that seems to be exhibiting problems with your audio interface, there are several workarounds you can try:

Most USB-C computers also have legacy USB-A ports, and in some cases these legacy USB-A ports are internally connected to a different USB controller chip that does not exhibit this buggy behavior. So the first thing to try is simply to connect your interface to one of the USB-A ports instead of a USB-C port. On many computers (for example the Razer Blade 14" 2017 edition) this will solve the issue immediately.

However some computers do not feature legacy USB-A ports, and others (such as the 2018 Apple Mac Mini) may have their legacy ports internally connected to the same problematic USB controller chip. In these cases the best workaround I have found is that if your computer is Thunderbolt compatible, simply attach an external Thunderbolt 3 hub to one the computer’s USB-C ports, and then attach your audio interface to one of the USB-A ports on the Thunderbolt hub. Note that most common “USB-C hubs” will not work — to work correctly like this the hub must be fully Thunderbolt 3 compatible. You can recognize a Thunderbolt 3 hub by checking that the following features are listed:

The description specifically says that is Thunderbolt 3
The USB-C connector shows a small lightning bolt symbol
It is capable of 40GB/s data transfer
The display port supports 60 Hz operation

Note that Thunderbolt 3 hubs are usually also considerably more expensive than standard USB-C hubs — expect to pay around $150 or higher. I recommend Thunderbolt 3 hubs from CalDigit — I have tested these and they work very well, and are very well constructed.

If you are using a desktop PC without legacy USB-A ports, a cheaper workaround is to add a PCI card with USB-A ports — theoretically these should work well, though I have not yet tested this solution.

Further Information

For more detailed information on the USB-C specification, please see this Wikipedia article.