What is a Bus Powered Audio Interface?

What is a Bus Powered Audio Interface

If you want to record any form of audio or music at home, then you need an audio interface. I’ve owned a fair few in my time, but before I knew anything about audio production, I had a tonne of questions. There is a lot going on in an audio interface and many things to consider before buying one.

No doubt you’re here now because you’re wondering ‘what is a bus powered audio interface?’. Even the name ‘bus power’ is odd. What the hell does it have to do with buses!? Well, absolutely nothing. And actually, it’s not the only time that the word ‘bus’ comes up in audio production.

Anyway, don’t worry. In this article I’m going to cover everything about bus power, what it is, why it matters, and if you should buy a bus powered audio interface or not. So, sit back, relax, and enjoy the ride. Get it? It’s a pun. I thought it was funny anyhow. Let’s move on…


What is a Bus Powered Audio Interface?

A bus powered audio interface is powered through a USB cable that connects directly to your computer. This means you do not need a power adapter or access to a wall outlet to power your audio interfaces. However, only smaller audio interfaces can be bus powered, meaning your choice of audio interfaces is limited.


What is Bus Power?

What is Bus Power

A bus powered device is one that is connected and powered through a USB connection. This means you do not need an external power adapter that plugs into a wall outlet. It simply gets its power through a USB cable. What does this mean in terms of audio interfaces?

Audio interfaces usually connect to your computer via a USB or Thunderbolt cable. That way your DAW can recognise them, enabling you to record audio directly. But some need an external power supply to power them. Others don’t. They get their power by connecting directly to your computer via a USB cable. These audio interfaces are bus powered. Simple.


Are All USB Audio Interfaces Bus Powered?

Actually, no. Why though? It’s all down to size. As you might have guessed, USB power has its limitations. It can only provide up to 5V and 900mA, which isn’t exactly a lot. So, bus power isn’t enough for larger audio interfaces, but it’s perfect for smaller ones with less inputs and outputs.


Does Bus Power Affect the Sound?

Absolutely not, bus powered audio interfaces will sound exactly the same as wall outlet powered audio interfaces. This was different in the past, but things have changed. As long as you’re buying from a reliable audio company, then there should be no concerns around audio quality.


What Are the Pros and Cons of Bus Power?

What Are the Pros and Cons of Bus Power

When writing this article, I too was curious if there were any cons of bus powered audio interfaces. After all, USB only supplies 5V of power compared to power adapters which supply 9V. When doing some digging, I could only find forum posts almost a decade old.

In which, one poster states that due to the power constraints of bus powered devices, the headphone outputs and phantom power will not perform as adequately as wall outlet powered devices. However, audio gear has come a long way in ten years.

After speaking to Focusrite (one of favourite audio interface manufactures), they assured me that bus powered interfaces perform exactly the same as wall outlet ones. Capable of powering headphones up to 200 ohms.

As long as you’re buying from a reputable brand, there really are no cons to using bus powered devices. The only downside is that your choice of audio interfaces will be limited, as only small ones like the Focusrite Solo can be bus powered.

One big advantage of bus powered audio interfaces is their portability. If you like to produce music on the move, you never have to worry about being close to a wall outlet. You can simply plug your audio interface into your computer and get to work.


Which Audio Interface Should You Buy?

There you have it. Bus power is easy enough to understand. Ultimately then, your choice will come down to the size of audio interface you need and whether want something more portable. Your budget will of course also come into play here.

I have a list of ‘The Best Audio Interfaces in 2021’ if you need help deciding. But if you want to learn more about audio interfaces first, be sure to read my article ‘What is an Audio Interface’ which goes much more in-depth.

Did this article help you out? Let me know in the comments, or feel free to ask me any questions. I’m here to help.

Chris (Chris’s Sound Lab)

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