Can I use USB to host for MIDI?
What is MIDI?
MIDI stands for Musical Instrument Digital Interface. It is a technical standard that describes a protocol for musical instruments, computers, and other hardware to connect and communicate (A Brief History of MIDI). MIDI allows digital musical instruments, controllers, computers, tablets, etc. to connect and talk to each other. The protocol defines the data format, electrical connectors, cabling, and rules for communication between devices.
The MIDI standard was published in 1983 by a group of leading musical instrument manufacturers to create a common interface that would allow their instruments to connect. This enabled musicians to control multiple instruments from a single controller or keyboard. It also allowed seamless communication between electronic instruments from different manufacturers (History of MIDI – What is MIDI?).
Prior to MIDI, electronic musical instruments from different companies were incompatible with each other. MIDI enabled devices to connect regardless of brand or manufacturer. This interoperability fueled an explosion in the use of electronic instruments and music technology.
MIDI over USB
MIDI over USB is a way to send and receive MIDI data over USB cables instead of the original 5-pin DIN cables. It allows connecting MIDI devices like keyboards, controllers, and sound modules to computers and mobile devices that only have USB ports. Compared to the 31.25 kbps bandwidth of original MIDI ports, USB provides much higher bandwidth which allows for faster MIDI communication.
USB MIDI has become widely adopted in the music tech industry. Most modern MIDI gear comes equipped with USB ports or can be connected to computers via USB-MIDI interfaces. This allows producers and musicians to integrate MIDI devices with their digital audio workstation (DAW) software for music production, recording, and performance. Some key advantages of MIDI over USB include:
- Higher bandwidth for faster MIDI data transfer
- Plug-and-play connectivity via USB
- Allows connecting to gear that only has USB ports
- Enables easy integration with computer-based DAW software
However, there are some limitations to be aware of as well. The main one is potential latency issues that can occur especially when using MIDI with mobile devices. Careful testing should be done to ensure stable and responsive MIDI timing over USB connections (https://homestudioguys.com/cables-and-connectivity/midi-cables-and-connectivity-ensuring-seamless-communication/). USB power considerations and cable requirements are other factors to keep in mind.
Hosting MIDI with USB
A USB host acts as the main controller in a USB connection. USB hosts have upstream ports that devices connect to. Computers, mobile devices, audio interfaces, etc. can act as USB hosts for MIDI, allowing you to connect MIDI controllers, keyboards, and other devices. The host sends and receives MIDI data from the connected devices.
When you connect a MIDI controller or keyboard to your computer via USB, the computer is acting as the USB host. It provides power to the device and handles the MIDI data being sent over the bus. The keyboard or controller acts as the USB device in this setup. It only communicates when polled by the host.
Some audio interfaces and standalone hardware units also have USB host ports specifically for connecting MIDI devices. For example, the Focusrite Scarlett 2i2 audio interface has a USB Type-A port that can host a MIDI controller. This allows you to connect a MIDI keyboard directly to the interface rather than occupying one of your computer’s USB ports.
Using a USB host for MIDI simplifies connections and setup. It allows a single host to communicate with multiple MIDI devices over the high-speed USB bus. The host manages all the MIDI data routing, providing an easy way to integrate MIDI gear with modern computers and mobile devices.
MIDI Controller Options
Many MIDI keyboards, drum pads, and other controllers connect via USB these days. When selecting a MIDI controller, look for ones that have ‘USB MIDI’ or ‘USB to Host’ ports to enable connecting to a computer or mobile device over USB.
Popular USB MIDI controller options include:
When connecting to mobile devices like phones or tablets, you may need a USB OTG (On-The-Go) adapter to allow the mobile device to act as a USB host and connect to MIDI controllers and interfaces. So check mobile device compatibility and adapter requirements when selecting a USB MIDI controller.
Connecting to a Computer
Most computers have USB host ports to connect MIDI devices (Getting Started with MIDI Keyboards, 2023). This allows you to connect a MIDI keyboard, controller, or other device directly to your computer via a USB cable. However, you may need a USB-MIDI driver or interface to enable communication between the MIDI device and your computer’s operating system.
A common option is LoopBe30, a free and open source MIDI interface for computers that handles the USB-MIDI translation and allows you to route the MIDI data to music applications on your computer (How to connect a MIDI Keyboard to a Computer, 2022). Other paid options like Roland’s USB-MIDI drivers also exist.
Once connected via USB and a MIDI interface, you can use your MIDI controller to send note and control data to a wide variety of music software on your computer. This includes digital audio workstations (DAWs) like Ableton Live, music production tools like Logic Pro, soft-synths and virtual instruments, and educational tools like Synthesia. The MIDI data from your keyboard can be used to play and record virtual instruments and control parameters in real-time.
Connecting to Mobile Devices
iOS and Android devices can connect to MIDI over USB with the right adapter. For Android devices, you need a USB OTG (On-The-Go) adapter. This allows the Android device to act as a USB host. For iOS devices like iPhones and iPads, you need Apple’s Lightning to USB Camera Connection Kit.
Having the proper adapter allows you to connect MIDI controllers and keyboards to your mobile device. It enables using hardware MIDI controllers with synthesizer and music apps on your smartphone or tablet. The MIDI data is sent over the USB connection to the mobile device which acts as the MIDI host.
Some key advantages of using MIDI over USB with mobile devices are portability, tactile control, and larger keys if you use a MIDI keyboard. The main downside is there can be latency over USB which may impact playability for certain apps. But for things like controlling synths and sequencing, it provides flexible mobile MIDI solutions.
Latency Considerations
Latency refers to the delay between playing a note on a MIDI controller and hearing the corresponding sound from a synthesizer or virtual instrument. This is an important consideration when using MIDI over USB, as latency can negatively impact the playability and musical timing.
In general, USB MIDI provides very low latency compared to wireless MIDI solutions like Bluetooth. The latency for USB MIDI is typically under 10 milliseconds, which is imperceptible for most musical applications 1. However, running MIDI through a computer introduces additional latency as the signal passes through the operating system and music software.
To avoid distracting latency when performing, it is recommended to use an audio interface with direct monitoring. This allows the musician to hear the instrument sound directly from the interface output, bypassing any latency induced inside the computer. Direct monitoring greatly improves the live playing experience when using USB MIDI controllers.
With proper hardware and drivers, USB MIDI provides excellent timing and tight integration between controllers and sound sources. The low latency makes it well-suited for live performance and recording.
Power Considerations
When using USB to host MIDI devices, power usage is an important consideration. Many USB MIDI controllers and interfaces rely on bus power drawn from the host device through the USB cable [1]. This means they do not require a separate power connection and are convenient for portable setups.
However, some USB hosts like mobile devices and laptops may not be able to provide enough power, especially if you have multiple USB devices connected [2]. In these cases, you may need a powered USB hub or host with extra power output to avoid issues.
If your USB MIDI device came with an optional power adapter, using it instead of bus power can resolve problems and provide more stable performance. But this adds bulk and cables to deal with. Overall, bus power offers simplicity while external power adapters provide reliability.
Cables and Adapters
Many instruments and MIDI controllers use a standard USB-B port, requiring a USB-A to USB-B cable to connect to a computer’s USB-A port. USB-A to USB-B cables are commonly found for printers and are available in various lengths
to accommodate different setups (ibasenice Adapter Cable USB).
Mobile devices like smartphones and tablets use other USB connectors like USB-C or USB mini. In these cases, an adapter or OTG (On-The-Go) cable is required for connecting the MIDI controller. OTG cables allow a phone or tablet to act as a USB host device. There are OTG adapters available with various combos of USB-A, USB-C, and USB mini to enable connecting to mobile devices (VICASKY Adapter Cable USB Adaptor).
Summary
USB MIDI allows connecting digital instruments like keyboards, drum machines, and synthesizers to computers, phones, tablets, and other devices. The USB host, whether a computer or mobile device, acts as the central controller and data router between the MIDI devices. Latency and power needs to be considered for the best experience when using USB MIDI. With the right cables and adapters, USB MIDI provides flexible connectivity options between electronic instruments, computers, tablets, phones, and more. The USB specification supports transmitting MIDI data alongside power over a single USB cable for convenience.