MIDI interfaces are designed to link your computer with your MIDI gear and come in one of two possible forms: a cable with a converter chip built into the plug or a small adapter crammed into a small housing. Interface cables are often equipped with a MIDI IN plug at one end and a MIDI OUT plug at the other, while MIDI interface units usually offer more options.
DIN-MIDI and USB-MIDI
DIN-MIDI is the original MIDI standard that we've been using since the eighties; the cables feature large 5-pin plugs. Essentially, USB MIDI transfers MIDI signals via a USB cable. In terms of data, USB-MIDI and DIN-MIDI do the same exact thing. The advantage of USB-MIDI-compatible keyboards and digital instruments equipped with a USB port is that they can be directly connected to a computer without the need for a MIDI interface.
Audio Interfaces with MIDI
Some audio interfaces feature a built-in MIDI interface and can be hooked up to classic MIDI gear via one or more 5-pin DIN ports, doing away with the need for a separate MIDI interface.
MIDI Interface Cables
The MIDI interface cable is the most compact kind of MIDI interface you can get. It's usually also the most affordable solution for connecting a single DIN-MIDI device to a computer. MIDI interface cables look like standard cables but actually feature a built-in chip that ensures the MIDI signal of, say, your synthesizer is converted and prepared for transfer via USB.
MIDI Ports: MIDI IN, OUT and THRU
Most MIDI gear comes outfitted with thee DIN ports: IN, OUT and THRU. Needless to say, inputs are designed to receive MIDI data while outputs send out the signals and THRU ports can pass received MIDI data on to a MIDI OUT. Want to hook two synths up to a computer? Simply connect your computer to the MIDI IN of the first synth before using a DIN-MIDI cable to link its THRU port with the MIDI in of the second synth. Bear in mind that both synthesizers will receive the same MIDI signals and play the same sounds. As a workaround, you could decide to mute specific MIDI channels per synth.
2x2 and 4x4 MIDI Interfaces
A 2x2 MIDI interface sets you up with two DIN outputs and two DIN inputs, allowing you to create two MIDI signal chains. If you're not running too many bits of MIDI kit, the 32 channels of a 2x2 interface should be more than enough, especially seeing as MIDI THRU ports support multiple MIDI devices within a 'chain'. As you'd expect, a 4x4 MIDI interface gets you four DIN outputs and four DIN inputs for the option to create and control as many as four MIDI signal chains. Four outputs also means access to 4 x 6 = 64 MIDI channels which can be useful even if you aren't running a massively extensive MIDI set-up, since daisy-chaining too many MIDI devices always leads to signal degradation.
Frequently Asked Questions About MIDI Interfaces
How do you connect MIDI gear?
Want to connect a musical instrument, a MIDI keyboard or any other device equipped with MIDI ports to your computer? Depending on the type of port, you'll need either a USB-A to USB-B USB cable or a MIDI interface in combination with a 5-pin DIN MIDI cable.
What does a MIDI interface do?
MIDI interfaces allow you to connect 'old-school' 5-pin DIN MIDI ports to a computer and use software to control an external MIDI device, or vice versa by sending MIDI data to your computer from your instrument.
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