How to connect synthesizer to computer

In-depth information on methods of connecting synthesizer or MIDI keyboard to computer; also, interconnecting devices equipped with different interfaces is described.

To connect a synthesizer to a computer, following are needed:

  1. a cable (flex, wire) to connect synthesizer to computer physically;
  2. a computer program to record and playback music performed on the synthesizer.
What is synthesizer

Synthesizer here stands for a device that generates sound (tone generator) and a musical keyboard (similar to piano keyboard) designed as a single device.

Unlike synthesizer, MIDI keyboard does not have its own tone generator and cannot generate sound on its own (without a computer or another device equipped with a tone generator). Some MIDI keyboards are equipped with a built-in tone generator and are effectively synthesizers capable of connecting to a computer.

Physical connection between synthesizer and computer

What method of physical connection between of a synthesizer and a computer to use depends on what ports they have:

  • universal USB port (available on most of computers, modern synthesizers and MIDI keyboards);
  • circular 5-pin MIDI port (typically available on synthesizers, MIDI keyboards and professional audio cards).

USB connection (USB To Host)

Connection via USB is the most modern and usable method of connecting synthesizer (or MIDI keyboard) to computer. This is accomplished using a standard USB cable of AMBM type (exactly the same cable is used to connect modern printers, scanners and other USB devices to computer).

Such cable is connected to computer using a plug with sectional view of oblong rectangle, and to synthesizer — using a plug with sectional view of square with two bevelled corners.

Such connection is universal: most of computers have a USB port. Also, unlike synthesizers, it’s usually enough for MIDI keyboards to receive power via USB itself, so there is no need for a separate power adapter.

When USB connection is used, exchange of MIDI data between synthesizer and computer is done using a virtual MIDI port. Functioning of this port is provided by a special software driver. Such driver usually comes bundled with synthesizer (or MIDI keyboard) or is available on website of its manufacturer. Some modern synthesizers and MIDI keyboards are automatically recognized by the system as MIDI devices and do not need a dedicated driver.

When USB connection is used, synthesizer should necessarily be connected to computer before starting sequencer (DAW) software. Otherwise, virtual MIDI port that the synthesizer is connected to would most likely not be visible in sequencer, and it would be impossible to use the synthesizer. This is because, unlike regular MIDI connection, virtual MIDI port of USB connection does not permanently exist in the system and usually appears only after connecting synthesizer (or MIDI keyboard) to computer physically.

Many synthesizers and MIDI keyboards that support transmitting MIDI signal via USB are still also equipped with the standard MIDI interface. This provides maximum compatibility with wide range of MIDI devices. However, as for consumer-grade MIDI keyboards (that, in most cases, are purchased exactly to be connected to computer), there is a trend of dropping the regular MIDI interface completely in favor of the more demanded USB interface.

In synthesizers and digital pianos of Yamaha, USB port intended for connecting to computer is usually named USB To Host.

The fact that a synthesizer has a USB port does not guarantee that it’s possible to use the synthesizer as a MIDI keyboard using this USB port: on some synthesizers, USB port, despite of its existence, is not intended to be used as MIDI interface and serves just to exchange files between computer and synthesizer. This takes place, for example, on Roland EXR-3/5/7 synthesizers (similar models from the more recent EXRs series do not have this shortcoming anymore).

MIDI connection

MIDI interface is the classic and oldest method of interconnecting wide range of professional audio equipment. Most of synthesizers (that support transmitting MIDI signal) and MIDI keyboards are equipped with this interface.


To connect a synthesizer to a computer using MIDI interface, MIDI output of the synthesizer should be connected to a MIDI input (input MIDI port) of the computer using a MIDI cable.

Computer’s MIDI port can be of two types:

  • standard 5-pin MIDI connector with circular sectional view;
  • connector combined with 15-pin game port of audio card and having trapezoidal sectional view.

Circular MIDI connectors are typical for professional sound cards, external MIDI interfaces and standalone musical hardware. That’s how classic MIDI interface is implemented on synthesizers and MIDI keyboards.

Design that features computer’s MIDI port combined with 15-pin Game port is now obsolete: most of vendors have entirely dropped equipping sound cards with Game port since modern game devices (gamepads, wheels, etc.) support solely USB.

The type of a MIDI cable needed for connection depends on the type of the MIDI port available on the computer.

When connecting, the MIDI out connector of the synthesizer should be connected with the MIDI in plug of the MIDI-cable.

Devices and drivers

When connecting via MIDI, the synth itself is not displayed as a device anywhere in the system. What’s displayed is just a MIDI port that can used to connect a synth / MIDI keyboard as well as any other MIDI device. This MIDI port is exactly that should be selected as an input MIDI port (source of MIDI events) in sequencer software like Cubase or Sonar. In some sequencers (e. g. Cubase), MIDI events are received by default from all input MIDI ports available in the system, so selecting a MIDI port manually is unneeded.

When using the standard MIDI interface, the synth (or MIDI keyboard) itself does not need any drivers. A driver is needed only for the device (a sound card or an external MIDI interface) that have the MIDI port that the synthesizer is connected to.

In computer software, MIDI port may be titled different ways depending on specific device (sound card, MIDI interface) that the MIDI port is a part of, and on drivers installed for this device: for example, for the SB Live! sound card using standard Windows XP SP2 drivers, the MIDI port is titled SB Live! MIDI UART.

MIDI mode of synth

To transmit MIDI signal to MIDI output of a synthesizer, it is usually needed to switch the synth to MIDI mode via a switcher of working modes on its case. The mode switcher is sometimes combined with the On/Off switcher of the synth. MIDI keyboard does not need this since it does not intended to be used separately from computer and always transmit MIDI signal to its MIDI output, so the only needed thing is to turn the MIDI keyboard on.

Connecting synth equipped with MIDI out to USB-capable computer (e. g. laptop)

Sometimes it’s needed to interconnect MIDI devices equipped with interfaces of distinct types. In particular, this is the case when a synth or a MIDI keyboard equipped with classic (not USB) MIDI interface is connected to a laptop. Laptops do not usually have MIDI interface while almost always have USB ports.

In this case, to connect, it’s enough to purchase an external MIDI interface which is roughly a USB-MIDI adapter: from one side, it is connected to MIDI output of the synth, while the interface’s USB port is connected to the computer (e. g. laptop).

A simplest external MIDI interface has a price starting from $35-40: for example, Roland UM-ONE mk2, M-Audio Uno, or ESI MIDIMATE II.

Like a synth using USB connection, a USB-MIDI interface should be connected to computer before starting sequencer software. This is required for the MIDI interface to be «visible» in sequencer.

Old connection method: To Host interface (Com, RS-232)

Some old synth models (mainly by Yamaha) have a To Host connector that allows to connect the synth to serial port (COM, RS-232) of computer. As with USB connection, for the synth to function as a MIDI keyboard in this case, it requires a driver which usually comes with the synth.

This connection method is currently obsolete since the physical-level connection itself is obsolete — due to extremely low data-transfer rate, most of modern computers are not equipped with the serial interface (somewhen it has been used to connect a mouse).

To Host connector is not to be confused with USB connector installed on modern synth models (for example, DGX-220/520/620) and digital pianos by Yamaha and is titled similarly: USB To Host. These are totally different and absolutely incompatible connectors.

If MIDI connection is unavailable, then it makes sense to use classic MIDI interface or an external USB-MIDI interface.

Interconnection of synths not equipped with MIDI interface

Sometimes it’s needed to connect a synth to another one, for example, to play on the keyboard of the former with timbres of the latter.

But some modern synths and MIDI keyboards do not have MIDI interface and are only equipped with USB interface. In such case, direct connection of a synth with USB output to synth with MIDI input is impossible, as well as it’s impossible to interconnect synths via USB.

The goal can be achieved by using an intermediate computer. Such computer may be a desktop or a laptop as well as, for example, a netbook.

And then the task of interconnecting synths one of which has no MIDI port can be solved with the following simple steps:

  1. connecting synthesizer with USB interface (or both synths if both are USB-capable) directly to the intermediate computer;
  2. if one of synths is only equipped with MIDI interface, it should be connected directly to the intermediate computer (if its sound card has classic MIDI interface) or to an external MIDI interface connected to the intermediate computer via USB;
  3. setting up a computer sequencer (e. g. Cubase) installed on the intermediate computer so that it outputs MIDI events from MIDI input corresponding to the one synth to MIDI output corresponding to the other synth.

Sequencer software

To connect a synthesizer to a computer, it’s not enough just to connect them physically. To be able to record, playback and edit MIDI data, you need a special program called sequencer.

Sequencer is a computer program intended for multitrack recording and editing MIDI data (received or recorded, for example, from a MIDI keyboard), usually having advanced tools for simplifying arrangement, automating routines, etc.

Some of popular software sequencers:

Two of programs that are most popular today are Steinberg Cubase and Cakewalk Sonar which are full-fledged digital audio workstations (DAW) and allow not to just work with MIDI, but are also capable of recording digital audio, applying effects, etc.

PreSonus Studio One Free is a freeware version of PreSonus Studio One.

Cockos Reaper and EnergyXT are low-cost and have price of about 60 $. Reaper has a fully-functional demo version that continues to work even after trial period is expired.

By the way
There are also hardware sequencers — they are functionally similar to software sequencers, but implemented as standalone devices or as parts of professional audio workstations. In this article, sequencer is considered as computer software.