First, let’s look at a MIDI signal chain that uses a soft synth (Figure 1). Your system might have a hardware synthesizer or sound module, but many of the same principles apply. During playback, the recorded MIDI sequence “plays” the soft synth patch, and its audio is routed through your interface and monitors. Let’s say you set up a MIDI track to record your MIDI sequence, and you set up an audio track that contains the soft synth as a plug-in. (Your sequencer might use a different arrangement.) Make these settings:
- In the MIDI track, set the synth bank and patch (bass, drums, piano, etc).
- In the MIDI track input, specify the MIDI channel that the synth responds to—either Omni mode (any channel), or the same channel number that your MIDI controller is set to.
- In the MIDI track output, specify the synth you want the MIDI track to play.
- Set the audio track output to the stereo output of your interface.
If any part of the chain is not turned on, or has the wrong settings, you won’t hear a sound when you monitor the synth. Here are some possible reasons why your synth can’t sing, and what to do about it.
- MIDI Out or MIDI Thru is not connected to MIDI In somewhere in your system. Trace the cable connections from beginning to end, and see whether a MIDI cable is not plugged in where it should be. The cable itself might be broken.
- Your computer is not communicating with your MIDI interface. A missing or flaky PCI, USB, or FireWire connection can disrupt the data flow between interface and computer. Re-plug or replace the cable. You might need to restart your sequencer program, too. Some recording software has an on-screen indicator that flashes when the software is receiving MIDI data, so check it out.
- When you are tracking, the MIDI sequencer track is not selected. Some sequencer software does not monitor the soft synth unless you select its MIDI track. In some sequencers, you can live-monitor only one synth at a time, but you can playback multiple synth tracks at once.
- The MIDI sequencer track has no MIDI channel assigned, or is set to a different channel than the MIDI controller. Just as you need to set your TV to a certain channel to see a station’s programming, you must set your MIDI sequencer’s track to the same channel your controller is sending data on. It might be easiest to set the MIDI track input to your interface in Omni mode, so the track will hear any channel you are sending. You can set multiple MIDI tracks to Omni—just record one track at a time.
- The MIDI sequencer track output is not pointing at your soft synth. You have to tell the MIDI track which synth to play.
- The wrong sound bank was selected in a synth. You might have specified a bank that contains no sounds. Or the MIDI mapping on your controller is set so the notes aren’t playing the patches you want them to play. Check the bank setting, patch settings, and MIDI mapping.
- In the sequencer’s options menu, under MIDI devices, your MIDI interface is not selected. The sequencer does not know where to find the driver that communicates with your interface, so you don’t hear anything. If your sequencer has a MIDI data indicator that’s not flashing in response to your playing, this might be the problem.
- The synth’s audio-track volume, or the MIDI track’s key velocity, is turned down. Disable the mute buttons, and turn up the faders for those tracks. Check that no other tracks are soloed.
- You started playing the file in the middle of a long note, rather than at its beginning. A synth needs to receive a Note-On command in order to play a note. If you start playing the sequence from a point after the beginning of a note, the synth does not receive the note-on code, so it remains silent.
- Your hardware synthesizer lost the program-change command. Although you told the synth which patch to play, sometimes this information is lost. Change the patch on the synth, and then set it back as it was, or record the program change at the beginning of the song.
- The input to your sequencer track lost the setting for its MIDI input device. Sometimes when you close a sequencer program and reopen it, the MIDI track inputs might forget their settings. Temporarily set the MIDI track input to another device, then set it back as it was.
- The MIDI driver is buggy. Download the latest update from the interface manufacturer.
- The synth audio output is not assigned to your interface’s stereo output channels. In other words, the synth is making music, but not sending it anywhere.
- No audio playing through your monitors? If not, the monitor power amp, or your mixer’s monitor controls, might be off or turned down. Maybe the cables between your interface and monitors are not plugged in. Seems obvious, but it has happened to me.