Yamaha MT4X User Manual page 39

Play the overdub part along with the MIDI instrument(s) and the previously
recorded tracks.
7) Adjust the recording and monitoring levels while watching the level meters.
8) When you are satisfied with the levels, press the RETURN TO ZERO key to stop the
rehearsal and rewind the tape.
Recording
9) Press the REC/PAUSE and PLAY keys to start recording.
The MIDI instrument(s) will play automatically. Play the overdub part again.
10) When the recording is complete, press the RETURN TO ZERO key to stop and
rewind the tape.
Check the recording
11) Press the PLAY key to start playback of the tape.
If the resulting recording needs to be redone, repeat from step 5.
Recording a synchronized performance
You may want to record your MIDI instrument(s) while they are synchronized with the
FSK signal recorded on track 4. The procedure is similar to the previous section (see
"Overdubbing with a synchronized performance" on page 36).
User's Guide
Synchronization 38