NN-XT features two Low Frequency Oscillators - LFO 1 and LFO 2. "Normal" oscillators generate a waveform and a frequency, and produce sound. Low frequency Oscillators on the other hand, also generate a waveform and a frequency, but there are two major differences:
LFOs only generate sounds of a low frequency.
LFOs don't produce sound, but are instead used for modulating various parameters.
The most typical use of an LFO is to modulate the pitch of a sound (generated by an oscillator or - in the case of NN-XT - a sample), to produce vibrato.
There are two fundamental differences between LFO 1 and LFO 2:
LFO 2 is always key synced, that is, each time you press a key, the LFO waveform starts over from scratch. LFO 1 can be switched between key synced and non-key synced modes.
This knob controls the frequency of the LFO. For a faster modulation rate, turn the knob to the right.
The Rate knob of LFO 1 is also used for setting the timedivision when synchronizing the LFO to the song tempo (see below).
This can be used for setting a delay between when a note is played and when the LFO modulation starts kicking in (gradually). This way, you can make the sound start unmodulated, and then have the LFO modulation start after you have kept the key(s) pressed down for a while.
This lets you set the "operation mode" for the LFO. Click the button to switch between the available modes:
In this mode, the LFO will run at the rate set for it's group in the group section, rather than at the rate set here. This way, all zones in the group will have the exact same modulation rate.
In this mode, the LFO will be synchronized to the song tempo, in one of 16 possible time divisions.
When tempo sync is activated, the Rate knob is used for selecting the desired timedivision. Turn the Rate knob and observe the tool tip for an indication of the timedivision.
In free run mode, the LFO simply runs at the rate set with the Rate parameter. Furthermore, if Key Sync is deactivated, the modulation cycle will not be retriggered each time you press a key - it will run continuously.
Here, you select which type of waveform should be used for modulating the destination parameters.
Click the button to switch between the following waveforms, from top to bottom:
By activating key sync, you "force" the LFO to restart its modulation cycle each time a key is pressed.
The following parameters can be modulated by LFO 1:
This will make the LFO modulate the pitch, for vibrato, trills, etc. It can be set to -2400 - 0 - 2400 cents which equals 4 octaves. The set pitch will change up and down by this amount, with each modulation cycle. Turning the knob to the right will make the modulation cycle start above the set pitch, while turning it to the left will invert the cycle. Keeping this in the middle position means that the pitch will not be affected by the LFO.
This will make the LFO modulate the cutoff frequency of the Filter, for auto-wah effects, etc. The positive/negative effect is the same as for pitch.
This will make the LFO modulate NN-XT's output level, for tremolo effects, etc. The positive/negative effect is the same as for pitch.
The following parameters can be modulated by LFO 2:
This makes the LFO modulate the pan position of a zone. The sound will move back and forth in the stereo field. Turning the knob to the left makes the sound move from left to right, and turning it to the right thus makes it move from right to left. The middle position provides no modulation at all.
Just like for LFO 1 (see above), this makes LFO 2 modulate the pitch. The range is also the same as for LFO 1.