LFO

Low Frequency Oscillation. More techno from Warp in Sheffield, home of Steel. Not to be confused with the American boyband with same name, but a different acronym. Light Fluffy Orifices, or something.

When I first heard the crappy boy band LFO, I thought it was a parody boy band joke. Seriously, no one could get a record contract with lyrics that corny and tired resampled beats. So I thought... Turns out they were serious. Any group that has an entire song about Jennifer Love Hewitt really needs some help. But even worse was the fact that it got played on MTV, radio, and people bought the album. I am beginning to mourn the human race. I mean really, with lyrics such as "When you take a sip, you buzz like a hornet, Billy Shakespeare wrote a whole bunch of sonnets", how do you get a record contract?

Also seen this used referring to Low Flying Objects. The most common example are birds that are not paying attention and crash into your house windows with a loud thud. Also used to describe planes flying near the ground. Could possibly include bugs that hit your vehicle windshield while driving.

In a synthesizer, A LFO is a low frequency oscillator, which can be set to oscillate (think of the verb) parameters like filter cutoff, resonance, volume, etc. Furthermore, the depth (change between highest and lowest parameter) and frequency (how long it takes to go from highest to lowest). When the frequency is cranked up, you get the kind of wailing fuzzy effect used a lot in trance and other electronica style music.

A low frequency oscillator is an oscillator - typically a sine wave generator, although there is no inherent reason for it to be so - which produces frequencies typically in a range from less than 1hz to 200hz.

Although LFOs makes great desk ornaments, and they are used as scientific instruments, they are most commonly found in the field of electronic music, as a component - either a module, or integrated - of a synthesiser. The function of an LFO is sometimes performed by a regular oscillator - one which typically produces audible frequencies - a good example of this practice being the classic Arp 2600, in which each of the three oscillators can be used as an LFO. However, the majority of synthesisers in the analogue and digital eras use dedicated LFO circuitry. Although an LFO is of limited use on its own (sub-bass reinforcement and illegal psycho-acoustic noise experiments, essentially, as the human ear cannot determine pitch at such a low level), it is extremely useful as a control source.

For example, if the output of an LFO is routed into the modulation input of filter's cut-off frequency control, the cut-off frequency of the filter can be made to oscillate around a pre-set range at the frequency and amplitude of the LFO.

As another example, an LFO can be used to modulate the pitch of an oscillator, thus producing a vibrato effect, or it could be used to modulate the amplitude of an amplifier, thus producing tremolo. Filter modulation, vibrato and tremolo are the classic LFO effects, with pulse width modulation next on the list. Most synthesisers have several LFOs so as to modulate several parameters independently, and thet LFOs can be made to produce various different waveforms, usually including a 'random' wave.

With a modular sythesiser, an LFO can be routed to anything - other LFOs, a reverb unit, a slew limiter, a quadrastatic phase-shifting pitch-o-matic bloam-a-sträuft, and so forth. With a preset synthesiser the LFO can typically only modulate amplitude, pitch, and the level of the filter and its resonance control.