An Introduction to the Seaboard RISE 3.3 - LFOs Video Lecture - Introduction

the last piece of the modulation panel
that we're gonna take a look at are the
two low frequency oscillators also known
as LFOs low frequency oscillators have
been around for a long time but they
became super popular around the rise of
dubstep which is characteristically
defined by a wobble bass of all the
complex ideas and relationships we've
discussed thus far in the course I think
the low frequency oscillator is one of
the easier terms to understand in a
sense an LFO is exactly what the name
suggests that it is it's an oscillator
which emits an electronic signal just
like the oscillators on the synth panel
but it's signal is at a very very low
frequency so low in fact that it's
outside the scope of human hearing you
might ask yourself why would someone
create an oscillator which emits the
sound we can't hear and well the answer
goes back to the idea of vibrations
oscillators create waveforms which
travel back and forth back and forth
back and forth like a pendulum and we
can use that movement to create a lot of
musical effects as we saw in the other
oscillators in the synth panel there are
many types of oscillation there's a
smooth sine wave there's a square wave
there's a triangle wave as well as a
sawtooth wave and many other complex
waves the LFO has the pendulum swinging
here but outputting a signal we can't
hear so it's not adding any new colors
to the sound we use the oscillation as a
control signal we set the oscillation of
the LFO waveform to control other
parameters on the synth assigning those
parameters that back and forth movement
with we've been talking about tremolo
and vibrato are two of the most common
LFO uses we encounter if the LFO is set
to control the volume on one or all of
the other components in the synth the
volume will follow that pendulum swing
of the LFO up and down when this happens
it sounds like a tremolo sound very
characteristic of early electronic
keyboards like the Wurlitzer
if it's mapped to a tuning parameter it
will sound like a warble or a vibrato
besides volume and pitch it's also very
common for an LFO to be mapped to the
cutoff frequency of a low-pass filter
that creates a distinctive opening and
closing effect which is how we get those
wobble bass lines
check this out further by navigating to
preset number 70 named Imperial pad just
looking at the settings for the sound
you can probably guess what's mapped to
the LFOs because the knobs associated
with those parameters are currently in
motion and at a very fast rate if we
click on LFO 1 you'll see that it's
mapped to the fine knob on oscillator 1
and 3 which will bend the pitches in a
very fine granular about a measurement
known as sense LFO 2 is mapped to the
width of oscillator 3 which creates a
sort of chorus or detuned effect as well
let's press and hold a key wave in the
upper register so it's easy for us to
hear what's going on you can clearly
hear the vibrato that the LFO is
creating the word frequency obviously
relates to pitch but frequency also
means how often something occurs on an
LFO frequency has more to do with speed
than it does with pitch if you turn down
the frequency on both of the LFOs you'll
notice that the rate at which the dials
are swinging slows down since very low
frequencies vibrate at very slow rates
when we adjust this level down to 2
Hertz it will be swinging back and forth
slower than if we were at a higher
frequency like so the movement of this
LFO is currently instructed to affect
pitch via the mapping
[Music]
if we adjust the level you'll see that
the oscillation becomes more or less
pronounced if we pull this all the way
up to a hundred percent it's gonna reach
the highest and lowest values of the
mapping and if we lower the less far the
dial travels the fade knob is a
time-based parameter which will dictate
how long it takes for this LFO to fade
in and out and just like the envelopes
we have a value of 0 to 5 seconds to
choose from so if I turn this all the
way up you'll see that it's gonna take a
moment so nothing really kick in
now let's do something a little bit more
advanced I'm gonna map envelope 5 to the
frequency and level of LFO 1 & 2 and
what I want is for this vibrato the LFOs
are creating to come in slowly reach its
maximum value and then fade out on the
release and since this is a time-based
modulation I'm gonna use an envelope to
make it happen so let's work through
this together and see if we can
understand how everything is working in
tandem click along with me as I do this
and remember you can always reset the
preset by navigating away and right back
to it and you can also start and stop
this video as many times as you need to
we'll start by turning on envelope 5 now
turn up the attack and release time so
you get a slope that has a gradual fade
in and fade out and looks something like
this now we need to turn down the base
value of both the frequency and the
level on both LFO s so that we have some
Headroom to travel once we hit a key
wave then with envelope 5 selected map
it to increase those same parameters
that we just lowered
so now when we press a key wave let's
see what happens keep an eye on the fine
and with knobs on oscillator one and
three Natalie do they speed up in
frequency but they also sweep back and
forth more dramatically as we reach the
full value on the envelope and then as
we release the key wave the converse
action takes place for those of you who
are just starting to learn about
envelopes and LFOs that may have been a
lot to digest if you're in that boat I
would go back and watch the previous
video and this video a few more times
for starters then I want you to go
through all the different presets see
what different mappings already exist on
the envelopes and LFOs and watch them in
action when you find one that intrigues
you try visualizing an adjustment you
could make work it out in your head
first is how you might go about creating
what you want to hear then see what
happens when you execute that plan the
more you experiment and use your ears
the more you'll understand and be in
control of these devices not only that
but it will actually make you smarter
since you'll be using the creative right
side of your brain to imagine a sound
and the analytical left side of your
brain to deal with technical stuff and
by doing that you create new
neurological pathways between the two