synth lfo

Easy Synth Programming – Synth LFO

Easy Synth Programming – Synth LFO

Here’s the ugly truth: if you don’t know how to wield the power of a synth LFO effectively, then you are not making world-class sounds.  There is no way around this fact.  You need to learn not only what an LFO is and what it does but also where it goes, how much it goes there, and many more details which aren’t immediately apparent.  Download the demo of Syntorial here so you can follow along and master your synth.

Definite Accuracy

There are few thing you need to keep in mind about making your sounds evolve over time.  One is that your sticky human fingers are not very accurate in turning knobs.  Another is that, since it takes at least one hand to move one parameter, you are physically limited as to how many things you can change at once.  Luckly you have synth LFO available to you.

What is an LFO?  LFO stands for Low Frequency Oscillator.  Since I know you’ve been following along with this Easy Synth Programming series, you by now know what a a low frequency is as well as an oscillator.  But didn’t I just cover low frequency oscillators in my sub oscillator video?

Well, yes and no.  The difference between a sub oscillator and an LFO is that you can hear one directly and the other you only hear indirectly.  Both can play very low frequencies but, typically and as the name suggests, an LFO usually plays lower.

Low and Slow

How low exactly?  As you probably know, humans have a rule-of-thumb hearing range of 20 cycles per second all the way to 20,000 cycles per second.  Whereas a sub oscillator will usually stay within that bottom range, a synth LFO goes even slower.  An LFO can even have a cycle period of over an actual second.

Since there’s no way to hear something that low then it makes sense you can’t usually hear an LFO directly.  The way a synth LFO works is by, essentially, turning knobs and moving sliders on your behalf.  They can do this as fast or slow as you’d like (within reason), as much or as little, but far more accurately.

Another great thing about them is they solve the old ‘two-handed’ dilemma that people face.  Though we only have one hand with which to play and another to turn knobs, many LFOs can be made to effect multiple destinations.  It’s like a modulation bonanza!

Lines and Spheres

But what is the difference between a synth LFO and a modulation envelope?  The main difference is that most ADSR envelopes are linear.  They start in one place and end at another.  Whereas envelopes go on a journey, just like mail does with the postal service, an LFO is more like a loop which keeps on spinning.  Take that, herpes!

So how do you implement a synth LFO then?  I’m going to go over two ways in which you can make this happen.  In the first way, I’m going to use Syntorial’s Primer VST instrument which is included when you download the program.  The second example I’m going to show you is going to use Native Instrument’s venerable Massive synthesizer.

If you are a rank beginner, and there is no shame in that, then I suggest that you start with Primer.  Primer is a relatively bare bones synthesizer designed to get you up and running as quickly as possible.  It’s just like your very first coat of paint.  Hey, I wonder where they got the name!

If you’re a bit more advanced then join me as I use Massive.  I have already gone through the entire Syntorial program using another synth, Analog from Ableton Live Suite, but now as I walk you through, Massive is the one I’m currently using.  In the event that you’re super advanced then I’m not sure why you’re reading this but thank you and be sure to share this article with someone you think can use it.

Around the Track

Go ahead and open up Primer and initialize the patch.  I will discuss two assignments using the synth LFO, pitch and cutoff, before moving on to Massive.  We really need to focus here because there are many options available to you that may distract you.

All I want you to do is leave the triangle waveform selected.  Now, set your destination to pitch.  The amount knob should be set to it’s maximum value.  Rate doesn’t matter here much so leave it at it’s default for now.

As you play a note on your keyboard, or trigger a MIDI sequence, you’ll notice that the synth LFO is automatically changing the pitch of whatever notes are playing.  Don’t worry about the ‘poly’ setting today.  Briefly, what that does is retrigger another synth LFO for each and every individual note you play.  So, if you play 10 notes, you will also trigger 10 different synth LFOs.

Variety is Key

Setting the synth LFO destination to pitch is awesome for a number different techniques.  You can use this assignment to create vibrato, like a guitar player slightly bending a string, or you can even create wild lazer-like zap sounds.  I mean, isn’t that why we all got into synths for in the first place?  Lazer sounds from friggin’ sharks’ heads, yeah baby.

Now the next thing I want you to do is initialize the patch so we can start assigning the next destination.   For this time around I want you to select the saw tooth waveform in the synth LFO section.  Next, set the rate to 1/8th notes.  The amount should remain at full and your destination should go to cutoff.  Play a note to invoke the ghost of deadmau5.

You may need to turn the actual filter cutoff knob down a few degrees in order to get the sound you want.  Turn it down low enough and the effect you will create is known as a ‘gate’.  The reason for this is because your synth LFO will effectively cut off your sound when the filter cutoff is at its lowest setting.

Experiment with assigning this saw wave to the volume also.  If done using the right combination of settings, you will end up with a pluck sound.  You can also use a pulse wave to create a similar gated effect using the synth LFO.

Bigger Than Before

Now, in Native Instruments’ Massive VST, the synth LFO system is quite a bit different.  With Massive, you can have up to four separate LFOs and assign them to a wide variety of destinations.  In addition to the bread and butter destinations which Primer makes available to you, you can modulate: FX mix, EQ, distortion, noise color, filter mix settings, and more.

Besides that, you also have many more wave shapes available to you with which to modulate all of those destinations.  You have the basic waveforms like sine, triangle, and pulse at your fingertips on the GUI.  But, if you click the drop down menu, there are at least 15-20 more shapes that await your selection.

Don’t be shy!  Go in there and start making assignments.  By now, you should know how to do this but if you don’t then you’ll be surprised how easy it really is.  To assign a synth LFO inside of Massive, just select one of those green cross hatch icons next to the word LFO in the center screen and drag it somewhere there is an empty box, say the filter cutoff.

Massively Detailed

If you’ve already initialized the patch in Massive then you will need to select a filter type for anything to happen, at this point.  Use the drop-down menu to select a 4 pole LPF and now you’re good to go.  Just drag the number where you’ve assigned the synth LFO, probably number 5 in this case, and you’ll see symmetrical bands begin to encircle your filter cutoff knob.  That’s your LFO amount, in this case.

Play a key or trigger a MIDI sequence to hear your synth LFO modulating your filter cutoff.  Now you can go back to the LFO screen and find the rate knob.  The LFO defaults to a relatively slow and uninteresting value.  Make it faster or even sync it to your host’s tempo, if applicable.

Feel free to select from the available wave shapes, turn sync on or off.  You can also deselect retrigger so that the synth LFO wave shape won’t start over every time you hit a note.  Turning this off can be very effective for ambient non-rhythmic sounds.

Make sure you take the time to experiment on your own.  If you’re new, I don’t recommend that you use any other synths until you’ve completed Syntorial’s basic program or, if you’re following along with me here, the lessons I’m sharing with you.  It’s easy to get confused, overwhelmed, and ultimately quit.


Let’s recap.  You now know that sounds need to change over time to be interesting.  You also know that your fingers are not very accurate and using the synth LFO is a great way to get computer-accurate changes in sound, modulations, into your patches.  I also showed you how to actually perform these miracles inside of two synths.

Synthesis is very much a long term game.  I think that by now I have been involved with synths fairly regularly for over five years.  Granted, I’m not on synths every day all day.  Even so, consider this fact next time you feel you aren’t making progress or that it might not seem possible.

This is the reason why I love Syntorial so much.  As someone like many of you who needs to balance a variety of skills and tasks, I find it nice that someone has gone ahead and structured the learning environment for me.  This way, all I have to do is show up and give my best effort.

Meet the Master

If for some reason you haven’t heard of Syntorial, it’s pretty much a synth teaching video game.  It runs cross platform, including iOS, and is pretty much like those pink noise audio ear training drills but far more powerful.  Whether you want to learn synthesis, make better mixes or masters, or just appreciate music to a deeper degree, you would be well invested to download the free demo here.

Naturally, as an affiliate I will receive a commission should you choose to buy it.  I became a Syntorial affiliate because I was evangelizing for the product even before I was one and people thought I was anyway.  Actually I’d originally heard of the program via word of mouth several times so I know that many others like how awesome it is too.

In any case, download the demo today since you have nothing to lose.  It’s 100% free, comes with 22 included lessons and will get you going with all the benefits you want.  Plus, I’m pretty sure that you can at least view the curriculum’s overall arc so, if you decide that you don’t like it, at least you’ll understand how to break down the synth learning process in a very well-organized manner.

Thanks Bro

I want to take this opportunity to thank my readers, supporters, customers, and patrons.  Putting out content every week is challenging and I’m grateful for anyone who is interested.  Although I primarily do this for myself – anyone who tells you different is lying – it’s great to be able to share the skills that I’ve gathered over my music-making career.

If you are enjoying what I’m doing then please consider supporting me.  A number of ways are available including making a donation on PayPal, becoming a Patron ($3/mo. gets you extra Ninja Training for every Easy Synth Programming video I release), or even free ways like subscribing on YouTube, joining the Hexie Dose Newsletter, or just sharing or saying thanks on social media where you can find me @hexspa.

That pretty much covers it.  I’m still releasing new music-making tutorials and original music every Monday at 4PM PST in video and article format.  If you haven’t heard my music you can check it out here.  Thank for being a part of Hexspa and I’ll see you next week!



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