43 posts / 0 new
Last post
SToons Music
Offline
Joined: 03/01/2018 - 02:48
Understanding Amplitude Modulation and Ring Modulation

Caustic Song file (optional): 

^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Hopefully this type of example bridges the gap between text and video. It will be good to get feedback as to how well this translates the intended info.

And unlike a video it can also be very personally interactive. If you play the file in Song mode there is a gap between each example to give you time to switch between synths and visibly follow along. In Pattern mode you can play around and dissect all you like.

What is sound; what is it we hear?

There is a source and then there are modulators, things that have an effect on the source. Filters, effects like chorus/ flangers / delay, reverb, bitcrushers, eq ... these are all modulators of some sort.

A rifle might be the source of sound. However, before we actually hear the sound it is modulated. It is modulated in many ways such as hundreds or thousands (or more) of subtle echoes (reflections) from walls or trees, rocks etc. It is modulated by air itself and the amount of moisture in the air which affects how frequencies are dampened.

Amplitude is Volume. Modulation is to cause change. So, Amplitude Modulation, AM for short, is quite simply changing the volume.

A very simple form of AM is Tremolo. Many musicians are familiar with Tremolo pedals and effects. Tremolo, along with reverb, was one of the first effects to be built into amplifiers years ago as it only required a simple analog circuit.

Vibrato, often confused with Tremolo, differs in that it modulates the *frequency* (or "pitch") of sound so it is a form of
Frequency Modulation or FM.

In the Caustic file synth 1 is a fairly simple setup. There is a Source, the waveform generator (often referred to as as oscillator) which is modulated by an envelope.

Synth 2 is identical in sound, the only difference in the setup is that the sound is first sent into a mixer. By attaching the DADSR envelope to the Mod input of the mixer instead of the waveform generator it clearly demonstrates that the Mod input jacks function identically. Make sense?

This is cool because now this setup allows TWO different ways to modulate amplitude. (3 for the more advanced readers as the Volume Mod input visible in the upper right corner exists but let's not cloud the issue for now).

On to synth 3. The DADSR is again attached to the waveform generator allowing control of tne initial sound. We can control the attack, decay etc. For example if you press a key the volume still swells in and slowly releases. However, there is now a MiniLFO attached to the mixer Mod.

The MiniLFO is quite simply a waveform generator, nothing more. However the frequency coming from it is so slow it doesn't even produce sound in the range of human hearing.

The sine wave coming from the MiniLFO is Modulating the amplitude whenever the DADSR envelope is allowing sound to pass into the mixer, in other words when you play a note.

This creates a distinct Tremolo effect. The MiniLFO is helping out as it automatically raises and lowers the volume as long as the note sounds.

You'll notice the rate of the MiniLFO is automated. As the speed of the amplitude modulation increases, when the MiniLFO reaches a high enough frequency, it starts to produce a "sympathetic"note. The sympathetic note first added to the sound is actually a lower pitch than the original produced by the waveform generator.

If we want higher pitched notes we need an oscillator that will run a little bit faster than the MiniLFO. That's where the Sub Oscillator comes in. At the lower octave settings the Sub Osc produces roughly the same speed of modulation as the MiniLFO at it's highest rate.

In synth 4 the MiniLFO has been replaced by the Sub Osc. When you play the file the initial sound is a similiar pitch to where the MiniLFO finished. Now we can listen to what happens as we increase the amplitude modulation even more.

Eventually we reach the maximum speed limit (frequency limit) of the Sub Osc just as we did with the MiniLFO, so, now we need ANOTHER way to Modulate the amplitude at a faster frequency.

That's pretty easy - now we use a standard waveform generator as visible in synths 5 and 6.

So, there are 3 principal ways to generate a sine wave in the Modsynth so far:

1 - MiniLFO (frequencies generally too low for human hearing)

2 - Sub Oscillator (frequencies at the lowest range of human hearing, similiar to low end rumble like earthquakes, passing trucks, explosions etc. We feel these freq as much of more than we actually hear them).

3 - Waveform Generator (frequencies that generally cover the full range of human hearing)

You can Modulate the amplitude using other waveforms like a square wave. Notice that with synth 7 that, unlike the smooth volume changes that occur with a sine wave, the sound is either on or off.

Using different waveforms to Modulate the amplitude gives different results so understanding that helps determine choices.

The other examples are a little more difficult to understand but essentially with the alarm sounds the amplitude is still being modulated, whether it is two sounds at the same time (alarm 1 with a mixer), at the opposite time (alarm 2 with a crossfader) or being panned between two sides (the following alarms).

The Crossfade module replaces the mixer in some of the alarm examples, as does the Pan module. This allows Modulating two different sources at once. If the mixer were used, both sounds would turn on or off at the same time. With the crossfader you can modulate between different sources. With the Pan module you can modulaye from side to side. Using both to Pan alternate between the two sounds and simultaneously Pan them.

Notice the MiniLFO allows controlling the mixer, panner and crossfader at the same time.

The sudden change in amplitude caused by the square wave can sometimes result in clicking. In the final example a lag processor is used. It slightly smooths the abrupt change in volume. It is not even audible as it happens so quickly but it slows the attack of each modulation just enough to eliminate the clicking.

And finally, the output of the MiniLFO used in the final alarm is automated. When it is turned off (output is zero) the waveforms are no longer modulated by the LFO... the amplitude does not change and the two source sounds no longer pan.

Hopefully amplitude, mudulayion and the modular synth are now slightly less confusing or intimidating than before.

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
Hi SToons,

Hi SToons,

Well done! I understood AM but your examples opened the door to controlling something other than sound with an oscillator (LFO, Sub, Waveform Generator). I knew you could do it but it was very helpful to have it broken into parts, step by step.  I do have a question, if all we are doing is modulating the amplitude of a single note, making it louder and softer (or on and off), why is a second, "sympathetic" note generated?  Where does it come from?

Thanks for the work you put into it!  I will be creating my own spaghetti using what I learned.

Funzerkerr
Funzerkerr's picture
Offline
Joined: 10/16/2018 - 12:17
@JHSound afaik LFO generates

@JHSound afaik LFO generates sound/signal that is used for modulation, so that "symphatetic" note is generated by this mini LFO even if the main purpose for this module is to MODULATE. So there were always two notes. LFO note/signal just appears when wave goes into spectrum where human ear can hear it.

@SToons this is the level of details that makes everything much easier to understand.

Amel
Amel's picture
Offline
Joined: 02/21/2015 - 10:00
That note comes from stereo

That note comes from stereo output. So this how it actually works.
Sequencer has the stereo output, while the pattern mode has mono output. Both playmodes have the same amount of velocity. With those two modes combined, the third note, FM note stays between them, kind of blocked and never understood.
The proper picture that describes how sound is evolving trough caustic is shown on this link.

https://en.m.wikipedia.org/wiki/Rado_graph

Also, explore more this strange geometric shapes, I have found strange and powerful connection between sound and graph geometry. :)

Listen to Rej by MELEVEN #np on #SoundCloud
https://soundcloud.com/user-meleven/rej

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
@Funzerkerr, that makes sense

@Funzerkerr, that makes sense on the surface but all the LFO is doing is modulating amplitude of another note, not frequency, and the LFO is not connected in any way to the sound path from note to output.

@Amel, I'm sorry but as far as I can tell you are only adding jibberish to the conversation. Don't hijack this thread with your stuff.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
This explains it much better

This explains it much better than I could.

http://synthesizeracademy.com/voltage-controlled-amplifier-vca/

Thanks for the feedback guys. The great part is @JHSound your question made me ask questions which led me to some other really cool discoveries that, while they might seem basic to the resident experts, really enlightened me as to how the Modsynth reacts and started to really simplify things. I also discovered I may have made a few mistakes recently in my posts so I I have to sort that out. Has to do with the difference between AM and RM and how the AM and Mod inputs react to different signal types.

Will fill everyone in later. It's not super complicated but it's a step up on the learning curve.

Essentially your question led me to this:

http://synthesizeracademy.com/ring-modulator/

If you look at the attached caustic file you'll see my little experiment. It shows how various setups result in AM or RM.

I need to do this for myself because I haven't yet found Caustic documentation that really explains it. For me to truly understand the Modsynth I need to wrap my head around this.

If you're curious, until I have time to write this stuff up, I'll give you a hint:

Notice that the link explains that the primary difference between AM and RM is whether or not the carrier is leftover after Modulating two sounds. If you play the caustic file on Song mode you may deduce what's happening.

○●○●○●○●○●○●○●○

Update - file now has MiniLFO with both outputs thru a scope. Starting to catch the drift...

Where the heck are UncleAFX and paulovski when you need them ;-]

Caustic Song file (optional): 

Amel
Amel's picture
Offline
Joined: 02/21/2015 - 10:00
It's called thinking outside

It's called thinking outside of the box. Imagine that numbers on this picture are the number of notes used in one pattern or number of notes in a song. And you will figure out how side chains work. How the 4th or non harmonic note is generated. And how to master a song usIng only sidechaning. I done it once just for experimentation. I will try to find I file and post it here. It's one of the best projects I have. And it's somewhere in my Dropbox, and my Dropbox has a bunch of files so you will probably see it tomorrow on a same thread.

Listen to Rej by MELEVEN #np on #SoundCloud
https://soundcloud.com/user-meleven/rej

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Amel, please do not obfuscate

Amel, please do not obfuscate this thread with such unrelated thoughts.

JHSound asked the same of you and your response was more gibberish.

You are not helping at all. I feel terrible saying that but lately you seem to be in a lot of threads discussing unrelated thoughts which confuses those trying to learn. Whether or not your words are of some value or not in a different thread is a seperate issue, but they are of no value here if they have no context to the subject of the thread/topic.

I'm trying really hard to be diplomatic, don't really want to get banned.

paulovski
paulovski's picture
Offline
Joined: 09/19/2012 - 06:13
This is all cool stuff. I

This is all cool stuff. I thought you were doing fine, by yourself, until Amel got here.

@Amel. You've got your own threads to write nonsense in. I, quite, look forward to them, myself. But it would be, very much, appreciated, by everyone, if you could keep it there, without cluttering up the real stuff. Then we all know where it is. Thanks in advance.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
I need to stop my own

I need to stop my own nonsense and try to keep everything in one or two threads lol. In fact just changed the thread name and I'll try to keep everything together here since , as I'm learning, the two are so closely related.

On a side note, been looking at some of AZ's crazy Mod stuff for fun. That's gonna be another topic soon.

So, all this stuff is slooowwwwllllyyyy starting to click! Very soon I'll be dissecting and putting your contributions thru hard labor.

Understanding this stuff is crucial in the long run if you're into the Modsynth as you likely know. Efficiency is important both to free up slots and so the signal path is not unnecessarily cluttered.

Case in point ... a little reading and I saw how inefficient my original setups were. And on that train of thought let me introduce ring mods version 2.0

Caustic Song file (optional): 

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
Thanks for those links, they

Thanks for those links, they were very helpful.  Will check out that last file when I get a chance.  Actually, it might be neater if you started different threads for different subjects, rather than dumping them into one that will get long and possibly confusing.

 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
I am enjoying this ;-p

I am enjoying this ;-p

Caustic Song file (optional): 

paulovski
paulovski's picture
Offline
Joined: 09/19/2012 - 06:13
Ha ha. Maybe, less threads on

Ha ha. Maybe, less threads on the same subject.

Things you do, always seem to evolve with the modsynth. You bring in things that you know from other synths, and it works. But, then, later, it dawns on you that there's a, much better, way to do it in the modsynth.

I've been sifting through some old presets of mine, and I'm wondering what the Hell I was thinking.

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
OK, this is what I was

OK, this is what I was talking about before. I look at STringMods.caustic and spaghetti-syndrome kicks in. Sorry, but I am slow. Can you do what you did before and step through the signal chain so we can see what happened to what?  How are you creating RM and losing the main frequency? It looks like you have Beatbox modulating AM even though I don't see any notes in BB pattern... how does that work?  I have already played around with your setups and having fun but still feel the need to know how the heck we got here....

 

Also, I'd like to point out that we need to ditch the delay so we know what the actual effect of the mod patches are as opposed to sounds created by delay. 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Over the years I've worked

Over the years I've worked with several hardware ring modulators, some specifically oriented at guitarists and some studio units (Moog makes some killers).

I knew the sound although there are variations. You can hear it's alot like FM can be at times, bright and chimey with tons of overtones.

What I *didn't* know was that AM at higher freq sounded so much like ring modulation. That's new to me.

After making the ring modulators it started bothering me ... the circuit as it looks would seem to indicate it's AM but I'm calling it RM. Uh oh.

Tried to find any relevant info in the Mod tutorial on YouTube and Caustic manual as well as searching the site but came up empty.

Looked at the site where I got the links above and I see this explanation where he's saying AM is extremely similiar to RM and I started thinking darn, I just found out AM can sound like RM and I'm posting calling it RM. Figured humble pie was coming.

Was worried I was about to look pretty dumb and by all rights I was, I just lucked out.

The only way to figure out what was up was to design some method to determine whether the carrier was present in the end result.

If you look at the first Mod, that is essentially what I created and was calling a ring modulator (it is). That is the reference sound for the experiment.

The waveform generator top left is the carrier. The carrier is a simple A440 sine wave. If that note/pitch is present in the output of the original design, Mod1 would have to be be Amplitude Modulation. If it gets eliminated before the output it would be ring modulation.

If you solo and play Mod1 your hear the test subject.

If you solo and play Mod2 you hear the carrier.

Now look at the design of Mod3.

Identical to the first Mod to be tested with one exception - there is a mixer in the top right corner. If you look carefully you will see I have wired the output of the waveform generator to Input 1. That is the carrier.

Then note that I have taken the wire that used to go to L-Mono output and instead routed it to the new mixer, Input 2. Top right, directly below the outputs.

Turn up Input 1 - carrier
Turn up Input 2 - sum and difference frequencies

http://synthesizeracademy.com/ring-modulator/

explains sum and difference vs carrier. But you don't need an oscilloscope for this experiment.

Again be sure to Solo Mod3 or the experiment is contaminated. Press play. While it plays raise and lower the Inputs 1 and 2 and listen to them. Separately. Together. As many times as necessary. Clearly the carrier is *not* present which demonstrates it is in fact RM. Pretty sure if I rendered it and checked with the Spectrum analyzer in the wave editor out would be confirmed. When I post the follow test shortly you will no doubt hear the difference when the carrier is present in the test subject.

That raised a bunch more questions that I had to figure out (I have now, whew) which I'll answer soon. The answer, and what tipped me off, was the fact that the MiniLFO has 2 different outputs. The key to this lies in polarity. Trust me, it's not nearly as complicated as you think.

And JH you're not slow, there isn't a ton of available documentation on how the Mod units function in Caustic but it's unfortunate because it turns out to be brilliant how the AM and Mod inputs work- they can perform both AM and RM depending on the type (+ or - value) of input.

If you look again at the link above there is a picture of a Morpheum VCA and a bit about it. Turns out the AM and Mod Inputs function very similarly.

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Ok, here's part 2 of the

Ok, here's part 2 of the experiment.

Very importantly, notice everything here is identical to the previous test with one critical exception: it uses the alternate output of the MiniLFO to modulate the carrier.

Repeat everything as before. Hopefully your ears are keen enough that you will notice that the carrier you hear when you raise Input 1 of Mod3, an A 440 sine wave, is ALSO present when you listen to Input 2. That proves that simply using the alternate MiniLFO output creates AM instead of RM.

○●○ Use the top output of the MiniLFO to modulate the amplitude and you get ring modulation.

●○● Use the lower output of the MiniLFO to modulate the amplitude and you get amplitude modulation.

Regardless of whether you plug it into the Mod or AM inputs.

Don't worry about the what's or why's yet, just realize the experiments proved one thing: the Mod input can produce AM or RM depending on which output of the MiniLFO is connected.

Next posts will explain what's up with that and I'll fill you in on the drum stuff.

Caustic Song file (optional): 

UncleAfx
UncleAfx's picture
Offline
Joined: 03/06/2016 - 20:08
Well I got plenty of catching

Well I got plenty of catching up to do. :-) Thanks a lot for going above and beyond with all of the work you've been putting into these tutorials lately man. I love these sorts of things, so It's good to know they'll always be here for whenever I do have the time. ;-)

Amel
Amel's picture
Offline
Joined: 02/21/2015 - 10:00
Ok, sorry guys. I will try be

Ok, sorry guys. I will try be more objective next time I think that will work for everyone.

Listen to Rej by MELEVEN #np on #SoundCloud
https://soundcloud.com/user-meleven/rej

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
Feedback on Part 1 (without

Feedback on Part 1 (without looking at Part 2): I read through the links you supplied and got a good idea of the intersecting waves creating harmonic notes. I found something interesting in Mod 3. When you slow the rate of the LFO, you return to the same frequency as the carrier (but obviously pulsing from the LFO) The new frequencies only come in when the rate of the LFO is high.

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
OK, feedback on Part 2.  I am

OK, feedback on Part 2.  I am assuming the different results from the LFO outputs is due to upper output goes above and below 0.  The lower output stays on the same side as 0. I guess to get RM (with no carrier signal present) you must create a wave that crosses from positive to negative. 

I still don't know why the rate of the LFO in Part 1 seemed to affect whether there was RM or not. A slower rate on the LFO definitely left the carrier frequency (and only that frequency, though pulsing).  My guess is that there is math involved....

paulovski
paulovski's picture
Offline
Joined: 09/19/2012 - 06:13
Indeed, there is. You can

Indeed, there is. You can read it here, if you want. Can't say I've ever bothered with the 'hard sums' bit, though.

https://www.google.co.uk/amp/s/www.soundonsound.com/techniques/amplitude...

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Awesomen you get it. Whether

Awesome, sure sounds like you get it. Whether it is AM or RM, you only start to get the upper harmonics beyond a certain freq of the LFO and then the difference becomes whether or not the carrier is present in the audible results.

At a lower freq they sound identical. Think about it, if you are turning the volume up and down only 3 times a second there will be no (audible? ) overtones it's just creating tremolo. I think the lowest minimum LFO speed that would produce overtones would be at least 20 Hz and would depended on the freq of the carrier since they are being multiplied.

Realistically that's not a major concern of mine as the main thing is leaning how to tame the beast.

Got one coming later to answer your question about the drums.

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
Well, I hope you are enjoying

Well, I hope you are enjoying this. I am enjoying getting to wrap my brain around it and the step by step approach works well for me.

@paulovski, I tried, I really did, but it's getting late and as soon as they said "cosine" my eyes glazed over.......

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Hey paulovski, your post hadn

Hey paulovski, your post hadn't appeared when I last responded so thanks for the cool link.

The math is interesting and super glad you posted that, well worth the read. Likely the math itself won't aid me much (trying to mathematically match the carriers and modulators for 1,880 16th notes in a song is not currently on my to do list. Especially as I glide and twist every second note so that complicates the issue)

However there was some good stuff in there that will save me typing it out regarding fixed modulators/ carriers vs those that track the pitch etc.

In the unlikely case that anyone gets this far, modifying the ring modulators to act fixed or respond to CV (essentially matching the notes sent to both modulator and carrier) is really simple, ask and I'll tell you how. I kinda figured most who get this far will understand but you never know.

(The following is not directed at you paul cause I'm sure you already know this).

One cool strategy that they didn't mention (or I missed it) is to neither fix the modulator nor to follow the CV (essentially using matching notes if you are manually programming it in Caustic).

Why not have the modulator doing something just plain different from the carrier? In Drum ex 1 I'm about to post you can see the "modulator" of the TriRing3 Modsynth is sliding from a C3 to an F#3 over the period of a measure while the "carrier" notes are completely unrelated. Well, they're not even really notes per se as they are drum/percussion hits kalthough of course even they do have a pitch)

I use the parenthesis because in the end the terminology is really interchangeable. You're multiplying two signals, depending on the circumstance it makes sense to reverse the terminology.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Here's a little example that

Here's a little example that will explain a few different strategies about Edit: blah blah blah... removed and included in the long diatribe below.

paulovski
paulovski's picture
Offline
Joined: 09/19/2012 - 06:13
@JHSound. So did mine :)

@JHSound. So did mine :)

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Uh oh. This will surely be a

Uh oh. This will surely be a snoozefest.

Next up, a little explanation of how these Ring Mod setups work.

In these examples either the drums or bass are the carriers and the two or three wave generators at the bottom of the Modsynths are the modulators. Each is using an external source as the input - think of these RMs as FX units. You can create and pull up the Modsynth presets in any project and shove any synth you want you want thru them. Or remove the machine input and add another waveform generator in as a carrier.

For the ring modulators to work you have to tell the modulators, the waveform generators, what frequency to run at. You do that by putting notes in the Modsynth piano roll. Or playing the keyboard.

The first combined setup is the Beatbox and RM1. The BBox is the carrier which goes to the machine input of RM1 which contains two modulators at the bottom

When you start playing the first 16 measures there is no sound coming from RM1 although you can see the Beatbox is working away. That's because the ring modulators aren't getting a signal. They are receiving the carrier but no Note CV signal to tell them what freq to operate at.

There are notes visible in the Drum grid so the carrier is getting a Note CV but there are none in the RM1 Modsynth.

As the first 16 bars play start pressing keys on the RM1 keyboard and you hear the modulators working, you hear ring modulated drums.

Note that there is no special relationship in this case between the frequencies of the carrier and modulators; the modulators are not fixed because everytime you play a key and send a CV signal to the modulators the carrier is getting its own. The frequency of the modulator is not "fixed" (staying on one single freq) because you are playing it - unless you just hold one key down for the entire duration - nor is it likely following the freq of the carrier.

When the next section starts playing at measure 18 the same Beatbox is now being used. This time the BBox is being fed into RM2.

If you look at Modsynth RM2 there is a single 16th note on C3. That is serving a dual purpose. Since the "Send Notes To Source" button is activated it's telling the BBox to play the Kick drum.

Note: the 8 BBox drums respond to the notes C3 up to B4. This means that if you play any note in the Modsynth outside of that range no drum pad will be triggered and only RM waveform generators will sound.

But wait... That doesn't sound like a kick at all. That's because the volume of the BBox is turned down on the mixer, you are not hearing the carrier, you are hearing the end result of the carrier and modulators being multiplied.

The center waveform generator is automated. As the octave of that modulator (there are 3 ring modulators in this Modsynth) changes and therefore the freq, the overtones produced change.

When the next section starts playing, the exact same notes used in the BBox at the beginning of the song are now visible in the piano roll of RM2.

Again they serve a dual purpose as each note triggers a drum, the carrier, and also the modulators. Since the same Note CV is being sent to both, the modulator is not "fixed", it's is "following" or receiving the same CV as the carrier.

In reality that's not generally a big deal here as drums kits and may other percussive sounds don't produce notes that behave in a manner like most synths, they are not pitched in semi - tones etc.

However, what if you feed an instrument like a bass into the ring mods? If you give the same CV to the carrier as the modulator then the overtones follow the original sound and often seen less harsh of metallic and more musical.

That's not good or bad it just depends on the effect yu want to produce.

Next up is some bass from the SubSynth, no RM, the notes are in the SubSynth piano roll. This time the ring modulation will come in on top of the bass and then drums. These examples are absolutely not tuned to sound any particular way so don't expect something that is musically pleasing at the moment (although that is rather subjective).

This example ends with the SubSynth playing thru RM4. This is to demonstrate another approach to using RM which is essentially where the example began and you "played" the ring modular on the keyboard.

Since the SubSynth is getting the Note CV from it's own piano roll, you can play around with the notes sending the CV any way you like. Glide them, use the Arpeggiator; you can play them like a seperate instrument.

There is an 8 bar C1 note slowly gliding up to C5. You can distinctly hear the overtones from the ring modulators gliding up as the bass just does it's thing. The modulators are not fixed or following the Note CV of the carrier and it creates it's own distinctive effect.

You can also control whatever you want to with the (ring) modulators in the Modsynth. Stick LFO's or envelopes on the pitch or the FM inputs, add a mixer and combine the machine input and modulated output inside the Modsynth and crossfade or pan that with an LFO; pretty flexible.

Tweaking or automating the Octave, Semi and Cents of the modulators is a must. Changing the waveform from sine to saw and square. The only way to get a feel for them is to shove a signal in and play around.

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
"I guess to get RM (with no

"I guess to get RM (with no carrier signal present) you must create a wave that crosses from positive to negative"

That's my guess too. The funny thing is, and I do mean funny, that the word must seems to be misplaced. I say that because my knowledge there is about $0.02 ahead of you at this point.

To the best on my knowledge, you *must* use the lower output of the LFO to get AM that sounds chimey and splits into the audible 3 bands of overtones.

Every modulation source I'm aware of in the Modsynth produces a signal that is both + or - so if they create a high enough freq to cause the ringing it will be RM. I know there has been success creating inverted and entirely + or - signals/waves but I don't recall seeing a smooth sine wave entirely positive like the MiniLFO.

Perhaps one of the more knowledgeable people here can answer that. Maybe one could be created using a manual DC offset in a more feature laden wave editor and then brought in via PCMsynth and machine input.

And considering the MiniLFO can barely get to producing a basic tone as the modulator let alone rates for AM for I'm not sure how you'd get smooth AM modulation. Maybe there's a way to modulate the pitch of the MiniLFO with something else but you'd think that would probably force it back into the + - domain. Must admit I am curious.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Hmmmmm...... so here's some

Hmmmmm...... so here's some actual AM. I think. Still have to measure it. Just chopped the negative samples out of a sine waves and looped it, put it in the wave editor. Not as smooth as a sine wave but it seems to work.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Hunh. Whatta'ya know. There

Hunh. Whatta'ya know. There we go. You can hear this one clear as day. Crazy.

Caustic Song file (optional): 

paulovski
paulovski's picture
Offline
Joined: 09/19/2012 - 06:13
Yeah. You got it.

Yeah. You got it.

Here's a UMF. Two Wave Generators, both being modulate by an LFO (a sub oscillator). The left side with AM. The right side with RM.

If you play the keyboard, you hear the left side. Round the back, there is a mixer input, bottom left, marked with song automation. Bring that up full, and you'll hear the right side.

Bottom right, there's a mixer output marked with song automation. This controls the LFO rate (up into audio frequencies).

If you run a cable from output B of the pan module, to the left of this mixer, into it's mod input (with the rate control up), you will modulate the LFO frequency with another LFO.

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
OK this is too cool. Press

OK this is too cool. Press Play, there is a PADsynth playing. Solo the AM channel to hear the effect of AM. Super cool. You can still hear the original chord clear as day but it's all dirtied up with beautiful overtones.

Solo the RM and as it doesn't contain the carrier it sounds out there.

AM doesn't seem interesting with drums etc. because the original sound gets thru so you barely hear the overtones.

Update:

This 100% confirms everything.

If you listen to the PADsynth and the RM together you get the same result as listening to the Solo AM.

It seems that AM at high frequencies is not necessary because you can simply achieve it by mixing the original back in with the RM signal which doesn't require the PCM, positive signals and stuff.

Still wrapping my head around this.

Rej probably knew this already and might be getting a kick out of me rediscovering the wheel lol. Just kidding, this is probably not even on his radar.

Update 2: nope, wrong again, on closer listen similar but not the same. You can clearly hear a really strong major 3rd produced by the RM that doesn't seem present in the AM. If it's there then it's far less prominent.

Still can't make sense of that major 3rd Harmonic difference. Starting to wonder if it's because the wave I created isn't a true sine shape so it's coloring the "experiment". Hopefully someone who got past grade 11 (excludes me...) can chime in.

I should probably be testing with a single sine carrier instead of stacked chords with morphing textures...

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
If anyone else feels like

If anyone else feels like messing around here's a simple setup.

Caustic Song file (optional): 

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
I'm running as fast as I can

I'm running as fast as I can to catch up...  I'm about 3 posts behind you. As to your last statement, yes I would think that all tests have to be run with a pure sine wave, like your initial examples.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
@paulovski Sorry, not

@paulovski Sorry, not ignoring you. For some odd reason your posts aren't appearing to me till a few hours after the fact. Thanks for the input and throwing that together. Will try to make wrap my poor overtaxed brain around it.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
AM RM.caustic

AM RM.caustic

Nicely done, very clever. I have questions but probably best I try so figure it out myself before I ask, I learn more that way. Well not more but I retain it and understand the implications better. Thanks again.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
AM RM.caustic

Deleted repost

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Doh! Does this look familiar?

Doh! Does this look familiar? You guys and the spaghetti, making me work too hard.

Anyone who has survived this wordy journey now gets to see where this comes from. And you thought it was almost over...

http://www.singlecellsoftware.com/node/17827#comment-109796

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Wow, major breakthrough

Wow, major breakthrough tonight. I just wasn't getting it so I went back and re-read the Ultra Low LFO and UMF thread and the bulb went off.

Bring a musician I was thinking of everything as an audio path with modifiers but the difference between the concept of the AC DC wasn't there.

Obviously you guys get this already but for the sake of making sure I have this right so far, please correct me anywhere I'm off.

So essentially all the CV are DC and all the Osc are AC.

The Env are just DC modifiers.

The filters have several different effects on "attenuating" (yeah, I know, audio term) the DC depending on the filter. Some notable points being the neg bias of the BP and the ability to use the Resonance control as a manual attenuator.

And the freaky 50/50 attenuation of the Vintage Ladder although I can't really see how it's odd behaviour would be advantageous.

Anyways, the attached caustic file is pretty self-explanatory.

Caustic Song file (optional): 

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Part 2.

Part 2.

Press Play, some are modulated by LFO, some use Note CV so it has to be playing. If a knob is highlighted you should turn it as it plays.

Caustic Song file (optional): 

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
Still a lot of catchin up to

Still a lot of catchin up to do, but I wanted to point out that in your previous examples, the waveform generators weren't the modifiers. The machine input signal was actually modifying the notes from the Modular (working through the envelope AM). The reason you can't do it the other way around is that the machine input does not give you CV, at least that's how I see it.  This all may be a distinction without a difference, and it might be wrong.

JHSound
JHSound's picture
Offline
Joined: 06/04/2015 - 11:21
One more question. How is

One more question. How is this different from using the Vocoder. I have done tracks where I used the Vocoder, with a drum rhythm modifiying other signals and once you started playing with various settings and EQ got very interesting sound.

SToons Music
Offline
Joined: 03/01/2018 - 02:48
Good analogy, alot of the

Good analogy, alot of the time (most) when I use the vocoder it's together with another synth.

The difference? TheModSynth is a completely different beast. Both are really powerful and take time to get to the point where you can really exploit.

The ModSynth is insanely flexible though, you can use an envelope like an LFO and an LFO like a cheap handyman.