What is AM Modulation
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Old 15-02-2017, 06:23 PM   #1
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What is AM Modulation

I was wondering if any of you have more technical insight behind home AM works. I've been using FM modulation a lot, for bass sounds and sounds commonly heard in future styles. But AM is also really effective, I know Tchami uses it. I'm interested in knowing how it works inside the synth and how waveforms are affected in order to know how to use it more effectively and intuitively.

Thank you!

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Old 15-02-2017, 06:42 PM   #2
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Re: What is AM Modulation

It's the process of varying one or more hours of my existence, usually referred to as my "daily life", with time spent online, typically containing information that results in my worldview being altered ever-so-slightly.

I know it sounds really complex, but it's not really..but that's the simplest way I can verbalize it for you.

Hope this helps.

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Old 15-02-2017, 06:49 PM   #4
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Re: What is AM Modulation

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Originally Posted by A.M View Post
It's the process of varying one or more hours of my existence, usually referred to as my "daily life", with time spent online, that typically contains information results in my worldview being altered ever-so-slightly.

I know it sounds really complex, but it's not really..but that's the simplest way I can verbalizing for you.

Hope this helps.
lol appreciate it
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Old 15-02-2017, 08:12 PM   #5
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Re: What is AM Modulation

This will probably be long and overly wordy so sit back and grab a beverage.

So first, terms. AM modulation isn't a correct term- it's like saying ATM Machine, because the M in ATM stands for machine, so ATM machine means Automated Teller Machine machine. AM stands for Amplitude modulation, so AM modulation is Amplitude Modulation modulation.

I'm going to assume you know a bit about audio and electricity and the basics of what happens when you pluck an electric guitar string (or scream in a mic or whatever) and how that electrical waveform gets changed into sound. You don't need to know the details, just the general idea. What we're talking about is a form of that, and a workaround when you can't just send that signal over a cable.

Modulation just means you're using one signal to change another signal. An LFO on a bass patch is a great example. As the LFO wave goes up, some patch parameter (volume, pitch, panning, whatever) goes up. When it goes down, parameter goes down. That's modulation - you're using the simple waveform of the LFO to change another waveform, in this case the bass patch.

Just like an electric guitar string vibrating doesn't have enough power on its own to resonate and really be heard without being amplified, the little electrical signals made from record players and mics in radio studios have to get amplified to be heard. The question is how do you do that when there's not a cable running to the amp? Well, you use a big beefy signal that everyone in the area can pick up, and you stuff that weak little audio signal inside it.

It's important to note that a carrier signal is the thing you're changing - it carries the information. The background on modulation is it was used for encoding information, primarily for radio transmission. A high frequency signal (like a radio wave) gets modulated by a lower frequency wave (the electrical waveform from a mic that someone's talking into) and the resulting encoded carrier signal (the high frequency wave modulated by the lower frequency wave) can get broadcast out and picked up by radios. At the receiving end, the signal gets decoded - the radio separates the encoded audio wave from the carrier signal, then amplifies the audio signal and sends it to the speakers and you hear the dude talking in the studio or whatever. That's demodulation.


Frequency Modulation (FM) uses different frequencies to modify the carrier signal and encode information. It doesn't matter how loud the signal is as long as there's enough resolution to adequately modulate the carrier signal and encode the information. Amplitude Modulation (AM) uses the amplitude (power) of a signal to modulate. AM doesn't care if the frequencies are sub-bass or 25k+, it just uses the peaks and valleys of the power output to change the carrier.

The pros and cons are many, with FM mostly winning. Because FM uses the frequency and not the power, it's much less susceptible to noise from power fluctuation and has a naturally higher bandwidth so it sounds better by encoding more information. AM is cheaper and easier to set up for and carries a lot farther. If you're ever spinning the dial on a road trip, you'll find you can pick up AM stations for a lot longer than FM. The lower AM bandwidth also means you can jam more stations in a given segment (FM fills up quickly - higher bandwidth in a tighter frequency band).

When you're talking about synths most of the issues with AM goes away as it's all digital signal now. Power fluctuations don't happen, bandwidth isn't really an issue. In AM synthesis, the carrier signal (the one getting altered/encoded) is your actual audio file. The modulation tends to be simple waveforms (sine, square, etc) that create an envelope. If you raise the modulation to really rapid speeds, the quickly changing amplitude of the carrier signal creates additional frequencies (usually called sidebands) that add content. Those sidebands have a lot of weird and interesting harmonic information. If you cancel out the original signal and only listen to the sidebands it sounds very robotic. That's what a ring modulator does. It's just a specific form of AM synthesis.

So that's that. AM doesn't get a lot of love, mostly because it's a bit more inflexible than more modern forms of synthesis and modulation like FM, granular and wavetable. On the other hand there's some very specific sorts of sounds associated with it, and if you put in a lot of time tweaking and understand some of the underlying principles it's a very effective way to add some really out there sounds to your line up. If you want to get into the hardcore stuff, look at additive synthesis. That's where the future is.

Last edited by Artificer; 15-02-2017 at 08:24 PM.. Reason: holy spelling errors, batman
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Old 15-02-2017, 08:32 PM   #6
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Re: What is AM Modulation

AM - modulating signal changes strength (loudness in case of sound) of carrier signal
FM - modulating signal changes freq of carrier signal.

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Old 15-02-2017, 08:35 PM   #7
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Re: What is AM Modulation

Classic morning modulations

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Old 15-02-2017, 08:40 PM   #8
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Re: What is AM Modulation

More fun stuff!

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Imagine the signal is your bass patch, or the underlying fundamental of it. The bottom two are how you're changing it. Louder/softer vs faster/slower. That's AM/FM in a nutshell.

Quote:
Originally Posted by A.M.
/thread
Aww, no! There's so much more to say! I'm hoping people chime in with all sorts of technical info and anecdotes and clips of songs using different synth methods!

I mostly understand this because I like electronics and fixing old radios and shocking myself a lot and knowing how shit works, plus a lot of student loans for science degrees I don't really use. I honestly don't use a lot of synths in my art, almost all of what I do is sample based. I will fuck a sample up with some modulation though, so it's helpful to understand how different modulation styles work.

I'm a firm believer that knowledge is never a bad thing and in no way stifles creativity. No musician was ever worse off for knowing how their equipment works. I'm not advocating learning all the math behind it, but knowing the basics of synthesis and modulation blows the doors wide open for any electronic musician. I didn't type all that stuff up because I was bored - there's no way to understand FM and AM synthesis without understanding modulation and the easiest way for me to get my head around that is radio, which also is the basis of the modulation in the first place.

That said: additive additive additive. Complex as fuck but there's literally nothing you can't do with it. Who'd have thought adding sine waves was so baller?
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Old 15-02-2017, 09:00 PM   #9
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Re: What is AM Modulation

Quote:
Originally Posted by Artificer View Post
More fun stuff!

(from [Only registered and activated users can see links. Click here to register]
)

Imagine the signal is your bass patch, or the underlying fundamental of it. The bottom two are how you're changing it. Louder/softer vs faster/slower. That's AM/FM in a nutshell.


Aww, no! There's so much more to say! I'm hoping people chime in with all sorts of technical info and anecdotes and clips of songs using different synth methods!

I mostly understand this because I like electronics and fixing old radios and shocking myself a lot and knowing how shit works, plus a lot of student loans for science degrees I don't really use. I honestly don't use a lot of synths in my art, almost all of what I do is sample based. I will fuck a sample up with some modulation though, so it's helpful to understand how different modulation styles work.

I'm a firm believer that knowledge is never a bad thing and in no way stifles creativity. No musician was ever worse off for knowing how their equipment works. I'm not advocating learning all the math behind it, but knowing the basics of synthesis and modulation blows the doors wide open for any electronic musician. I didn't type all that stuff up because I was bored - there's no way to understand FM and AM synthesis without understanding modulation and the easiest way for me to get my head around that is radio, which also is the basis of the modulation in the first place.

That said: additive additive additive. Complex as fuck but there's literally nothing you can't do with it. Who'd have thought adding sine waves was so baller?

On a more serious note (Bb I think), just wanted to say thanks for going into so much detail on this..way beyond the call of duty..kudos, man.

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Old 15-02-2017, 09:55 PM   #10
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Re: What is AM Modulation

the difference between AM and FM is also explained surprisingly well in this very ancient video. Pretty cool

youtube.com/watch?v=D65KXwfDs3s
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Old 15-02-2017, 10:03 PM   #11
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Re: What is AM Modulation

Quote:
Originally Posted by _nanonoise_ View Post
the difference between AM and FM is also explained surprisingly well in this very ancient video. Pretty cool

youtube.com/watch?v=D65KXwfDs3s
Posted it for ya.


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Old 15-02-2017, 10:04 PM   #12
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Re: What is AM Modulation

wow.. a forum where people actually know things and help each other. they said it was all a myth <3 <3 lol thank you guys
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Old 15-02-2017, 10:07 PM   #13
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Re: What is AM Modulation

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wow.. a forum where people actually know things and help each other. they said it was all a myth <3 <3 lol thank you guys
On behalf of myself and everyone else who's posted an reply..you're more than welcome, Blanky, mate. IDMf really IS the best place for finding what you need to know about music and producing the same.

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Old 15-02-2017, 10:20 PM   #14
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Re: What is AM Modulation

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On behalf of myself and everyone else who's posted an reply..you're more than welcome, Blanky, mate. IDMf really IS the best place for finding what you need to know about music and producing the same.
lol that is my name now: Blanky. haha mind if i send you some pms to ask about more techniques?
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Old 15-02-2017, 10:26 PM   #15
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Re: What is AM Modulation

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lol that is my name now: Blanky. haha mind if i send you some pms to ask about more techniques?
Knock yourself out.

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Old 15-02-2017, 11:23 PM   #16
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Re: What is AM Modulation

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Knock yourself out.
I don't think we know him well enough to start advocating violence or self-harm.
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Old 15-02-2017, 11:28 PM   #17
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Re: What is AM Modulation

^




Actually, your reply's made me think I should clarify that in case there is anybody reading this who took what I said literally.

Basically..for those who don't know or are not familiar with the phrase..[Only registered and activated users can see links. Click here to register]

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Old 16-02-2017, 12:33 AM   #18
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Re: What is AM Modulation

The best way for me to think of AM is "half RM". In Sytrus, which I learned a lot about from SeamlessR on youtube, you can use FM synthesis, or switch the grid to RM synthesis. If you then set your modulating operator to be only positive polarity, it's equivalent to AM (or so he says, I don't know nearly as much about this as Artificer, so he may correct me).

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Old 16-02-2017, 01:08 AM   #19
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Re: What is AM Modulation

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The best way for me to think of AM is "half RM". In Sytrus, which I learned a lot about from SeamlessR on youtube, you can use FM synthesis, or switch the grid to RM synthesis. If you then set your modulating operator to be only positive polarity, it's equivalent to AM (or so he says, I don't know nearly as much about this as Artificer, so he may correct me).
Nope, that's spot on. I was really hand waving and simplifying in my first post, but RM is what's commonly referred to as bipolar, meaning the range is -1 to 1, as opposed to AM where the range is 0 to 1 (unipolar). If modulations were parked in a trailer park, you could say that RM was a double wide (hold my beer).

A byproduct of increasing the range into the negative is phase cancellation. The original carrier frequency in the center gets phased cancelled by the sidebands and you end up with nothing but the ring modulation itself which is naturally dense in harmonics. That's why everything gets all Mr. Roboto - you're losing the original carrier that contained all the (usually) natural tones and replacing it with the weirdo sideband harmonics.

Despite me giggling at Seamless being a fat dorky guy in a basement, I think at this point it's safe to say he knows his shit forwards and backwards. If you watch any of his live demos for FL it's obvious he gets the stuff at a really deep level. He's not always great at explaining it to people that don't understand it, but I've rarely heard him say anything that's just flat wrong.

Last edited by Artificer; 16-02-2017 at 01:16 AM..

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