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Modulation
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Zadarki
IsraTrance Junior Member
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17
Posts :
27
Posted : Jul 11, 2013 17:28:23
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Hi guys, i was wondering if someone can explain me in a simple way the theory of
AM MODULATION,FM MODULATION and RING MODULATION and some effective ways to apply them when creating sound, until now i have used them with a small idea and guided by the sound and i started to get curious about the real way it works, cheers. |
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knocz
Moderator
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Posted : Jul 11, 2013 17:58
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You've hit the mother load here man! I recommend you explore Google, as there is so much information on these topics. However, I'll try to start you off.
An audio signal has two main components: an amplitude and a frequency. The amplitude is how much it varies from it's center (how big or tall the wave is) and the frequency is how long it takes to perform a full cycle (how long it takes to go up, than down, than back to the middle).
Using synthesis we can modulate (this is, move, use, tweak, etc) these parameters (among others  ). So, automating the AM (amplitude modulation) means we will be defining the wave height over time - typical tremolo effect; using FM (frequency modulation) we will be modulating the wave's frequency - which can also be done with any pith parameter (or MIDI notes), however using FM we generally can use inaudible frequencies to obtain different textures (so a simple LFO on the pitch usually doesn't go where we want it to in FM). RM (Ring modulation) consists of multiplying two signals (in a simple manner).
Check this out:
https://en.wikipedia.org/wiki/File:Amfm3-en-de.gif
https://en.wikipedia.org/wiki/Frequency_modulation
http://en.wikipedia.org/wiki/Ring_modulation
To get in touch of what each of these techniques sound / feel like, try them out for yourself! Get a capable synth (real, or VSTi), and an empty preset patch (everything off, simple sine wave playing) and start designing your sounds from scratch -> eventually you'll understand each parameter and how they behave, and when reading the manual you'll see (this setting of knob allows you to set the FM for the oscillators) and you'll get there.
Please everyone more knowledgeable, fill out the gaps and correct me where I'm wrong!
 Super Banana Sauce http://www.soundcloud.com/knocz |
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Zadarki
IsraTrance Junior Member
Started Topics :
17
Posts :
27
Posted : Jul 11, 2013 18:23
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thanks for taking your time knocz,my doubts came especially from the ring modulation so RM multiplies the waves, so in another words it can be used a bit like voices in oscs right? well i can be wrong |
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PoM
IsraTrance Full Member
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162
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8087
Posted : Jul 11, 2013 18:26
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nice post man , juste one point with fm from osc we usually use audible frequencies dunno if it s what you meant
Ring take the sum and difference of 2 signal to create a new signal |
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Zadarki
IsraTrance Junior Member
Started Topics :
17
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27
Posted : Jul 11, 2013 19:08
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thanks for the help guys : ) |
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frisbeehead
IsraTrance Junior Member
Started Topics :
10
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1352
Posted : Jul 12, 2013 03:57
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Quote:
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On 2013-07-11 18:23, Zadarki wrote:
thanks for taking your time knocz,my doubts came especially from the ring modulation so RM multiplies the waves, so in another words it can be used a bit like voices in oscs right? well i can be wrong
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not like that. it's got to do with the sum and difference of two signals. that's why it's a form of modulation. instead of having one oscillator modulating another's frequency like you would on FM synthesis (with a carrier and modulator), you'll get the harmonics that are not present on the oscillator's (or signals) frequencies. see? totally different then "unison" which multiplies the voices, or a doubler that does the same - or chorus that can create the illusion of that and much more... different stuff.
suggested route: take two oscillators, tune them apart from each other and play with the RM knob on a synthesizer, then play with the oscillator's pitch and listen to how it changes the sound.
you can use it in combination with other forms of synthesis to. and as an external effect also - that works differently in that the fx unit (or plug-in) also has some kind of audio oscillator to make the sum and difference with the input signal, same principle. |
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knocz
Moderator
Started Topics :
40
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1151
Posted : Jul 12, 2013 16:28
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Quote:
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On 2013-07-11 18:26, PoM wrote:
juste one point with fm from osc we usually use audible frequencies dunno if it s what you meant
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Exactly! Type-o from my part, Frequency Modulation is like using an LFO on the pitch, however at a frequency speed in the audible range (so over 40Hz -> 40 times per second).
Thanks for complementing the information. Hmm got to build me a Ring Modulator VST to get a better hand at the involved maths
Super Banana Sauce http://www.soundcloud.com/knocz |
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frisbeehead
IsraTrance Junior Member
Started Topics :
10
Posts :
1352
Posted : Jul 12, 2013 16:49
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Quote:
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On 2013-07-12 16:28, knocz wrote:
Quote:
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On 2013-07-11 18:26, PoM wrote:
juste one point with fm from osc we usually use audible frequencies dunno if it s what you meant
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Exactly! Type-o from my part, Frequency Modulation is like using an LFO on the pitch, however at a frequency speed in the audible range (so over 40Hz -> 40 times per second).
Thanks for complementing the information. Hmm got to build me a Ring Modulator VST to get a better hand at the involved maths
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just pick something already done in Reaktor and take it from there. that's what I'd do. a lot of brilliant hobbyists hanging over there on user library  |
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knocz
Moderator
Started Topics :
40
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Posted : Jul 12, 2013 18:51
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Quote:
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On 2013-07-12 16:49, frisbeehead wrote:
just pick something already done in Reaktor and take it from there. that's what I'd do. a lot of brilliant hobbyists hanging over there on user library
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Naah! I love the pure and cruel low level C++ without any external libs (except for the VST SDK), like that I'm able to make it well optimized (using my own metrics) and I get to understand the pure DSP behind the curtains. Using a pre-configured module system (Reaktor, SynthMaker, etc), development becomes easier (no memory allocation debugging) but customization is trickier. Also, I find it rather easy and intuitive to develop low level GUIs and connect them to the code 
Super Banana Sauce http://www.soundcloud.com/knocz |
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Zadarki
IsraTrance Junior Member
Started Topics :
17
Posts :
27
Posted : Jul 12, 2013 22:13
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haa man i dont know if im seeing it in the right way xD
so ring modulation is when two signals multiplying each other making a new signal that reach "new" harmonics creating a "new" difrent signal,is correct or im saying shit? XDDD
correct me if im wrong pls |
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frisbeehead
IsraTrance Junior Member
Started Topics :
10
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1352
Posted : Jul 12, 2013 23:47
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it's correct: what you ear is the sum and the difference of the two signals.
not like when you're combining the sound of two oscillators together for enrichening the signal with more harmonics: the resulting output will share no similarity with that, tends to produce odd partials and harmonics, timbres that will most likely surprise you. so just try it yourself and have fun!
there's a video about it from access music:
https://www.youtube.com/watch?v=5fB3WRBPvXE
check it out!
so that must be confusing: combining the ring modulation with FM, but... still great fun and not to be missed. |
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Zadarki
IsraTrance Junior Member
Started Topics :
17
Posts :
27
Posted : Jul 13, 2013 00:09
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thanks : ) |
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Upavas
Upavas
Started Topics :
150
Posts :
3315
Posted : Jul 13, 2013 13:22
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Hmm got to build me a Ring Modulator VST to get a better hand at the involved maths
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If you can write a good Ringmodulator VST you can make big bucks with it mate, there is none out there that even comes remotely close to Hardware Ringmodulation, not even Omnisphere has proper Ringmodulation, which is why I was lucky enough to get a Moogerfooger Ringmodulator for my last birthday, since then ther term Ringmodulation has been completely redefined for me...
Upavas - Here And Now (Sangoma Rec.) new EP out Oct.29th, get it here:
http://timecode.bandcamp.com
http://upavas.com
http://soundcloud.com/upavas-1/ |
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