Simply, what is an Additive Synth?

[codymackaz]

I have yet to find a simple explanation to what an Additive Synth is. Is it a synth with more than one oscillator? What is an additive synth used for?

[amphibian]

I have yet to find a simple explanation to what an Additive Synth is. Is it a synth with more than one oscillator? What is an additive synth used for?

Absolute freakin' fail. I just googled "additive synth", first link:

http://en.wikipedia.org/wiki/Additive_synthesis

[codymackaz]

Absolute freakin' fail. I just googled "additive synth", first link:

http://en.wikipedia.org/wiki/Additive_synthesis[/quote]



However, when seeing this:

y[n] is the output sample at discrete time n,
ak[n] = rk[n] cos(φk[n])
bk[n] = rk[n] sin(φk[n])
rk[n] is the amplitude of the kth harmonic at discrete time n,
φk[n] is the phase of the kth harmonic at discrete time n,
Fs is the sampling frequency,
f0 is the fundamental frequency of the waveform or the note frequency,
k f0 is the frequency of the kth harmonic,
kmax < floor(Fs/(2 f0)) is the number of harmonics,
kmaxf0 is the highest harmonic and below the Nyquist frequency, Fs/2.

it's a little indimidating.

[amphibian]

lol, agreed - but unless you're a sound engineer you needn't worry about that, and instead focus on:

Additive synthesis is a technique of audio synthesis which creates musical timbre.

The timbre of an instrument is composed of multiple harmonic or non-harmonic partials (individual sine waves), of different frequencies and amplitudes, that change over time. Additive synthesis allows the emulation of sounds by giving control over the frequency and amplitude of each individual harmonic or partial. Often, each harmonic generator has its own customizable volume envelope, creating a realistic, dynamic sound that changes over time.

And your question is answered. Then, if you need to go further, wikipedia provides what are called "links" around hot topics, such as musical timbre

[back2onett]

Additive synthesis is basically the opposite of subtractive synthesis; with subtractive synthesis it's all about using filters to subtract harmonics from whatever waveform you're using to get a new sound.

With additive synthesis you're constructing a new wavefrom by adding harmonics (in the shape on sine waves). That's a simple way of putting it

EDIT: Too late

[amphibian]

Further to this - I think most synths are additive synthesizers. Subtractive synthesizers are far and few between.

[upstateface]

Further to this - I think most synths are additive synthesizers. Subtractive synthesizers are far and few between.

Nope other way around.

[amphibian]

ah, ty for the correction

[futures_untold]

Additive synthesis is basically the opposite of subtractive synthesis; with subtractive synthesis it's all about using filters to subtract harmonics from whatever waveform you're using to get a new sound.

With additive synthesis you're constructing a new wavefrom by adding harmonics (in the shape on sine waves). That's a simple way of putting it

EDIT: Too late

Further to this, most additive synths also allow each partial to have its own phase position...

Lets find another way to sum up the concept of additive synthesis..

Additive synths often use a bar graph to display each harmonic or partial of a fundamental frequency. Going from left to right, each bar represents a harmonic or partial of the fundamentla frequency.

Imagine a sine wave playing a bass tone at 50Hz. To show this, we would only have one bar on the very left of the graph. This is the fundamental frequency. To reverse its phase polarity (whether it pushes the speaker out or pulls it in), we use a second bar graph which represents the phase of the fundamental frequency.

Now imagine we add another bar at 100Hz, and a second at 200Hz. This makes the sound more complex with audioble overtones. These are harmonics of the fundamental frequency, because they relate perfectly to the fundamental frequency. we can change the phase of these harmonics to cause more interesting waveforms.

Finally, if we add another bar on the frequency spectrum at 319.5Hz, we will get a more dissonant tone. This is a partial of the fundamental frequency, and is not related fully (a multiple) of the fundamental frequency. Partials may also have their phase polarity changed using the phase graph.

To build complex sounds, we can add many harmonics and partials to a fundamental frequency using our bar chart. The higher the bar goes, the louder that freqeuncy becomes.

As we move from left to right, we go up the audible frequency spectrum from 20Hz to 20kHz. To make a tone at 250Hz, our fundamental frequency (the first bar on the chart) must be placed at 250Hz, position on the bar graph (roughly one third in from the left).

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Additive synthesis can be used to resynthesise sounds by analysing the frequency components and phase relationships of each frequency component in a sound.

It is also worth noting that additive synthesis usually uses sine waves to build complex tones, but newer synths also allow for other waveshapes to be used.

When sculpting a sound, you can either remove frequency components directly using the frequency bar graph or a filter (which is what subtractive synthesisers do).

Check out:

http://www.kvraudio.com/get/397.html

http://www.discodsp.com/vertigo/

http://www.soundonsound.com/sos/jun00/a ... nthsec.htm

[grooki]

Interesting Futures!

[staticcast]

Uh, to cut a long story short....

All waveforms are made up of the sum of sine waves of different frequencies.

A complex waveform has lots of these sine components. For example, a square wave of fundamental frequency 100 Hz can be represented by the sum of sine waves at 100, 300, 500, 700, 900, ..... etc Hz, each with a different amplitude and phase (phase can be considered a measure of time delay).

Bearing that in mind:

* A subtractive synth starts out with a complex waveform and changes what's already there, generally by filtering. More often than not, this means removing certain frequencies and boosting others.

* An additive synth builds up a complex waveform from scratch, by adding together individual sine waves of specific frequency and phase.

So yes, additive synths inherently must have a lot of oscillators. But not all multi-oscillator synths are additive (rather few are, actually).

[back2onett]

All waveforms are made up of the sum of sine waves of different frequencies

I thought all waveforms could be generated this way but this only happens in additive synths. Also when I analyse single cycles (made in another synth or resampled) with my additive synth it never comes out identical to the original, is this likely an error in the synth or more of a general problem with additive synthesis

[Dropkick_Kid]

Futures knows too much

[futures_untold]

Uh, to cut a long story short....

All waveforms are made up of the sum of sine waves of different frequencies.

A complex waveform has lots of these sine components. For example, a square wave of fundamental frequency 100 Hz can be represented by the sum of sine waves at 100, 300, 500, 700, 900, ..... etc Hz, each with a different amplitude and phase (phase can be considered a measure of time delay).

Bearing that in mind:

* A subtractive synth starts out with a complex waveform and changes what's already there, generally by filtering. More often than not, this means removing certain frequencies and boosting others.

* An additive synth builds up a complex waveform from scratch, by adding together individual sine waves of specific frequency and phase.

So yes, additive synths inherently must have a lot of oscillators. But not all multi-oscillator synths are additive (rather few are, actually).

I neglected to explain this

Nice post! (I think the OP has enough info now between our posts to start sussing additive synthesis lol)

All waveforms are made up of the sum of sine waves of different frequencies

I thought all waveforms could be generated this way but this only happens in additive synths. Also when I analyse single cycles (made in another synth or resampled) with my additive synth it never comes out identical to the original, is this likely an error in the synth or more of a general problem with additive synthesis

the problem you describe is more to do with the limited state of additive synthesis generally. In theory, we should be able to recreate any sound perfectly..... In practice, we need more oscillators...

ask static_cast, he seems to know his stuff!

[CBK81]

http://www.dubstepforum.com/nice-vid-on ... l#p1822588

Here you go. This will make it clear.

[meer]

All waveforms are made up of the sum of sine waves of different frequencies

I thought all waveforms could be generated this way but this only happens in additive synths. Also when I analyse single cycles (made in another synth or resampled) with my additive synth it never comes out identical to the original, is this likely an error in the synth or more of a general problem with additive synthesis

It should sound pretty close to the single cycle of the other synth looped, but nothing like the whole synth sound, as additive synths are usually pretty static.

[codymackaz]

thank you guys for all the replies, you really helped me out