Additive synthesis is very good way to appreciate how sound is built up from individual sine waves - the

basic waveforms of subtractive synthesis can be studied appreciating their harmonic and amplitude

content. The patch we created enables us to recreate roughly (with the very limited number of sine

oscillators available) the saw, triangle and square waveforms. The partials or overtones of notes can be

experimented with giving an appreciation of the natural harmonic series of tones. The limitations of the

patch was evident considering the number of oscillators required to to produce a perfect saw up to

Nyquist frequency for a pitch at 100 HZ (221 !)

The patch is relatively easy to control - as long as integers are inputted for partials - we will get

harmonic sounds - but there seems to be a limited number of timbres. Setting some of the oscillators to

inharmonic partials and blending in slightly produces more interesting sounds and totally inharmonic

metallic sounds with indeterminate pitch are easily created.

This patch is a great tool for learning the synthesis method of Hammond Organs - obviously we can

improve this patch by adding an emulation of the Leslie cabinet.

As a synthesis method in Scope, it is a method of getting other types of waveform, but is rather

cumbersome. To get more interesting results we could place a multistage envelope for every oscillator

and add more oscillators, but the patch would be very complicated and uncomfortable to work with.

Perhaps a dedicated additive VST synthesiser would produce these types of sound more quickly and easily

(e.g Camel Audio Alchemy (600 Oscillators)).

Additive_Musings.doc

1. Set up 8 additive operators blocks (I've used or abused the term operator to describe the synthesiser elements of sine oscillator partial, adsr, vca)

2. Gave each oscillator it's own harmonic. Oscillator 1 having the fundamental, oscillator two the second harmonic, oscillator three the third harmonic and so on.

3. Set up three patches. The first an initialised state as there are so many controls I thought it best to have an initialised template. The second patch featuring all even harmonics and the third patch all the odd harmonics. Patch three and four provide a rough saw and square sound.

4. Although there are subtle differences in sound below c3 in both patches I notice major differences from c3 onwards. Found that moving towards c6 and higher the saw and square sound are more obvious to my ears and more easily recognised on the oscilloscope. Not sure why this would be. I assume that my ears find it easier to differentiate higher harmonics. If this is the case then additive synthesis with only 8 operator blocks would be sufficient for patches with higher frequency content.

5. ADSR set to bell with a slow attack (pad bell) Found that even saw harmonics tend to provide a nice shimmer/chorusing type effect while odd square harmonics sound flat.

6. ADSR set to bass. With Odd harmonics I find that the fundamental and the third are enough to get a good deep bass. With even harmonics set this way the bass sounds a bit mushy and unfocused. However even bass sounds fuller/richer when the higher harmonics are added in the even

7. Lead sounds definitely need to have the fundamental play nice and loud. However leads can be enhanced by setting the decay on other harmonics to different settings and also changing the slope.

8. Sequencer sounds seem to definitely belong to odd square harmonics

• 64 partials per source
• possible to combine 6 sources to cover the freq range
• complex amp and filter ad1d2sr envelopes, able to loop between d1 and d2
• 128 band formant filter.
  

Additions:

1) I had to add some Modulation to keep from dying of boredom.

A pitch modifier w/ Triangle ModWheel LFO, and the CM2 Chorus.

2) Then I added a Filter w/ a Sine LFO for Modulation instead of the Envelope Modulation.

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I am glad to learn the basic forms of Additive synthesis but I only have one example that I would ever use. A Hammond B3 emulation.

It allows realtime manipulation of the waveforms with drawbars, and while the Leslie cabinet is a doppler effect, and not a form of additive synthesis it is a vital component.

But I find additive synthesis requires too much work with little results other than pitch manipulations. Bells, basic EPiano sounds and OK but between Additive, Samples of PhysModelled instruments. PhysModulation offers the best results because it allows realtime parameter control and isn't static like a sample, but had much more tonal variety.

I am glad we aren't spending too much time on this type of synthesis, but I realize the importance of knowing its basics.

That sums of my experience with it. However I am using the B2003 nightly and have done this for decades with a real Hammond C3 and 147 Walnut Leslie. IMHO it is the best example of additive because it offers realtime dynamics, and waveform manipulation which is very musical.

JAV

Sound synthesis is one of those fields that diplomas arent worth the paper they are printed on. There are very few jobs in the field of sound synthesis, and the ones that are on offer, require experience rather than diplomas.

This creates a wonderfull situation in which people come in order to learn a subject they realy love. Not to gain diplomas, please one's parents or  society - but in order to be able to make better music or in other words, gain a deeper understanding and control over their own music.

And indeed a class of 10-16 students, all eager to know, is one of the most productive melting pots i've seen! Friendships that create music,  music that creates friendships. And the positive feedback of knowledge exchange.

I feel lucky to have such students, year after year, with such curiosity and imagination. 

Thank you. 

L1_Waldorf.zip

Patch + presets - some used in .mp3 posted

Tutorial_1.mp3

Lesson 1 - 1 Waldorf Osc for all sound - and only Vinco