Synthesis 101 Basics

[sureno]

Ok so i was thinking to myself iv gotten away with not posting in my opinion something members could benefit from for far too long now. so i have done a small Synthesis 101 for absolute beginners as i myself fall into this category! im sure there may be mistakes so please more knowledgeable members please correct me but seeing as no one has done it yet, i would.

ok well we all know what happens when we load a preset into a synth and press a key right? we hear a sound! ok so at the root of this sound, lays what is known as an oscillator or in some cases more than one oscillator mixed together. what's an oscillator i hear you cry? an oscillator is what produces the sound in a waveform.
the waveform is played continuously with variables in pitch and speed of the note pressed. lets say you where to lower the pitch of the oscillator so much so that the speed of it drops considerabley, enough for you actually begin to here the shape of the wave form e.g in a square wave you would here the sound silence pattern with no graduation in either. this brings me to LFO's (Low frequency oscillator) these oscillate at frequencies so low that the human ear doesn't hear them until they have been tuned to with in the hearing range (normally between 20Hz-20KHz). so LFO's are really used to modulate (adjust) parameters in your synthesizer. hope your still with me.

basic waveforms that oscillators produce are:

• Sawtooth Wave - shaped like the teeth on a saw blade, this produces a very common sharp, biting tone.

• Square Wave - looks like a (near) perfect square, produces a reedy, hollow sound.

• Pulse Wave - a variation on the above, the pulse wave is half as wide as a square wave, and has the unique ability to have its width modulated (called ‘Pulse Width Modulation').

• Triangle Wave - unsurprisingly shaped like a triangle, this is not as rich sounding as a sawtooth wave and it is often mixed with other wave forms to give a glittery feel.

• Sine Wave - a smooth rising and falling shape (like a horizontal ‘S'), this produces a mild, soft tone.

• Noise - not exactly a waveform, but a source of sound produced by a certain colour of noise. often pink or white noise.

pics of these waveforms and a couple additional ones



modern synthesizers have 2-3 oscillators available but you don't always have to use all of them. so once you have a waveform going you are then able to tune it. this can be done in octaves, semitones or if you want really fine tuning in cents. by tuning multiple oscillators slightly different from each other you can give your sound that detuned feel.

ok so now that we have a sound where do we go with it? well i would suggest put a filter on it. Filters are very important in creating the specific sound your after and plays a big role in "subtractive" synthesis. i think filters are pretty self explanatory, but if your still wondering they filter out certain frequencies with in that sound or even boost it in areas. this can dramatically change the sound and even sound good if done well :-) so how do we control the filter? we adjust them by using the filters frequency (cut off) where anything out side, below or in between the cut off is eliminated depending on the type of filter. what type of filters are there?

• Low Pass – the most common type of filter, the low pass allows all frequencies below the cutoff point to pass through.

• High Pass – the opposite of the low pass filter, the high pass filter allows all frequencies above the cutoff point to pass through.

• Band Pass – allows a band on frequencies to pass through in the centre, but stops all frequencies outside of this band.

• Band Stop/Notch/Reject – so called because it looks like a notch, this filter stops a band of frequencies in the centre from passing through.

i wont get into filters too much but another control on the frequency is the "Q" or attenuation slope. these are usually marked as 6db, 12db, 18db and 24db per octave. the higher the number the steeper the slope on the cut off so the higher it is the more effective.



finally the sound can be manipulated by what is called "Resonance" this as i mention earlier basically boosts the frequency where the cut off point is and is often used in filter sweeps.



finally we will address envelopes? as what the name suggests it wraps it all up into one package where we can then adjust even more parameters for the over all sound and its articulation or simply how its delivered, getting it now :-)
with out an envelope the sound will will start immediately on pressing a key and stop on its "release". volume will be constant and it will be very basic. envelopes allow you to change the parameters for this giving the sound a more interesting feel. the basic four factors adjustable are:

• Attack – the sound rising up to its maximum level. If it’s set to nothing, the sound plays at full blast straight away, whereas if you set it quite high then the sound gradually fades up (good for string sounds).

• Decay – this is how long the sound stays at the level the attack brings it up to. If it’s set as high as it will go, it will stay at the maximum level forever (rendering the sustain stage useless).

• Sustain – this is the level that the sound stays at after the decay stage has passed. Some synthesizers also have a dedicated ‘sustain time’ setting, which decays the sustain stage after an adjustable amount of time too.

• Release – a bit like reverb at the end of your sound – it is how long the sustain level takes to die down to silence. Set the release to nothing and you won’t get that effect – it will be instant.

Picture of an ADSR envelope

so having read the four stages, this is what happens when your sound hits the envelope, the sound rises through the attack, it dies down through the decay maintaining on the sustain level until release is reached and dies accordingly to what the release is set too.
the final envelope type for now is a filter envelope, they do exactly the same as they do for sound as they do for the filter. there is normally a knob specifically for filter frequency just on the filter envelope.

a few odd bits that il cover is

monophonic and polyphonic. simply put monophonic is one key can be heard at any one time and polyphonic is used to play more than one key so chords are able to be played. monophonic is often good for bass and polyphonic is good for leads,pads and strings etc.

Portamento and Glide. ok using these gives the user the ability to slides between notes, giving it more of a graduated ascent or descent. the portamento and glide effect can be adjusted so that the be degree of "bending" varies, slow fast or what ever you wish.

ok so i hope what i covered can help some beginners, but bare in mind there is SO SO SO much more to it than what i have written but have decided to leave it out for two reasons, to keep it simple and because i wouldn't feel comfortable writing about it. this is a humble attempt at me being able to offer this community something back seeing as you guys have accommodated me so well. please feel free to add to this.

And remember
Nothing beats Trial and Error
so get on it!!!!

i have also posted a fairly good video explaining the basics of synthesis using the very popular subtractor found in reason

Domo arigatoo
SURENO




Some Great videos to watch on basic synthesis

http://vimeo.com/2206614

[conor_j]

awesome post sureno!

has sticky written all over it

[sureno]

Originally Posted by conor_j

awesome post sureno!

has sticky written all over it

glad you think so, been feeling a bit guilty recently

[conor_j]

by the time the rest of the 'crew' hop on this thread I can see it turning into the definitve guide to synthesis lol

[sureno]

Originally Posted by conor_j

by the time the rest of the 'crew' hop on this thread I can see it turning into the definitve guide to synthesis lol

lol im actually dreading being picked apart by my peers here

[TrevCircleStudios]

Awesome post man. I vote sticky!

[modz1]

et voila!

[sureno]

Thank you guys

[Wilty]

Great post, very concise. Cheers Sureno.

[krykos]

This reminds me of the presentation that I gave in a Physics lesson about synthesis and electronic music in general.
Nice 101 there sureno. I'm trying hard to find something you haven't yet mentioned...

[sureno]

Originally Posted by krykos

This reminds me of the presentation that I gave in a Physics lesson about synthesis and electronic music in general.
Nice 101 there sureno. I'm trying hard to find something you haven't yet mentioned...

just please don't say you where about 8 years old and it was extra curricular
oh krkos you never fail to let me down

[sphelan]

Great show of dedication. Well done. Looking forward to the next instalement!

[krykos]

Originally Posted by sureno

just please don't say you where about 8 years old and it was extra curricular
oh krkos you never fail to let me down

Nah, it was about a year ago, and I just wanted an excuse to bring my synth into school. The teacher said "make a presentation about whatever you like that's physics related".

[JAYDMF]

Nice post, i too was gonna do this at some point but just never got round to it.

Just one thing that i feel may be usefull is to add in the different methods of synthesis, as this may be handy for some people when considering synths.

Subtractive: As already mentioned, this is the most common type of synthesis used and can be found on most if not all (depends on how you look at things) synthesizers to a degree. The basic principles are that you start of by creating a very harmonically rich sound source using oscillators with the waveshapes mentioned previously. Obviously this can give you a very full frequency spectrum which may or may not be desirable. The name is derived from the next part of the signal path in which the Filter (which can be any of the types previously mentioned or other types such as comb and formant) subtracts or "filters" frequencies from this harmonically rich source until the desired sound is achieved.

Additive: Additive synthesis is the direct opposite to subtractive synthesis. It is built around the principal that all sounds are created from a complex arrangement of sinewaves added together at different levels each with different envelopes. This method of synthesis does however produce very realistic and pleasing results although programming is slow and an in depth knowledge of a waveforms construction is needed if a user is attempting a specific waveform ie Square wave or triangle. Additive synthesis is rarely found in either Hardware or Software due to the sheer number of parameters needed to program a sound as there are likely to be more than 64 sine waves each with its own envelope and level control. creating an interface that is quick and easy to edit is not an easy task. The most simple additive synthesizer is the organ as it works on the same principal with each pipe (is that the right word?) creating its own sinewave(ideally).

Examples : Kawai k5000, Chameleon 5000.

Wavetable: Wavetable synthesis is a method of synthesis that came about in the 70s as a way of generating more complex waveforms than in the original analogue oscillator designs. Originally this consisted of a "look up" table containing many different waveforms and a user could select any of the waveforms in the same way that sine, saw etc could be. This method of synthesis however has much more potential as the table in which it is stored can be used in a number of ways. Firstly through the process of interpolation it is possible to "morph" between 2 different waveforms in 2 different positions within the table creating sweeping harmonic changes. This method can then be applied as a basic method of sample playback where by each position in the table is a different section of the sample. This was used to great effect before memory became cheap as it was possible to cycle through many positions in a table to build a sample and required much less space due to the fact that for example the sustain section could be a loop of only 2 positions where as a sample would take up a vast amount of cycles in order to do the same task.
This was used to great effect in synths such as the Wavestation.

Examples: PPG wave, Prophet VS, Waldorf wave/microwave, Access Virus Ti.


Sample based (PCM): im not gonna spend too long here as its pretty obvious, this is a case of playing samples back at different pitches etc and using the modifiers (EGs,LFOs, Filters) found in other forms of synthesis and can be considered as subtractive synthesis with a different generator.

Examples: EMU proteus, Roland D110.


Granular: Granular synthesis is a fairly new type of synthesis in terms of how long it has been commercially available and there are few hardware synthesizers that use this method of synthesis. This method uses the same idea as film, the human ear can only recognise new sounds every 10ms or so and so like film and the eye granular synthesis takes advantage of this fact by splicing together many small segments or "grains" of sound (this could be a sample for example) of around 10ms in length. This is done by effectively giving each grain an envelope, this could be considered the same as a crosfade between each grain resulting in a smooth transition undetectable by the human ear. The results can be shimmering pad sounds etc as the content of the signal can be harmonically very rich. this type of synthesis can be used as a form of subtractive synthesis in that the system is technically a tone generator and can be applied to the subtractive synthesis model using modifers like the ones previously stated.

Examples : Reason Malstrom, Reaktor library (forget the name of the synths but theres a couple in there), The access virus Ti also now has some form of granular oscillator but i have yet to find out if this is in the same vein or something quiet different.


FM: FM synthesis or Frequency Modulation, uses the same principals as FM radio however everything the FM radio tries to avoid is present in FM synthesis. In this model generally oscillators are referred to as Operators (this is due to Yamahas naming in the DX7 era). Each operator consists of an oscillator, EG and amp. Operators are then chained together in order to carry out the Frequency modulation. The way in which this works is that one operator will be the carrier and one will be the modulator (in a simple 2 operator system) the modulator will modulate the Frequency of the Carrier waveform, however unlike a standard LFO this modulation occurs at audio frequencies. In the most basic model (the original DX7) operators are only capable of generating sine waves. The reason for this is that as stated in additive synthesis more complex waves are generated from a collection of sinewaves, this when placed into the FM model creates more complex harmonics as each component(sine wave) of the complex wave (square for example) is modulated differently. Operators much like any other oscillator can be tuned, but generally have a wider tuning range as this when used as a modulator will have wildly varying effects on the carrier signal. Operators have EGs in order to emulate more complex sounds in which different harmonics enter at later points in time, emulating much the same effects as the additive model with sine wave components each with their own EGs. FM synthesis is one of the only synthesis methods which does not usually (and i say usually because the DX7 II did) fit into a subtractive "source and modifier" model as there are no filters. It is also one of the hardest to program as it is really non intuitive and requires a lot of time in order to grasp exactly what is going on due mainly to the fact that its principals are based main on maths. This being said it does have a character unlike any other, creating great percussion and bell/metallic sounds.

Examples : Yamaha DX7 I/II, NI FM7/8, Yamaha FB01, Yamaha TX series.

Vector: This is not a synthesis method in its own right, it is more of an addition made to a normal subtractive synthesizer in order to create a better sense of movement and a greater "hands on" approach to a sounds evolution. First used on the Sequential Circuits Prophet VS (VS standing for Vector Synthesis) this is basically a 4 way cross fader for fading between 4 sources (oscillators, samplers etc) with the centre point being all 4 sources at equal amplitude. the user can move from one corner to another also and this give a simple 2 way cross fade or across the centre for more complex fades. This can give a sound much like the sweeping of a wavetable although there are only 4 positions and thus 4 waveforms. However what it did allow (on the Pro VS anyway) was a user to create ever more complex waves by "blending" complex waves and then storing them ready to use to create the next complex wave. This has been a feature on many synths since such as the yamaha SY series and the Korg wavestation (this is due to the fact that after sequential went bust the team moved first to yamaha and then to Korg under Dave smith) The vector "mixer" is charcterised by its diamon shape and joystick. The diamond shape is actually only for cosmetic purposes.

Examples : Yamaha SY series, Prophet VS, Korg Wavestation, some of the newer korgs also have it (i think the OASYS and M3 feature it)

I will edit this to add in FM and other variants such as Phase distortion, vector and LA soon

[sphelan]

Originally Posted by JAYDMF

Just one thing that i feel may be usefull is to add in the different methods of synthesis, as this may be handy for some people when considering synths.

That's what I was going to say! Well done Jaydmf...today is the day of the quick shooters!