ben m
Joined: 15 Sep 2002
Posts: 337
Location: UK |
| Week 5 - Synthesizers 2 |
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Hi Guys,
sorry for the slight delay in getting this online but here are this weeks activities.
Again, these are big questions that will require 'big' answers.
Ok, what you need to do is explore thoroughly the following Synthesis types;
 Analogue - Aidan
FM Synthesis - Mike
Physical Modelling - Nancy
Wavetable & S+S - Dani
For each of these concepts you need to explore the sub-headings outlined in the Syllabus.
On top of this you also need to consider these factors;
Examples of the type of synthesizer (i.e. FM - DX7)
Characteristic Sound Qualities of each Synthesis type
Usage (i.e. are they used to replicate 'real' instruments or are they used for more experimental noises, or both?)
Advantages/Disadvantages of synthesis type
Pros and Cons of Hardware/Software versions of Synthesis type
Also, in addition to the above, I'd like you to explore the ADSR concepts that were identified last week.
So, what are the ADSR characteristics of the following instruments;
Piano - Aidan
Guitar - Dani
Snare Drum - Mike
Violin - Nancy
How easily could each of the above instruments be 'replicated' with different synthesis methods?
Ok, thats enough for the minute.
On a practical note I'd like you to have a go at playing with a synth. The easiest way I can see of doing this is to find a Freeware VA VSTi synth. I know that not all of you have access to a VST host, so those of you who don't will have to try another approach. I'll keep an eye out for a freeware stand-alone VA synth for you non-VSTers out there.
Good Luck!
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ben@audiocourses.com |
Mon Mar 31, 2003 12:06 pm |
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MIKE_NOSTRADAMUS
Joined: 08 Jan 2003
Posts: 163
Location: Northfork Recording Studios |
| Fm Synth |
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http://tyala.freeyellow.com/2fmsynth.htm
http://www.computermusic.co.uk/tutorial/fm/fm1.asp
http://www.maran.com/dictionary/f/fm/ statement Good Computer dictionary
hhttp://www.quotestation.com/comp/comp64p34.htmttp://www.yamahasynth.com/pro/fs1r/what1.html
http://music.ashbysolutions.com/modsynth/generatn.html
http://www.synthzone.com/softsyn.htm(one super site of synths of all kinds)
http://www.dcs.gla.ac.uk/~stephen/lectures/ITHCI/ITHCI_sound_00-01.pdf Good basic site for all kinds of basic info
http://www.pctechguide.com/11sound.htm (good site for all around info)
well the sites above are just a few where I started some research.
What to say on something that is already becoming older technology.
To start FM synthesis was used in older tone generators and keyboards such as Ensonic ,casio,yamaha and many more.
The quality of sound was good for its time.It was used for games and lower end sound cards.Times have changed with wavetable in the picture where someone else will go into more detail.
I will be back with an update on
1)operators
2)Algorithms
3sound design with FM sythesizers
What is FM?
Frequency Modulation (FM) is where the output of one oscillator is used to modulate the pitch of another, the oscillators being called Modulator and Carrier respectively. "Modulate the Pitch"... that's the key phrase! The pitch of the Carrier is being changed (modulated) in tandem (in sync/ going up and down at the same time) by the Modulator.
Explained well for not so teckie people 
Think of it as one person singing and another person grabbing the throat of the first and shaking him in a rhythmic manner; the singer being the Carrier and the throttler being the Modulator.
In analogue synthesizers, you can use an LFO (Low Frequency Oscillator) to modulate a VCO (Voltage Controlled Oscillator). Let's take a slow LFO and modulate the VCO... what happens is that the slowly rising and falling LFO makes the pitch of the VCO rise and fall also, giving you a sort of wobbly sound (referred to as VIBRATO). Increase the modulating LFO Amount and there's more wobbling. Increase the modulating LFO Speed and the wobbling gets faster. This is also commonly called "Pitch Modulation".
What are Operators and Algorithms?
Operators are just Oscillators. Your FM synth will have either 4 or 6 Operators. Why so many Operators? Because the sounds from one Modulator & one Carrier aren't exactly that overwhelming.
Algorithms are the preset combinations of routing available to you. Note that the Carriers are always the last Operators in any Algorithm chain and all other Operators are Modulators.
A quote from computer music magazine
"Indeed, the new FM jargon seemed completely unfamiliar; gone were oscillators, filters, cutoff and resonance, and instead we had to get our heads round 'operators', 'modulators' and 'carriers' (or were they the same thing? we couldn't be sure), not to mention 'algorithms'. Also, programming a stonking sound through a tiny LCD with a bunch of pushbuttons and a single slider seemed like less fun than keyhole surgery."
http://www.computermusic.co.uk/tutorial/fm/fm2.asp
This is a tutorial on FM synthesis from Computer Music goes into quite the details.
Thank God I haven't got a DX7 yamaha or else I would prefer to wrestle with the bears over a bush of blueberries.I guess we really have come a long way because my keyboards I can program if I want or I can use presets but mine are well used without factory presets.I dont get frustrated with my Psr730 /Psr510 like I used to with my Ensonic.
http://music.ashbysolutions.com/modsynth/generatn.html
this site relates to why fm synths were created.
in a short story musicians wanted a certain sound but could'nt get the instrument so they used what sounded near what they wanted" Can you imagine they had programmers dedicated to just programing these tones because the musicians would'nt have time to play music if they had to.
Instruments that used FM synthesis include the DX-7, DX-100, and TX-81z, all by Yamaha
Other instruments include which I personaly have are FB01,PSR510 Yamaha,Honner and casio.All are either a keyboard or tone generators which work with MIDI.
I also have a PSR730 yamaha with XG midi/SOFTsynth/wavetable synth/
and MU80 tone generator which is the same as the 730 but without the keys.It is completely programed from the computer or its own face.
My 3 computers have yamaha sound cards with XG softsynth which are a dream to operate as compared to the units I started with in the late 70's
http://www.yamaha.co.uk/xg/
I'm not pluging for Yamaha but it is a good site to visit!and a good product 
I'll be back to edit more!!
Mike |
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Mon Mar 31, 2003 1:59 pm |
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resol69
Joined: 31 Dec 2002
Posts: 69
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| PM synthesis |
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Ok, here's what I found. I don't work with synths so feel free to jump in with more info. 
Explore thoroughly the following Synthesis types;
physical Modeling - Nancy
Theory of Physical Modeling
In the history of sound synthesis, there have been two different general methods for synthesis of musical instrument sounds. One approach is to look at the spectrum of a real instrument and try to recreate it. This includes methods such as additive synthesis and frequency modulation (FM). These produce sounds with similar structure, but the parameters involved have no relation to the physical parameters of an instrument. The other popular approach is to use a sample of the instrument, such as in wavetable synthesis and samplers. In both of these cases, you're creating sounds without any consideration for how the real instrument actually creates those sounds.
Unlike the previous methods, Physical Modeling uses the laws of physics to reproduce the behavior of an object. In other words, PM solves, in real time, mathematical equations describing how an object functions. It uses no sampling, it simply calculates the sound as you play in accordance to the controls it receives.
The driver is the part of the synth that you move or blow into to start the synthesis process. The resonator is what replicates the vibration of the air or strings when the instrument is played.
Modifiers are simple effects, such as filters or enhances added after the sound is created in the synth. I think.
Control of physical modeling synths
You have much more control over the sound created on a PM synth compared to other types of synths. Since you are controlling how the sound is created, you add more personal expression to the sound.
Examples of PM Synths
Yamaha VL-1 one of the first synths to utilize 100% physical modeling technology in 1993
Korg WaveDrum
Korg Prophecy
Roland VG-8
AAS Tassman
Native Instruments Reaktor
Characteristic Sound Qualities
PM results in very natural and realistic sounds and reproduces the control you would expect from real acoustic instruments, as well as the warmth of real analog circuits.
Usage
Since you can control how the sound is created, I think this type of synth could create sounds closer to the real instruments. And, since you have such a range of control, I think you could also use it to create freaky, experimental sounds.
Advantages/Disadvantages
Since physical modeling synths act more like the real thing, you have more control and get more of your personal expression of the music out of it. E.g. attack, vibrato can sound more natural.
The challenge for manufacturers is to create synthesizers that offer the great flexibility, but that are also easy to create sounds on. There can be so many parameters that could be used with a model that the user can become overwhelmed, particularly if he or she is not fluent with the particular instrument being modeled. The experienced musicians want to have total control over the synth to get truly expressive instruments, but novices would like to be able to create convincing sounds as well, without years of practice.
Software Pros:
The software comes with various instrument patches with hundreds of presets.
Some PM Synths come with a browser function. Browser is similar to those found in most email programs. Using a simple tree structure, all the elements used in the building and playing of synths are available using a visually intuitive, drag and drop approach, including instruments, sub-patches, modules and presets. The browser also allows you to export a synth and all of it's associated sub-patches and presets as a single file, for easy exchange with other users.
Software Cons:
One major problem with physical modeling is that for each instrument, you may need an entirely new model and algorithm to produce a realistic sound. If manufacturers want to offer a wide variety of instruments in their synths, they will need to make the hardware systems very flexible. This takes up a lot of memory.
PM Synthesis in Sound Design.
Because you can change how an instrument is played, you can get really wacky with PM Synthesis. For example, take a woodwind instrument and model it to be played with a bow. I think sound designers would use this type of synth a lot. I think sound designers can go crazy with PM Synthesis
Current PM Synths
Today’s PM synths can be a combination of hardware and software, or can use software only. The combos are good for those how prefer to “touch” knobs and such.
What are the ADSR characteristics of the following instruments;
Violin - Nancy
Attack: bow hitting the string
Decay: the sound created in the body of the violin
Sustain: how long you run the bow across the strings
How easily could each of the above instruments be 'replicated' with different synthesis methods?
I think PM would replicate the sound best because of the control aspect mentioned about. I think there’s a lot of behind the scenes mathematics going on here though. A sample would work also, but not sound as natural. |
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Fri Apr 04, 2003 5:17 pm |
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Dani
Joined: 28 Jan 2003
Posts: 35
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Wavetable
Wavetable music synthesis (not to be confused with common PCM sample buffer playback) is similar to simple digital sine wave generation, but extended at least two ways.
First, the waveform lookup table contains samples for not just a single period of a sine function but for a single period of a more general waveshape. Second, a mechanism exists for dynamically
changing the waveshape as the musical note evolves, thus generating a quasi-periodic function in time.
Put simply the wave shape is that of a real instrument, digitally reproduced. It is one the more realistic forms of synthesis when reproducing real instruments especially pianos and organs. It would be difficult to tell the difference between a real piano and a high level synthesized one.
Another aspect is adding different waveforms together, for example the attack portion of a piano added to the decay part of a guitar. This gives us access to unique sounds.
Of course the sound then also passes through filters to change the sound even more, so, although wavetable sysnthesis sounds like it could be limiting, like a sample playback machine, it is actually very versatile.
Some examples of wavetable synthesis can be found in computer soundcards such as the Soundblaster Series, Korg synths are also big fans of wavetables.
Hardware versions of this type of synthesis are preffered. The waveforms need to be accessed very quickly and the delay in softwared ong this would result in high latency.
ADSR- Guitar
Attack - Fast, string being plucked.
Decay - Volume holds for a bit
Sustain - Gradual fade out as the string stops vibrating.
Release - Short release but not too short, in an acoustic guitar, the body is still reverberating even when the srtring has been muted. |
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Sat Apr 05, 2003 4:15 pm |
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Aidan
Joined: 08 Jan 2003
Posts: 38
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ANALOGUE SYNTHESIZERS
In general these synthesizers use analog style units such as oscillators and filters that are controlled by voltage -the outputs of oscillators are mixed together and fed into a filter ,where frequencies are added or subtracted after which they are fed through an amplifier.Subtractive synthesis is achieved by taking a tone with lotsof harmonics and filtering them to get desired tone-with Additive synthesis the opposite-you put together a number of different wave components,either partials or harmoncs to get your desired tone. An example of this approach is Fourier synthesis which involves mixing together a large number of sine waves harmonics to achieve a specific sound eg KAWAI K5000.
Analogue synths use Voltage controlled oscillators where the pich of the output is controlled by a certain voltage.Its then passed to a Voltage Controlled Filter whose cutoff frequency can be controlled byvoltage.This means that attaching the voltage of an LFO,an oscillator that runs continuously at a very low speed, to it will produce wowing sweeps,envelope voltage will produce a different shape and so on.The signal is then passed to the Voltage controlled amplifier-here the voltage of an envelopewhich is the signal processing device that controls amplitude over time, will produce a patch whose volume corresponds to the envelopes shape .In addition a Ring modulator can be used which is a mixer that takes two signals and produces either the sum or the difference of the two signals.
Early analogs such as the Minimoog have what is called discrete circuitry such as transistors & resistors with later synths using more compact technologies such as op-amps and linear integrated circuits.However the analogue circuitry was never as stable as digital circuitry which arrived in 80s although its sometimes the out of tune or warm sound that enables analogue syths to still fetch high prices today.In the early 80s people began to experiment with analog circiutry and started using digital technology to control parts such as patch memory or the control of the oscillators.They also helped prove more reliable particularly in tuning area .
Its however a design classic thats never really gone out of fashion and athough digital synthesis has largely replaced it there are still a large number in use and often the basis of many modern samplers dance classics as the sound is raw and warm and able to cut through clearly.In recent times developments have meant the creation of DSP or digital signal processing chips which can emulate analogue filters eg Nord Lead and Access Virus. in addition to analogue based synths newly created such as Waldorf Pulse and Novation Super bassstations.
In addition there are currently a large number of synths available that use sample playback with hard coded samples stored in Rom and then processing these sounds eg Korg Triton and Yamaha E5.
Another variation of synthesis has arrived in 90s with the advent of software based sounds available on PCs which emulate a lot of analogue sounds and characteristics but often can be more reliable and adaptable.eg Native Instruments Reaktor,Sonic Foundrys Acid and Metasynth .
ADSR CHARACTERISTICS OF :PIANO
Attack would be fairly quick with delay short leading to a long sustain often controlled by a pedal and release slow or fast depending on use of this pedal. |
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Mon Apr 07, 2003 7:31 pm |
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