2019-07-01_Computer_Music

Let’slookatFathomCM’swavetable

creationfunction.Fireit upinyour

host,gotoAudioComponents, thenthe

Oscillatormenu,andfindaWaveTable

componentintheWavesub-category.

Dragthattoa newpatch.Thedisplayisa

bitdifferenttotheoneswe’veseenbefore.

1

Bydefault,we’vegotthesamesortof

sawtoothwavewehadinourlast

tutorial.However,althoughwecouldenter

a WaveDrawmode,wewon’t– instead,we

clicktheParametersbuttoninthelower

left.Therearethreewaveformdisplays,

andtwoidenticalsetsofparameters.

2

There’sa pairofWaveIndex

parameters,usedtoselectwhich

waveisplayedfroma tableof 16 single-

cyclewaveforms.Weneedn’tberestricted

tothedefaulttable.Opena browserand

draga single-cyclewaveofourowninto

theleft-mostdisplay.We’veputa fewin

TutorialFiles– useCMWT1.wav.

3

WeturntheleftWaveIndexupto 16

andimportanother:CMWT2.wav.

Thisputsourownwavesatthestartand

endofthetable.If weclicktheleftFill

button,Fathomfillsthespotsinbetween

withwaves.Let’sdothesameusingthe

right-mostwavetableslotandCMWT3.

wavandCMWT4.wav.

4

Whatisa wavetable?

Initspurestform,wavetable
synthesisisa typeofdigital
synthesis based on sampling.
Introduced by WolfgangPalmon
his PPG Wave synthesisers,
wavetable synthesis brieflyruled
the airwaves in the early80s.
Often (and unfortunately)
confused with ROMpler-style
sample playback, wavetable
synthesis does indeed relyon
digitally stored samples,butsuch
samples consist only ofa single
cycle (or even one half ofa cycle)
rather than an entire noteorhit.
When looped and playedback,
these wave cycles are static,
with no dynamic motion.They
are just pure, raw – and often
very digital – tones.
However, the single cycle
wave is only the start. Inclassic
wavetable synthesis, manysuch
waves are strung togetherend-
to-end to form the so-called
‘wavetable’. The wavetable
oscillator can then be madeto
play back any includedwave
cycle in a continuous loop.Such
an oscillator offers far more
timbral variety than analogue
oscillators do.
The real magic, however,
happens when the wavetable
playback position is modulated
by an LFO, envelope generator,or
some other mod source.This
allows for some interesting,
evolving sounds when different
scanning speeds, shapesand
directions are set up.

> Stepbystep

4.WavetablecreationinFathomCM

Fathom CM offersnumerousmeansto

create originalwaveforms.We’ve

already used FMsynthesistocreatea

complex waveformusinga pairofsimple

sine waves, but anothermethodcomesin

the form of the WaveDrawoscillator.It

can be found bygoingtoAudio

Components, openingtheOscillator

category, then theWavesubmenu.

1

Bydefault,thisoscillatormakesa

soundnotunlikea plainol’sawtooth

waveform.However,wecantakecontrol

ofthatwaveformbyclickingthe

waveformdisplayonthelower-right,

whereuponwe’llbetakentoa new

windowwithourwavedisplayedfrontand

centre.Wecanreshapetheexistingwave

byclickinganddragginginthedisplay.

2

If youprefertostartfromscratch,you

canusetheInitializeWaveform

buttontozerooutallofthepartials.If you

needfinercontroloveryourmasterpiece,

youcandialdownEdgeSelect, and

increasethevalueoftheSharpness

parameter.YoucantogglethePlay

WaveformswitchtoRawSamplesforan

old-schoolaliasedsound.

3

Step by step 3.FathomCM’sWaveDrawoscillator

July 2019 / COMPUTER MUSIC / 65

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