Theory - Access VIRUS CLASSIC User Manual

Even if you only play octaves, the "Natural" setting often causes beating between the notes! This
effect is therefore independant of the chord structure, and can/should be accentuated via oscillator
Detune (or even Unison mode) to beef up the sound. That's how the monumental sound of a sym-
phony orchestra arises: the richness of the sound is solely dependant upon the number of musi-
cians (oscillators), not upon harmonic complexity.
PureTuning works perfectly for major triads and dominant seventh chords. Due to the physics
involved (see below), minor chords are more of a problem – they don't sound quite as pure. How-
ever, PureTuning is also very effective here because the subharmonics are managed well.
Equal-temperament was a radical break from all the other "tempered" methods, where polyphonic
instruments could only be played in a few diatonic modes. Note that Johann Sebastian Bach's "The
Well-Tempered Clavier" is thought to have been based on a variation of "Werckmeister 3" tuning.
Much more suitable for playing in any key, but not quite the same as Equal Temperament!
PureTuning combines classical intonation with the universality of Equal Temperament.
Let Pure Tuning inspire you!

Theory

Interestingly, the feeling of harmony in a major chord is a phenomenon based upon physics, not on
psycho-acoustics alone. The notes in a perfectly tuned C-major triad (C, E, G) have exact integer
frequency ratios: From E to C is 5:4 (or 1:1.25) and from G to C is 3:2 (1: 1.5). The same applies to
any major chord. It is fairly common knowledge that the frequency ratio of an octave is 2:1 – the
upper note is exactly double the frequency of the lower one. Assuming a C is exactly 1000 Hz, the E
would be 1250 Hz and the G would be 1500 Hz. The next C would be 2000 Hz. Very simple, very
nice...
Reality isn't quite that simple. We expect more from our (chromatic) keyboard instruments. We
demand that the frequency ratio of all semitone steps should be the same, that no particular key
has "priority" over any other. Chords in the key of B or C# should sound just as good as they do in
C. The truth is that they actually sound just as bad!
Rule Number One: An octave interval should be an octave, it should be exactly double/half the fre-
quency of the reference note. If you take this rule as the basis and work out a constant ratio you can
th
apply to all 12 semitones, you arrive at the 12 root of 2, i.e. 1.059463. Test this by multiplying this
VIRUS CLASSIC MANUAL 139
Pure Tuning