Doepfer A-127 Triple VC Resonance Filter - Manual (Page 8)

A-127 Triple VC Resonance Filter System A - 100 doepfer
8
• S&H filter effects with an A-148
the A-148 Sample&Hold samples signals from mo-
dulation sources (LFO, Noise, Random, VCO, etc.)
at regular clock intervals (see fig. 3)
fig. 3: S&H filter effects with an A-148
One of the A-127’s particular strengths is its ability to
bring out the formants that are crucial in re-creating
some sounds. It’s able to latch on to particular frequen-
cies or ranges of frequencies which are characteristic
of an instrument, a room, or an acoustic effect, and
emphasise them within the whole frequency spectrum.
Equalisation is often used to suppress these formants
when a room’s acoustics need to be neutralised; but
the A-127 can actually work the other way, to simulate
a real room’s formants, and bring a sound alive.
A special application of this ability to build up formants
can be to simulate human speech - or more exactly,
human vowel sounds.
What happens when a person pronounces a vowel is
that the overtone-rich vocal cord sound sets off all
sorts of resonances in the mouth, nose and throat,
whose frequency depends mostly on the shape of the
mouth and position of the tongue.
The characteristic sound of each vowel is created by
formants - ranges of frequencies emphasised by the
mouth and throat creating resonant cavities which pick
out harmonics from the basic sound of the vocal cords.
The most important frequencies for formants in Ger-
man vowel sounds is shown in fig. 4.
A-127
ext.
CV 1
2 3
Mix
Out
S&H
S&H
S&H
Mod.
Source
Clock
Clock
Clock
Mod.
Source
Mod.
Source
Clock Audio In