Doepfer A-129-1/2 Vocoder Basic Modules - Manual (Page 7)

doepfer System A - 100 Modular Vocoder A-129 /1/2
7
5. User examples
Basic principles
To get the best results from the vocoder, it’s essential
to take note of the following important points:
• For professional results, the quality of the speech
signal is crucial.
If you use a cheap and cheerful microphone,
connecting it up to the vocoder via the A-119 won’t
guarantee good results.
Any unwanted noise (rumble, airborne background
sounds, etc.) will greatly reduce the effectiveness
of the vocoding.
According to various musicians including Kraftwerk,
the speech signal is easier to use if it isn’t live, but
has been taped or sampled, and thus has reliable
levels and signal-to-noise - and is repeatable.
• For early experiments, radio news stations provide
good raw material, because they are nearly always
putting out a steady stream of human speech.
• In addition, we plan to bundle an audio cassette of
speech with each vocoder.
• For the best results, speech and carrier signals
need to have similar frequency spectra. A quiet
female voice, or a child’s, needs a different carrier
signal compared with a low-register male voice. If
you use a VCO as the carrier signal, you can tune
it to find the ideal frequency.
• Basically, the instrument’s carrier signal needs to
be as overtone-rich as possible, with a dense audio
spectrum. With a VCO the sawtooth output is best
suited to the task. An exact square wave has only
half as many harmonics, and triangle and sine
waves are completely unsuitable (see the notes to
the A-110 and/or A-111).
• For professional results, it’s recommended to use a
graphic or parametric EQ to equalize the speech
signal to produce the most speech-like results at
the vocoder’s output. Good results can also be
obtained using computer-generated speech (as on
the A-100 demo CD).