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If there's one thing I love, it's writing the same article again
for commusic after writing it for usenet newsletters, without a
copy.
I have a
PAiA 6710(?) vocoder with my own style power supply. The Vocoder
9 was $100, supply parts were probably $25, and then I built it.
This vocoder vocoded a pulse tone with a
professional FM announcer (off the radio) so that 9 out of ten words
were understandable. However, it is sensitive, and external
limiters on the instrument and voice inputs should be used
(I never did this). It also has a
fuzz switch and various adjustments (instrument input level, voice
input level, output level, sensitivity, through level etc.) The mic
input doesn't amplify enough, so use the line input level,
or a powerful mic. There is no cabinet or chassis, it just screws
into a 19" rack with the front panel supporting the PC board, so I
put cardboard on the bottom to keep it from shorting out. As Is.
With manual. I was one of the first owners, and sent corrections
of the manual back to PAiA. I think they tried to give a reverb
in return, but since there was no cover letter, I just sent it back.
I didn't use it very often, just on one TV show and one live
performance. It was good for covering Laurie Anderson's O, Superman
at home, but in live performance on my own pieces it wasn't as useful.
It can be used as a sort of gate, so that the sound signal of drum
hits can allow sound from a chord on a synth to pass through.
You can vocode anything you want, such white noise, chords
(stick to open octaves and fifths, like laurie anderson, or it
peaks out) or even pulse tones. The vocoder impresses the color
of a sound, such as your vowels, and its envelope, onto another sound,
if the other sound has enough harmonics in it to be impressed. It
handles sibilants well enough, I guess.
The vocoder has a bank of filters with voltage-controlled amplifiers
on them. the control inputs to the amplifiers are the voltages
representing the amount of energy in the corresponding frequency
bands of the "voice" input.
The original vocoder was built in the late 1930's as part of Bell
Labs research into efficient ways of encoding voice for long telephone
lines.
Tom
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