HARMonizers

[COBLEY A (on DUNDEE DEC-10) <A.Cobley%dundee.ac.uk@cs.ucl.ac.uk>]

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	somebody asked how a harmonizer works, well its something like this..

	first of all you need to know about delay lines
	two type analogue and digital
	
	bassicaly both take  a signal as a input and store the past n milli seconds.  now both types also do this by taking samples     at a certain clock rate, and this clock rate can be changed ( this is
	how to get vibrato change thew clock at a slow rate say 2-10 Hz )

	now if you take two delay lines that work like this and connect
	them in parrallel (sp?) you can make a harmonizer (or more 
	correctly a frequency shifter). ok so read a signal into one
	delay line at a rate of n Hz and when its full write it out at
	m Hz now you have a frequency shift.ok but while you are reading
	the signal out you miss some of the incoming signal so read that into
	another delay line  at n Hz, when its full start to write it out
	at m HZ and use the first delay line for the next store

	PROBLEM even doing this some signal is lost, and the greater the
	freqency difference the greater the loss hence only a shift of
	+ and - one octave.

	Harmonizers have in fact been around a long time at least 7 years
	if not longer and quite often come with a keyboard to play your
	voice.They can do lost of other tricks to like lock in to produce 
	a 3 rd , 5 th or what ever allowing you to harmonize with your self.

	since they use delay lines other things you can do include
	vibrato,flanging,reverb,echo, automatic double tracking, phase 
	shifting and no doubt other things not thought of yet

		your recident hippy
		love and peace
		andy cobley
cobley%dundee.micro%dundee@ucl-cs



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