Amplitude filtering? (and more)

[Kenneth]

Normally we do filtering on the frequencys, like lowpass, hipass and bandpass. But the amplitude, VCA? yes, but that works the same on all input. Compressing? Well, that's one thing you can do using this idea + a lowpass. But think of the ability to "bandpass" or "equalize" ceartain amplitudes, do this:

(input)--(FM modulator)--(Filter)- -(FM demodulator)--(output)

I'm sure this is not a new idéa as a technology, no Idéas are new anymore

But in music? Is it used before?

Waveshaping is one intresting usage, compression of course and maybe more. If someone got the equiment to test it? I would do it right away if I could


(pobably a lot of distortion that comes from the modulations)

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Well, got things to do anyway, just got my hands on a LM358 (from a telephone modem 75/1200 BAUD anno 1987) and a NE558 (286/386 ISA HD/RS232/Centronics controller card) I do not buy components so far, I'm in the learning so I use what I get =)

I'm thinking of a lowpassfilter box with a built in LFO to control sweeps that I can use together with my Yamaha Electone... Any suggestions of a simple contsruction?

I do not care about the best performances, I'm looking for simplicity, most important is that I understand how it works, a 2'nd order filter + triangle LFO for sweeps is good enough (I will work something out myself, I'm sure but suggestions is nice anyway)

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One thinking, the NE558, it can be used as four timers in a sequence, 4-step sequencer? (who can build the smallest analog sequencer? yeha, special desings on chip, but using "store stuff" =)

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Another Idéa, (this is as weird as the punch card sequencer). I found a "digital pot" (microwawe owen front panel). It works click click click... when you turn, it's digital. When it is in a fixed position it is no connection but when you are in the middle of two clicks it is leading, no resistance. So it gives pulses, one for each click and it is a 360 degree turner. Have a electric engine rotating the "pot" (it's not a pot, I know, it's a switch but it looks like a pot, have three connectors for no reason at all) input voltage is the amplitude of your choise for the pulse. Speed of engine is of course voltage controled... (this is not a project, just a weird idéa)

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(instead of several posts I been thinking of the latest days)

BTW: Blue Hell, if you connect the rubberband to a piezo and then play the rubberband and hit the piezo with the teaspoones, then you can use that for "VCO", the rest, standard modular synth stuff...

[Kenneth]

[DrJustice]

[Kenneth]

Ah, nice (all parts), thank's for replying

I used an analog Ohm metre to test the encoder, that's why I thought it was only one and the same output on both terminals.

Yeha, I later realised it was the thing used in "alpha wheels" ever since the first digital syntesizers in the 80's.