More blathering about octave dividers and the Blue Box

[R.G.]

to emphasize the fundamental, rather than the 2nd harmonic...

That's not quite what I meant. If you filter first, then rectify, you get a better return on effort in filtering. Rectification introduces a blather of harmonics as well as giving you a peak every once in a while.

The way patents work, I suspect I could apply with filter first and then rectify, and get patent protection on that.

[puretube]

ahh - when the emphasis was on: "in front",
that`s probably to save n opamp buffers in front of the filters, which want to be driven non-interactive from a low impedance;
where n is the number of filterbands...
(the active rectifiers take care of that).

[GFR]

to emphasize the fundamental, rather than the 2nd harmonic...

That's not quite what I meant. If you filter first, then rectify, you get a better return on effort in filtering. Rectification introduces a blather of harmonics as well as giving you a peak every once in a while.

The way patents work, I suspect I could apply with filter first and then rectify, and get patent protection on that.

In some situations, 1/2 wave rectifying followed by AC coupling can help eliminate "spurious" zero crossings - look at the graph below.

While it's true that rectification is introducing lots of new harmonics, it can at the same time improve the fundamental to 2nd harmonic ratio (the higher order harmonics are spread out). If you want to get a pure sine wave then rectifying before filtering is no good cause then you'll have more harmonics to filter out. If on the other hand the intention is not to get a pure sine but only get rid of the unwanted zero crossings it can help.





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[markusw]

Hi all,

was the filter bank in that Bode patent ever used in a commercially available fx or synth?

I know the reply is a bit late but since I intend to breadboard such a circuit I'm really curious 

At the moment I do not get what the rectifier stage at the inputs are supposed to do, even more because there is a second one after the filter. I still have to read the patent more thoroughly .....

Markus

[A.S.P.]

yes

[markusw]

yes

Would you mind sharing some more details ? 

Markus

[A.S.P.]

yes

Would you mind sharing some more details ? 

Markus

"yes" approved the following (last) sentence... 

I still have to read the patent more thoroughly .....

[markusw]

yes

Would you mind sharing some more details ?

Markus

"yes" approved the following (last) sentence...

I still have to read the patent more thoroughly .....

And it still is valid....


...also I still don't know whether it was ever used in an fx or maybe synth module??

Markus

[A.S.P.]

this doesn`t finally answer your question,
but oughtta be read by aspiring time & frequency manglers:
http://www.experimentaltvcenter.org/history/tools/ttext.php3?id=1

[markusw]

this doesn`t finally answer your question,
but oughtta be read by aspiring time & frequency manglers:
http://www.experimentaltvcenter.org/history/tools/ttext.php3?id=1

Thanks for the link! Interesting read.

Markus