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Subject: Re: [motm] Stupid V/Hz and V/Oct question

From: "Paul Schreiber" <synth1@...>
Date: 2002-02-08

> Alright, just checking on something here. A "Volt/Octave" VCO is
> actually an expoential VCO, since it converts a linear voltage into
> an expoential response... so a MIDI-CV converter, or CV Keyboard
> would actually be putting out a liner change as you go up the
> keyboard.

Correct.

>
> So, an LFO patched straight into the Volt/Octave input of a VCO, say
> a uVCO, would be able to make the osc. shift up and down an octave
> each way, right?

Right.

> But the 800s are exponential, so plugging them
> straight into a Volt/Octage input on a VCO would make an apparent
> expoential change in audio, even thogh it was already expoential, it
> would ∗sound∗ exponential, because it would actually be doubly
> exponential?

It is "doubly exponential".


> I assume, in that case, you'd use the "Exp" setting on
> a MOTM-300's FM jack to get an apparent linear response, right?

Well, there is a difference. The LINear position has a MUCH smaller overall range (maybe 2:1 for
5 V) versus the EXPonential range of 5 octaves!

Lest's look at a "musical" approach: if you want FM bells and drums, use LIN setting.


>
> Another question is the FM on the various filters, (420 and 440
> really). Does that FM expect a linear or exponential curve? Or, is
> Volt/Octave expecting a linear signal, and FM expecting an
> exponential one?

They are all exponential. The FM inputs can vary up to about 0.5V/Octave (twice the spead).

Paul S.


>