Some thoughts of my own on exp vs. lin...
I used to use an Emu mono series keyboard (4000) before I used their 4060
poly kbd. It had a pot to sweep between linear and exp. glide shape. I think
JH has documented just the glide portion of this circuit and it's floating
around somewhere on Synthfool DIY.
It is a very musical and versatile setup. Exp provides equal glide time no
matter what interval you play. It also sounds more natural to your ear, with
that rate slowdown as you approach the final voltage. Lin is also good for
certain playing effects.
The Encore Expressionist does not have exponential glide as noted below, but
just glides linearly at different rate for different intervals to make the
total time come out the same. This does not sound nearly as good as gliding
along an exponential curve. I've asked Tony to consider adding interpolation
tables to allow true exponential glide, and he's considering it for his next
software update. Of course, I've also bombarded him with about 10 other
requests, so I don't know what he'll manage to get in. For us modular users,
it is maybe easier to just use a true analog lag circuit to get what we
want.
Another good use for exponential lag: input a gate signal, get an AR
envelope signal out.
Dave
>
> From: "Eric S. Crawley" <esc@...>
>
> So, I tried some experiments to understand linear vs. exponential
> lag/portamento/slew limiting and found some very wide ranging results.
> This wasn't very scientific (YMMV) and I'm still not sure I understand all
> the ins and outs and terminology but here's what I found:
>
> Encore Expressionist:
> This MIDI/CV converter has "fixed" and "variable" portamento. "Fixed" is
> an extremely linear rate of glide. "Variable" changes the rate
> to make all
> the slides the same amount of time, regardless of the key distance. [In
> some sense, these terms are backwards in terms of glide time, IMHO.]
>
<snip other good stuff>