Rhodes Chroma Polaris

I am wondering about what the mod lever on the polaris actually does. it seems to engage the sweep (lfo) at the rate that the sweep lever is set. but is its 'detination' [to use a modern term] the filter cutoff---or filter envelope? or what?? so then, it adds the sweep rate to the filter--- at the 'level' set by the assignable control--- and how does this differ from the 'vibrato' that also seems to be adding this LFO at this single set rate? I have other more modern synths that allow you to assign the mod wheel to many parameters--so im wondering what does this control do on the polaris in 'modern' terms . I kinda wish it did more--or could be modded to have more or more intense actions. it seems to have a fairly limited scope compared to my other synths. any comments/ explainations?

> From: steven
>
> I am wondering about what the mod lever on the polaris
> actually does. it seems to engage the sweep (lfo) at the
> rate that the sweep lever is set. but is its 'detination'
> [to use a modern term] the filter cutoff---or filter
> envelope? or what?? so then, it adds the sweep rate to the
> filter--- at the 'level' set by the assignable control--- and
> how does this differ from the 'vibrato' that also seems to be
> adding this LFO at this single set rate?

In arithmetic terms:

pitch1 = key + transpose + lever2 * bend_lever_range
+ sweep * (osc1_vibrato * delay_envelope + lever1 * mod_lever_range)

pitch2 = key + transpose + lever2 * bend_lever_range
+ sweep * (osc2_vibrato * delay_envelope + lever1 * mod_lever_range)

So you can see that it applies vibrato to both oscillators equally, and has
nothing to do with the filter.

> I have other more
> modern synths that allow you to assign the mod wheel to many
> parameters--so im wondering what does this control do on the
> polaris in 'modern' terms . I kinda wish it did more--or
> could be modded to have more or more intense actions. it
> seems to have a fairly limited scope compared to my other
> synths. any comments/ explainations?

There's also a less modern synth that lets you do this: the Chroma.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

> From: Paul D. DeRocco
>
> In arithmetic terms:
>
> pitch1 = key + transpose + lever2 * bend_lever_range
> + sweep * (osc1_vibrato * delay_envelope + lever1 * mod_lever_range)
>
> pitch2 = key + transpose + lever2 * bend_lever_range
> + sweep * (osc2_vibrato * delay_envelope + lever1 * mod_lever_range)

Oops, I left out some stuff:

pitch1 = glide_value + transpose + lever2 * bend_lever_range
+ sweep * (osc1_vibrato * delay_envelope + lever1 * mod_lever_range
+ pedal * vibrato_pedal)

pitch2 = glide_value + transpose + lever2 * bend_lever_range
+ sweep * (osc2_vibrato * delay_envelope + lever1 * mod_lever_range
+ pedal * vibrato_pedal) + envelope * osc2_env

But the result is the same for the mod lever (lever1).

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

> From: steven pistrich
>
> at the moment im sure i sound like an idiot, but i guess im
> not sure what the pitch 1 and 2 are that you describe---
> and their relation to the 'mod lever' effect. so the
> modlever affects the vco (oscillators) , not the filter? Im
> used to understanding ,lets say, how the mod lever on my Juno
> can affect 3 things , pitch, filter or LFO-- or on a DSI
> you select a 'destination' for the mod wheel that can be
> selected from an assortment of parameters. Could you
> describe the Polaris mod lever and its range in those
> terms? what parameter am i controlling with it? your answer
> was a bit more complex than i expected and now im more confused

Pitch1 and pitch2 are the numeric values that control the pitch of the two
oscillators. Ignoring the rest of the formulae, the mod lever position,
which ranges from -1 to +1, is multiplied by the (undelayed) sweep signal,
which can be a sine wave or a square wave, and modulates the pitch of both
oscillators equally. It doesn't modulate the filter or anything else. The
sweep can modulate filter tuning or oscillator pulse width, but not through
the mod lever.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...

> From: steven pistrich
>
> ok --so im thinking that you are saying the mod lever applies
> the same vibrato effect LFO on the oscillators as the
> seperate 'vibrato osc 1 and 2 assignable parameters ' but to
> both oscillators together ?
> is this the same then as the 'vibrato pedal'? which also
> affects both oscillators

Yes, except that the pedal goes from 0 to 1, not -1 to 1.

The primary reason there are separate fixed vibrato levels for each
oscillator is so that you can turn on sync and apply heavy sweep mod to
oscillator 2.

If you combine fixed vibrato with mod lever or pedal vibrato, they add
together. Since the mod lever goes negative when you pull it, it can
subtract from the fixed vibrato.

Also be aware that the fixed vibrato isn't entirely fixed, because it has a
delay envelope applied to it, while the vibrato that is injected via the mod
lever or pedal has no delay.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...